Topic: Oil leaking out of dipstick, wth?

[hevykevy420]

Oil is leaking out of the dipstick hole on my '78 cb750K, and i can't figure out why.  it never did this before the rebuild.  the seal on the dipstick looks good, and i've even cranked the dipstick tight with a wrench, to get it good and tight.  really tight!!

I still get oil running down the oil tank after each run.  I changed the oil, and made sure i didn't overfill, and it is still leaking.  what is going on here?  is this something to do with the 836cc conversion?  I'm also getting a bit of oil leak out of the valve cover, not sure if that is related.

Is this just something i have to live with?? what is going on here?

[StevieMac]

Is your valve cover vented properly?  If that gets blocked it can cause oil to leak out strange places.

[Bob Wessner]

Are you sure it's from the dipstick and not the oil tank drain plug? I just went through this myself. The washer on my drain plug was pretty beat-up and seeped oil after sitting. I used an alternative washer I found at the hardware store with a combined rubber gasket. I worked OK for single use, but apparently the gasket didn't like the loosen/re-tighten routine and seeped again. I was sure it was the filler cap until I traced it again to the drain plug. I ordered 4 new, correct washers (oil pan drain plug uses the same) and the problem is solved. Should have done it right the first time. 

[hevykevy420]

Is your valve cover vented properly?  If that gets blocked it can cause oil to leak out strange places.

I have no idea if it is vented properly, maybe it is not?  I have a hose hooked up from the cylinder head to I think the filter thing underneath the battery box, then a line goes to the airbox, and a line goes underneath the bike.  I'd have to double check.  Is this correct?

the only other thing wrong with the valve cover that i remember is that when disassembled, I noted that it looked like at some point the cam chain wore though the cover a tiny tiny bit underneath that rectangular cover on top of the valve cover, but I didn't think it would effect anything, so I reused the cover.  

[hevykevy420]

Are you sure it's from the dipstick and not the oil tank drain plug? I just went through this myself. The washer on my drain plug was pretty beat-up and seeped oil after sitting. I used an alternative washer I found at the hardware store with a combined rubber gasket. I worked OK for single use, but apparently the gasket didn't like the loosen/re-tighten routine and seeped again. I was sure it was the filler cap until I traced it again to the drain plug. I ordered 4 new, correct washers (oil pan drain plug uses the same) and the problem is solved. Should have done it right the first time. 

Bob- I'm sure its from the dipstick, because it runs down the oil tank from the dipstick.  I wipe it off, and it runs down again.  The drain plug appears to be fine, I didn't think oil could leak up from the drain plug, and cover the outside of the tank.  Is that what was happening to you?

[hevykevy420]

Oh jeez, i just searched a bit for crankase pressure problems, and came across the wiseco 836 thread which basically says that the piston bottoms are too flat causing too much crankcase pressure.   well, i'm not sure if this is my problem, but i sure can't get to the bottom of the pistons now. 

i'm pretty sure i have my vent lines running correctly, i even blew through the cylinder head vent tube to check the valve and it wasn't blocked.  i will try to check the vent tube coming out of the bottom of the block for blockage...not sure if i can get to it though...

I will also check the general routing of all of the lines.

If anyother 836cc people have some advice, I'm all ears...

[Bob Wessner]

Bob- I'm sure its from the dipstick, because it runs down the oil tank from the dipstick.  I wipe it off, and it runs down again.  The drain plug appears to be fine, I didn't think oil could leak up from the drain plug, and cover the outside of the tank.  Is that what was happening to you?

At first, yes, but then I realized what I was seeing on the side was from checking the oil level and being a bit sloppy about it. Once I realized that, it was slowly seeping from the drain bolt and finding it's way down over the course of a day or so, to a spot on the floor beneath the tank. Sounds like you have a diff. issue.

[hevykevy420]

Update- I decided to experiment for #$%*z 'n giggles on my way to work this morning, and I disconnected my cylinder head breather tube, and also the tube coming out of the lower engine block that goes into the oil tank (in front of the rear swing arm, on the right side of bike).  No, this was not some vengeful act aimed at mother nature, but rather the result of researching increased crancase pressure from Wiseco 836cc posts on this forum.  (After all, I do not mess with Texas  )

I didn't leak any oil AT ALL out of the dipstick during my 20 mile highway ride, AND my cylinder head gasket appeared to stop leaking on the right side (its been doing this since I installed the 836 kit, even after adding non-hardening gasket sealer, and engine stop leak additive to the oil).   I guess the oil tank breather line was pressurizing the oil tank, forcing oil out of the dipstick and also out of the cylinder cover gasket.

While I am thrilled by possibly figuring out the oil leaks (seems to be caused by too much crankcase pressure not being relieved, but further testing should confirm), I noticed the disconnected tube going into the oil tank spewed a bit of oil all over the muffler and rear swingarm, which is not a good thing considering the proximity of the rear tire  .

From researching other posts, should I put a breather filter on the oil tank breather line?  Will the filter stop the oil from escaping, but allow the engine to breathe??  If dumb question, then I apologize!!

Why would nirvana inspiring honda engineers have a breather tube leading to a pressurized oil container?  Or do i have sht connected wrong here???  WTF???  I tried blowing into the breather tube going into the oil tank, and nothing would go in, but when blowing in the cylinder head breather tube, it seemed to be clear.  I guess I'm a bit confused, I am sure somebody will show me the light...Usually it is Eldar 

[dusterdude]

ELDAR?,god help ya man.

[Bob Wessner]

Why would nirvana inspiring Honda engineers have a breather tube leading to a pressurized oil container?

There should be virtually no pressure in the oil tank. The scavenge pump returns oil from the sump to the tank via one line and the other is strictly gravity feed back down to the oil pump. Both oil lines are practically zero pressure. Are you sure you don't have too much oil in the system?

