Fix Oil Leak turns to Starter problem

[jcdas]

Well, this one is a little different spin on the 1st gen starter problem.

 

I have a 1986 VR which I've upgraded the starter wiring, put in new starter brushes, new solenoid, all done in 2006. This spring I put in a new regular lead acid battery. The starter was operating nicely and wasn't giving me any problems.

 

As part of my spring mainenance, I adjusted the valves. I've been riding it a bit to work this spring, which is about 115KM round trip. So far about 3000 KM this season.

 

I started to notice an oil leak on the left side, dropping from somewhere under where the clutch slave cylinder is. I checked the valve covers, and there was a hint of oil leakage, but nothing significant. So I washed the whole left side off with Varsol solvent, and rinsed it off with water. I went for a short ride with all the lower body parts off. When I got back to my garage, I noticed that the leak was really coming from the cover seal right around where the starter is located. Not from the starter o ring, but the left side case to main crank case gasket.

 

So I pulled the left side case covers off. Front cover, and middle drive cover.

 

When pulling the main cover off, the starter gear idler came out with the case.

 

I cleaned up all the gasket surfaces. I didn't have a gasket, and I was going to try just using grey RTV silicone gasket cement.

 

I checked out the starter idler gears, and put them back in, in what I think is the only way that they can really go in so that the gears fully mesh. The small gear can go on two ways, but in one position, the gears will only mesh on 1/2 of the gear faces.

 

So I assembled everything. After sitting a couple of hours, I tightened up the screws a bit extra, and poured in some oil.

 

Now when I started it, the starter turned the engine over very slowly. Just enough that my finely tuned machine started, but definitely NOT NORMAL.

I thought it might be that the idler shaft might have gotten a bit dry with the solvent, so I let it sit and cool down, hoping that maybe some oil might seep into the case cover bearing surface.

 

Still extremely slow.

 

So has anyone else ever had this experience?

 

Could the missing gasket cause the case to be tight enough to tighten up on the idler gear shaft which has to flote in the journals in the main case, and cover? Is this a hint about what causes a warm engine to give starting problems when the idler gears are tight?

 

Is it possible to actually reverse the idler gear to drop the effective gear ratio between the Starter and the crank gear? Anyone have a spare engine appart that can check this?

 

I'll probably pull it all apart tonight and see what I find. Maybe some extra silicone when into something it shouldn't.

 

Appreciate any suggestions.

[jasonm.]

YOU MUST USE THE GASKET! The clearances are so tight in these engines. There is only a few thousandths between the spinning gears of the starter drive and case. Once the gasket is removed=no clearance. You are grinding the gears into the engine and case cover. TRUST ME ON THIS, get a new gasket. Also your leak originally is likely the damn grommets that seal the ignition & stator wires. Wires are braded and act like wicks to the oil. The rubber gets old and does not seal as well. Old Yamahas are notorious for this.

[Snaggletooth]

Here is a pic of the proper order and placement of the idler gears. Only one way for them of go in a work. I'm not sure if they could be reversed and reduce the rotation ratio.

 

And I agree with Jason. Gasket and sealant around the wires from the pickup coils and stator.

[jcdas]

So I took it apart again tonight.

 

Mia Culpa.

 

Jason is correct that the gasket is critical for thickness. There was some evidence of the tight pressure on the faces of the gears that were rubbing a bit too tight on the cover and case surfaces. Oh well. All cleaned up again. I had checked it by dry fitting everything, and it looked like the cover had nothing holding it back. So it isn't much, but it is critical.

 

I'm still wondering though if something does get tight during the cooldown cycle that gets things just a bit too tight for a moment. My bike used to be OK if I stalled it and had to restart it. But if it was off for a quick gas fill, it would complain. Leave it an extra 5 minutes, and it was totally normal. I think a fresh battery really helps though.

 

I also checked, and there really isn't a way to put the gears in backwards to decrease the mechanical leverage of the gears. So you really can't goo too far wrong here.

 

It's just ABSOLUTELY critical, that you use a gasket.

 

Now I just have to order gaskets. I guess I'll get both sets, though the middle drive gasket doesn't look critical.

 

The oil was indeed leaking from the gasket surface though, and not significant amounts from the electrical wire gromets. during my first attempt to find the source of the leak, I had the wire area nice and clean from the brake bleed cover. I couldn't detect any leakage from that location, but there was definitely a stream coming out of the front gasket area. It was getting bad enough that it was looking like an old Harley when I parked it anywhere. So far, this is the first real gasket leak I've had with several Yamaha's over 30 years of riding.

 

Thanks for both of your prompt replies. Great to have help on this forum.

[Squeeze]

Glad to hear good News. Now, let's hope you didn't ruin the Starter Clutch due to your draging Starter Gears.

 

 

If so, contact danob11, he'll have a once in a Lifetime Solution for you.

[Gearhead]

I'm still wondering though if something does get tight during the cooldown cycle that gets things just a bit too tight for a moment. My bike used to be OK if I stalled it and had to restart it. But if it was off for a quick gas fill, it would complain. Leave it an extra 5 minutes, and it was totally normal. I think a fresh battery really helps though.

 

Interesting theory, I always assumed the 5-minute shutdown allows heat from the headers to warm up the starter motor itself. Same thing happens on a small block Chevy with headers. Does anybody know why heat soak affects the performance of a starter motor?

 

Jeremy

[jcdas]

Not sure why heat might really bother the starter. (not saying it doesn't).

I'd maybe be convinced if it was a permanent magnet motor like on some newer cars, but it's a series wound starter, so hot or cold, it should create the same magnetic force I would think.

 

That being said, the newer 4 pole starters do seem to cure the problem as well.

 

John.