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EXHIBIT 10.4

GUARANTY

        THIS GUARANTY, dated as of December 31, 2002 (as amended, modified or
supplemented from time to time in accordance with its terms, this "Guaranty"),
is issued by UNIVERSAL COMPRESSION HOLDINGS, INC., a Delaware corporation
(together with its successors and permitted assigns, the "Guarantor"), for the
benefit of UCO COMPRESSION 2002 LLC, a Delaware limited liability company
(together with its successors and permitted assigns, the "Head Lessee"), BRL
UNIVERSAL COMPRESSION FUNDING I 2002, L.P., a Delaware limited partnership
(together with its successors and permitted assigns, the "Issuer" or the "Head
Lessor"), and WELLS FARGO BANK MINNESOTA, NATIONAL ASSOCIATION, a national
banking association, as indenture trustee on behalf of the parties set forth in
the hereinafter defined Indenture (together with its successors and permitted
assigns, the "Indenture Trustee"; each of the Head Lessee, the Head Lessor and
the Indenture Trustee (for the benefit of the Noteholders, any Series Enhancer
and any Interest Rate Hedge Provider), a "Beneficiary" and collectively, the
"Beneficiaries").

        PRELIMINARY STATEMENTS:

        (1)  The Head Lessee and the Head Lessor have entered into that certain
Master Equipment Lease Agreement, dated as of December 31, 2002 (as amended,
modified or supplemented from time to time in accordance with its terms, the
"Head Lease") pursuant to which the Head Lessor has and will lease certain
Compressors to the Head Lessee;

        (2)  The Head Lessee, the Head Lessor and Universal Compression, Inc.
("UCI") have entered into that certain Management Agreement, dated as of
December 31, 2002 (as amended, modified or supplemented from time to time in
accordance with its terms, the "Management Agreement") pursuant to which UCI has
and will manage certain Compressors on behalf of the Head Lessor or the Head
Lessee, as the case may be;

        (3)  The Issuer is issuing one or more classes of notes (collectively,
the "Notes") pursuant to that certain Indenture (as amended, modified or
supplemented from time to time in accordance with its terms, the "Indenture"),
dated as of December 31, 2002, between the Issuer and the Indenture Trustee,
which Notes will be collateralized by, inter alia, all of the Issuer's right,
title and interest in and to the Head Lease, the Owner Compressors, the User
Leases and the Management Agreement;

        (4)  UCI is a wholly-owned subsidiary of the Guarantor;

        (5)  Issuer requires that the Guarantor guarantee the payment and
performance by UCI under the Management Agreement as a condition to leasing
Compressors to Head Lessee under the Head Lease;

        (6)  Guarantor will obtain substantial direct and indirect benefit from
the lease of the Compressors to the Head Lessee and the management thereof by
UCI, and is willing to provide this guaranty on the terms and conditions set
forth herein; and

        (7)  Beneficiaries have entered into the Indenture in reliance upon the
benefits of this Guaranty;

        NOW, THEREFORE, in consideration of the premises and other
consideration, the receipt and sufficiency of which is hereby acknowledged by
the Guarantor, the Guarantor hereby agrees as follows:

        SECTION 1.    Definitions.    Capitalized terms used in this Guaranty,
unless otherwise defined herein, shall have the meaning set forth in Appendix A
to the Indenture.

        SECTION 2.    Guaranty.    Guarantor hereby irrevocably, absolutely and
unconditionally guarantees, as primary obligor and as a guarantor of payment and
not merely as surety or guarantor of collection to the Beneficiaries: (i) the
full and prompt payment when due, whether by stated maturity, acceleration or
otherwise, and at all times thereafter, of the payment and deposit obligations
of UCI as the initial Manager under the Management Agreement (UCI in this
capacity, the "Guaranteed Party") and all other amounts from time to time owing
by UCI under the Management Agreement, and