[hevykevy420]

ELDAR?,god help ya man.

ITS A K8 THING!!!!!!! 

[hevykevy420]

Why would nirvana inspiring Honda engineers have a breather tube leading to a pressurized oil container?

There should be virtually no pressure in the oil tank. The scavenge pump returns oil from the sump to the tank via one line and the other is strictly gravity feed back down to the oil pump. Both oil lines are practically zero pressure. Are you sure you don't have too much oil in the system?

I agree, there SHOULD be no pressure, but for some reason there is.  I was very careful filling with oil after last oil change, no more than 3.5 quarts with a filter change.  BUT, i didn't kick over the engine to get all of the oil out like some people do, and I'm not sure how much oil that leaves in the engine.

I've been checking the oil tank breather outlet (with the hose disconnected) and I'm getting oil dripping down from that outlet, not out of the crankcase.  So, I'm thinking maybe I somehow did overfill the oil tank OR the increased crankcase pressure from the Wiseco pistons is somehow pressurizing the oil tank.  I believe it to be the pistons causing excess pressure.  If the breather tube was meant to route excess oil in the oiltank to the engine, then there is increased pressure in the crankcase causing the oil to have no where to go (there are only three lines on my oil tank, send, return, and breather) which would explain how the oil was able to forceably blow out the dipstick that I cranked tight with a wrench!

I'm hesitant to use less oil on this aircooled engine, because its Africa hot here in Texas 100+ everyday now...

I bought a Drag specialties crankcase filter ($20 at the HD shop today), and I'm going to add a "T" fitting into the oil tank breather line.  That way excess oil will leak down from the oil tank to the engine, and excess pressure will be relieved via the added filter.  Not sure what else i can do, except take some oil out of the system i guess, but i would think that if crankcase pressure is in fact boosted, it wouldn't matter how much oil I have in the tank, it will still want to blow it out...

I'll post the results, and if successful maybe this should be a FAQ for 836cc conversions? 

[eldar]

Well since I have not done an 836, i am not sure what to say. many people here though only fill about 3 quarts oil on a change, maybe a little more. Just as a test and to make a mess, start the engine without the dipstick in and see if it overflows or if it is ok. If it is ok, then I would say it is pressure build-up from air. If it still over flows, I would say it is too much oil.  Just guessin though.

[Pinhead]

Doesn't the breather tube at the top of the head go into the airbox? There should be a slight vacuum in the airbox, allowing the pressure to leave the engine through the breather and into the airbox. At least that's how my 650 is set up.

[dusterdude]

ELDAR?,god help ya man.

ITS A K8 THING!!!!!!! 

i hear ya 

[eldar]

The tube from the cover does go to the airbox.

just gave me an idea. When engine is running, put your thumb over the tube and see if you feel pressure. If you dont, it is plugged somehow. If you feel the pressure coming out, then it should be venting ok.

[Bob Wessner]

no more than 3.5 quarts with a filter change.

3.5 qts would overfill mine, but I seem to have an odd situation on my K0. The current oil tank is thinner than most so it's total capacity is down. Right to the top mark on the dip stick is 3.0 qts.. period and that's after every little trick short of turning the bike upside down and shaking it to get all the oil out at change time. Anything more and it blows the excess out the breather tube in front of the tire.  Have another oil tank on the way to try and increase the capacity.

[hevykevy420]

Seems I have solved the problem.  I just added a plastic "T" fitting that  I bought at the hardware store, cut the crankcase to oil tank breather line in half, added this "T" to the line, and ran an additional hose line from the "T" to a Drag Specialties crankcase breather filter.  I made a bracket for the filter and mounted it right below the oil tank.  Looks pretty cool, and my oil tank doesn't appear to be pressurizing and no leaking oil out of cylinder head    I'll post pics tomorrow...

[eosmontana]

I've also heard of some riders running the 836 drilling and adding breather fittings and drain hoses to 2 of the tappets covers on the backside of the valve cover to relieve excess pressure... just a thought.

[lrutt]

The root cause of the problem is the rings just not sealing properly. How many miles on them? What type of oil? If you ran syn right away the rings just didn't seat.

You need to fix the source of the problem if you're getting that much blowby. IMO.

[scondon]

  EDIT: I just realized that I had 'kevy confused with 'keddie AND that this thread is a year old. I have deleted parts of my post that are no longer relevant

  I just finished rebuilding my transmission yesterday and rode the bike to work today for it's first real test. I also read that thread about 836 crankcase pressure and have routed the lower case breather up and along the rear seat rail instead of to the oil tank overflow line. I made it to work and found my rear wheel splattered with oil. On examination I found the oil tank overflow to be the culprit. On further examination I found my oil level to be 1/4 - 1/2 quart too high.

  When I refilled the oil yesterday I added just under 3 quarts and let the engine idle for a minute. Shut it down and topped the tank to the top of the fill line on the dipstick. When I got to work this morning the oil level was a good 1/2 inch above the fill line. Anyway, I drained enough oil from the reservoir to bring the oil level down to 1/4 " from the top fill line. 15 mile ride home in 95 degree weather and not a single drop from the overflow

   I plan on adding a catch bottle to the oil tank overflow. I think a filter will just saturate and drip oil in short order.

[scondon]

The root cause of the problem is the rings just not sealing properly. How many miles on them? What type of oil? If you ran syn right away the rings just didn't seat.

You need to fix the source of the problem if you're getting that much blowby. IMO.

   Agreed that you can expect a little blowby since the new piston rings take some miles to get good and seated in the bore. All the talk about the 836 pistons and added crankcase pressure has pointed towards the shape of the piston bottom rather than poor ring sealing, is there some new info about Wiseco rings having poor sealing qualities?