Piston Rings or Valve seals...

[StangLou]

...

I wonder which one my culprit is?

For the last week or so, Ive noticed some blue smoke out the exhaust whenever the car goes above 3500rpms or so. During startup there is no bluish tint to it, during normal driving I can not see anything either, but whenever I mat it to downshift, I get a nice blue cloud behind me. There is a slight loss in oil, I put in around a quart every 1000 miles or so, but I credited that to the bad oil pan gasket leak I have.

For the hell of it, down time at work at the moment, I just went outside to see if there is any oil in the intake. After I took the tube off the TB there were a few droplets of oil outside the TB blade, on the side of the air filter, not the intake. The inside felt slightly oily, but no visible oil puddling.

My oil pressure has been fluxuating a bit, but I put a new oil pressure sending unit on, have a new oil pump, and oil pan gasket seal going on it next week to fix the leak I have. Not to mention the extra $800 in suspension I have going on as well. For what its worth, there is no pressure build up that I noticed from the engine. After driving it for 30 mins this am I pulled into work, cut it off, and took off the oil cap to see if there was a pressure build up. No hiss or nothing.

Oddly enough, this comes after a Cobra upper/lower intake swap. I never had any issues before the swap

Guess my next investment should be a rebuild? Any ideas on what could be the guilty party. Either one would/will require a rebuild, but Im just curious. Could the PCV be going bad? I took it out and shook it, it rattled, so I figured its still good.

 

[Jack's95gt]

It is good to do some troubleshooting first. Pull and plug the vacuum line going to the PVC valve and drive around like that for a while and see if your blue smoke stops and your oil comsumption goes down. If it's still the same, then do a compression test. Bad valve seals would give the most smoke when you just start the engine after the oil seeps in the cylinders.

 

[StangLou]

Im going to buy a compression guage friday and hopefully check the compression on all cylinders Sat. Is there a write up on here about how to do this properly? Ill do a quick search and see what I find...

 

[bill302]

check this out. click on link.

http://www.geocities.com/SiliconValley/2072/carcomp.htm

 

[JMD Engineering]

chances are:

- when car in NOT under load; and blue smoke is apparent- its piston rings.
- when car IS under load; and blue smoke is apparent- its the valve seals.

 

[mcclean]

You made sure screen and deflector for pcv valve under lower intake was there right?? Just clearing obvious. Its either that or valve seals.

 

[StangLou]

You made sure screen and deflector for pcv valve under lower intake was there right?? Just clearing obvious. Its either that or valve seals.

I reinstalled the black plastic "fitting" that the pcv goes into on the Cobra Lower. There was no screen to start with under the pcv valve. It was so gunked up back in '00 it was a solid black sheet. It was causing a massive build up of pressure in the engine. Oil cap would almost shoot off if you didnt have your hand securely on it. A guy I worked with told me to check that screen. Sure enough it was clogging the pcv. We couldnt find a new one so it was left out. Never had any issues with it from '00 till now. Guess I could try and track down a new screen and give that a shot...

Keep the ideas coming

 

[Black1987Stang]

if it wasnt doing this with the old intake and just started doing it once u put on the Cobra intake then why do u think its the rings or valve seals? ya know Do a compression test and go from there

 

[2002BLGT]

StangLou , put the breather screen back in the cobra intake , you can get one at a parts store for like 3 bucks ..... and also , get a cheap breather filter that will clamp on a 5/16 -3/8s metal line ....and clamp it on under your oil cap and then put a vacuum cap on the pipe coming out of the throttle body .......if this doesnt fix it , I would say pull the heads and get a lap job done on the valves , new valve stems seals and buy a set of the cheap edelbrock replacement valve springs .....they about 60 bucks I think .....now would be a good time to start looking at some cast iron gt40 heads on ebay if I were you .....its not the rings ....if it were the rings it would smoke all the time .......

 

[Rick 91GT]

I would first put the screen in, then so a leak down and a compression test (both wet and dry) this will tell you the condition on the motor.