[senseless]

Hi - I'm looking for a diagnosis for my sick Catalina.

Engine is a 68 YC 400, approx 75K miles, runs a little crappy and blows oil out the dipstick.
No exhaust smoke, no lost coolant, just smoke from oil running down the hot manifold.

Compression #'s

pass side, front to rear = 195, 185, 175, 195
driver's side = 135, 135, 145, 25 (!)

25psi cylinder doesn't improve after squirting some oil in there.

Just wondering if I'm looking at a valve job or worse?

Any ideas would be greatly appreciated.

Thanks!

jeff

[Malky]

Strange how the passenger side #'s are consistently high, and the drivers side are low. Do you have the identical heads on each side?
Any chance throttle plates closed when you were doing driver's side?
If you have dual exhaust do you have oily soot in driver's side tail pipe?
You seem to have 2 problems, a bad valve on the driver's side and a mysterious low pressure on all driver's side cylinders.
If you get hold of a leak-down tester, it works really well at pinpointing the problem, especially the bad one - rings, intake valve, or exhaust valve. It needs a compressed air supply. You pull each plug, connect air supply, and basically pressurize the cylinder. Listening for loud hiss at carb, exhaust pipe, and dipstick tube pinpoints if rings, or which valve is leaking.

[My64GTO]

A friend had the same problem. When he got "agressive" with his car it would pop out the dipstick and spew oil all over the engine compartment.
He changed the oil, substituting a quart of Marvel Mystery Oil for a quart of regular oil.
He drove it for about 500 miles and changed the oil again. It seems to have fixed the problem for him.
You may also want to increase the bend on the dipstick so it sits in the channel a little tighter.

[BillyGoat]

Blows oil out the dipstick sounds like a clogged PCV. A 25# cylinder sounds like a burnt valve. I would start there.

[Blue '66]

When I bought back my '66 GTO it had alot of blow by.The engine compartment was covered with
oil crud.When I tore the engine down the rings in one of the pistons was broken in several places.So you may have to do more than a valve job.

[senseless]

I was thinking PCV too, but the valve itself is new and rattles nicely. The hose is clear, so I'm thinking there's some blockage at the dark and scary end of the PCV valve, but I'm not really sure what's down below that could be clogged.
I'll try the Marvel Mystery oil just to loosen everything up, but no way I can go 500 miles. It starts smoking and stinking after one trip around the block.

many thanks for the help so far!

Jeff

[gtochism]

if you have 25lbs in one cyl, and it did not come up when you added oil you have a bad valve in that cyl. just becouse the pcv rattles doesn't make it ok. could be crud behind the spring in it. make sure it is the correct one for your year engine. check for good vacume by putting your finger on the end of the valve while the engine is running. i've always used the rule "if the variation between cylinders wasn't over 15lbs" it was ok for a stock engine. past that you get a rough idle. pull the head, valve job time.

[Kenth]

Congratulation, you´re about to restore a nice Pontiac engine

[senseless]

Hi - I'm looking for a diagnosis for my sick Catalina.

Engine is a 68 YC 400, approx 75K miles, runs a little crappy and blows oil out the dipstick.
No exhaust smoke, no lost coolant, just smoke from oil running down the hot manifold.

Compression #'s

pass side, front to rear = 195, 185, 175, 195
driver's side = 135, 135, 145, 25 (!)

25psi cylinder doesn't improve after squirting some oil in there.

Just wondering if I'm looking at a valve job or worse?

Any ideas would be greatly appreciated.

Thanks!

jeff