Exhibit 4.25 - Guaranty of Payment od Debt Dated July 24, 2001

                           GUARANTY OF PAYMENT OF DEBT

         1.       RECITALS.

         AMCAST INDUSTRIAL  CORPORATION,  an Ohio corporation (together with its
successors  and  assigns,  "Borrower"),  the  financial  institutions  listed on
Schedule 1 to the Credit Agreement,  as hereinafter defined (together with their
respective  successors  and assigns,  collectively  "Banks"  and,  individually,
"Bank"),  and  KEYBANK  NATIONAL  ASSOCIATION,  as agent for the Banks under the
Credit  Agreement  ("Agent"),  are  parties  to the  Credit  Agreement.  CASTING
TECHNOLOGY COMPANY, an Indiana general partnership  ("Guarantor"),  desires that
the  Banks  continue  to grant  the  financial  accommodations  to  Borrower  as
described in the Credit Agreement.

         Guarantor,  a subsidiary of Borrower whose financing is provided by the
Loans and  Letters  of Credit,  as  hereinafter  defined,  deems it to be in the
direct pecuniary and business  interests of Guarantor that Borrower  continue to
obtain from the Banks the Commitment,  as defined in the Credit  Agreement,  and
the Loans and Letters of Credit provided for in the Credit Agreement.

         Guarantor  understands  that the Banks are willing to continue to grant
the financial  accommodations  provided for in the Credit  Agreement to Borrower
only upon certain terms and conditions, one of which is that Guarantor guarantee
the payment of the Debt (as hereinafter  defined),  and this Guaranty of Payment
of Debt (as the same may from time to time be  amended,  restated  or  otherwise
modified,  this "Agreement") is being executed and delivered in consideration of
each  financial  accommodation  granted  to  Borrower  and  for  other  valuable
considerations.

     2.  DEFINITIONS.  As used  herein,  the  following  terms  shall  have  the
following meanings:

     2.1. "Collateral" shall mean, collectively,  all property, if any, securing
the Debt or any part thereof at the time in question.

         2.2. "Credit Agreement" shall mean the Credit Agreement executed by and
among Borrower,  Agent and the Banks and dated as of August 14, 1997, as amended
and as the same may from time to time be further amended,  restated or otherwise
modified.



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         2.3.  "Debt"  shall  mean,  collectively,  (a) all Loans and Letters of
Credit;  (b) all other  indebtedness now owing or hereafter incurred by Borrower
to Agent and the Banks  pursuant to the Credit  Agreement and the Notes executed
in  connection  therewith;  (c)  each  renewal,   extension,   consolidation  or
refinancing of any of the foregoing,  in whole or in part; (d) all interest from
time to time accruing on any of the foregoing, and all commitment and other fees
payable  pursuant  to the Credit  Agreement;  (e) all other  amounts  payable by
Borrower to Agent or any of the Banks  pursuant to the Credit  Agreement  or any
other Loan Document; and (f) all costs and expenses,  including attorneys' fees,
incurred by Agent in  connection  with the Credit  Agreement  or by Agent or the
Banks in connection  with the collection of any portion of the  indebtedness  or
other obligations described in (a), (b), (c), (d) or (e) hereof.

     2.4. "Letter of Credit" shall mean any Letter of Credit,  as defined in the
Credit Agreement, issued pursuant to the Credit Agreement.

     2.5.  "Loan"  shall mean any Loan,  as  defined  in the  Credit  Agreement,
granted pursuant to the Credit Agreement.

         2.6. "Obligor" shall mean any Person that, or any of whose property, is
or  shall  be  obligated  on the  Debt or any part  thereof  in any  manner  and
includes,  without  limiting  the  generality  of  the  foregoing,  Borrower  or
Guarantor, and any other co-maker, endorser, guarantor of payment, subordinating
creditor,  assignor,  grantor of a security interest,  pledgor, mortgagor or any
hypothecator of property, if any.

         2.7.   "Person"  shall  mean  any  individual,   sole   proprietorship,
partnership, joint venture,  unincorporated organization,  corporation,  limited
liability company,  institution,  trust,  estate,  government or other agency or
political subdivision thereof or any other entity.

Except as specifically  defined herein,  capitalized  terms used herein that are
defined in the Credit Agreement shall have their respective meanings ascribed to
them in the Credit Agreement.

