Can you tell the difference between worn valve guides or cracked rings?

[tmkaos]

Hi all,

My '92 has had a miss under warm up which disappears once warm. One cylinder only, #3 as you sit on the bike and go left to right. At the same time, it started to blow oil smoke in conjuction with the miss, which also disappeared shortly after the miss fades out. At the same time, I noticed a small oil leak on the front of the motor around the #3 header.

I've just spent a few hours fitting oil temp and pressure gauges as I'm getting a bit concerned about my 148,000km motor, and as I had to remove the headers and re-fit them it has shifted the seal point at the block between the exhaust and block, so as I warmed her up to check the gauge fittings for oil leaks, you can actually see huge amounts of oil being fired into #3 cylinder and going into the exhaust, blowing out around the header and running down the front of the block.
This has been the miss - oil drowning spark, and then burning off as the smoke once the leak disappears once everything warms up and expands.

So - worn valve guides or cracked rings on #3? What goes away once warm?

Any ideas?

Cheers,

Sad James

[Tiger]

...or maybe something as simple as worn valve guide seals 

John.

[Pat Conlon]

A compression test will tell you if it's the rings and/or valves, not valve guides, they are behind the valve seat.
If your compression numbers are low, squirt some oil in the cylinder, recheck the compression numbers. If the numbers improve from adding the oil, it indicates the rings are the culprit (oil seals the rings). If the compression numbers don't improve by adding the oil, that  indicates that the valves are leaking.
A leakdown test will be more accurate and pinpoint if you are losing compression from either your rings, intake or exhaust valves. You can hear it.

It sure sounds like your valve guide seals to me....RPM has some nice upgraded seals they offer for FJs.

[Alf]

If you change the valve seals, change the valve guides too. If not, even with new seals, the engine will spend oil again due to the worn valve guides

[Pat Conlon]

Yep, might as well lap and reseat your valves while you are in there....

[tmkaos]

Thanks for the replies guys.

As with all the annoying things in life this has cropped up with impeccably bad timing, we've just had a baby, so we are now single income and I have no time between being a Dad, full time work and part time study, and the bike is my only method of transport.. The big guy is laughing at me I'm sure..

I'll be heading around to a tame mechanic tonight to get him to give me a approximate labour cost to pull the motor down and diagnose it - I'll probably yank it out at home and give him the whole thing. Once he tells me what's up i can order the parts from Randy - for sure be cheaper than what he could get locally in NZ. Even if it's just head work required I think I'll pull the motor out, gives me a chance to do those motor mounts properly and fix a few other on going cosmetic and maintainence items..

I'll be missingmy Kookaloo for  few weeks I think..

James

[Pat Conlon]

Dropping the engine is a lot of work. Why not see what your compression numbers are first?
Maybe the rings and valves are fine and just your valve seals are leaking?
If you do need to pull the head, you can do so without removing the engine.

[tmkaos]

Ok so here's an update, and the bad news is my tame mechanic says it's the rings. Worn valve gear should smoke slightly on the over-run, and then billow a cloud as you gas away again, but it doesn't. It smokes and misses and spews large amounts of oil into the exhaust on cyl 3 constantly only til it warms up then all the symptoms disappear.
I'd like to tackle it myself but for all the reasons listed above there is no time so all I can do is a quick and dirty motor yank out, and deliver it to the mechanic. He reckons about $500 for labour, and then I did a quick estimate on Randy's site of goodness and I'm looking at another $500 easy worth of parts. Call it $1200 - $1500 because everything always costs more than you think and it might be back on the road. I'm sure when we look into exactly what we do need to buy, we'll find a few more things to replace in there. I'm thinking all the cam tensioners and valve springs etc will be toast too for the kms this thing has done...

Another FJ will cost me between $3500 - and $5000 for what I've got but no mods and less Km's.

Another bike - don't really want to buy something else -the only bike I've considered is FJR and the cheapest one I've found here is an '04 for around $13,000 - ouch!

I guess while it's out everything else will get done too, might as well try to future proof the poor girl for another 148,000km of abuse..