Oil Leak - Air Box Vent Hose - 82 GS1100G

[williamcryan]

Oh, man, I posted a lengthy problem and lost all but the title when I tried to post. Here I go again. I will copy before I post this time.

My bike is leaking a little oil around the head and valve cover gaskets. I can live with that.

I have had problems with an oil leak from my carb airbox vent hose before. I posted a related problem some months ago having to do with possible bad petcock, more on this later.

Keeping that in mind, I wanted to monitor the leak this time more closely.

Yesterday, I changed the oil and filter, I use Castrol 4 cyl M/C oil 20-50W. I refilled with 3.5 qts. Oil level was below full.

I rode 16 miles out to my coffee place and check the oil level when I arrived and it showed the level approx when I started my ride. I had my coffee, rode back home 16 miles, and parked after putting my side stand down, left side. Black oil immediately began flowing out of my carb airbox vent hose on the left side. A significant puddle, maybe 1/8 of a qt formed under the vent hose right off with residual dripping. A short time later, I moved the bike to another spot and put it on the center stand no more leaking.

The oil must be coming from the overhead valve cover vent that leads to my carb airbox and then to the airbox vent hose on the left side. When I park with the side stand down, the bike is leaning left and oil accumulated in the airbox is flowing to the vent on the left side.

What can be causing this oil to be flowing from the valve cover? What can I do to fix the problem?

More about the previous posting. I am fuel fouling plugs on cyls 1 and 2, more cyl 1 than 2. I had remarked that several times, my oil level read higher than when I started. The symptoms pointed to fuel flowing past a bad petcock into my crankcase. The recommendation was to replace the petcock. Regretfully, money was short and I haven’t', but I am going to put my order in now in the hopes that I can fix the plug fouling problem and fuel getting into the crankcase.

That said, I'm still at a loss on what is causing the oil flowing out of the overhead into my airbox and onto the ground.

[bwringer]

These problems all have the same root cause -- a bad petcock.

Firstly, your airbox isn't leaking oil. It's gas that picked up dirt and mung from your airbox.

Pieces of corrosion from inside your old petcock have made their way into your carbs, where they're holding one or more the float valves open slightly.

Since it's a vacuum operated petcock, gas only flows from the tank when the bike is running. That's when the float bowls overflow, sending gas into the airbox and excess gas into the engine. (If the rubber bits in the petcock are bad, it can also leak when it's sitting, or leak fuel into the vacuum line on the #2 carb.)

The excess gas makes your plugs turn black, and it also flows down past the rings into the engine, where it gets into the engine oil and makes it look like your bike is manufacturing oil.

Replace the petcock, clean the float valves and flush any remaining mung from the fuel lines and fuel tees, and you should be good to go.

Please don't ride the bike until you fix it. Fires and hydrolocking are great ways to make you and/or your bike dead.

It would also be an extremely good idea to replace the contaminated engine oil.

[williamcryan]

haha, bwringer, shotgun golf. Blasting the golf ball out of the air with a shotgun is a a bit different than me blasting the ball with my club into areas where I can't find them.

I just ordered a new Petcock, should receive in four days or so, no loss, it's raining right now in Oregon and I should have all that you have recommended completed for the next dry weather day ride.

Thanks so much for your insight and analysis. I'll replace petcock, pull the carbs and clean out, replace plugs, resynch carbs, take it for a ride and see how it all works out.

Also do another oil change before the ride

[duaneage]

If you don't have steel wool in the breather on top of the engine then oil will be pulled out through the hose into the airbox. Put some #2 steel wool inside.

[williamcryan]

Update on oil leak problem.
Duaneage: Steel wool is in breather cover.

Replaced petcock with new one.

I had been using a lot of plugs due to plug fouling. I had been having a friend sand blast the plugs clean so I could resuse them. I then read about a tip to burn the fuel fouling off, so I did that to some plugs.

Bike fired up right off from sitting for a few days without choke. Engine sounded good, but not quite as smooth as I like, just sounded a touch off. Figured maybe my burn cleaning of plugs affecting smoothness.

I headed out on my 16 mile ride and the engine was running strong, but still not smooth and figured it needed to be opened up a bit.

About mile 8, bike began running rough again accelerating, I figured crap, sounds like a plug is fouling again and planned on pulling over at mile 14 ro check plugs, bike began riding worse, no power in accelerating, at mile 15, I pulled into uhaul shop and the engine died. I tried restarting and it would die quickly. I put the kick stand down and oil began flowing out of my vent hose from my airbox. The problem I orginally reported. Checked the fluid, fuel or oil? Definetely oil. Checked plugs, found fuel fouling on 4 so replaced plug. Still wouldn't run for more than a minute.

One rider came by to see if I needed help while I waited for AAA towing. Another guy came by and we discussed. He's a mechanic, said check compression and give him a call, probably rings. I had bike top end rebuilt three years ago.

Had bike towed home. Fortunately I have AAA plus.

Took compression reading. Results; Cyls: 1 - 110, 2 - 35, 3 - 100, 4 - 105

Appears rings worn out, maybe because of fuel running through cylinder because of petcock problem. Oil is blowing past the rings through the valve cover vent into my airbox and draining through the vent hose on the left side when I put the side stand down.

Next is cost and effort associated with replacing rings and checking piston for #2.

Should I replace all rings or is it ok to just replace the rings in the #2 cyl?

