CONTINENTAL MODELS AV-1790 AND AO-895 AND GMC MODELS 6V53/6V53T AND 8V71T SERIES ENGINES: REPAIR OF ALUMINUM OIL COOLERS

* TB 9-2300-403-45

DEPARTMENT

THE

ARMY

TECHNICAL

BULLETIN

CONTINENTAL MODELS AV-1790 AND AO-895 AND

GMC MODELS 6V53/6V53T AND 8V71T SERIES ENGINES:

REPAIR OF ALUMINUM OIL COOLERS

Headquarters, Department of the Army, Washington, D. C.,

15 March 1971

d. Housing welding procedure.

1. Purpose. This bulletin provides general support,

CAUTION

depot, and contractor maintenance personnel with

instructions for repair of aluminum oil coolers by

Use extreme care in welding aluminum cool-

ers to prevent damage to fins and tubes.

welding or brazing.

Refer to TM 9-237 for preliminary instruc-

2. Scope. This bulletin applies to all GS, depot, and

tions on welding of aluminum.

contractor repair of Continental Model AV-1790

and AO-895 and GMC 6V53/6V53T and 8V71T engines.

NOTE

An interpass temperature of 250 F to 395 F,

3. Equipment required. a. Arc welding machine

measured two inches from the weld, will be

for inert gas shielded tungsten arc (Heliarc, Argon-

maintained until the joint is completely

arc) or inert gas shielded metal arc consuming

welded.

electrode process.

(1) When preheat temperature of 350 F plus or

b. Class 4043 electrode, conforming to specifica-

minus 35 F has been reached, position housing in

tion QQ-R-556A or MIL-E-16053.

the most advantageous welding position. Cover all

c. ALCOA No. 33 torch brazing flux or equivalent.

but the area to be repaired with asbestos blankets

d. ALCOA No. 718 or 716 brazing alloy or equiva-

to maintain heat.

lent, 1/16 and l/8-inch diameter.

(2) Weld the milled groove, assuring a good

4. Repair Procedure. a. Degrease coolers, using

root weld; then, apply fillet welds until groove

vapor or liquid solvents. Dry with compressed air.

is filled and closed.

WARNING

(3) Remove blankets and allow to cool to room

Degrease vapors may produce phosgene gas.

temperature.

Do not place coolers into alkali strip tanks.

e. Machine the repaired surfaces back to original

b. Prepare surface by removing all foreign matter

configuration. Repaired bolt holes must be proper-

from area to be welded by use of stainless steel wire

ly located, drilled, and threaded to original size and

brush, drill, burring tool, approved chemical proc-

thread pitch.

ess, or steam cleaning.

f. Replacement of Header Tube:

c. Preparation of cracks, fractures, and areas

(1) Clean in accordance with a above.

having metal missing:

(2) Plug all parts to prevent entrance of con-

(1) Use dye method to determine length of

crack, if not visible.

taminants.

(3) Saw-cut each end of header tank.

(2) Drill 3/16-inch stop holes at ends of the crack

or fracture.

(4) Saw-cut each end of tube for removal.

(3) Mill or grind out cracks to provide a "V"

(5) Remove remainder of tube by reaming.

aperture.

(6) Saw-cut one end, as shown in Figure 1, to

*This Bulletin supersedes TB 9-288, 10 November 1959.