Possible engine going to blow up. Need advice

[mgusciora]

Well I don’t wanna be making this but here I am. My 86 350x runs great but right when you start it it smokes pretty bad. Thick white oil smell smoke for probably 2 minutes then it’s none and normal. Today I went to start it and it just wouldn’t. Usually will go in 2 kicks. It is very cold out but it started yesterday. Ten I got to looking and found oil on the side cover.... wiped it up and got it started. Did the smoke thing but didn’t see any leaks. Now that story time is over hahah. What do you guys think about the smoke. Rings? Head gasket? And the oil on the side? There is an exhaust joint right above so might leak out of there? Any advise is great!


~Matt Gusciora

[lndy650]

valve seals. your gonna have to do a tear down and there may be other things that need replacing but id say valve seals for sure

[mgusciora]

valve seals

That would make sense where are they? I also did adjust valves but is smoked before then


~Matt Gusciora

[lndy650]

to do it right your going to need to remove at least the whole cylinder head and id recommend popping the cylinder off too and checking the ring and rod bearing clearances. we can help you step by step if you need it ive rebuilt dozens of 350x engines and theres others here that really know their stuff.. the valve seals are underneath the valve springs on the top side of the head they keep the oil in the valve cover from trickling down the valve stems and into the ports. when the engine sits not running the oil pools up thus the smoke cloud when you start it.
if you pressurize the cylinder it can be done by only taking the valve cover off but i'd recommend a full top end tear down to check everything else out.

[knappyfeet]

i'd recommend a full top end tear down to check everything else out.

Yea Indy is spot on.....probably valve seals.

I don't always do it but usually when the head comes off I like to do it all up.........like rings, gaskets, etc.....some head work, valve lapping. Since your already in there what's another hour worth of work.

Good luck.

[Shawn Powell]

I’m gonna agree with starting at the valve seals. My 87xl600r did the same thing. I automatically assumed rings. Got it apart and my seals where almost gone just dried up and broke. Checked my ring gaps all good. New seals and head gasket (unneeded but was already bought) and she ran great no oil burn. Good luck.


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[lndy650]

rings are a common go to when a four stroke is smoking but after all my years in this profession ive found its rarely bad rings. if an engine is taken care of and has proper oil changes there is always a film of oil between the rings and the cylinder. on four strokes you do have the oil scrapper ring but the oil barrier is still there. rings can wear out but its usually not the problem. in this case seeing as the smoke clears after a while id say its definitely not the rings.

[fieldy]

Will a sea foam treatment do any good on the head seals?

[Rob Canadian]

Will a sea foam treatment do any good on the head seals?

No. Once the seals are gone from heat/age they are done. Need replacement.

Yes I think the oil on the side case is from the joint leaking above it. A pic would help. If it just smokes during warm up and does not smoke after that I would also say valve seals. Honestly the treads topic is a bit off. I don't think she is going to blow up on you. May foul a plug though.

[lndy650]

ya thats true its not really in danger of blowing up but it should be fixed. i had a 200x i built before i had a sonic checker and when i ported it i broke through the valve seat on the intake and built the top up with epoxy. it was fine for a long time we had a tiny tach on it and around 200 hours it finally failed. it was my buddies by this point i built it to drag and honestly didnt think it would last nearly as long as it did. anyway it leaked pretty bad and he drove it around his house like that for well this was in like 2012 and last i knew he still drives it like that. its fast as hell but smokes like crazy lol. it will destroy his 250 polaris in a drag

[BarnBoy]

Have a 200M that used to do that. Smoke on start up then clear up. Now it just smokes all the time, so I guess I let it go too long. Good idea to get it fixed.

[BOB MARLIN]

I've also had that problem when switching to synthetic oil in an old 350x engine. Washed all the seals too good and they started to leak.