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(ii) the full and timely performance of, and compliance with each and every
duty, agreement, covenant, undertaking, indemnity, and obligation of the
Guaranteed Party under the Management Agreement, in each case, howsoever
created, arising or evidenced, whether direct or indirect, primary or secondary,
absolute or contingent, joint or several, now or hereafter existing or due or to
become due, which arises out of or in connection with the Management Agreement
(all of such obligations described in clauses (i) and (ii) being hereinafter
collectively called the "Liabilities"); provided that nothing contained herein
shall be deemed to constitute credit recourse to the Guarantor for payment of:
(A) losses arising solely from the financial inability of a User to make rental
or other payments under a User Lease, (B) losses arising solely from the failure
of the remarketing proceeds of a Compressor to equal or exceed the Appraised
Value thereof for reasons other than the Manager's failure to comply with the
Services Standard, or (C) the Notes or the Certificates. Guarantor further
agrees to pay all costs and expenses (including reasonable attorneys' fees and
legal expenses) paid or incurred by any Beneficiary in endeavoring to collect
the Liabilities, or any part thereof, and in enforcing this Guaranty.

        SECTION 3.    Continuing Guaranty.    This Guaranty shall in all
respects be a continuing, absolute and unconditional guaranty, and shall remain
in full force and effect (notwithstanding, without limitation, that at any time
or from time to time all Liabilities may have been paid in full), subject to
discontinuance only upon payment and performance in full of: (i) all Liabilities
and (ii) any and all expenses paid or incurred by a Beneficiary in endeavoring
to collect the Liabilities and in enforcing this Guaranty; and all of the
agreements and obligations under this Guaranty shall remain fully in effect
until all such obligations and expenses finally shall have been paid in full.

        SECTION 4.    Rescission.    Guarantor further agrees that, if at any
time all or any part of any payment theretofore applied by Beneficiary to any of
the Liabilities is or must be rescinded or returned by Beneficiary for any
reason whatsoever, such Liabilities shall, for the purposes of this Guaranty, to
the extent that such payment is or must be rescinded or returned, be deemed to
have continued in existence, notwithstanding such application by Beneficiary,
and this Guaranty shall continue to be effective or be reinstated, as the case
may be, as to such Liabilities, all as though such application by Beneficiary
had not been made.

        SECTION 5.    Certain Actions.    Each Beneficiary may, from time to
time at its sole discretion and without notice to Guarantor, take any or all of
the following actions without affecting the obligations of Guarantor hereunder:
(a) retain or obtain a Lien upon or a security interest in any property to
secure any of the Liabilities or any obligation hereunder; (b) retain or obtain
the primary or secondary obligation of any obligor or obligors, in addition to
Guarantor, with respect to any of the Liabilities or any obligation hereunder;
(c) extend or renew for one or more periods (regardless of whether longer than
the original period), alter or exchange any of the Liabilities, or release or
compromise any obligation of Guarantor hereunder or any obligation of any nature
of any other obligor including UCI with respect to any of the Liabilities; (d)
release or fail to perfect its Lien upon or security interest in, or impair,
surrender, release or permit any substitution or exchange for, all or any part
of any property securing any of the Liabilities or any obligation hereunder, or
extend or renew for one or more periods (regardless of whether longer than the
original period) or release, compromise, alter or exchange any obligations of
any nature of any obligor with respect to any such property; and (e) resort to
Guarantor for payment of any of the Liabilities, regardless of whether
Beneficiary shall have resorted to any property securing any of the Liabilities
or any obligation hereunder or shall have proceeded against any other obligor
primarily or secondarily obligated with respect to any of the Liabilities.