         3. GUARANTY OF DEBT.  Guarantor hereby  absolutely and  unconditionally
guarantees  the  prompt  payment  in full of all of the  Debt  as and  when  the
respective parts thereof become due and payable. If the Debt or any part thereof
shall not be paid in full when due and payable, Agent and the Majority Banks (as
defined in the Credit Agreement),  in each case, shall have the right to proceed
directly  against  Guarantor under this Agreement to collect the payment in full
of the Debt,  regardless  of whether or not Agent and the  Majority  Banks shall
have theretofore  proceeded or shall then be proceeding  against Borrower or any
other  Obligor  or  Collateral,  if  any,  or  any of the  foregoing,  it  being
understood  that Agent and the Majority  Banks,  in their sole  discretion,  may
proceed  against any Obligor and any  Collateral,  and may exercise  each right,
power or privilege that Agent or the Banks may then have, either  simultaneously
or separately, and, in any event, at such time or times and as often and in such
order as Agent and the Majority Banks, in their sole  discretion,  may from time
to time deem expedient to collect the payment in full of the Debt.



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         4. PAYMENTS  CONDITIONAL.  Whenever  Agent or any Bank shall credit any
payment to the Debt or any part thereof, whatever the source or form of payment,
the credit shall be  conditional  as to  Guarantor  unless and until the payment
shall be final and valid as to all the world. Without limiting the generality of
the foregoing, Guarantor agrees that if any check or other instrument so applied
shall be  dishonored by the drawer or any party  thereto,  or if any proceeds of
Collateral or payment so applied shall thereafter be recovered by any trustee in
bankruptcy or any other Person,  each Bank, in each case,  may reverse any entry
relating thereto on its books and Guarantor shall remain liable  therefor,  even
if such Bank may no longer have in its  possession  any  evidence of the Debt to
which the payment in question was applied.

         5. GUARANTOR'S  OBLIGATIONS  ABSOLUTE AND UNCONDITIONAL.  Regardless of
the duration of time, regardless of whether Borrower may from time to time cease
to be indebted to the Banks and  irrespective of any act,  omission or course of
dealing whatever on the part of Agent or any Bank,  Guarantor's  liabilities and
other  obligations  under this  Agreement  shall remain in full effect until the
payment in full of the Debt. Without limiting the generality of the foregoing:

     5.1.  Banks  Have No Duty To Make  Advances.  No Bank  shall at any time be
under any duty to Guarantor to grant any  financial  accommodation  to Borrower,
irrespective  of any duty or commitment  of any of the Banks to Borrower,  or to
follow  or  direct  the  application  of  the  proceeds  of any  such  financial
accommodation;

         5.2. Guarantor's Waiver of Notice,  Presentment,  etc. Guarantor waives
(a) notice of the granting of any Loan to  Borrower,  the issuance of any Letter
of Credit or the  incurring of any other  indebtedness  by Borrower or the terms
and  conditions  thereof,  (b)  presentment,  demand for  payment  and notice of
dishonor of the Debt or any part thereof, or any other indebtedness  incurred by
Borrower  to any of the  Banks,  (c)  notice of any  indulgence  granted  to any
Obligor, and (d) any other notice to which Guarantor might, but for this waiver,
be entitled;

         5.3. Banks' Rights Not Prejudiced by Action or Omission.  Agent and the
Banks,  in their sole  discretion,  may,  without any  prejudice to their rights
under this Agreement,  at any time or times, without notice to or the consent of
Guarantor,  (a) grant Borrower whatever financial  accommodations that Agent and
the Banks may from time to time deem  advisable,  even if  Borrower  might be in
default in any  respect  and even if those  financial  accommodations  might not
constitute indebtedness the payment of which is guaranteed hereunder, (b) assent
to any renewal, extension, consolidation or refinancing of the Debt, or any part
thereof, (c) forbear from demanding security,  if Agent and the Banks shall have
the right to do so,  (d)  release  any  Obligor or  Collateral  or assent to any
exchange of  Collateral,  if any,  irrespective  of the  consideration,  if any,
received  therefor,  (e) grant any waiver or consent or forbear from  exercising
any right, power or privilege that Agent and the Banks may have or acquire,  (f)
assent to any amendment,  deletion,  addition,  supplement or other modification
in, to or of any writing  evidencing  or securing  any Debt or pursuant to which
any Debt is created,  (g) grant any other indulgence to any Obligor,  (h) accept
any Collateral for, or any other Obligor upon, the Debt or any part thereof, and
(i)  fail,  neglect  or omit in any way to  realize  upon any  Collateral  or to
protect the Debt or any part thereof or any Collateral therefor;

     5.4. Liabilities Survive Guarantor's  Dissolution.  Guarantor's liabilities
and other  obligations  under this  Agreement  shall survive any  dissolution of
Guarantor; and



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         5.5.  Liabilities Absolute and Unconditional.  Guarantor's  liabilities
and other  obligations  under this Agreement shall be absolute and unconditional
irrespective of any lack of validity or  enforceability of the Credit Agreement,
the Notes,  any Loan  Document or any other  agreement,  instrument  or document
evidencing  the Loans or  Letters  of Credit or  related  thereto,  or any other
defense available to Guarantor in respect of this Agreement.

