valve stem seal?

[98COBRA281]

A common test is to run on the highway, remove foot from accelerator which produces a strong vacuum in the intake. After a few seconds, punch the accelerator and see if you get a puff of blue smoke. If so, blame it on the valve seals and replace them... They can let vacuum pull oil past the seal which lets it run down the intake valve and into the combustion chamber when it will produce smoke...

no that dosent happen, it pretty much stopped after i changed the pcv, even if they are a little worn, i just bought all new pi intake, exhaust, head, valve stem,valve cover,and timing cover gaskets for my head swap

 

[BobHyatt]

3 things.

1. Them being $18 and you having stuff apart make no difference. You cant replace the seals with the valves in there, so the head has to come off - all the money is in the labor. And having the cams off wouldn't shorten this process.

2. If the seal is leaking then when the car sits the oil that puddles at the seal to lubricate the next start up would run down the valve to the valve neck, and would burn almost all at once at start up (if you need a vid of my bro's supra i can make one, lol). During idle once warm there would be no/very little blue smoke

3. 1/2 quart ever 3k miles is fairly usually for these cars. I agree might be piston rings or pcv.

Head does not need to come off. Here's the procedure...

1. position #1 at TDC, and use air pressure thru the spark plug hole. 30-40psi will hold the vavle closed just fine. There is a special tool you can use and avoid removing the camshaft completely. It uses the cam as a fulcrum point so that you can depress the valve and remove the follower.

2. using this tool, you now depress the valve spring, letting the air pressure hold the valve up. Remove the two keepers, the retainer, the valve spring, and then lift the "perfect seal" out.

3. Insert a new seal, followed by the spring, the retainer and the keepers. Repeat 15 more times and you are done...

All without removing the head or the timing chains/cams...

 

[CobraRed_96_GT]

Head does not need to come off. Here's the procedure...

1. position #1 at TDC, and use air pressure thru the spark plug hole. 30-40psi will hold the vavle closed just fine. There is a special tool you can use and avoid removing the camshaft completely. It uses the cam as a fulcrum point so that you can depress the valve and remove the follower.

2. using this tool, you now depress the valve spring, letting the air pressure hold the valve up. Remove the two keepers, the retainer, the valve spring, and then lift the "perfect seal" out.

3. Insert a new seal, followed by the spring, the retainer and the keepers. Repeat 15 more times and you are done...

yeah, i learned about the air pressure. And i know about about the fulcrum tool - using it right now locating a collapsed cam follower that's making a ticking noise. So i have to pull each out and find the faulty one.

 

[BobHyatt]

well its still doing it... i have now noticed that it does not smoke when its reved or first started, it only smokes as the rpms drop down from a rev, the pcv is not stuck but there is alot of oil in the pcv hose, i am woundering when the throttle body closes after a rev, does the iac open up right away? im think it is sucking the air through the pcv for a second or two and that why im getting it only as the rpms drop?

as the motor is slowing down, you have a high engine vacuum. Certainly sounds like seals on the intake valves leaking... Isn't going to be oil on the cylinder walls getting by the rings most likely, given your description.

 

[98COBRA281]

as the motor is slowing down, you have a high engine vacuum. Certainly sounds like seals on the intake valves leaking... Isn't going to be oil on the cylinder walls getting by the rings most likely, given your description.

yeah i not rely worried about it since i will be doing my heads swap in the next month or so...i dont think its rings because i had 195-200psi on the compression test

 

[nyuk98gt]

98COBRA281:

Before you jump right onto the seal-changing job you should wait a while to let the accumulated oil leave the intake. If the PCV valve was stuck open and a lot of oil came into the intake, there will be little pools in all of the low spots and it is going to take some time to get it all out. You could use a product like Seafoam (but be careful how much you bleed in at any time since it is a liquid and not compressible (i.e.--too much will 'hydrolock' your engine). I haven't used the stuff so I can't tell you if it will work but it is supposed to be a pretty good cleaner. Personally, I'd just let the oil work itself out over time.

HTH,

Chris

 

[98COBRA281]

98COBRA281:

Before you jump right onto the seal-changing job you should wait a while to let the accumulated oil leave the intake. If the PCV valve was stuck open and a lot of oil came into the intake, there will be little pools in all of the low spots and it is going to take some time to get it all out. You could use a product like Seafoam (but be careful how much you bleed in at any time since it is a liquid and not compressible (i.e.--too much will 'hydrolock' your engine). I haven't used the stuff so I can't tell you if it will work but it is supposed to be a pretty good cleaner. Personally, I'd just let the oil work itself out over time.

HTH,

Chris

well i not going to change them because im doing my head swap soon, and have all new gaskets and seals