engine diagnosis

[jacobsond]

I have the valve cover off. I found a little chunk of something hard on the sidewall under the valve cover. Carbon or something similar. I'm going to get some stronger stuff for a flush but will not be running the engine with it in there the 1st time through. Going to see what comes out of the crankcase 1st.Hopefully nothing shiny. Flush until oil runs clean. Then fill with clean oil maybe a little of the engine flush stuff. Run for a short time drain and refill with the 10w30 which I believe is the recommended oil. Synthetic my have loosened 30+ years of something and stuck the oil ring. There are no external leaks anywhere. No hurry on the repair. We have the club car now. Still I like my old G9. Engine tear down may be in its future.

[meimk]

You mentioned earlier the fact that Yamaha only spec'd a valve guide seal on the intake side. I have found that to be true in several of the Yamaha engines. However, I did have a customers G-16 that smoked worse than the mosquito fogger at the lake. Replaced the intake valve guide seal AND installed one (same part#) on the exhaust side. Smoke was gone - after running it long enough to get the oil cooked out of the exhaust.

[CP241]

Originally Posted by jacobsond

I have the valve cover off. I found a little chunk of something hard on the sidewall under the valve cover. Carbon or something similar.

Could you post a picture? IF it really is a hard chunk of something, I would investigate this much further. I can't think of a circumstance where there would be anything resembling carbon inside the head or engine case. Engine sludge can be pretty solid/chunky but not "hard" if that makes sense. The only thing I can think of is that perhaps your valve seal hardened up and broke apart.


As I am typing this, this actually makes quite a bit of sense. This would also explain the significant oil consumption and smoke all of the sudden. Rubber hardens over time, and eventually can crack and break.

At this point, it's as good of a theory as any

[raydhd]

It was my impression that stock yamahas and clones do not have a valve seal on the exhaust valve as the heat would degrade it. Special Viton seals can be had for the clone to withstand this heat. I don't know about doing this on a yamaha.

[jacobsond]

I have the intake valve seal and will put it on when I reassemble. I hope this weekend. If the honey due list does not get to much in the way. I will post any results when I get it going again.

[jacobsond]

Ok now I am up for the dumb A award. 1st didn’t check oil like I should and almost ran it out.2nd didn’t remember where the 1qt line on the dipstick was. Everything back together. Valve lash good.Compression good. Leak down test good. Drain the oil to get a fresh start. Guess how much oil I got out. 1 3/4 qts. Yep 3/4 over. Now who is the dipstick? Me of course. The 1qt mark on the dipstick is only about 1/2 way up on this cart. Not the top of the range like I had it. So no wonder it was smoking up a storm. I still think its using some oil. There is a slight puff at start up.I will monitor closely. Maybe some new rings for a winter project.

[villebacker]

For what it's worth I had the same thing happen on my 1993 Club Car. Always used conventional oil, didn't smoke or use oil. Changed it to synthetic and every seal started leaking oil and started burning oil. Had to do a complete overhaul. A friend asked me to changed his oil in his Yamaha and he provided Mobil 1. Within 2 weeks he had a puddle of oil underneath it 18" in diameter. I wound up overhauling it also. From my experience if it is an older cart and has always had conventional oil don't change it to synthetic.

That being said I now have a 2017 Yamaha with 200 hours and has oil changed once with Yamalube and now due an oil change. Don Plowman assured me I shouldn't have any problems going to synthetic but still hesitant to do it from my past experience. With the newer cart and relatively low hours I may try Mobil 1 but with my fingers crossed

[jacobsond]

Just a follow up on this old post. I ended up putting new rings on to solve the issue. The piston was on the high end of the tolerance but the ring gap was good so I just put the rings on. It runs great now. Sadly I had to let it go. To may toys in the shop. My daughter has it now. She could not be happier with the cart.

[SandbaggerYDRA]

Originally Posted by villebacker

For what it's worth I had the same thing happen on my 1993 Club Car. Always used conventional oil, didn't smoke or use oil. Changed it to synthetic and every seal started leaking oil and started burning oil. Had to do a complete overhaul. A friend asked me to changed his oil in his Yamaha and he provided Mobil 1. Within 2 weeks he had a puddle of oil underneath it 18" in diameter. I wound up overhauling it also. From my experience if it is an older cart and has always had conventional oil don't change it to synthetic.

That being said I now have a 2017 Yamaha with 200 hours and has oil changed once with Yamalube and now due an oil change. Don Plowman assured me I shouldn't have any problems going to synthetic but still hesitant to do it from my past experience. With the newer cart and relatively low hours I may try Mobil 1 but with my fingers crossed

That's interesting, and a nod back to old rumors (facts?) when synthetic oil first started to become widely advertised for use in automobiles. The wisdom back then was that if you switch to synthetic, it would cause the seals to swell up, and if you then switched back to conventional oil, the seals would leak like a sieve. Presumably, newer cars have migrated to seals which are less affected by the type of oil. I have been a faithful user of synthetic oil in my cars, trucks and boats for the last 30 years without a leak issue. But I also have never gone back to conventional oil either. It's possible that the seals used in these golf carts could be more susceptible to the effects of synthetic oil. But many people use it with no issue. So maybe it's also related to the age and hours on the engine.

[villebacker]

I was talking with a friend a couple of days ago about the issue of changing to synthetic oil on his Yamaha cart and he had the same experience. It started leaking and using so much oil he had to overhaul his also. If it is a small engine and I don't know if it has been running on synthetic I am not going to put synthetic in it.

That being said I went ahead and put Mobil 1 in my 2017 Yamaha with 200 hours on it Sunday. I have played 4 or 5 rounds of golf with it since. I need to check and see if it is leaking anywhere now. With all the extra insulation of the Quietech technology it wouldn't show up for a while unless it is leaking real bad so probably can't tell anything.