Topic: Oil pan leak after engine rebuild...

[LadyTano]

So I'm working with a cb750a.

For the most part the teething process post rebuild has been decent. Aside from oil pan.


I bought the Athena gasket kit.

Torqued all bolts to spec. Leak.
Changed oil plug gasket. Leak (this one I'm perplexed on, it's a new aluminum one). I'm wondering if fiber might be better?

So I tried resnuggging the pan bolts after a little riding. It DID help some. It seems to mostly be the left side of the motor (riders left). And seems to be coming from the bolts themselves (it's shiniest and drippy looking around them).

Now, I know seals can take time to "set" sometimes. But, I'm worried it'll cause a problem beyond having to add oil. My rear tire left side is getting a generous costing of oil every time... Which kinda freaks me out.


I re-torqued the bolts several times. I'm wondering if I would have been better off using silicon sealant like the crank case.



Anyway, any/all advice is welcome. This was a new adventure for me, so I'm sure I'm missing something knowledge wise.



*I saw some stuff you spray on the outside that's supposed to help? Permatex. But it seems gimmicky).


**The surfaces of the pan, and motor, were clean as a whistle and checked.


Pic cause while not everyone's taste, you can see the time and love into her.

[bryanj]

You could try a copper washer under each bolt head, shouldnt need them but ive never seen an auto

[nanahan]

Cycle X has some good anti leak gaskets. You should check them out.


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[MauiK3]

could try removing the pan, clean everything and reinstall with a little Hondabond under each pan bolt head.
might work, Hondabond is good stuff.

[Alan F.]

I've used oem oil pan gaskets both times I've replaced them, a tip I've read here over the years many times. The aluminum crush washer should seal and last through several oil changes. What torque are you using? Are you using a reliable torque wrench? I applied the gasket dry with no sealer after buffing the surfaces with 600 grit paper. The 6mm bolts got torqued to 6ft/lbs then after 15 minutes to 8ft/lbs. Drain hole surface got a good scuff with 600 grit too to make sure it was smooth and flat, then it got 19ft/lbs then 21, 23 and finally 25ft/lbs, the washer has crushed a little at this point. I've stripped drain plug threads before so I torque everything gradually now and give some time before going to the next setting. Nothing good happens from guessing or hurrying.

The copper washer idea is very sound logic, fairly cheap and easy too. Please strap your bike down or have a friend sit on it for safety while you're working on the bottom of the engine.

[Don R]

 As a plumber/car and bike guy my experience is, always look above the drip for the source.  If you use sealer on the gasket, apply it to the pan side and chap stick to the engine side. Then at least it will come back off and the hard to clean part comes off and can be carried to the bench. 

[mrbreeze]

Sometimes a leak from somewhere else will flow to a seam. Then it will follow the seam which will make you think the leak is in that seam. People sometimes blame a leaking cam puck seal with a valve cover leak. One thing I've done on cars is put dye in the oil and shine a black light where it's leaking. It's usually pretty apparent where the leak is originating. You can get the dye at an auto parts store. They have it for oil,coolant, or AC. The black light may be harder to come by but I got mine from Amazon. If you don't want to buy one you may be able to find a shop with one. They might not charge you or maybe not much to just shine the light on it if you put the dye in yourself. Good luck with it.

[LadyTano]

Gonna do my best to respond to each.

Bryanj: of give it a shot to be honest. I was thinking of using gasket sealant on each bolt..

Nanahan: I hadn't heard about them but to be honest I'd rather not spend more of the season waiting on parts.but,not I can't nail down the leak issue....

Maulk3: it's kinda where I'm thinking. Is hondabond that much better than permatex's gasket sealer?

AlanF: so I was using a new torque wrench, so I'm hoping it's decent. But I honestly can't be sure without something to compare it to.it seems to be accurate but....ya never know.

 Copper wise, that's a quick and easy check to be honest, I may give that a go. I have a few fiber drain plug washers on hand I was gonna give a try tonight. I went Athena cause whole kit, but also good reviews :/


DonR: I've been trying to see above the leak for reference. Which might be the pan gasket itself? But when I pulled a couple screws they were soaked? So might be a mix.

The drops were bottom of pan, so following up it seems the rear left of the pan is the problem spot/area. Like, from that cornered, one bolt forward, and 3 on the rear.

MrBreeze: if it keeps causing an issue Ill add that to my list. I'd rather not, but push/shove that seems the best option..