        SECTION 6.    Subrogation.    Any amounts received by a Beneficiary from
whatsoever source on account of the Liabilities may be applied by it toward the
payment of such of the Liabilities, and in such order of application, as
Beneficiary may from time to time elect. Until one year and one day after
payment of the full amount of all Liabilities, the performance of all of
Guarantor's obligations hereunder and the termination of this Guaranty, no
payment made by or for the account of Guarantor pursuant to this Guaranty shall
entitle Guarantor by subrogation, indemnity or otherwise to any

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payment by UCI or from or out of any property of UCI, and Guarantor shall not
exercise any right or remedy against UCI or any property of UCI by reason of any
performance by Guarantor of this Guaranty. If any amount shall be paid to the
Guarantor on account of such subrogation rights at any time when all of the
Liabilities shall not have been paid in full, such amount shall be held in trust
for the benefit of the Beneficiaries and shall forthwith be paid to the
Indenture Trustee to be credited and applied upon the Liabilities, whether
matured or unmatured, in accordance with the terms of this Guaranty.

        SECTION 7.    Waiver; Waiver of Defenses.    Guarantor hereby expressly
waives: (a) notice of any Beneficiary's acceptance of this Guaranty; (b) notice
of the existence or creation or non-payment of all or any of the Liabilities;
(c) presentment, demand, notice of dishonor, protest, and all other notices
whatsoever (provided that nothing contained in this clause (c) shall affect any
obligations to give notice or make demand as set forth in the Management
Agreement); and (d) all diligence in collection or protection of or realization
upon the Liabilities or any thereof, any obligation hereunder, or any security
for or guaranty of any of the foregoing. To the fullest extent permitted by
applicable law, Guarantor agrees not to assert, and hereby waives for the
benefit of each Beneficiary, all rights (whether by counterclaim, setoff or
otherwise) and defenses (including, without limitation, the defense of fraud or
fraud in the inducement), whether acquired by subrogation, assignment or
otherwise, to the extent that such rights and defenses may be available to
Guarantor to avoid payment of its obligations under this Guaranty in accordance
with the express provisions of this Guaranty.

        SECTION 8.    Unconditional Nature of Guaranty.    This Guaranty shall
constitute a guaranty of payment or of performance and not of collection, and
the Guarantor specifically agrees that it shall not be necessary, and that the
Guarantor shall not be entitled to require, before or as a condition of
enforcing the liability of the Guarantor under this Guaranty or requiring
payment or performance of the Liabilities by the Guarantor hereunder, or at any
time thereafter, that any Person: (a) file suit or proceed to obtain or assert a
claim for personal judgment against UCI or any other Person that may be liable
for any Liabilities; (b) make any other effort to obtain payment or performance
of any Liabilities from UCI or any other Person that may be liable for such
Liabilities; (c) foreclose against or seek to realize upon any security now or
hereafter existing for such Liabilities; (d) exercise or assert any other right
or remedy to which such Person is or may be entitled in connection with any
Liabilities or any security or other guaranty therefor; or (e) assert or file
any claim against the assets of UCI or any other Person liable for any
Liabilities. Notwithstanding anything herein to the contrary, no provision of
this Guaranty shall require the Guarantor to pay, perform or discharge any
Liabilities prior to the time such Liabilities are due and payable. No delay on
any Beneficiary's part in the exercise of any right or remedy shall operate as a
waiver thereof, and no single or partial exercise by any Beneficiary of any
right or remedy shall preclude other or further exercise thereof or the exercise
of any other right or remedy; nor shall any modification or waiver of any of the
provisions of this Guaranty be binding upon Beneficiary except as expressly set
forth in a writing duly signed by each Beneficiary. The Beneficiaries may in all
events pursue their rights under this Guaranty prior to or simultaneously with
pursuing their various rights referred to in the Management Agreement, as the
Beneficiaries may determine. No action of any Beneficiary permitted hereunder
shall in any way affect or impair any Beneficiary's rights or Guarantor's
obligations under this Guaranty. For the purposes of this Guaranty, Liabilities
shall include all of UCI's obligations under the Management Agreement,
notwithstanding any right or power of UCI or anyone else to assert any claim or
defense as to the invalidity or unenforceability of any such obligation, and no
such claim or defense shall affect or impair the obligations of Guarantor
hereunder. The obligations of the Guarantor are unlimited in amount (but not
greater than the Liabilities plus costs and expenses payable hereunder) and
shall be continuing and irrevocable, absolute and unconditional, primary,
original and immediate and not contingent and shall remain in full force and
effect without regard to and not be released, discharged or in any way affected
by any circumstance or

