<PAGE>   1
EXHIBIT 4.1

                 FIRST AMENDMENT TO LOAN AND SECURITY AGREEMENT

         This First Amendment to Loan and Security Agreement (the "First
Amendment") is made as of the 30th day of July, 2001, by and between TransPro,
Inc., Evap, Inc. and GO/DAN Industries, Inc., as borrowers (individually, each a
"Borrower" and collectively, the "Borrowers"), Allen Heat Transfer Products,
Inc., GO/DAN de Mexico, SA de C.V. and Radiadores GDI, SA de C.V., as guarantors
(each an "Obligor", and collectively, the "Obligors", as defined in the Loan
Agreement (defined hereinafter)) and CONGRESS FINANCIAL CORPORATION (NEW
ENGLAND), as lender (the "Lender").

         WHEREAS, the Lender and Borrowers entered into a certain Loan and
Security Agreement dated as of January 4, 2001 (the "Loan Agreement");

         WHEREAS, the Borrowers have requested that the Lender amend the Loan
Agreement to (i) increase the time period in which the Borrowers must furnish
the Lender with monthly financial statements under Section 9.6 of the Loan
Agreement and (ii) reduce the Adjusted Net Worth under Section 9.15 of the Loan
Agreement;

         WHEREAS, the Lender has agreed to enter into the First Amendment
subject to the terms and conditions set forth below;

         NOW THEREFORE, based on these premises, and in consideration of the
mutual promises contained herein and for other good and valuable consideration,
the receipt and sufficiency of which are hereby acknowledged by the parties, the
Borrowers and Lender hereby agree as follows:

         1.       Amendment to Loan Agreement.

                  1.1.     Section 9.6(a)(i) of the Loan Agreement is hereby
amended by deleting "thirty (30) days" and substituting in lieu thereof "forty
five (45) days".

                  1.2.     Section 9.15 of the Loan Agreement is hereby amended
by deleting "$67,500,000.00" and substituting in lieu thereof "$63,000,000.00".

         2.       Conditions Precedent. This First Amendment and the Lender's
obligations hereunder shall not be effective until each of the following
conditions are satisfied (the "First Amendment Effective Date"):

                  2.1.     Borrowers shall have duly executed and delivered this
First Amendment, and all other instruments, documents and agreements required by
Lender;

                  2.2.     All requisite corporate action and proceedings of the
Borrowers in connection with this First Amendment shall be satisfactory in form
and substance to Lender;



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                  2.3.     There shall be no claim, lawsuit or action pending or
threatened that would affect the performance by the Borrowers of their
Obligations under the Financing Agreements or of the Lender under the Financing
Agreements.

         3.       Representations and Warranties. Each Borrower jointly and
severally represents and warrants to Lender the following:

                  3.1.     Organization and Qualification. Each of the Borrowers
is duly incorporated or formed, as applicable, validly existing, and in good
standing under the laws of their respective jurisdictions of incorporation or
formation, as applicable. Each Borrower is duly qualified to do business and is
in good standing as a foreign corporation in all states and jurisdictions in
which the failure to be so qualified would have a material adverse effect on the
financial condition, business or properties of any such Borrower.

                  3.2.     Power and Authority. Each Borrower is duly authorized
and empowered to enter, deliver, and perform this First Amendment, and each of
the Financing Agreements to which it is a party. The execution, delivery, and
performance of this First Amendment and each of the other Financing Agreements
have been duly authorized by all necessary corporate action of each of the
Borrowers. The execution, delivery and performance of this First Amendment and
each of the other Financing Agreements do not and will not (i) require any
consent or approval of the shareholders of the Borrowers; (ii) contravene the
charter or by-laws of any of the Borrowers; (iii) violate, or cause any Borrower
to be in default under, any provision of any law, rule, regulation, order, writ,
judgment, injunction, decree, determination or award in effect having
applicability to such Borrower; (iv) result in a breach of or constitute a
default under any indenture or loan or credit agreement or any other agreement,
lease or instrument to which any Borrower is a party or by which such Borrower's
properties may be bound or affected, which breach or default is reasonably
likely to have a material adverse effect of the financial condition, business or
properties of such Borrower; or (v) result in, or require, the creation or
imposition of any lien (other than the liens set forth in Schedule 8.4 to the
Loan Agreement) upon or with respect to any of the properties now owned or
hereafter acquired by any Borrower.

                  3.3.     Legally Enforceable Agreement. This First Amendment
and each of the other Financing Agreements delivered under this First Amendment
is, a legal, valid and binding obligation of each Borrower, enforceable against
each Borrower in accordance with its respective terms subject to bankruptcy,
reorganization, moratorium or similar laws affecting the enforcement of
creditors' rights generally.

