82 Maxim XJ750, Major Oil Leak

I've been dealing with an intermittent oil leak for awhile now. Yesterday I sprayed the engine down with degreaser and filled the crankcase to capacity with oil to let it run a few minutes on the stand. Hopefully this would illuminate the problem.

Found it - it is leaking from the very bottom of the case where I believe (correct me if I'm wrong) the oil pump is. It is hard to see since the bottom of the stock exhaust unit is mostly covering up the site of the leak. With a mirror and a flashlight I can see something that looks like orange rubber/plastic hanging off of the case - clearly something is broken there. Now that the bike is completely full of oil it is leaking like crazy - at least a quarter liter in the past 24 hours.

I'm clearly going to have to pull the exhaust to get at it and see what I'm dealing with. I'll try to put some pictures up later today. My questions are:

1) Anything to be aware of in pulling the exhaust? Do I have to remove the whole thing at the engine or does it have a sub-assembly (it looks like it might) below the oil filter? The bolts on the four pipes are the most corroded and nasty looking fasteners on the whole bike, I know to soak them with penetrating oil before doing anything. I suppose it couldn't hurt to put new ones on if I have to pull them in the first place.

2) Any idea what the random thing hanging off the bottom of the crankcase could be? Is this a typical leak?

3) I think I underestimated the severity of the leak because the oil spyglass was gunked over (engine degreaser fixed that) and because the oil was collecting in the exhaust assembly and cooking off at speed. Will that have caused any damage to the exhaust I need to check for?

4) I'm using the centerstand and a front stand that holds the bike on its brake calipers. My dad wants to balance the bike between the bed of his pickup truck and the back porch so I can get under it, and I'm trying to explain to him that he is insane. I cannot bench press 520 pounds if this helps you form an opinion.

Thanks guys! After this leak is done I'll have done everything but sync the carbs (she doesn't need it!) and put in a modern fusebox.

 

STOP!! Don't ever get under your bike to work on it! It's foolish and not necessary anyway.

The oil pump is the lowest point of the engine and is behind the sump cover. Sounds like it could be the sump cover or oil sending unit that's causing the leak. The sending unit is about te diameter of a silver dollar and near the shifter on your bike. Either way, not a big deal. I just dropped the sump on mine and made some gruesome discoveries!

You will have to remove the exhaust to get acess and detrmine for sure where the leak is. I'm not sure if the headers need to come off or not, but the piece in the center of the bike that connects headers to mufflers will. My aftermarket headers did have to come off. Get a can of Kroil - I'm hooked on the stuff! Give all the bolts a good shot before you try to remove them and you'll be OK.

Post a pic or two and someone here will be able to ID it.

 

You most likely have a leaking Oil Level Sending Unit.

"The Book" says:
Replace the WHOLE Unit.

I have successfully done a Remove and Re-seal a Sender that just needed an O-ring and YamaBond.

You have to remove the Exhaust System.
Seized Collar Nuts and Clamp Bolts will present an obstacle.
Don't break-off Exhaust Studs trying to loosen Collar Nuts.
Cut-off Collar Nuts with a slanted cut through a side and chisel the Nut off.

The Pipes will be stuck and not want to come free.
Rubber Mallet
2X4 Block
Box of 10 Penny Nails

Beat the Pipes with a Rubber Mallet
Protect the Pipes with a 2X4 Block if you need to use a Heavy Hammer.
Grind the Nails to be wedges and knock them in between the Pipe and Collector,... spray-in Kroil.

Loosening the Faster that Suspends the Collector Box is going to take some muscling.

>XX<>XX> DON'T ATTEMPT IT ALONE <XX<>XX<

Have strong helpers on BOTH sides of the Bike.

 

This is why you guys are awesome. Thanks for the pointers, time to dive in.

I do want to add that this bike is partially responsible for me being kicked out of a roommate situation . . . the owner didn't like the bike leaking oil and was afraid he was going to track it onto the floormats in his Mercedes. I don't know why I find that funny.

 

As asked:

1: Since I believe you have a "collector box" system, the easiest thing to do is pull the mufflers off; then "drop" the headpipes and collector as a unit.

2: As above, it's your oil level sending unit; and no, not normal, it sounds like yours is possibly broken.

3: No damage to exhaust.

4: DO NOT "prop" up the bike by the BRAKE CALIPERS. Bad idea. So is the "hanging it in midair and crawling under" idea. The exhaust is in your way anyway.

-Support the front of the bike by putting said jackstand under the front frame crosstube, between headpipes #2 and #3. If positioned properly it won't even obstruct dropping the exhaust.

-The headpipes should be held on by nuts on studs; highly recommend soaking with Kroil first: http://www.kanolabs.com/google/ Works when nothing else will.

-Once the exhaust is off, you'll have plenty of room to get at the sending unit. It's supposed to be held on by two screws.