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condition (other than by payment in full of Liabilities) including, without
limitation, the occurrence of any one or more of the following:

          (i)  any lack of validity or enforceability of any of the Liabilities
under the Management Agreement or any document entered into in connection with
the transactions contemplated by the Management Agreement, any provision
thereof, or any other agreement or instrument relating thereto or the absence of
any action to enforce the same;

        (ii)  any failure, omission, delay or lack on the part of the
Beneficiaries to enforce, assert or exercise any right, power, privilege or
remedy conferred on the Beneficiaries in the Management Agreement or this
Guaranty, or the inability of the Beneficiaries to enforce any provision of the
Management Agreement for any reason, or any other act or omission on the part of
the Beneficiaries; provided that the foregoing shall not apply to applicable
statutes of limitation;

        (iii)  any change in the time, manner or place of performance or of
payment, or in any other term of, all or any of the Liabilities, or any other
modification, supplement, amendment or waiver of or any consent to departure
from the terms and conditions of any of the Management Agreement, the
Intercreditor Agreement or any document entered into in connection with the
transactions contemplated by the Management Agreement or the Related Documents;

        (iv)  any taking, exchange, release or non-perfection of any collateral
or security, or any taking, release or amendment or waiver of or consent to
departure from any other guaranty, for all or any of the Liabilities or the
acceptance of any security therefor;

        (v)  the waiver by the Beneficiaries of the performance or observance by
the Guaranteed Party of any Liabilities, the waiver of any default in the
performance or observance thereof, any extension by the Beneficiaries of the
time for payment or performance and discharge by the Guaranteed Party of any
Liabilities or any extension, indulgence or renewal of any Liabilities; provided
that the foregoing shall not apply to applicable statutes of limitation;

        (vi)  any bankruptcy, suspension of payments, insolvency, sale of
assets, winding-up, dissolution, liquidation, receivership or reorganization of,
or similar proceedings involving, the Guaranteed Party or its assets or any
resulting release or discharge of any of the Liabilities;

      (vii)  the recovery of any judgment against any Person or any action to
enforce the same;

      (viii)  any failure or delay in the enforcement of the Liabilities of any
Person under the Management Agreement or any document entered into in connection
with the transactions contemplated by the Management Agreement or any provision
thereof; provided that the foregoing shall not apply to applicable statutes of
limitation;

        (ix)  any set-off, counterclaim, deduction, defense, abatement,
suspension, deferment, diminution, recoupment, limitation or termination
available with respect to any Liabilities and, to the extent permitted by
Applicable Law, irrespective of any other circumstances that might otherwise
limit recourse by or against the Guarantor or any other Person;

        (x)  the obtaining, the amendment or the release of or consent to any
departure from the primary or secondary obligation of any other Person, in
addition to the Guarantor, with respect to any Liabilities;

        (xi)  any compromise, alteration, amendment, modification, extension,
renewal, release or other change, or waiver, consent or other action, or delay
or omission or failure to act, in respect of any of the terms, covenants or
conditions of the Management Agreement or any document entered into in
connection with the transactions contemplated by the Management Agreement or any
Liabilities, or any other agreement or any related document referred to therein,
or any assignment or transfer of any thereof;

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      (xii)  any manner of application of collateral, or proceeds thereof, to
all or any of the Liabilities, or any manner of sale or other disposition of any
collateral for all or any of the Liabilities or any other assets of the
Guaranteed Party or any of its subsidiaries, or any furnishing or acceptance of
additional collateral or any release of any existing securities;

      (xiii)  any change in control or the ownership of the Guaranteed Party,
any change, merger, demerger, consolidation, restructuring or termination of the
corporate structure or existence of the Guaranteed Party or its subsidiaries;

