Unusual Oil Leak Problem

Unusual Oil Leak Problem - PROBLEM SOLVED!

Having searched the internet far and wide, as well as searching this forum extensively (Was lead here by Google, and it appears I have found the largest repository of ST experts on the net), I come with a problem that I cannot find the match for anywhere.

About 4 years ago I acquired an ST1100 that not only had nearly every piece of tupperware broken in some way, shape or form by the previous owners, but also had what I thought originally was the dreaded "below the carb deck o-ring coolant leak". While working my way toward fixing this issue (ended up being loose coolant hose clamps, YAY!), I found several other sins committed by folks who thought they could just cobble this thing into working.

So the day comes when I finally have it all put back together (sans tupperware, which is being stripped, patched, and painted as I go), fresh gas in the tank, half a can of Seafoam (Because it's been at least 4 years since this bike has been started), new battery, hit the starter, turns over, and over and over...spritz a little gas into the rear horn in the breather, hit the switch, fire, turn, turn, fire, turn, turn, START!

YAY!

Runs rough, but that's to be expected. Let it idle on the choke while checking for leaks anywhere and everywhere. Bump the throttle occasionally, and she winds up a little rough, but that's to be expected...as I said, it's been sitting at least 4 years.

After about 15 minutes, the idle jumps up to around 2000, I kill the choke, and this old girl is sitting there purring like a kitten at 600 rpm.

ROCK ON!

I'm so excited that I grab the seat, drop it on the frame, and head up the street. No plastic, no lights, no plates (good thing I live in a small neighborhood) and she acts perfectly. Smooth acceleration, clean shifts, just like it should be.

Pull back into my driveway, leave it running, pull it up on the stand, pull the seat back off. I notice that it's finally climbed up to operating temp and I'm getting ready to check for leaks when a leak of a different kind makes it's grand appearance.

It's not coolant, but oil...Gushing out of the right side...We're talking a full quart on the ground in less than 30 seconds here.

(Expletives left out to avoid offending the faint of heart)

Shut the bike off, started checking around. It's dirty enough that pinpointing the exact location was impossible, so I spent about half an hour cleaning every surface on the right side of the bike. Fire the bike up, nothing. Not even a drip.

Hmmm....that's odd.

Let it idle for a few minutes, it gets back up to operating temp again, and the gusher begins again!

This time, with everything clean, it's easy to find where the leak is. It's coming from the rear of the right head. Not the cover, not the gasket, but the actual head. I can find no reference to this hole in any tech manual, Mother doesn't refer to it in her manual, or on any of the microfiches. I can find no instance of anyone in the whole wide world who has ever owned an ST and talks about it on the internet speaking of a leak coming from this spot.

The picture below is not of my bike, but the arrow is pointing to the exact spot where the oil is gushing from.

So the question I have to ask before I start ripping this thing completely apart is: Anyone have any clue why this thing is leaking from this exact spot? It'll make pitching the repair to She Who Must Be Obeyed much easier if I have an idea of how much replacement of parts I'm looking at.



Thanks all, and looking forward to hearing what the collective has to say on this one.

MK

From the picture, it looks like a dimple and not a hole.... might be the angle of the shot. From your description, it sounds like the crank case vent is somehow plugged or the return path for the oil for that head is restricted. If you have had the carbs off... or maybe the previous owner... it is possible to get the carb drain tube and the crank case vent hose confused when hooking them back. If they have been switched, the crank case cannot vent resulting in the build up of pressure and the results you are experiencing.

Heh heh... Vinny speaks from experience.

Other possibilities are a rag left stuffed tight in the oil drain channel in the head during a valve shim change. There is a drain channel for the spark plug recesses that exits at the rear of the heads but with your symptoms that doesn't seem to be a failed valve cover gasket.

You could ask on ST-Riders.net and my-mc-phoenix also. Pretty sure they've more (looong-time) ST1100 riders.

Where are you located in Iowa, MK?

John

John OoSTerhuis said:

Heh heh... Vinny speaks from experience.

Click to expand...

Hey! I resemble that remark! LOL

Hi John. I'm actually in Des Moines.

On that drain channel... Would that be a casing divot in about the center of the head, looks to be about 1/2" deep and about the circumference of a pencil? The reason I asked is that I just noticed that I didn't mention that the plug wells both filled up about halfway with oil the second time it blew oil (knew that was valve cover gasket, meant to mention it, but it was late), if that is only a drain for those wells, you may have just made my day!

MK

If the plug wells didn't drain, the drain channel may be blocked. Clean it out.

John (at the Pardeeville TechSTOC)

Sounds like a bad valve cover gasket. The section that loops around the spark plug tunnel is pinched, out of place or damaged. A pretty easy fix if so.


-Jeff

I will know for sure tomorrow when I can get back to the garage, but it sounds very much like I crossed the crankcase vent line, and the resulting pressure blew the valve cover gasket out.

More to come tomorrow!

An extremely happy update!!!

Finally got to the garage tonight and started pulling things apart. Whereupon I found that, as I suspected, John and Vinny pointed me in the right direction.


I hadn't crossed the lines, rather the P.O. had run the crankcase vent the wrong direction (out the back of the carb deck, instead of up between the 1 & 3 carbs), then used another piece of tubing at the bottom of the air filter box, and joined the 2 together with a piece of smaller diameter hose jammed into both tubes. One of those "That doesn't look quite right, but I can't find anything in the book yet, so I'll put it back together for the purposes of testing the leak I just fixed, and sort it out later" kinda' things.

Somehow I managed to kink the joining piece of tubing, effectively cutting off the crankcase breather.

The resulting buildup of pressure caused the valve cover gasket to leak around the spark plug wells, filling them below the rain caps (where I couldn't see it), and as you suggested John, the oil then drained through the drain holes in the bottom of the wells, and out the divot in the back of the head, which is what vexed me.

I verified the flow by spraying brake cleaner down the wells until the fluid rolled clean out the divot in the head.

Ran it up to operating temperature, no runs, no drips, no errors!!!!! Even had the fan kicked in a couple times, and verified that the radiator cap is doing it's job properly by making sure there was fluid movement between it and the new overflow tank I had to install because both ears were broken off of the old one, and it was hanging by a zip tie.

New valve cover gasket and grommets should arrive Wednesday, and I'll get those installed. I learned with Wings that if you break the seal on a valve cover gasket, you can never trust it...just bite the bullet and replace it.

All in all a fantastic day, and thanks a million you guys!!!!

Thanks for the follow up, MK. Always appreciated.

Would be a good time to check the valve clearances when you replace the gaskets. Too bad you couldn't have joined us at the Pardeeville TechSTOC this laST weekend. You and Afan could have ridden together. Say.... he knows how to check valves and R&R shims. You two local guys should get together!

Regards, John
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