         6. REPRESENTATIONS AND WARRANTIES. Guarantor represents and warrants to
Agent and each of the Banks that (a)  Guarantor  is a duly  formed  and  validly
existing  general  partnership,  in good standing under the laws of the state of
its formation (as referenced in the first paragraph of this  Agreement),  and is
qualified to do business in each state where a failure to so qualify  would have
a material adverse effect on Guarantor;  (b) Guarantor has legal power and right
to execute and deliver this  Agreement and to perform and observe the provisions
hereof;  (c) the general  partner  executing and  delivering  this  Agreement on
behalf of Guarantor has been duly authorized to do so, and this Agreement,  when
executed,  is legal and binding upon Guarantor in every respect;  (d) except for
matters described or referenced in the Credit Agreement or any Schedule thereto,
no litigation or proceeding is pending or threatened  against  Guarantor  before
any court or any  administrative  agency that,  in  Guarantor's  opinion,  after
consultation with Guarantor's counsel, is reasonably expected to have a material
adverse effect on Guarantor;  (e) Guarantor has received  consideration  that is
the  reasonable  equivalent  value  of  the  obligations  and  liabilities  that
Guarantor has incurred to Agent,  for the benefit of the Banks; (f) Guarantor is
not insolvent,  as defined in any applicable state or federal statute,  nor will
Guarantor be rendered  insolvent by the execution and delivery of this Agreement
to Agent and the Banks;  (g)  Guarantor is not engaged or about to engage in any
business or transaction  for which the assets  retained by Guarantor are or will
be an  unreasonably  small  amount of  capital,  taking into  consideration  the
obligations to the Banks incurred  hereunder;  and (h) Guarantor does not intend
to,  nor  does  Guarantor  believe  that  Guarantor  will,  incur  debts  beyond
Guarantor's ability to pay such debts as they mature.

         7. DISABILITY OF OBLIGOR. Without limiting the generality of any of the
other provisions hereof, Guarantor specifically agrees that upon the dissolution
of any Obligor  and/or the filing or other  commencement  of any  bankruptcy  or
insolvency  proceedings  by,  for or  against  any  Obligor,  including  without
limitation,  any  assignment  for the benefit of creditors or other  proceedings
intended to liquidate or rehabilitate any Obligor, Agent and the Majority Banks,
in their  sole  discretion,  may  declare  the unpaid  principal  balance of and
accrued  interest on the Debt to be  forthwith  due and payable in full  without
notice.  Upon the occurrence of any of the events  enumerated in the immediately
preceding  sentence,  Guarantor shall,  upon the demand of Agent or the Majority
Banks,  whenever  made,  pay to Agent,  for the benefit of the Banks,  an amount
equal to the then unpaid principal balance of and accrued interest on the Debt.



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         8. WAIVER OF GUARANTOR'S RIGHTS AGAINST BORROWER AND COLLATERAL. To the
extent  permitted  by law,  Guarantor  waives  any  claim  or other  right  that
Guarantor  might now have or  hereafter  acquire  against  Borrower or any other
Obligor that arises from the existence or performance of Guarantor's liabilities
or other obligations under this Agreement,  including,  without limitation,  any
right of subrogation, reimbursement, exoneration, contribution, indemnification,
and any right to participate in any claim or remedy of Agent or any Bank against
Borrower or any Collateral that Agent or any Bank now has or hereafter acquires,
whether or not such claim,  remedy or right arises in equity, or under contract,
statute or common law.
         9. MAXIMUM  LIABILITY OF GUARANTOR.  Anything in this  Agreement to the
contrary  notwithstanding,  in no event  shall  the  amount  of the  Obligations
secured by this Agreement exceed the maximum amount that (after giving effect to
the incurring of the obligations  hereunder and to any rights to contribution of
Guarantor  from other  affiliates  of  Borrower)  would not render the rights to
payment of Agent and the Banks hereunder  void,  voidable or avoidable under any
applicable fraudulent transfer law.