So lunch update. I rode her to work, checked oil before and after. Seems to read high still which has me worried. Would me having accidently added too much oil cause the issue?

Oil leak still rear left. And the drain bolt, but only Bottom of it seems oil damp, so it's at least one culprit. Also, no leak when not running. Only when warm and riding (which is really don't like cause oil on back tire... ).

Gonna check oil before I head home again, but level hasn't changed much. She seems to be running well, and not over heating so pretty sure oil pump is working right.


Anyway, if anymore idears toss em.out please

[mrbreeze]

I remember a Toyota Camry years ago that came into our shop that had an oil pan leak. We thought we had it fixed  by just replacing the old drain plug seal. It came back a couple of times and after closer inspection we found a crack in the threads in the pan. A new oil pan finally fixed it. Sometimes you have to get out the magnifying glass to get to the bottom of the problem! One of my shop teachers in college told us we have to be detectives!

[MauiK3]

Lady Tano
I think I have an unopened tube I could mail you, pm me if interested.
I think it works better since it seems to be just flexible enough to handle heat movement. When I put my K3 together I had two leaks.
The neutral switch, which was new but I replaced it and the leak stopped.
The oil pan, which I discovered I missed a bolt when tightening. Changed the gasket, pit it back together and all is good.
Be sure to reallY clean the whole area and above with Simple Green or similar and double check source of leak.

[Keith]

Check shifter shaft seal.

[scottly]

seems to be coming from the bolts themselves (it's shiniest and drippy looking around them).

Most screw holes for side covers and such are "blind" holes; they are closed on the end, so there is no way for oil to leak past the screw threads. Sometimes, too long of screws get installed, which can pop the closed end of the threaded hole open, and allow oil to leak past the threads. Did you happen to find any little aluminum half dome things when you had the cases apart? If your leaks are indeed past the threads, I would try wrapping some Teflon plumbing tape around the leaking screws.

[Alan F.]

Check shifter shaft seal.

+1

[pjlogue]

I had a similar problem with my 750K.  I chased an on-and-off oil leak for some time.  I had removed the engine during my restoration and worked on the engine and during that work the engine weight was on the oil pan.  Ever since I had the small oil leak.  I finally pulled the oil pan last spring and discovered a hairline crack on the thin part of the oil drain hole extending outward.  Instead of trying to patch it with JB weld I bought a used one off fleabay.  I was careful choosing one and made sure the photos in the description showed the oil drain hole threads.  I didn't want a pan with mucked up threads.  When I got it I honed the pan to engine mating surface using 600 grit wet-dry sandpaper and a granite lay out block so I knew the mating surface was absolutely flat.  Used Hondabond sparingly and a new gasket.  Retorqued pan bolts after a day and a heat cycle.  It's been bone dry since.

The crack was hard to see and I suspect the engine weight on the pan and bolt caused the crack to start which only grew bigger with the heat cycling.  I replaced the aluminum sealing washer with Dowty washers for both the oil pan and oil tank drain.  Gives a much better seal with less torque.

-P.

[Progas]

You might want to check the neutral switch and o-ring, they are right there and often leak. Seen it many times!

[LadyTano]

Update!!!


Ok, to I pulled the pan. The darn gasket shifted, so only like 1 mm was between the screw hole and the oil.... >.<


Resealed with permatex black. That seems significantly better. Drain plug doing excellent with fiber washer.


But, still oil. Less. But ..



I actually think it's either the oil pump gasket, or the shifter gasket.

But, one step forward is still a step forward.



I checked the neutral, dry. It should be, I replaced that seal. But I know that's never a guarantee.

Seems I may be draining oil, and resealing the pump section, and the shifter section.
:/

Plus side, I have hex head bolts arriving. This weekend so I can snug up better than just a Philips.

Just gotta keep reminding myself. Rebuilds have teething issues.



* Also, it seems my throttle is being weird. If I hit it hard, the engine like, stutters? Sometimes fixes itself, sometimes I gotta rev, sometimes I gotta back way off.

I did have one good "pop" sound and she ran well for awhile. I'm thinking crud in the fuel line maybe?

[Jerry Rxman Griffin aka MuthaF'er]

If you insist on using sealer you better be damn careful!! Next thing you know a small piece breaks off and clogs the oil jets at the cam towers and your top end is toast. Best to only use a sealer on the case halves (NOT RTV!) and the rubber sealing pucks under the cam towers.

[Alan F.]

Or it breaks off and plugs some port in that torque converter system....