                  3.4.     Continuous Nature of Representations and Warranties.
Each Borrower confirms and agrees that, except for the amendments to the Loan
Agreement provided herein, (a) all representations and warranties contained in
the Loan Agreement and in the other Financing Agreements are on the date hereof
true and correct in all material respects (except for changes that have occurred
as permitted by the covenants in Section 9 of the Loan Agreement), (b) all
Information Certificates delivered in conjunction with the Loan Agreement remain
true and correct in all material respects, and (c) it is unconditionally and
jointly and severally liable for the punctual and full payment


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of all Obligations, including, without limitation, all termination fees under
Section 12.1(c) of the Loan Agreement, charges, fees, expenses and costs
(including attorneys' fees and expenses) under the Financing Agreements, and
that no Borrower has any defenses, counterclaims or setoffs with respect to
full, complete and timely payment of all Obligations.

         4.       Acknowledgement of Obligations. Each Obligor, for value
received, hereby assents to the Borrowers' execution and delivery of this First
Amendment, and to the performance by the Borrowers of their respective
agreements and obligations hereunder. This First Amendment and the performance
or consummation of any transaction or matter contemplated under this First
Amendment, shall not limit, restrict, extinguish or otherwise impair any of the
Obligor's liability to Lender with respect to the payment and other performance
obligations of the Obligors pursuant to the Guarantees and other Financing
Agreements executed by the Obligors for the benefit of Lender. Each Obligor
acknowledges that it is unconditionally liable to Lender for the full and
complete payment of all Obligations including, without limitation, all charges,
fees, expenses and costs (including attorney's fees and expenses) under the
Financing Agreements and that such Obligor has no defenses, counterclaims or
setoffs with respect to full, complete and timely payment of any and all
Obligations.

         5.       Confirmation of Liens. Each Borrower acknowledges, confirms
and agrees that the Financing Agreements, as amended hereby, are effective to
grant to Lender duly perfected, valid and enforceable first priority security
interests and liens in the Collateral described therein, except for liens set
forth in Sections 8.4 and 9.8 and Schedule 8.4 (as amended hereby), and that the
locations for such Collateral specified in the Financing Agreements have not
changed except as provided herein or as previously disclosed to the Lender. Each
Borrower further acknowledges and agrees that all Obligations of the Borrowers
are and shall be secured by the Collateral.

         6.       Miscellaneous. Borrowers hereby agree to pay to Lender all
reasonable attorney's fees and costs which have been incurred or may in the
future be incurred by Lender in connection with the negotiation and preparation
of this First Amendment and any other documents and agreements prepared in
connection with this First Amendment. The undersigned confirm that the Financing
Agreements remain in full force and effect without amendment or modification of
any kind, except for the First Amendment prepared herein. The Borrowers and
Obligors further confirm that no Event of Default or events which with notice or
the passage of time or both would constitute an Event of Default have occurred
and are continuing. The execution and delivery of this First Amendment by Lender
shall not be construed as a waiver by Lender of any Event of Default under the
Financing Agreements. This First Amendment shall be deemed to be a Financing
Agreement and, together with the other Financing Agreements, constitute the
entire agreement between the parties with respect to the subject matter hereof
and supersedes all prior dealings, correspondence, conversations or
communications between the parties with respect to the subject matter hereof.

                      REST OF PAGE LEFT INTENTIONALLY BLANK



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         IN WITNESS WHEREOF, the Borrowers, the Obligors, and the Lender have
executed this First Amendment as of the date first above written, by their
respective officers hereunto duly authorized, under seal.

                                           BORROWERS:


WITNESS                                    TRANSPRO, INC.


By: /s/ R. E. Freeman                      By: /s/ R. A. Wisot
   ----------------------------------         ---------------------------------
                                           Title: Vice President
                                                 ------------------------------


                                           EVAP, INC.


By: /s/ R. E. Freeman                      By: /s/ R. A. Wisot
   ----------------------------------         ---------------------------------
                                           Title: Vice President
                                                 ------------------------------


                                           GO/DAN INDUSTRIES, INC.


By: /s/ R. E. Freeman                      By: /s/ R. A. Wisot
   ----------------------------------         ---------------------------------
                                           Title: Vice President
                                                 ------------------------------


                                           OBLIGORS:


                                           ALLEN HEAT TRANSFER PRODUCTS, INC.


By: /s/ R. E. Freeman                      By: /s/ R. A. Wisot
   ----------------------------------         ---------------------------------
                                           Title: Vice President
                                                 ------------------------------


                                           GO/DAN de MEXICO SA de C.V.


By: /s/ R. E. Freeman                      By: /s/ R. A. Wisot
   ----------------------------------         ---------------------------------
                                           Title: Vice President
                                                 ------------------------------




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                                           RADIADORES GDI, SA de C.V.


By: /s/ R. E. Freeman                      By: /s/ R. A. Wisot
   ----------------------------------         ---------------------------------
                                           Title: Vice President
                                                 ------------------------------


                                           LENDER

                                           CONGRESS FINANCIAL CORPORATION
                                           (NEW ENGLAND)


By:                                        By: /s/ Marc E. Swartz
   ----------------------------------         ---------------------------------
                                           Title: Senior Vice President
                                                 ------------------------------







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