Topic: Rebuilt engine TWICE, effing thing still leaks oil.Just about done with this bik

[hevykevy420]

I just completed my second 836 rebuild after the first leaked oil.  I followed every precaution even shelling out additional cash for APE studs, and replacing the entire cam tensioner assembly and all the damn gaskets.  The fuking thing still leaks oil out of somewhere above the head gasket from the center of the head.  I can't figure this out.  It is not coming from the head gasket, and its not coming from the rocker cover.  its not coming from any of the other areas missed by nubies like the tach seal or the tappet cover seals or anything else obvious.  I used a liberal amount of 3bond on the pucks under the cam towers, and also on the threads of the bolts that bolt the cam towers to the head.  I did not miss any o-rings.  To say i'm frustrated and at a loss is an understatement.  If anyone wants to make me an offer on this bike, I would consider it.  I've spent a ton of money on it, its got the wiseco kit, high lift cam, stainless brake line, i painted the frame/parts black during rebuild, paid to have parts polished etc., etc. the money has been spent on this bike.  It is a good runner, just pisses oil all over the ground.  I know i'll be losing a ton on this bike considering everything I put in and the whole leaking oil thing, but I have a '75 bmw r90/6 that doesn't leak a drop of oil, is 10x's easier to work on as far as engine overhauls go which it probably won't need until who knows when, and i'll probably get a zillion more miles out of that thing than this Honda.

i've had this bike apart for 5 years now and my patience is gone.  if anyone wants to look at the bike and make me an offer let me know, I'm in South Austin.  I can send pics if anyone wants them too.  I guess I should move this post to for sale...

[nickjtc]

Porous casting somewhere???

[hevykevy420]

Porous casting somewhere???

?  Not quite sure what you mean, the head is fine. 

[mlinder]

Tach cable..?

[Bikebuff]

If you are willing to sell the Kerker exhaust, I'm interested.  I totally understand if you don't want to-if someone can help you find the oil leak and then get her working well again, I wish that for you.

[nickjtc]

Porous casting somewhere???

Not quite sure what you mean, the head is fine. 

On some bikes of the era (although I can't say I remember if any were Japanese) the alloy of which the engine cases, cylinders and cylinder heads were made contained microscopic flaws (like tiny sponge holes) which allowed the fluid contents of said items to seep through.

[holysmokes]

warped head

[hevykevy420]

Tach cable..?

its not coming from any of the other areas missed by nubies like the tach seal or the tappet cover seals or anything else obvious."

[hevykevy420]

warped head

No, I would assume a warped head would cause leakage at the head and/or rocker gasket, and this leak is not coming from either of those places.

[Jonesy]

On some bikes of the era (although I can't say I remember if any were Japanese) the alloy of which the engine cases, cylinders and cylinder heads were made contained microscopic flaws (like tiny sponge holes) which allowed the fluid contents of said items to seep through.

That was one of the issues with the early cast aluminum wheels- they couldn't get them to hold air for a long time because of this.

I didn't see you make any mention of crankcase breathing. I thought I read somewhere that the crankcase venting usually needs to be improved when running larger displacements. The crankcase pressures can push oil out of places it wouldn't normally go...

Just a thought.

[hevykevy420]

Porous casting somewhere???

Not quite sure what you mean, the head is fine. 

On some bikes of the era (although I can't say I remember if any were Japanese) the alloy of which the engine cases, cylinders and cylinder heads were made contained microscopic flaws (like tiny sponge holes) which allowed the fluid contents of said items to seep through.

Hmmm, i never thought of this.  I did not see anything visually to indicate a type of casting flaw or crack anywhere.  I had a valve job done on the head and HD springs installed, and the shop never reported any problem, they said the head was actually in great shape prior to the valve job.

Does anybody know who/what sells a type of dye I can add to the oil to try to track down this leak?  I tried the foot powder trick and that was useless.  

[hevykevy420]

I didn't see you make any mention of crankcase breathing. I thought I read somewhere that the crankcase venting usually needs to be improved when running larger displacements. The crankcase pressures can push oil out of places it wouldn't normally go...

Just a thought.

How would I increase crankcase breathing?  I've checked the tube that goes into oil tank, and I can blow bubbles into the oil tank, so I assumed the crankcase breathing was ok.  BUT, after the first rebuild, I was having pressure in the oil tank, so I thought maybe I was getting blow-by, but I had the bore measured by the shop before rebuild #2, and it was SPOT on, even to the .001 thousandth, so I thought it could not have been blow-by related.

