G9 smokes fouls plugs, possible top end oil delivery problem

[Rumblefish]

Hey guys I have 1994 G-9A that I need some help with. I think the engine ran low on oil this summer. Its always leaked or burned a little since we got it about 6 years ago and it was just overlooked. Have no idea how many hours is on this thing. It's been used daily to drive around the farm. It got worse recently and start visibly smoking and fouling plugs. I downloaded the service manual and i've read a lot about the g2-g9 motors on here.

Can someone tell me if the "oil delivery" clear plastic hose should be filled with oil? I pulled the valve cover because it was leaking a lot of oil and found the top end had no visible oil in it. Everything looked caked. Checked the valve clearances and they were off the chart .035+ so i set them to .004 as spec and cleaned up and properly rtv'ed the valve cover back on, checked for vacuum leaks and that oil delivery tube is not filling up.

Also it appears the exhaust valve stem seal is gone. The intake seal is still there (i can see the rubber with the little spring). The compression is 185psi cold. I pulled the carb, did a quick clean job on it, made sure the intake was tight and not cracked. After all that tonight it will start and run a lot better than it did but it's still smoking (blue-white smoke) a little. Do you guys think I have a bad piston oil ring and how do i fix the oil delivery to the top end?

Thanks in advance...

[Mike Mac]

A number of things need to be done here. But to start,check oil level, then clean the check valve in the rubber hose coming out of the passenger side of the valve cover. Then make sure all hoses are good (not cracked and sealing good). You need oil pressure first. then you need to clean all the burned oil off the cylinder head fins and cylinder so air can circulate around them to carry heat away.
Good luck Mike

[Mike Mac]

Phase 2, is more complicated. You will need to replace exhaust valve seal. And/or rings.
185#compression sounds high even for sea level alt. 170 to 175 is said to be normal.


Big guys, step in here, I'm sure I haven't covered it all.

Now watch, Smallblock will come in here and say "trust me, its a tail lite problem" or something, and somehow he will be right!

[Rumblefish]

When i started look at it this time it had burned down to add. I added about 1/4 of a qt and it's about 3/4 of the way up the dipstick. I don't like to overfill anything so i'll leave it there.

I thought about adding some kerosene to the oil like the old-timers used to do on engines that were gunked up inside, run it, dump it and put in exactly 1 Quart like everyone says to do on here. This thing goes through so much oil I dont know when we last dumped it because we were always adding new to it.

I checked the one-way vacuum valve per the instructions in the service manual. All hoses sealed up good and i even blocked off the top vent that runs to the air filter cover.

I checked the "oil delivery line" while the motor is running and there is no vacuum nor pressure there.

I'll clean all the oil off the head. Are these motors sensitive to overheating?

It was 185psi before i adjusted the valves. They were probably opening and closing late because they were more than .035 what my feeler gauge would read up to. There is a lot of carbon build up on the piston so that may be raising the compression too. I'll do another test when i go back out to the garage. Do you want a warm reading also?

[Mike Mac]

Ok fish, you sound pretty savvy. Since the big guys aren't here yet, I would take an air hose and blow small amounts of air through the oil hose back into the crank case (to blow any gunk out the oil tube.) Take the rubber oil filler cap off and hold a rag over the oil inlet while you do this. Make sure that whole section is unobstructed all the way to the valve cover inlet. The tube you want to blow out is located on the back of the crank case and the oil line runs up the back of the motor, on the outside of the cooling shrouding (but I believe you know that)!
There is another port on the front of the motor, and that maybe plugged as well.
No, these motors do not over heat, but if oil has run down and burned/caked and clogged the cooling fins, the motor can't shed heat, its gonna get hot!!
If it runs, lets get oil pressure first.

[Rumblefish]

Thanks i'm hoping i can figure out whats wrong with this thing. I looked at the breakdown for the valves/springs on the G2-G9 service manual and the exhaust valve doesn't show a seal.

I was hesitant to put pressure down that oil delivery pipe, not knowing where it goes inside the motor. If you don't think it will harm anything I could do that or find something to snake it out.

Where is the oil port on the front of the motor?

[Mike Mac]

There is only 1 seal on the intake, exhaust does not have one.
On clearing the oil supply tube, you could dismantle it and run a piece of bailing wire through it, (never had one apart, but I believe it is a port that the oil slinger throws oil into and vacuum pulls the oil up to the rocker galley. Or possibly crank case pressure pushes it up.
Locate the port on the front by following the hoses that attach to that line that the check valve is attached to. But if it runs decent, and you have fuel pumping from the fuel pump, that port is probably ok.

PS. I say small amounts of air because I didn't want you to blow oil all over the place out the oil fill spout. Or blow the rubber cap off.

[smallblock450sl]

Originally Posted by Mike Mac

Phase 2, is more complicated. You will need to replace exhaust valve seal. And/or rings.
185#compression sounds high even for sea level alt. 170 to 175 is said to be normal.


Big guys, step in here, I'm sure I haven't covered it all.

Now watch, Smallblock will come in here and say "trust me, its a tail lite problem" or something, and somehow he will be right!

I only said "trust me" one time (about a G2/G9 airbox) and I will only add...I always install valve stem seals on both intake and exhaust when rebuilding an engine, the head is machined for them Yamaha just installed the one on the intake (cheapskates!) As for the tailight coment....

[Rumblefish]

So since the Exhaust Valve didn't come with a seal from the factory and the intake seal is still in place, plus there's hardly any oil in the valves area, the oil smoke/burning is probably a bad oil ring. Is there a top-end rebuild kit for this motor? I have a hone, micrometer, some other tools i may need.. Is there anything out of the usual garage i would need?

I haven't been back out to the garage in two days now because i got sick so it may be a couple days before i go back out to work on this thing...

[Mike Mac]

Fish I would say, you probably did do damage. But its not gonna cost you anything to do what your doing.
Anyway,if it runs and if it were me, I would get oil pressure, then I would clean all the gunk off the head and cylinder fins to get air flowing around it. Stop the oil leaks, change to a good oil and run it awhile. It might clean it self up and run forever!!
IF you can't get oil press. then tear it down for a rebuild or put a big block in it, or third choice, put a clone in it.
Hope you feel better, just getting over a cold myself, so good luck Mike


Sorry Block, I just had to!