      (xiv)  to the fullest extent permitted by Applicable Law, any other
circumstance which might otherwise constitute a defense available to, or a
discharge of, a guarantor or surety with respect to any Liabilities;

      (xv)  any default, failure or delay, whether as a result of actual or
alleged force majeure, commercial impracticability or otherwise, in the
performance of the Liabilities, or by any other act or circumstances which may
or might in any manner or to any extent vary the risk of the Guarantor, or which
would otherwise operate as a discharge of the Guarantor;

      (xvi)  the existence of any other obligation of the Guarantor, or any
limitation thereof, in the Management Agreement;

    (xvii)  any regulatory change or other governmental action (whether or not
adverse or other change in applicable law); or

    (xviii)  the partial payment or performance of the Liabilities (whether as a
result of the exercise of any right, remedy, power or privilege or otherwise) or
the invalidity of any payment for any reason whatsoever.

Should any money due or owing under this Guaranty not be recoverable from the
Guarantor due to any of the matters specified in clauses (i) through (xviii)
above or for any other reason, then, in any such case, such money shall
nevertheless be recoverable from the Guarantor as though the Guarantor were
principal debtor or obligor in respect thereof and not merely a guarantor and
shall be paid by the Guarantor forthwith.

        This Guaranty shall continue to be effective or be automatically
reinstated, as the case may be, if at any time any payment, or any part thereof,
of any of the Liabilities is rescinded or must otherwise be restored or returned
by the Beneficiaries for any reason whatsoever, whether upon the insolvency,
bankruptcy, dissolution, liquidation or reorganization of the Guaranteed Party
or otherwise, all as though such payment had not been made, and the Guarantor
agrees that it will indemnify the Beneficiaries on demand for all reasonable
costs and expenses (including, without limitation, fees and disbursements of
counsel) incurred by the Beneficiaries in connection with such rescission or
restoration. If an event permitting the exercise of remedies under the
Management Agreement shall at any time have occurred and be continuing and such
exercise, or any consequences thereof provided in the Management Agreement,
shall at such time be prevented by reason of the pendency against the Guaranteed
Party of a case or proceeding under a bankruptcy or insolvency law, the
Guarantor agrees that, for purposes of this Guaranty and its obligations
hereunder, amounts payable under the Management Agreement shall be deemed to
have been declared in default, with all attendant consequences as provided in
the Management Agreement as if such declaration of default and the consequences
thereof had been accomplished in accordance with the terms of the Management
Agreement, and the Guarantor shall forthwith pay any amounts guaranteed
hereunder, without further notice or demand.

        SECTION 9.    Information.    Guarantor has and will continue to have
independent means of obtaining information concerning UCI's affairs, financial
condition and business. Beneficiary shall not

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have any duty or responsibility to provide Guarantor with any credit or other
information concerning UCI's affairs, financial condition or business which may
come into Beneficiary's possession.

        SECTION 10.    Representations and Warranties.    Guarantor represents
and warrants as follows:

        (a)    Organization and Good Standing.    It has been duly organized and
is validly existing as a corporation in good standing under the laws of its
state of incorporation, with corporate power and authority to own its properties
and to conduct its business as such properties are presently owned and such
business is presently conducted.

        (b)    Due Qualification.    It is duly licensed, qualified and
authorized to do business and is in good standing in each jurisdiction where the
ownership, leasing or operation of its property or the conduct of its business
requires such license or qualification except for failures to be so qualified
which, individually or in the aggregate, could not reasonably be expected to
have a Material Adverse Effect.

        (c)    Power and Authority; Due Authorization.    It has (i) all
necessary power, authority and legal right to execute, deliver and perform its
obligations under this Guaranty and (ii) duly authorized by all necessary
corporate action such execution, delivery and performance of this Guaranty.

