Lincoln Engine >> UNUSUAL ENGINE PERF. CAUSED BY DEFECTIVE EXH. SYS.

Lincoln Engine >> UNUSUAL ENGINE PERF. CAUSED BY DEFECTIVE EXH. SYS.

Unusual Engine Performance On Late Model Cars
Caused By Defective Exhaust Systems


This bulletin is a reminder that defective exhaust systems cause unusual engine performance. A few recent case histories will emphasize the need to be alert for this problem:

(1) A Ford 6 cylinder OHV engine would not idle properly after the installation of a rebuilt engine. After many hours of testing, another short block was installed with the same results. Finally, the exhaust pipe was disconnected and the trouble
disappeared.

(2) A Buick V-8 would run well up to 45 mph then flatten out. After checking every tune up possibility with no results, the exhaust system was checked and the trouble found.

(3) A Cadillac made a screeching sound at 2200 rpm. A new converter and transmission overhaul failed to change matters. A new exhaust system cured the trouble.

(4) A Mustang 4.7L (289 CID) would run well at road speeds for 2 or 3 miles, then lose power. A scope indicated perfect tune, but the trouble continued until a new exhaust pipe was installed.

(5) A Lincoln had peculiar noise that would not go away until the exhaust pipe was changed. The inner pipe had burned through, allowing a piece of tubing to flutter like a faulty heat riser valve.

(6) An Oldsmobile ran like the camshaft was worn, but upon removal, it was found to be good. The exhaust system was changed to eliminate the problem, and, after cutting the old pipe, the cause was obvious. The inner pipe had closed down to provide an opening the size of a nickel.

(7) A 1966 Chevrolet 5.4L (327 CID) ran well at town speeds and checked out perfectly on a scope. At 2600 rpm, however, a total loss of power occurred. The cause was a collapsed inner pipe.

Case histories prove the need for service men to be cognizant of the problems caused by double wall exhaust pipes. The high heat generated inside the inner tube creates a metal fatigue that may result in deformities. Internal muffler deterioration and carbon build-up can also cause poor engine performance.

Inner pipe problems usually can be detected by puttiong the car on a hoist. With the engine running fast, listen along the length of the exhaust pipe. An obvious noise can be detected if the inner pipe is bad. The location to check first in pipes hooked to a V-8 with a single exhaust is just behind the Y of
the two pipes.
The AERA Technical Committee

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