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                                                                     EXHIBIT 5.1
 
                     [LETTERHEAD OF COLTEC INDUSTRIES INC]
                                                                   July 15, 1998
 
COLTEC CAPITAL TRUST
COLTEC INDUSTRIES INC
3 COLISEUM CENTRE
2550 WEST TYVOLA ROAD
CHARLOTTE, NORTH CAROLINA 28217
 
Ladies and Gentlemen:
 
     I am the Executive Vice President, General Counsel and Secretary of Coltec
Industries Inc, a Pennsylvania corporation (the "Company"). This opinion is
being furnished in accordance with the requirements of Item 601(b)(5) of
regulation S-K under the Securities Act of 1933, as amended (the "Act"), in
connection with the registration under the Act of (i) 3,000,000 5 1/4%
Convertible Preferred Securities Term Income Deferrable Equity Securities
(TIDES)(SM) or TIDES(SM) (liquidation preference $50 each) (the "TIDES")
representing undivided beneficial ownership interests in the assets of Coltec
Capital Trust, a statutory business trust formed under the laws of the State of
Delaware (the "Trust"); (ii) 5 1/4% Convertible Junior Subordinated Deferrable
Interest Debentures Due 2028 (the "Convertible Junior Subordinated Debentures")
of the Company, which may be distributed under certain circumstances to the
holders of the TIDES; (iii) the shares of common stock, par value $0.01 per
share (the "Common Stock"), of the Company issuable upon conversion of the TIDES
and the Convertible Junior Subordinated Debentures; and (iv) the Trust
Securities Guarantee of the Company (as defined below).
 
     The TIDES were issued pursuant to the amended and restated declaration of
trust of the Trust, dated as of April 14, 1998 (the "Declaration") among the
Company, as sponsor, Robert J. Tubbs, Thomas B. Jones, Jr. and David D.
Harrison, as administrative trustees, The Bank of New York (Delaware), as
Delaware trustee, and The Bank of New York, as property trustee, and guaranteed
by the Company as to the payment of distributions and as to payments on
liquidation, redemption and otherwise pursuant to the Guarantee Agreement, dated
as of April 14, 1998 (the "Trust Securities Guarantee"), between the Company and
The Bank of New York, as trustee. The proceeds from the sale by the trust of the
TIDES were invested in the Convertible Junior Subordinated Debentures, which
were issued pursuant to an Indenture, dated as of April 14, 1998 (the
"Indenture"), between the Company and The Bank of New York, as trustee.
 
     In connection with this opinion, I have examined originals or copies,
certified or otherwise identified to my satisfaction, of (i) the Registration
Statement on Form S-3 (File No. 3323-52975), as filed by the Company and the
Trust with the Securities and Exchange Commission (the "Commission") on May 18,
1998 under the Act and Amendment No. 1 thereto, as filed on the date hereof (the
registration statement, as so amended, being hereinafter referred to as the
"Registration Statement") relating to the TIDES, the Trust Securities Guarantee,
the Convertible Junior Subordinated Debentures and the Common Stock; (ii) an
executed copy of the Declaration filed as an exhibit to the registration
Statement; (iii) the form of the Common Stock and a specimen certificate
thereof; (iv) the Amended and Restated Articles of Incorporation of the Company
as currently in effect; (v) the by-laws of the Company as currently in effect;
(vi) certain resolutions of the Board of Directors of the company relating to
the issuance of the Convertible Junior Subordinated Debentures and the shares of
Common Stock issuable upon conversion; (vii) an executed copy of the Trust
Securities Guarantee; (viii) the form of TIDES filed as an exhibit to the
Registration Statement and a specimen certificate thereof; (ix) the designation
of the terms of the TIDES; (x) the form of the Convertible Junior Subordinated
Debentures filed as an exhibit to the Registration Statement and a specimen
certificate thereof; (xi) an executed copy of the Indenture; and (xii) an
executed copy of the Registration Rights Agreement, dated April 14, 1998, by and
among the Company, the Trust, Credit Suisse First Boston Corporation, CIBC
Oppenheimer Corp. and Lehman Brothers Inc., as the Initial purchasers, filed as
an exhibit to the Registration Statement.
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     In my examination, I have assumed the legal capacity of all natural
persons, the genuineness of all signatures, the authenticity of all documents
submitted to me as originals, the conformity to originals of all documents
submitted to me as certified or photostatic copies and the authenticity of the
originals of such latter documents. In making my examination of documents
executed by parties other than the Company, I have assumed that such parties had
the power, corporate or other, to enter into and perform all obligations
thereunder and have also assumed the due authorization by all requisite action,
corporate or other, and execution and delivery by such parties of such documents
and that such documents constitute valid and binding obligations of such
parties. In addition, I have assumed that the Common Stock as executed will be
in the form reviewed by me. As to any facts material to the opinions expressed
herein which were not independently established or verified, I have relied upon
oral or written statement and representations of officers, trustees and other
representatives of the Company, the Trust and others.
 
   
     The opinions expressed herein are limited to the Federal laws of the United
States of America, the laws of the State of New York and the corporate law of
the Commonwealth of Pennsylvania, and I express no opinion with respect to the
laws of any other country, state or jurisdiction.
    
 
     Based upon and subject to the foregoing, I am of opinion as follows:
 
          1. The shares of Common Stock initially issuable upon conversion of
     the TIDES and the Convertible Junior Subordinated Debentures, have been
     duly authorized and reserved for issuance upon conversion and, when
     certificates representing the Common Stock on the form of the specimen
     certificate examined by me have been manually signed by an authorized
     officer of the transfer agent and registrar for the Common Stock and, if
     and when issued upon conversion of the TIDES and the Convertible Junior
     Subordinated Debentures, such Common Stock will be validly issued, fully
     paid and nonassessable.
 
          2. The Trust Securities Guarantee is a valid and binding agreement of
     the Company, enforceable against the Company in accordance with its terms
     (subject to applicable bankruptcy, insolvency, reorganization, moratorium,
     fraudulent transfer or other similar laws affecting creditors' rights
     generally from time to time in effect and to general principles of equity,
     including concepts of materiality, reasonableness, good faith and fair
     dealing, regardless of whether such enforceability is considered in a
     proceeding in equity or at law).
 
          3. The Convertible Junior Subordinated Debentures are valid and
     binding obligations of the Company, entitled to the benefits of the
     Indenture and enforceable against the Company in accordance with their
     terms (subject to applicable bankruptcy, insolvency, reorganization,
     moratorium, fraudulent transfer or other similar laws affecting creditors'
     rights generally from time to time in effect and to general principles of
     equity, including concepts of materiality, reasonableness, good faith and
     fair dealing, regardless of whether such enforceability is considered in a
     proceeding in equity or at law).
 
     I hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement. I also consent to the reference to me
under the heading "Legal Matters" in the Registration Statement and in the
related Prospectus. In giving this consent, I do not thereby admit that I am
included in the category of persons whose consent is required under Section 7 of
the Act or the rules and regulations of the Commission.
 
   
     This opinion is being delivered to you in my capacity as the Executive Vice
President, General Counsel and Secretary of the Company and solely for the
purpose of being included as an exhibit to the Registration Statement. This
opinion addresses matters only as of the date hereof and is solely for the
benefit of the addressees hereof and may not be relied upon in any manner for
any other purpose without my prior written consent.
    
 
                                          Sincerely,
 
                                          By:       /s/  ROBERT J. TUBBS
 
                                            ------------------------------------
                                            Robert J. Tubbs
                                            Executive Vice President,
                                            General Counsel and Secretary
 
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