        (d)    Binding Obligations.    This Guaranty constitutes the legal,
valid and binding obligation of Guarantor, enforceable in accordance with its
terms, except as enforceability may be limited by bankruptcy, insolvency,
reorganization or other similar laws affecting the enforcement of creditors'
rights generally and by general principles of equity, regardless of whether such
enforceability is considered in a proceeding in equity or at law.

        (e)    No Violation.    The execution, delivery and performance of this
Guaranty will not (i) conflict with, or result in any breach of any of the terms
and provisions of, or constitute (with or without notice or lapse of time or
both) a default under (A) the certificate of incorporation or by-laws of
Guarantor or (B) any indenture, lease, loan agreement, receivables purchase
agreement, mortgage, deed of trust, or other agreement or instrument to which
Guarantor is a party or by which it or its property is bound, (ii) result in or
require the creation or imposition of any Lien upon any of its properties
pursuant to the terms of any such indenture, lease, loan agreement, receivables
purchase agreement, mortgage, deed of trust, or other agreement or instrument or
(iii) violate any law or any order, rule, regulation applicable to Guarantor of
any court or of any federal, state or foreign regulatory body, administrative
agency or other governmental instrumentality having jurisdiction over Guarantor
or any of its properties.

        (f)    Solvency.    The execution, delivery and performance by the
Guarantor of this Guaranty will not render the Guarantor insolvent, nor is it
being made in contemplation of the Guarantor's insolvency; the Guarantor does
not, in its reasonable judgment, have an unreasonably small capital for
conducting its business as presently contemplated by it.

        SECTION 11.    Successors and Assigns; Amendment.    (a) This Guaranty
shall be binding upon Guarantor and upon Guarantor's successors and assigns and
all references herein to Guarantor or UCI shall be deemed to include any
successor or successors whether immediate or remote, to such Person. Guarantor
shall not assign any of its obligations hereunder without the prior written
consent of each Beneficiary.

        (b)  This Guaranty shall inure to the benefit of each Beneficiary and
respective its successors and assigns and all references herein to Beneficiary
shall be deemed to include any successors and assigns of Beneficiary (whether or
not reference in a particular provision is made to such successors and assigns).

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        (c)  No amendment or waiver of any provision of this Guaranty, and no
consent to any departure by the Guarantor herefrom, shall in any event be
effective unless the same shall be in writing and signed by the Guarantor and
each Beneficiary and then such waiver or consent shall be effective only in the
specific instance and for the specific purpose for which given.

        SECTION 12.    GOVERNING LAW.    THIS GUARANTY SHALL BE CONSTRUED IN
ACCORDANCE WITH AND GOVERNED BY THE LAWS OF THE STATE OF NEW YORK, INCLUDING
SECTIONS 5-1401 AND 5-1402 OF THE NEW YORK GENERAL OBLIGATIONS LAW, BUT
OTHERWISE WITHOUT REGARD TO CONFLICT OF LAW PRINCIPLES. Wherever possible each
provision of this Guaranty shall be interpreted in such manner as to be
effective and valid under applicable law, but if any provision of this Guaranty
shall be prohibited by or invalid under such law, such provision shall be
ineffective only to the extent of such prohibition or invalidity, without
invalidating the remainder of such provision or the remaining provisions of this
Guaranty.

