<PAGE>

                                                                     EXHIBIT 4.1


                 EIGHTH AMENDMENT TO LOAN AND SECURITY AGREEMENT

     This Eighth Amendment to Loan and Security Agreement (the "Eighth
Amendment") is made as of November 22, 2002, by and between TransPro, Inc.
("TransPro"), Evap, Inc., GO/DAN Industries, Inc., and G&O Manufacturing
Company, 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, as amended (the "Loan Agreement");

     WHEREAS, the Borrowers have requested that the Lender agree to increase to
the Maximum Credit and Revolving Loan Ceiling under the Loan Agreement as
provided herein;

     WHEREAS, the Lender has agreed to increase the Maximum Credit and Revolving
Loan Ceiling and to enter into this Eighth Amendment subject to the terms and
conditions set forth herein;

     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, Obligors and Lender hereby agree as follows:

     1.   Amendments to Loan Agreement.

          1.1. Definition of Maximum Credit. Section 1.37 of the Loan Agreement
     hereby is deleted in its entirety and the following definition is
     substituted in lieu thereof:

          "1.37 'Maximum Credit' shall mean the amount of $65,000,000.00.

          1.2. Definition of Revolving Loan Ceiling. Section 1.50 of the Loan
     Agreement hereby is deleted in its entirety and the following definition is
     substituted in lieu thereof:

          "1.50 'Revolving Loan Ceiling' shall mean the amount of
     $65,000,000.00.

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

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          2.1. 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.

          2.2. Power and Authority. Each Borrower is duly authorized and
     empowered to enter, deliver, and perform this Eighth Amendment, and each of
     the Financing Agreements to which it is a party. The execution, delivery,
     and performance of this Eighth 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
     Eighth 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.

          2.3. Legally Enforceable Agreement. This Eighth Amendment and each of
     the other Financing Agreements delivered under this Eighth 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.

          2.4. 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, absolutely, and jointly and severally liable for
     the punctual and full payment 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.

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     3. Acknowledgement of Obligations. Each Obligor, for value received, hereby
assents to the Borrowers' execution and delivery of this Eighth Amendment, and
to the performance by the Borrowers of their respective agreements and
obligations hereunder. This Eighth Amendment and the performance or consummation
of any transaction or matter contemplated under this Eighth 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 and Guaranteed 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 and Guaranteed Obligations.

     4. 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.

     5. Miscellaneous. All capitalized terms not otherwise defined herein shall
have the meanings set forth in the Financing Agreements. 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 Eighth Amendment and any other documents and
agreements prepared in connection with this Eighth Amendment. The undersigned
confirm that the Financing Agreements remain in full force and effect without
amendment or modification of any kind, except for as set forth in this Eighth
Amendment (and as set forth in any previously executed amendments to the Loan
Agreement). 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 Eighth Amendment by Lender shall not be construed as a waiver by Lender of
any Event of Default under the Financing Agreements. This Eighth 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 Eighth Amendment as of the date first above written, by their
respective officers hereunto duly authorized, under seal.

                                                 BORROWERS:


WITNESS                                          TRANSPRO, INC.


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

                                                 EVAP, INC.


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


                                                 GO/DAN INDUSTRIES, INC.


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

                                                 G&O MANUFACTURING COMPANY, INC.


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

                               OBLIGORS:

                                                 GO/DAN de MEXICO SA de C.V.


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

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                                            RADIADORES GDI, SA de C.V.


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

                                            ALLEN HEAT TRANSFER PRODUCTS, INC.


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

                                            LENDER

                                            CONGRESS FINANCIAL CORPORATION
                                            (NEW ENGLAND)


Melissa Post                                By: John C. Sullivan
-------------------------------------          -----------------
                                            Title: Vice President
                                                   --------------



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