Blown valve seal

[Matthew Stuart]

These heads were just reworked 1,500mi ago when motor reworked.I think I Lost cylinder #5 seal. Got to be a workmanship issue. Do I have to pull the head to do this. What would you all recommend. Just have oil on that one plug and water and oil in car staying up ok. Car runs fairly well but will start smoking when up to temp. I'm still driving it back and forth to work about 2mi. each way. But that's all.....

 

[KendallF]

If it's smoking when the car is up to temp I doubt if it's a valve seal, unless the guide is extremely worn as well. Sounds more like a ring problem, IMO. I would do a compression check, or better yet, a leakdown; if it checks out OK then pull the valve cover and inspect the valve seals. You can usually see the seals decently through the valve springs (stock heads have seals on intakes valves only). If you want to check the guide for wear, you'll need to remove the valve spring (see www.gnttype.org for a valve spring changing article) and wiggle the valve in its' guide.

Good luck!

 

[Matthew Stuart]

leak check

Kendall......I am ignorant on leak checks....would you send me the right direction for that procedure. Thankyou. I know that is what I really need to do before I tear it down....again!!

 

[Buick From Hell]

While my car is far from being a 1500 miler at the moment, MY #5 cylinder just POURS oil thru the valve(s)...before I spun the bearing, changing that plug was necessary at every oil change! With the exception of my #2 (which oils the plug, but FAR LESS), all other cylinders are oil-free!

I mention this only because I've heard the #5 is famous for doing this!

 

[KendallF]

Re: leak check

Originally posted by Matthew Stuart
Kendall......I am ignorant on leak checks....would you send me the right direction for that procedure. Thankyou. I know that is what I really need to do before I tear it down....again!!

I think you should go see a mechanic for this, probably. I'll briefly describe each procedure though; they should be performed with the motor warm for best results.

A compression check is done with an air pressure gauge that screws into the sparkplug hole. Remove all plugs, disconnect ECM, turn car over 3-4 times; note psi reading on gauge. All cylinders should be within 10%.

Leakdown: A leakdown uses two gauges and an external air source; one hose is screwed into the sparkplug hole and the other is connected to a compressor. Cylinder being tested needs to be at TDC so valves are closed and piston is at a consistent position. You can remove the rocker shafts to make sure the valves are closed. You measure the difference between the two gauge readings to determine what % the cylinder is holding. Maximum acceptable leakdown should be less than 10% for a fresh motor (3-5% for a race prepped motor).

HTH,

 

[Matthew Stuart]

Thanks Kendall........How's Jax...I just moved from St. Aug in June. Company had me on the beach (Anasthasia) for a year....now I am land locked again....BUMMER.Thanks again..!!!