I even tried adding a filter to the crankcase to oil tank breather line, but occassionally I'd get a bit of oil spray out of it, then after speaking with some CB veterans, was told that stock breathing lines should be adhered to as the factory intended.  i've left the rocker cover vented to open air by the way.

if it is caused by too much crankcase pressure, what did i do wrong to cause all this add'l pressure?

[Jonesy]

The common mod I remember seeing was drilling a hole in one of the rear #2 or #3 tappet cap and routing an additional breather line from it. I'll dig around and see if I can find it in here...

You didn't do anything "wrong" per se, you increased the diameter of the pistons, so they push more air around in the crankcase. In theory, the 2 pistons moving down should counteract the 2 going up, but that isn't always the case. The breather system was engineered for a stock configuration. Most small engines implement a one-way valve in the breather to maintain a slight vacuum in the crankcase. Why? Oil control.

[scondon]

  Hey 'kevy, after just 15,000 miles I'm about ready to tear down my 836 as well(for the 3rd time). Maybe we could start a support group OK, not so funny 

  I've typically gotten a good 1000 miles before weeping began appearing. At 15,000 miles the seal around the oil feeds has begun to go(between 1&2 and 3&4 exhaust). The oil feed leaks make their way into the spark plug wells and from there onto the upper and lower fins on the side of the head. Actually, they make their way just about everywhere which makes tracking the source kinda difficult.

  I've read before about the crankcase pressure caused by using the Wiseco pistons and didn't pay it too much mind until now. I plan on using a looooong breather tube for the crankcase and route it up the frame downtube, past the oil tank and along the seat grab rail. I also plan on drilling #2 and #3 tappet covers and running a line from each into a filter.

   Of course this is to prevent oil leaks after some 1000's of miles. If you've just begun running your new motor and oil is coming out in copious amounts then I would suspect that you have something other than excessive crankcase pressure contributing. Are you just getting oil on the fins after a week of riding or is it spilling on the ground after a days ride?

  Finding the source of the leak before tearing down(or selling the bike) should be first priority. I've had good success with spraying Simple Green on a warm motor, letting it sit for a bit then hose it off. Once motor is clean, start it up and let it idle and watch for oil to appear. If it's coming out of a "general" area then clean again and concentrate on that area.

   The best advice I can offer ya is to park the bike for a couple of days and ignore it completely. After five years of work just to have it piss oil is enough to send even the most patient biker/gearhead into a sledghammer fit. Maybe getting rid of it would give ya peace of mind, or maybe it would always nag at ya. A few days off will help clear things so you can make a decision that's right for you.

[andy750]

Its no consolation but something similar happened to my CB750 engine - I had a unspecified oil leak much like the one Scondon described) and so pulled the engine and sought advice on how to do it. Having changed valve oil seals, gaskets etc etc...I reinstalled only to find te leak was much worse...not a very good feeling as you now know....anyway I pulled it again and this time changed the pucks under the cam towers and thought I was doing everything right (again)....anyway after many months in a cold garage I fired it up - sounded great. Only this time the oil was now pouring out (see one of my previous posts from way back - with photos) - I too tried the talc powder test and got now except to verify it was coming from between #1 and #2 exhaust ports....anyway cut a long story short, I pulled the engine once again...and this time gave it to Mike Reick (forum member) who competely changed my top end - turned out the gasket I was using wasnt too good along with other ailments (bad valves etc) that I had missed.

Moral of my story -it was time for a second opinion after I had tried it twice myself.

Good luck and keep us posted on what you decide to do or find out.
cheers
Andy

[trinorman]

For dyes, try this site.

http://www.apexdyes.com/Catalog/Novasolve.asp

But if you know generally where the leak is coming from I would try the spray on foot powder trick again.  Degrease your top end thoroughly and let it dry.  Spray the powder on so it is good and white, even areas you don't think it is coming from.  Take a SHORT ride--up and down your street and check for wet powder.  If none, try a little longer ride, working up slowly until the leak becomes visible.  You don't want to go too far or fast as the air movement will really move the leaking oil around making it harder to pinpoint where it is coming from.  Good luck!

[kghost]

I had the same problem which I solved with a PCV (positive crankcase ventilation) valve.

See this topic.

http://www.sohc4.us/forums/index.php?topic=1133.0

[tomkimberly]

Don't laugh but I had the same problem with a CB650C, turns out the torque wrench I was using was not calibrated correctly and was way low on the actual torque. If it was my bike, I would re-torque the head with a known good wrench.

Tom

[hevykevy420]

All I have to say is I am a real IDIOT!!!  I'll explain...

