Need advice oil on spark plug #8

[STROKED_LX]

i posted this on other forums thought i would do it here too.

I been having misfire problem for a while, so today i checked every spark plug. Number 8 spark plug found wet with oil and carbon build up. I had my heads rebuild not too long ago. The valve seals are brand new. My only guess now is piston oil ring worn out in that cylinder.

My question is if i do a compression test would it reveal and confirm my worn out piston ring? What other things can i do to maybe fix this problem with out rebuilding it, i wont be able to take the bottom end apart for a while. is there a quick fix untill i can get to it? Im already running 15w/40 diesel oil. i have about 300K miles on the bottom end.

 

[liljoe07]

Yes a compression test would tell you. If the numbers you get on that cylinder are out of range % of the others, then that tells you that the Rings could be worn. You can add oil into that cylinder then do another Compression test on it and see if the Compression jumps up. If it does, then its a ring issue. Noway to fix it with out a tear down.

Edit: Wow......300k. Id say your lucky you only have one cylinder thats giving you problems. I rebuild is almost certain for that mileage.

 

[STROKED_LX]

Alright thanks, ill give the wet compression test a try. Im also pretty sure the ring is done. Wish i could drive it little longer before tear down.

Is it possible to remove the piston from the bottom with the engine still inside?

 

[54deuce]

Alright thanks, ill give the wet compression test a try. Im also pretty sure the ring is done. Wish i could drive it little longer before tear down.

Is it possible to remove the piston from the bottom with the engine still inside?

The only way is if you dropped the K member but you have to support the motor from the top so there is no point in doing it because it would take more time to do that then just pull the motor. So I would say no. You were able to do that on alot of your 50s cars just by dropping the oil pan and pulling the heads block staying in the car for changing rings.

 

[strtrcr50]

Do a leakdown test to see if it's the rings that are leaking.
If you do it the easy way, it wouldn't take you long or cost much to just swap cylinder 8 valve seals. I know they were recently rebuilt, but that doesn't mean the reassembler didn't f up a seal when he installed it. Use a leakdown tester to pressurize the cylinder with the piston at the top of the bore(in case you lose air pressure, the valve won't drop all the way into the cylinder). Take a socket about the size of the top of the spring retainer. Put it on top of the spring retainer and give it a smack with a hammer. This will release the valve keepers. Remove keepers, retainer, and spring. The leakdown tester pressure will keep the valve against the bottom of the head. Change the valve seals. Reinstall the spring and retainer. Place the keepers into place. Put the same socket on the retainer and push down by hand. This might take a few times, but the keepers will drop into place. You will be able to see if it worked right by comparing against the other valves.
Congrats. You have just changed valve seals without pulling the head.

PS. Plug all the oil return holes in the area with rags, and hold the socket down against the retainer while hitting it with a hammer. Ideally, you'd like the keepers to stay right under the socket. Also, it doesn't take much of a hit with a hammer. Don't go crazy and try to win a carnival prize. Worst case, you don't want them going down an oil return hole.
IIRC, the last time I did this, I didn't have a leakdown tester, so I took the compression tester fitting and plugged it directly into an air line from a compressor. I can't remember if I had to change fittings or not.

 

[STROKED_LX]

54deuce - thanks, looks like ill end up having to just keep cleaning my plugs (sand blast) and driving it untill i can get the engine torn down.

strtrcr50 - yup i will be doing the leak down test and definitely check the valve seals make sure they were installed properly maybe the shop messed up with them. BTW i have a valve spring compressor that works with the heads on. Im sure i wont have any problem redoing the valve seals.