        SECTION 13.    Consent to Jurisdiction; Waiver of Jury Trial.    Each
Beneficiary may enforce any claim arising out of this Guaranty in any state or
federal court having subject matter jurisdiction and located in New York, New
York and with respect to any such claim, Guarantor hereby irrevocably submits to
the jurisdiction of such courts. Guarantor irrevocably consents to the service
of process out of said courts by mailing a copy thereof, by registered mail,
postage prepaid, to Guarantor, and agrees that such service, to the fullest
extent permitted by law, (i) shall be deemed in every respect effective service
of process upon it in any such suit, action or proceeding and (ii) shall be
taken and held to be valid personal service upon and personal delivery to it.
Nothing herein contained shall preclude Beneficiary from bringing an action or
proceeding in respect hereof in any other country, state or place having
jurisdiction over such action. Guarantor irrevocably waives, to the fullest
extent permitted by law, any objection which it may now or hereafter have to the
laying of the venue of any such suit, action or proceeding brought in such a
court located in New York, New York and any claim that any such suit, action or
proceeding brought in such court has been brought in an inconvenient forum.
GUARANTOR HEREBY EXPRESSLY WAIVES ANY RIGHT TO A TRIAL BY JURY IN ANY ACTION OR
PROCEEDING TO ENFORCE OR DEFEND ANY RIGHTS UNDER THIS GUARANTY OR UNDER ANY
AMENDMENT, INSTRUMENT, DOCUMENT OR AGREEMENT DELIVERED OR WHICH MAY IN THE
FUTURE BE DELIVERED IN CONNECTION HEREWITH OR ARISING FROM ANY RELATIONSHIP
EXISTING IN CONNECTION WITH THIS GUARANTY, AND AGREES THAT ANY SUCH ACTION OR
PROCEEDING SHALL BE TRIED BEFORE A COURT AND NOT BEFORE A JURY.

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        SECTION 14.    Notices.    All notices, demands or requests given
pursuant to this Guaranty shall be in writing, sent by overnight courier service
or by telefax or hand delivery to the following addresses:

To Manager:   Universal Compression, Inc.
4444 Brittmoore Road
Houston, Texas 77042
To Issuer:
 
BRL Universal Compression Management 2002, Inc.
2911 Turtle Creek Boulevard, Suite 1240
Dallas, Texas 75219
To Lessee:
 
UCO Compression 2002 LLC
4444 Brittmoore Road
Houston, Texas 77042
To the Indenture Trustee:
 
Wells Fargo Bank Minnesota, National Association
Sixth & Marquette Avenue
MAC N9311-161
Minneapolis, MN 55479
To any Series Enhancer:
 
At the address as set forth in the related Enhancement Agreement.
To any Interest Rate Hedge Provider:
 
At the address as set forth in the related Interest Rate Swap Agreement.

        Notice shall be effective and deemed received (a) one (1) day after
being delivered to the courier service, if sent by courier, (b) upon receipt of
confirmation of transmission, if sent by telecopy, or (c) when delivered, if
delivered by hand. Copies of each such notice shall be sent to the
Administrative Agent at Wachovia Securities, Inc., 301 S. College St., TW-10,
Charlotte, North Carolina 28288-0610, Attention: Manoj Kumar.

        SECTION 15.    Third Party Beneficiary.    In addition to its rights as
a Beneficiary hereunder as a secured party under the Indenture, the Series
Enhancer shall be a third party beneficiary of this Guaranty and shall be
entitled to directly enforce its rights hereunder as though it were a party
hereto.

[SIGNATURE PAGE FOLLOWS]

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        IN WITNESS WHEREOF, this Guaranty has been executed and delivered by
Guarantor's duly authorized officer as of the date first written above.

      UNIVERSAL COMPRESSION HOLDINGS, INC.
 
 
 
By:
/s/  RICHARD W. FITZGERALD      

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      Name: Richard W. FitzGerald       Title: Senior Vice President
Accepted and Agreed:
 
 
 
WELLS FARGO BANK MINNESOTA,
NATIONAL ASSOCIATION, as
    Indenture Trustee
 
 
 
By:
/s/  EDNA BARBER      

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  Name: Edna Barber       Title: Assistant Vice President      
UCO COMPRESSION 2002 LLC
 
 
 
By:
/s/  RICHARD W. FITZGERALD      

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  Name: Richard W. FitzGerald       Title: Senior Vice President      
BRL UNIVERSAL COMPRESSION
FUNDING I 2002, L.P.
 
 
 
By:
BRL UNIVERSAL COMPRESSION
MANAGEMENT 2002, Inc., its
general partner
 
 
 
By:
/s/  GREGORY C. GREENE      

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  Name: Gregory C. Greene       Title: President      

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EXHIBIT 10.4

GUARANTY