Comments and advice is appreciated.
Bill

[gearhead13]

Your compression #'s dont look that great on the good cylinders, I would do all 4 while I had it that far apart.
Was the test done on a warm engine with throttle wide open?

[williamcryan]

Compression test

Your compression #'s dont look that great on the good cylinders, I would do all 4 while I had it that far apart.
Was the test done on a warm engine with throttle wide open?

Ahh, test was done with engine cold, not open throttle. I'll recheck this weekend and post results.

Still, #2 needs new rings and I agree, the rest should be replaced at the same time.

Thanks for the feedback. Bill

[duaneage]

Could just be a bad head gasket, the bad inboard numbers suggest that. You need to take a look inside. Open the valve cover gasket and see if the gasket has blown into the cam chain tunnel. You can see evidence sometimes.
Reringing may get expensive. The rings are 25 to 40 dollars a cylinder and if the piston is damaged tack that on. Also, the bores may be damaged so you might need a new set of jugs.
I would consider an engine swap if possible since the cost of the engine and shipping may compare favorably with rebuilding this one. You can part out the bad engine to recover a great deal of the money.
Look at Greyhound bus for shipping rates if you find another engine.

[williamcryan]

Bad Head Gasket?

Could just be a bad head gasket, the bad inboard numbers suggest that. You need to take a look inside. Open the valve cover gasket and see if the gasket has blown into the cam chain tunnel. You can see evidence sometimes.
Reringing may get expensive. The rings are 25 to 40 dollars a cylinder and if the piston is damaged tack that on. Also, the bores may be damaged so you might need a new set of jugs.
I would consider an engine swap if possible since the cost of the engine and shipping may compare favorably with rebuilding this one. You can part out the bad engine to recover a great deal of the money.
Look at Greyhound bus for shipping rates if you find another engine.

Thanks for the additional feedback. In addition to rechecking compression with open throttle, I was going to pull off valve cover and check valves clearances. As someone had mentioned, replacing a valve is better than rebuilding the engine, so I could get lucky, but I'm not counting on it.
I'll check the head gasket.
My top end rebuild three or four years ago, ran me about $1,400. Rings, valve job, carb intake boots. I had the money then. Now I'm retired and on a much reduced income. I could do ok with the parts expense, but the labor is more than I can swing now taking it to the shop as before. I'm pretty mechanically handy, but would need assistance and a place to work on it. I'll look around for some options, maybe some local help from the GS group in the Portland area, or an engine replacement. Prior to this problem, the bike was a strong and fast runner.
I'll post my check of the compression and my findings when I remove the valve cover.

[williamcryan]

Update on oil leak airbox gs1100g

Last post indicated bike would start and then stall, no power. Towed to home and then to shop.
Tear down revealed a couple of rings broken and ovalness on some cylinders. Seems to be the reason that I was getting a lot of oil leaking and leaking from the air box. Oil just blowing though the bad rings.
I couldn't afford reboring and piston and ring replacement as well as new valve seals and valves, Total cost over $2K.
I did a search on Ebay and surprise, found a 82 GS1100G cylinder block and pistons for $150 + $38 shipping. I crossed my fingers and ordered the parts. Worried it wouldn't be any better than what I have, but thought maybe if they were better, I would save rebore, new pistons and just replace rings. The cylinder does seem to be better shape, but darn it, the
cylinder is the black one, for the 82 GS1100L like my buddies. What the heck, it will look a bit odd, but I'll put in new rings, have the valves lapped, then reassemble everything and get it back on the road for $700 labor and $400 parts. If I had a garage, I would have tried it myself, but I don't. The last rebuild lasted me five years, I'm hoping for another five years. I'll give everyone an update in a couple of weeks when it's back together and I'm on the road. The bike was very fast and smooth until about five months ago or so when I would occasionally have a problem with a fouled plug on #1 and #2. I then replaced the petcock and shortly after encountered the problems that led me to take it to the shop.

[williamcryan]

Oil Leak - Air Box Vent Hose - 82GS1100G Update

An update. I was not able to have the cylinders rebored and replaced with new oversized pistons and rings or to have new valves and inserts replaced. I found a used cylinder block on ebay with pistons for I think it was $150 and thought I'd take a chance. I received the set and it wasn't apparent from the photos but they were black, not silver. I thought, oh heck, maybe my friend Phil with the black engine that needs a top engine rebuild could use it as I also saw a silver set come up on Ebay. But he wasn't able to do the rebuild at this time, so I kept them. Turned out to be a good idea as the cylinders and pistons were in great shape. The shop did cylinder flex hone, replaced the rings and instead of replacing valve seats and valves, refaced the valves and and head. Ventually the work was done about the same time as I was able to somehow come up with the approx $1400 for the work. I thought several times about salvaging the bike and getting an earlier Bandit or a Honda ST1100, but didn't have the money and I like my 82 Suzuki GS1100G with the Windjammer fairing. I broke it in slowly and the bike is just a fantastic bike to ride. It's comfortable, very fast, I'm glad it only has the 80 mph speedometer as I'd be pushing it over a 100 easily. No more oil leaks, yeahhh. I was really getting tired of that. The black cylinder block doesn't look that bad, hardly noticeable. I'm quite happy and hope I get a few more years out of the 30 year old bike.

[BassCliff]

Hi,

I'm glad you're back on two wheels.



Thank you for your indulgence,

BassCliff