VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 Engine Problem

My 1952 Styleline Deluxe 4-Door is equipped with a 1954 F54Z (adjustable valve lifter) 235 engine, and a single speed Powerglide transmission. While driving recently the engine suddenly developed a metallic rattle that is worst under load and almost nonexistent at idle or going downhill. Since acquiring the car 21 months ago I have driven it almost 3,000 miles with no engine problems. It doesn't use oil (10w-30), has hight oil pressure, and the spark plug contacts are all a light brown indicating a good fuel/air mixture.Since the problem developed a compression check is as followa; #1-135, #2-40, #3-135, #4-140, #5- 135, #6-137.Since the problem developed I have noticed a slight engine miss probably due to the low compression on #2 cylinder. The valve tappet adjustments are according to specs on all cylinders. Since the low compression on #2 appears to be associated with the engine rattle what should I look for after dropping the pan?

Would the #2 piston be cracked or broken?

First I would try lubricating the valve guides on the low cyliinder if it is a valve sticking. This can be done by removing the air cleaner and pouring some Marvel Mystery oil or ATF into the throat of the carb. with the engine running at a fast idle.

#2 disconnect the spark plug wire on that cylinder and see if it changes them noise. If it does it is probably a piston. Those 235's did not really have broken piston problems with te original pistons. Your aged engine may have been rebuilt with inferior pistons.

I don't know for certain but I believe the engine was rebuilt,or at least overhauled, not long before I purchased the car.
The valves on the #2 cylinder are seating s the problem most likely involves the piston as both of you suspect.
Can the pistons on this engine be removed and replaced from the bottom without removing the cylinder head ?

Thanks for the information.
Fred, VCCA#52403

Try airing up that cylinder will tell you whether valves are leaking intake or exhaust or piston if hissing is in crankcase.

The connecting rod must be "un-done" and the rod and piston pushed up through the top.....yes, head has to be removed which is not a bad job on a 235.

Can not suggest what end to start on - top or bottom. Dropping the pan and checking the rod bearing and pulling the piston down to see the lower part of the skirt may be the best. Also possible that there is something rattling aoround in the combuston chamver or the piston did a melt down in the ring area. causing the low comperssion or even a valve problem.

I appreciate all the forum response to my post. All good. Now I have to decide whether, at age 86, I still have the energy and desire, to tackle the job myself, or to let someone else do the work. it is not an easy decision since I have been working on antique and classic vehicles for over 60 years. I will let you know what turns out to be the problem and what was done to repair it.
Many Thanks,
Fred, VCCA #52403

I wonder if a look with one of those cameras with the flexible, hose like lens attachment might tell you something going in through the spark plug hole? Maybe someone you know has one?
Dave

Fred, I am your age and know what you mean......best of luck to you and your problem.

If you don't have a lift then start on the bottom, the ground is only going to dirtier once the head comes off

Fred, if you make the decision to "farm out " the job, be CERTAIN the mechanic you choose has EXPERIENCE with these 235 engines.

A good source for mechanic recommendations could be from a local VCCA region or local antique car club.

If you decide to tackle the job, have your GM ISSUED CHEVY SERVICE MANUAL 1949 to 1953, with 1954 supplement at your side.

Some young car enthusiasts with strong backs could be your assistants.

Good luck with your project.

I have worked on the 235 engine, although not in recent years. My head says I can still do the job but it's the rest of me , at my age , that is resisting. Fortunately I have a friend who has been running a local 3 man repair garage for many years. He is a Chevy man from the old school and is very knowledgeable om the 6 cylinder Chevy engine. Even if he assigns my car to one of his men, he will supervise the work. I have the 1949 to 1953 manual with the 1954 supplement and will leave it in the car for his use.
Will keep you posted.
Fred

Sounds like a good plan, Fred.
Keep us updated.