         10. NOTICE.  All notices,  requests,  demands and other  communications
provided  for  hereunder  shall be in writing  and, if to  Guarantor,  mailed or
delivered to it, addressed to it at the address  specified on the signature page
of this Agreement,  and, if to a Bank,  mailed or delivered to it,  addressed to
the  address  of such  Bank  specified  on the  signature  pages  of the  Credit
Agreement. All notices,  statements,  requests, demands and other communications
provided  for  hereunder  shall be deemed to be given or made when  delivered or
forty-eight  (48) hours after being  deposited in the mails with postage prepaid
by registered or certified  mail,  addressed as aforesaid,  or sent by facsimile
with telephonic  confirmation of receipt,  except that notices from Guarantor to
Agent  or the  Banks  pursuant  to any of the  provisions  hereof  shall  not be
effective until received by Agent or the Banks.

         11. MISCELLANEOUS.  This Agreement shall bind Guarantor and Guarantor's
successors and assigns and shall inure to the benefit of Agent and each Bank and
their respective  successors and assigns,  including  (without  limitation) each
holder of any Note  evidencing any Debt. If, at any time, one or more provisions
of this Agreement is or becomes invalid, illegal or unenforceable in whole or in
part,  the validity,  legality and  enforceability  of the remaining  provisions
shall not in any way be affected or impaired thereby. This Agreement constitutes
a final written expression of all of the terms of this Agreement,  is a complete
and exclusive statement of those terms and supersedes all oral  representations,
negotiations  and prior  writings,  if any,  with respect to the subject  matter
hereof. The relationship  between (a) Guarantor and (b) Agent and the Banks with
respect to this  Agreement is and shall be solely that of debtor and  creditors,
respectively,  and Agent and the Banks shall have no fiduciary obligation toward
Guarantor  with  respect  to this  Agreement  or the  transactions  contemplated
hereby.  The captions  herein are for convenience of reference only and shall be
ignored in interpreting the provisions of this Agreement.



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         12. GOVERNING LAW;  SUBMISSION TO JURISDICTION.  The provisions of this
Agreement and the respective rights and duties of Guarantor, Agent and the Banks
hereunder  shall be  governed  by and  construed  in  accordance  with Ohio law,
without regard to principles of conflict of laws.  Guarantor hereby  irrevocably
submits to the  non-exclusive  jurisdiction  of any Ohio state or federal  court
sitting in  Cleveland,  Ohio,  over any action or  proceeding  arising out of or
relating  to this  Agreement,  any Loan  Document or any  Related  Writing,  and
Guarantor hereby irrevocably agrees that all claims in respect of such action or
proceeding  may be heard and  determined  in such Ohio state or  federal  court.
Guarantor, on behalf of itself and its Subsidiaries,  hereby irrevocably waives,
to the fullest  extent  permitted by law, any  objection it may now or hereafter
have to the  laying of venue in any  action or  proceeding  in any such court as
well as any  right  it may  now or  hereafter  have to  remove  such  action  or
proceeding,  once  commenced,  to  another  court on the  grounds  of FORUM  NON
CONVENIENS or otherwise.  Guarantor agrees that a final,  nonappealable judgment
in any such  action or  proceeding  shall be  conclusive  and may be enforced in
other  jurisdictions  by suit on the judgment or in any other manner provided by
law.



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         13. JURY TRIAL WAIVER.  GUARANTOR,  AGENT AND THE BANKS,  TO THE EXTENT
PERMITTED BY LAW, EACH WAIVES ANY RIGHT TO HAVE A JURY  PARTICIPATE IN RESOLVING
ANY DISPUTE, WHETHER SOUNDING IN CONTRACT, TORT, OR OTHERWISE,  AMONG AGENT, ANY
OF THE BANKS,  BORROWER  AND/OR  GUARANTOR  ARISING OUT OF, IN CONNECTION  WITH,
RELATED TO, OR INCIDENTAL TO THE RELATIONSHIP  ESTABLISHED  BETWEEN EACH OF THEM
AND GUARANTOR IN CONNECTION WITH THIS AGREEMENT OR ANY NOTE OR OTHER  AGREEMENT,
INSTRUMENT  OR DOCUMENT  EXECUTED OR  DELIVERED IN  CONNECTION  THEREWITH OR THE
TRANSACTIONS RELATED THERETO.

Signed as of the  24th  day of July, 2001, at  Dayton,  Ohio.



                                          CASTING TECHNOLOGY COMPANY

Address: 9887 Washington Village Drive    By: Amcast Casting Technologies, Inc.,
         Dayton, Ohio 45459                     General Partner
         Attention:  Michael Higgins
                                                By:   /s/ Michael Higgins
                                                Name:     Michael Higgins
                                                Title:    Treasurer