You'll find it in the fiche under "Electrical 1." (Part #41.) http://www.yamahapartshouse.net/pages/O ... brand=YAM#

 

This is the kind of front stand I have:
http://www.pit-bull.com/mm5/merchant.mv ... ont_stands

I don't have a regular jackstand. That and the centerstand have been very stable.

Can't find Kroil in this neighborhood (I used to have some for silencer cleaning) but PB Lube works pretty well as a penetrant. It's soaking in now.

Thanks for that part number, it seems to be in stock. Once again, you guys are awesome.

I wasn't going to get underneath the bike, I'm just trying to dissuade my dad from such redneck engineering projects. Thankfully he doesn't work on his own bikes. When he bought his BMW R1200C the mechanic bill to bring it up to spec was as much as I paid for my XJ750!

 

The exhaust came off really quickly, that was good. It wasn't that tight to begin with.

Definitely looks like the oil level sensor . . . it looks like someone took a chisel to it - it is no longer round and during operation oil bubbles out through the crack. Looks like I'll have to pull the whole unit and replace it. I have no idea how that happened - the bike has obviously been dropped hard 2+ times, I wonder if someone wasn't running the full exhaust when it was damaged. The collector box should have taken that hit but it appears pristine . . . maybe a replacement.

I'll throw a pic up when I get my camera recharged. Thanks!

 

Grrrr . . . so the oil level sensor is chipped but no oil is coming out of it! After scrubbing down with engine degreaser and sitting for a few hours the crankcase is again covered with oil but definitely NOT from the chipped sensor. It looks like it is coming somewhere from around the left crankcase plate or the shift lever . . . I'm still trying to figure this out. Any other common leak spots to check? Thanks again.

 

Too bad it wasn't the oil-level sensor. Mine was leaking and all I did was replace the o-ring.

You could try taking the shifter cover plate off. The selector mechanism area should be oil free, but the selector stem passes into the gear assembly, and there is a small oil seal around it to keep the oil in the crankcase from passing into the shifter mechanism area. So if there's oil in there, that oil seal is leaking.

The crankshaft itself is centered between the crankcase halves, with an oil seal at each end. Those seals are behind the YICS covers, one on each side. Again, behind those covers should be oil free and if one or both have oil, it's because those crankshaft oil seals are leaking.

 

I've been iteratively stripping parts off of the bike, hosing down with degreaser, rinse, wash, repeat. The source of the leak in my mind keeps moving further and further aft. I'm now thinking it is the rubber seal between the crankcase and the driveshaft arm. I don't think it is the oil in the shaft because it is separate (right?) and would have been completely gone by now, plus I'd have to find another huge leak to account for the engine oil disappearing. I've pulled the battery and left peg and clutch pedal to get at it.

It's currently clean and I'm letting it sit with clean paper towels around the suspected spot. There is a higher splotch of fresh oil on the plastic bottom of the air filter box but I really think that was "blow up" from the oil cooking on the exhaust collector and condensing on that surface . . . if that makes any sense at all.

Any thoughts on the driveshaft seal? The spring around it is intact but the metal plate it interfaces with seems weak and flexible, and when I push it with my finger fresh oil seeps out.

 

Okay, main driveshaft is clear of leak. Leak accumulates on the lower left frame . . . the oil seems to ride down on either the oil level sensor wire or the neutral sensor wire. These are routed into nooks in the case so it's really hard to tell where the leak is coming from. I've been feeling around the left side cover of the case and haven't found any primary dampness . . . would love to hear any suggestions of what to do next, short of pulling the engine out of the frame.

I'm losing around 100 ml of oil a day from this leak.

 

The good: I figured out where the leak is coming from, definitively.

The bad: well, there really isn't a bad, it's just going to be fun pulling the left side of the crankcase off.

The leak is coming from between the left crankcase cover and the main body at the lowest and leftmost bolt, or just a little above it. It doesn't seem to be the bolt itself, and it will absolutely not tighten (I've already shattered the drum brake adjustment bolt inside the thread by overtightening, I don't dare push it any harder). The wire that comes out of the pickup coil (where it says YICS on the left side) rubs up against that corner of the crankcase right by that lower left bolt - that is where the leak is, exactly. I think that 29 years of vibration made the plastic sheathed wire rub through the rubber seal on the case cover, or something to that effect.

I'm going to drain the oil now and pull off the left cover. Hopefully I can see exactly what is going on at that spot. What are my options if it is the rubber lining?

 

I got two of the bolts off and then broke the handle of my wrench trying to get the third one . . . either it needs to sit with lubricant for a long long time or I need to think of something else. I'm quitting for the night before I do something stupid.