I walked away from the bike for day, just like someone advised in this thread, just to think about the problem and chill out a bit.  Thinking about the problem, my logical thinking was that the leak had to be coming from the valve cover as I made sure all the internal o-rings were in place, and the cam pucks gobbed with 3bond.  I also used HD studs this time around and really made sure everything was put back together properly and torqued properly.  I thought maybe oil was leaking in the front of the cover between #2 and #3, and coming out down by the plugs a bit lower.  because the head recesses right there, it didn't look like it was leaking from the cover there, but maybe it is methinks.  i knew i had one stripped cover bolt (did'nt think it would cause leak), so I took the cover off, and helicoiled it, then did another questionable thread too.

This is when I realize the cover gasket was put in upside down by some tool (uh, that would be me), and EUREKA the cover gasket is not "reversible" even though it looks like it is, there is an actual right way to put the darned thing in because the cam opening by the gear is a bit lopsided on one side of the gear.  if you are a tool and put it in WRONG like I did, the gasket around the cam gear in the front of the engine will not line up and seal properly, and you'll soon post some obnoxious post like this one because of your frustration!  so feeling like einstein discovering the theory of relativity, I put a new gasket in the RIGHT way this time, and you guessed it, no leaking oil. 

so the bike is at the shop having Gordon's frame kit welded in place and she ran damn good over to the shop and no frigging oil slick to be seen!
Thanks everyone for your words of wisdom and advice!

[kghost]

Congrats. That sure is a happy feeling and day.

[hevykevy420]

I had the same problem which I solved with a PCV (positive crankcase ventilation) valve.

See this topic.

http://www.sohc4.us/forums/index.php?topic=1133.0

kghost- I already drilled holes in the #2,3 tappet covers previously because i thought my oil problems were related to crankcase pressure.  I've yet to figure out if I need these or not, i already ordered a new set of tappet covers to see if i can do without the add'l. breathing through the drilled holes.

I put some duct tape over them to ride the bike to the shop, and the pressure just blew the tape off, so i am thinking i definitely have some increased pressure in there.  How did you do your positive PCV mod?  I didn't see anything in that link, unless i missed it?  can you describe/explain??

[RRRToolSolutions]

Kevin, I'm glad it worked out. I am looking forward to seeing those frame pieces nicely installed.

I got home early Sat morning, caught a few Z's, then took my block down to Charles. He cooked it at 350 for 10 minutes and then set it up on the bench - we had all of the studs out in 5 minutes. Once heated, they just turn right out - not a hint of breaking a stud. I had the crank balancing appointment at 12 PM, so that's knocked out too. The Honda CB750 cranks are very well balanced from the factory. He could not get the strobe to come on. I watched the needles and the .2 grams minimum setting never got met. He commented that he'd never seen one that close. Buzz told me to expect the same results since they were factory balanced to exacting specs.

Regards,
Gordon

[scondon]

 From one "tool" to another let me say that is great news indeed 'kevy

kghost- I already drilled holes in the #2,3 tappet covers previously because i thought my oil problems were related to crankcase pressure.  I've yet to figure out if I need these or not, i already ordered a new set of tappet covers to see if i can do without the add'l. breathing through the drilled holes.

I put some duct tape over them to ride the bike to the shop, and the pressure just blew the tape off, so i am thinking i definitely have some increased pressure in there.  How did you do your positive PCV mod?  I didn't see anything in that link, unless i missed it?  can you describe/explain??

   Ya got my ears up as well, kghost. Those PCV valves are certainly cheap enough and readily available. If it's simply a matter of installing one inline on the upper or lower breather tube then I'll hit the auto store tomorrow.

[hevykevy420]

Congrats. That sure is a happy feeling and day.

ABSOLUTELY!!  ALL THIS WORK HAS PAID OFF, AND NOW I HAVE A DRY MOTOR.  I HAVE TO THANK GORDON FOR HIS SUPPORT!!  I'M LOOKING FORWARD TO GETTING THE FRAME KIT DONE, THEN I CAN TIDY EVERYTHING UP AND RIDE 

[hevykevy420]

Kevin, I'm glad it worked out. I am looking forward to seeing those frame pieces nicely installed.

I got home early Sat morning, caught a few Z's, then took my block down to Charles. He cooked it at 350 for 10 minutes and then set it up on the bench - we had all of the studs out in 5 minutes. Once heated, they just turn right out - not a hint of breaking a stud. I had the crank balancing appointment at 12 PM, so that's knocked out too. The Honda CB750 cranks are very well balanced from the factory. He could not get the strobe to come on. I watched the needles and the .2 grams minimum setting never got met. He commented that he'd never seen one that close. Buzz told me to expect the same results since they were factory balanced to exacting specs.

Regards,
Gordon

Glad to hear those studs came out nicely.  Yet another excellent usage of the kitchen oven for the CB750!  keep us posted on the build and those carillo rods...do those get balanced as well??