Leaks but runs great .....crankshaft seals question.

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Steve72J
Posts: 28
Joined: Fri May 18, 2018 1:25 pm

Leaks but runs great .....crankshaft seals question.

Post by Steve72J »

I've read all the crankshaft seal posts but most postings are rebuild questions or a total failure scenerio.
My GT750J was owned and garage kept until it was sold to a young man who kept it outside and after "short" period dropped it and quit riding. Slightly bent the turn signal stem at the headlight bucket and it looked like the road "filed" a flat spot on the upper left corner of the radiator guard and crunched the points cover.

The bike required new steering stem bearing because of detent(s) that formed in the bearing race from sitting for a long time. May have contributed to the 2nd owners fall because it was obvious to me that something was wrong the 1st time I rode it after getting it running. All the bike needed was new points and it started a click of the starter, still does after the ten years I've owned it. Been through the usual R/R of an older bike, ie replaced the chain and sprockets (which were the 72 OEM), couple of carb rebuilds, tank cleaning and coating, petcock rebuild.

So the question I have is how much oil is expected to be on the garage floor after sitting for a few days coming off a good engine warming ride ? Bike smokes when starting after sitting for a week or more but pretty much disappears after a few miles. Very little smoke if ridden daily.

I've got a 97 GMC truck with 214,000 miles that has never dripped a drop of oil but I find it hard to believe this two strokes crankshaft would be 100 % intact and pliable after 46 years and having sat for years on end before I acquired it. Not borrowing trouble here because it runs great, starts great and is a lot of fun to ride. Be thrilled to hear these seals can go forever.

So how much "normal" oil do see on your floor from the exhausts after a few days ? The bike has done this since I've owned it and since my garage is epoxied coated I just wipe the drips it up when I see them. One paper towel is all it takes, half a towel would do it.
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: Leaks but runs great .....crankshaft seals question.

Post by Alan H »

There 'shouldn't' be any, but in my experience there's usuall a couple of spots appear if you leave it on the side stand. Make sure it's not coming from the neutral switch near the gearbox sprocket and dribbling from the back of the casing under the (front) of the chain.
Easily fixed cheaply without much heartache.
My 750B has a slight ooze from the gear indicator switch. I'll sort it someday, when I can be bothered........
Proof that four strokes are over complicated
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Chris57
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Joined: Wed Mar 16, 2016 8:04 am

Re: Leaks but runs great .....crankshaft seals question.

Post by Chris57 »

If Juan Shiet is all you need then I'd not worry Sir, maybe just thrash the bugger a little more often ;)
barney01
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Joined: Wed Sep 26, 2012 7:33 pm
Location: Prestatyn.Wales

Re: Leaks but runs great .....crankshaft seals question.

Post by barney01 »

IMHO there are a few factors involved here. When did you last check your SRIS valves? If you spend a long time at low revs say in traffic and your valves don't function too well the engine will over oil and will end up in the exhaust. A good blast will usually do the trick. Remember some folks remove the SRIS system altogether.
I also think the type of oil choice affects this. Some mineral oils (usually the cheapest) don't mix too well with fuel and also end up in the exhaust.
It's worthy of noting that it's generally accepted that Suzuki did over oil the engines and I know some guys actually wind down the oil pump 'a little'
Incidently my 550 J leaks a spot of oil I ride it hard daily. But then I'm happy with that. Better than no oil present!
NO SMOKE .......NO POKE
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canaletto5
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Location: Derbyshire

Re: Leaks but runs great .....crankshaft seals question.

Post by canaletto5 »

Alan H wrote:There 'shouldn't' be any, but in my experience there's usuall a couple of spots appear if you leave it on the side stand. Make sure it's not coming from the neutral switch near the gearbox sprocket and dribbling from the back of the casing under the (front) of the chain.
Easily fixed cheaply without much heartache.
My 750B has a slight ooze from the gear indicator switch. I'll sort it someday, when I can be bothered........
Yup, just sorted mine with the same problem. The factory fitted o ring is too thin and fails. Discount Bike Spares do a beefier version that solves that problem. Is the oil leak clean or dirty oil? Kev
Steve72J
Posts: 28
Joined: Fri May 18, 2018 1:25 pm

Re: Leaks but runs great .....crankshaft seals question.

Post by Steve72J »

Lot of good things to check, thank you all. More info as to oil, 99% of the drips from the mufflers are black and thick spreading to 1-2 cm on the floor, occasionally it's a molasses color and of a low viscosity.

Have never looked at the SRIS system other than to locate the tubes so definitely something I need to do. Other than the muffler hole drip there is a area under the shifter that drips so the neutral switch could very well be leaking. It's lighter and thinner.

Baffles have never been an issue getting out and all appear to be similarly "coated" but never dripping when pulled out, kind of crusty.

Oil pump setting is according to the book (carb slide indention / slash mark on pump indicator). Oil is the Suzuki CCI (white bottle). Dealer wanted to get rid of them and I took them all. Have not kept track of consumption other than to make sure the reservoir does not go empty.
teazer
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Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: Leaks but runs great .....crankshaft seals question.

Post by teazer »

Let's back up a bit to look at the question. Oil in the exhaust can be from a bad seal allowing transmission oil to be sucked in, but is just as likely to be from the oil pump.

Yes, it is quite likely that the crank seals are hard and leaking and the way to determine that is to do a leakdown test where each cylinder in turn is pressurized to 6=8psi and the idea is to see if the seals hold that pressure or if it immediately leaks down through the seals.

The other source of oily pipes is from teh pump system. Under the pump and connected to the crankcase is the oil distribution aka octopus and it contains a check valve in each line to prevent crankcase pressure from blowing back up the line. That same ball valve stops oil from weeping down into the motor when it's not running.

Those tend to leak over time allowing excess oil into the bottom end.

And as previously mentioned, the bike needs to be run fairly hard to burn off any excess oil in the exhaust.
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slosher
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Location: Walsall,Black Country

Re: Leaks but runs great .....crankshaft seals question.

Post by slosher »

Steve iv'e noticed with my kettle any fluids slightly over the level required and these old fossils spit it out doh ask me how i know :oops:

Cheers Dave
GT750L
GT550L
TL1000 97s
T140V
Loctite Trained Engineer :lol:(since having the Bonnie)
wents75
Posts: 262
Joined: Wed Nov 25, 2015 8:25 pm
Location: Colchester Essex UK

Re: Leaks but runs great .....crankshaft seals question.

Post by wents75 »

Alan H wrote: Thu Sep 27, 2018 11:52 pm There 'shouldn't' be any, but in my experience there's usuall a couple of spots appear if you leave it on the side stand. Make sure it's not coming from the neutral switch near the gearbox sprocket and dribbling from the back of the casing under the (front) of the chain.
Easily fixed cheaply without much heartache.
My 750B has a slight ooze from the gear indicator switch. I'll sort it someday, when I can be bothered........
Hi Alan
We spoke recently regarding the gear indicator O rings mine leak also on my 550 M They are different sizes. Do you know where I can source them?
Many thanks
Ian
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