62 lesabre with odd compression readings. (50-60psi)

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Brandonbuick

Member
Hello fellow Buick people! I recently purchased a 1962 lesabre with 80,000 miles. So far she runs ok and seems to have a lot of power going down the road but the compression test I did today stumped me. The highest reading I got out of all 8 cylinders was 60psi and it varied roughly from 60-50psi amongst the others to lastly 40 on number 1. This seems very off considering I’ve read it can be anywhere from 160psi to 180psi. I was told by a buddy it could possibly be the timing has jumped a tooth or it has nylon timing gears? Something along the lines of the valves are not closing. Please help!
 
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If the timing chain jumped and someone adjusted it to run, the the timing marks will be way off. I had one like that and the top piston rings were all broken due to severe wear with taper in the cylinders causing the rings to flex; it also had a ridge at the top and bottom of the cylinders.
 
322bnh said:
If the timing chain jumped and someone adjusted it to run, the the timing marks will be way off. I had one like that and the top piston rings were all broken due to severe wear with taper in the cylinders causing the rings to flex; it also had a ridge at the top and bottom of the cylinders.
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That would make sense. Is there an easy way to check for that without removing the timing cover etc? I have seen it recommended to remove the distributor cap and put a wrench on the crank, then see how far you can move the crank before the distributor moves? I am planning to pull off the fuel pump and check for the nylon coated timing gears as well.
 
Like Tom stated go with easy stuff first. Do you have a Chinese compression tester set? Is the tester hose leaking? Do you know how to properly do a compression test?
You stated it has power and is running. 60 psi the car wouldn't be responding that way you stated unless you are going downhill, down the road. All this other stuff nylon gears and timing is for a car that is running poorly.
 
Hi, Brandon - Dave here - I will be very interested to hear what you eventually find as the cause of this low compression phenomenon...

I have a 1959 LeSabre with the 364, and it also has 60-40 psi on all cylinders, however runs smooth and quiet and drives OK

I check the compression as a routine thing every car I buy; and this one is extremely low; most healthy engines have 140 plus IME

I am not sure you said what engine you are dealing with however guessing its the 401...
 
i had the same thing with the 70lesabre that sat 20yrs i just bought. mine was a bit higher. did a dry and a wet test about the same. snap on tester. checked the chain all good. went ahead and fired it up and ran like a top. thing the ring may have been stuck and they freed up with fresh oil and running for a while. next you try a cylinder leak down test.
 
So gentlemen, I figured out I had used the wrong hose on the compression tester (cornwell tester) as Tom T and G03 suggested start with the easy stuff LOL. The hose I had used was one with a shrader valve inline and was for pressurizing the cylinder. So that explains that. Did a cold compression test this morning with the correct hose, (5 cranks, ignition disabled, Throttle all the way open, dry) and found it to have compression from 125-140 at best all around which I am satisfied with at least for cold. I have done an oil change to some heavier oil and poured some marvel mystery oil in each cylinder. I will try to run it longer and bring the rings around once I have more than likely replaced the radiator which is giving me trouble.
 
Canadian Buick Mogul said:
Hi, Brandon - Dave here - I will be very interested to hear what you eventually find as the cause of this low compression phenomenon...

I have a 1959 LeSabre with the 364, and it also has 60-40 psi on all cylinders, however runs smooth and quiet and drives OK

I check the compression as a routine thing every car I buy; and this one is extremely low; most healthy engines have 140 plus IME

I am not sure you said what engine you are dealing with however guessing its the 401...
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Dave, I do indeed have the 401 motor, I believe the “economy” option. I am not too schooled on the differences between that and the 364 yet but I hope to learn more about these Buicks as I work on mine. If it has good power and drives ok I’d be interested in the valve timing at best. I’m new to this all buddy sorry if I can’t be much of a help.
 
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