Is there a way to seal it from the outside? If I know it is just seeping in that one tiny place? I pulled the retainer clip for the induction coil wire and exposed the leak area, it definitely has just that corner of rubber worn down.

 

Would putting something like Permatex high-temp thread sealant at the one exterior spot where the rubber lining is weak be a dumb idea?

 

Metabolic they make a dye you can put in the oil to help locate leaks you use a blacklight to see were the leak starts from. You can smear some sealer on the area you think is leaking but it probably wont stay on there very long.

 

What kind of sealer would you recommend? What if I make a small aluminum strip over the leak and then seal that? If that doesn't work I'm just going to rig something to catch the oil and keep it off of the exhaust and the ground, I'm not sure this is fixable short of getting a new case housing. She runs great and cost me very little so I'm not sure how much surgery I'm willing to perform.

Anyone know the operating temperature and pressure of the oil reservoir?

 

Post a pic. I don't think that's the actual source; I still think it's coming from elsewhere and ending up running out there.

Take a really close look at your cam chain tensioner body where it meets the cylinder block; get a flashlight and look in from the left. On the 550, a leak there will run down and appear to be coming from the same place you're seeing it on your bike. Just a thought.

What kind of wrench did you break on a case bolt? I recommend using a 5mm allen bit on a 3/8 or 1/4 drive ratchet or similar.

The "oil reservoir" on an XJ motor is the sump; and it's not under any real pressure; oil pressure is created by the pump and fed to all the vital engine components.

I would not recommend "exterior" fixes; they generally don't work anyway.

I think you're getting closer but aren't really at the source yet. Like I said, post a pic it would help immensely.

 

Let's try this:



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I'm laying underneath and to the left side of the bike. The screwdriver is pointing at the spot where the oil seeps from. I've degreased this area over and over meticulously and plugged up various spots with clean paper towels to see where oil comes from - it is definitely this spot and it is not being wicked from anywhere else. If I scrub it clean and hold a clean paper towel strip over the seam just above the screwdriver the oil seeps through right at the seam.

I've pulled aside the induction coil wire to show the spot. It is the exact spot the wire rested/rubbed on. If you squint you can see where the rubber lining on the case is eroded or missing at that spot.

The case is stained that color, it is not the least bit dirty or oily there. The length of the seam that is seeping is no more than a centimeter.

 

Managed to get the crankcase cover off. The gasket was a little eroded at that spot but very brittle overall. What's the best way to get the old rubber off? Heat and a scraper?

 

Permatex SPRAY-type gasket remover from NAPA. The non-spray stuff with the cutesy "applicator top" and "no unpleasant odor" doesn't work for squat.

I would also recommend you invest in a real "gasket scraper." You'll have it forever and get a lot of use out of it. I've literally had the same one for over 40 years; it's one of these: http://www.google.com/products/catalog? ... CMQ8wIwAA#

 

Sweet, thanks. Is the gasket just a generic material that I cut off of a sheet or do I need to find an original replacement part?

Edit: answered my own question, found the gasket from that link you posted earlier.

 

I have replaced that Cover Gasket many times.

You can try soaking the Gasket remains that are "Baked-on" with Lacquer Thinner to soften it and loosen it up some.

If the baked-on Gasket is on the Cover, ... you can Wire Brush it away.
You need to buy a BRASS Wire Wheel for the job.
You don't want the Mating Surfaces scratched or marred muscling-off the remnant.

Wire Brush the Gasket away until its nothing but a discolored film on the Cover.
Then, apply Lacquer Thinner to a ScotchBrite Pad (Gray) and rub the Cover's Mating Surface clean.

 

Cool, I'll try that. The whole gasket came off on the cover, except for about two inches which broke off and stayed on the case. I've got a Dremel with some soft brass rotary brushes, that should do the trick.

 

Metabolic you said take oil was on the left side near the oil sender wire. Is it possible that the oil is coming from the alternator which does leak through a weep hole in the bottom of the cover? There is a seal on the alternator shaft that can leak run out the weep hole down the case between the small crank end cover and a cover just in front of the shifter shaft. It is very hard to see it back in the space between these two covers. It then runs down under the engine near the oil level sensor and blows back across the cases when you are moving. This would be much more apparent if you were to fill the crankcase with oil bringing the oil level up above the alternator shaft.

 

Rtanner, I did consider that when I was trying to isolate the leak. I had a general idea of the pathway the oil took before collecting on the frame, and a good feel for the rate at which it accumulated. I'd spray with degreaser, clean and dry thoroughly, then take scraps of clean paper towel and plug them into various places going successively higher and higher with each round. Oil quit getting onto the sender wire when I put towel patches into the spot where the leak is coming from. I had clean patches in the other areas you mentioned but no fresh oil in any volume came from there.

I'm a computer programmer, I was surprised to learn how much oil leaks and paper towels have in common with bugs and print statements.