Hey all, I have an 88 cutlass 307Y burning oil bad.. I'm thinking valve seals. Have any of you guys run into any other common problems that could cause this? I don't think its a leak because I check underneath periodically and I don't see drips/leaks anywhere. Thanks guys.

 

Valve seals usually only smoke when first started, as the valve train gets only a small amount of lubrication.
Heavy amounts of oil burning indicate worn rings.
The oil control ring(middle) is supposed to keep oil in the bottom end of the motor by scraping the cylinder walls.
Internal overheating of bearings and other parts cooks the oil creating excessive blow by.
How do your plugs look?
They will tell the story.

 

Also make sure you have a baffle on your PCV valve. If you have stock valve covers, pull the PCV valve and make sure you can't see the rockers.

 

I had a 72 Cutlass, back in 1985 or so. It smoked so badly the tune-up shop I worked at wouldn't allow it inside the shop. Managers specific instructions were "change the plugs and get it gone - no warranty." The owner brought it in every few months for a new set of plugs.

Eventually, he offered to sell it to me for $50, and I took it. Took it home, did a more complete tune-up -- and it turned out the PCV valve had disintegrated. There was just a plastic shell left. I put in a metal PCV valve, and the smoke disappeared almost completely.

I later put in a cam/lifters/ timing chain, and scraped about ten pounds of horrible, nasty sludge out from under the intake...

Otherwise it ran great! Sold it later for maybe $1200 or so, and still wish I hadn't.

 

Here's the things I would check:

1. PCV Valve working properly and the vacuum hose going from the pcvc valve to the carb is not collapsed.

2. Check for excessive blow by. Take the oil cap off when running to see if you are getting large amounts of smoke coming out.

3. Pull the valve covers and check to make sure the oil return holes are not plugged up. If the oil is not draining back properly, it will pool up in the heads and make its way down the valves and into the combustion chamber.

4. Replace the intake manifold gasket.

In my case, I was going through a quart of oil every 200-300 miles on an engine that had 162k on it. I found that the oil return holes were plugged in the heads and my intake manifold gasket was shot as well. Once I cleaned out the return holes in the heads and replaced the intake gasket, it runs great and burns no oil.

 

Valve seals or valve guides, even worse piston rings!

Start w a compression test and check spark plugs!

 

One other thing to look for is plugged oil drainback holes in the head. If the engine was poorly maintained, you can get sludge in the motor that will clog the oil drainback holes. Oil puddles in the valve cover area and ends up being forced past the valve guides. Of course, by the time this happens, you'll also see a large leak from the valve cover gaskets.

 

Mine was smoking badly. I opened the valve covers and saw that the umbrellas seals had crumbled into small pieces that were blocking the oil return holes.

Oil would drain back, but at higher rpms (like 2500), the oil would fill up the rocker area, leak into the valve guide holes and cause the engine to smoke a lot.

I cleaned up the debris and that opened the drain holes, and this helped tremendously, but eventually, I had the engine redone and the problem was solved. Luckily, we had no oil starvation issues or spun bearings because I drove like a grandma during that time, but with possible oil starvation in the pan, it could have been a really bad situation.

 

Once, while replacing the PCV valve, I noticed that there was no vacuum to the valve at any rpm. It turned out that the PCV vacuum port in the base of the fuel injection body was solidly plugged with carbonized oil fumes.
I had to remove the fuel injection base to gouge out all of the crud . It took a while ! Meanwhile, all of the crankcase blowby was coming out of one rocker cover hose and blowing into the air filter housing. That is supposed to be a fresh air intake for the PCV system, and not a blowby exhaust .

 

Mine is burning oil form the manifolds