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Has anyone ever tried a serious cure for that problem? For example milling an O'ring groove into the cover?

Recognize there are huge differences in the volume of metal in the mating parts that touch the timing chain cover. Also there are more than two that come together. Understand that the coeficient of expansion and contraction differ from the heavy part and the thinner cover part which is seemingly what causes that sealant to let go with time.

Had mine sealed under warranty a couple years ago at Daytona BMW and just noticed some wet oil after a trip to Tallahassee. Nuts! It is major surgery to seal it and no more warranty.

Doesn't put me out of business but oil pukes suck...

Anyone know of a permanent fix?
 

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I came up with some ideas from previous exchanges on i-bmw, but mines not leaked badley enough yet to put them into practice.

Here's my thoughts: I don't believe any sort of 'goo' is a permanent fix. First I'd always check the flatness of the cover on a surface plate or float glass. Cast and pressed steel covers can start life pre-stressed when manufactured, then distort as they age and heat cycle on the motor.

I did some research with my local gasket supplier into a suitable material available in sheet form. They recommended a viton rubber and cork mix composite gasket sheet sold in various thicknesses. Milling a cover and fitting O ring rubber is a real quality way to go if you have the facilities or deep pockets. But if the mating surfaces are not distorted, a decent hand made gasket would do the job if it can be fitted. Since I've not removed my cover I don't know yet if there would be obstacles to using a gasket. I've made many special gaskets in the past. Usually I scan or photocopy a cover, make a paper template first, then cut out the profile. I use a set of leather punches or a nut and bolt to cut holes. Intricate shaping can be got with scissors and a scalpel.

These covers suck, so you only want to do the job (better than BMW) once and have it right for ever.



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timing cover leak

Yes, the secret seems to be use Hondabond HT sealant. On the previous forum I posted a description of how I fixed mine after the dealer's fix failed. Search for that pdf file or I'll find the link later for you. My repair failed too so I recently started over and changed from Permatex Ultra Black to Hondabond HT. The document I wrote explains how to get at the mating surfaces and get them really clean - I think that is another important issue. I think the procedures are right, its just the sealant I recommend changing.

I've only got 3 months and about 500 miles on this repair, I think you need a couple thousand to really be sure it is working, so I was waiting to say anything on the forum, but so far it looks really good.

Also, I removed the front cover on my '98 R11R, had it powdercoated and replaced it using Hondabond HT and it sealed the first time. This cover is functionally the same as the K12RS timing cover.

Mark
 

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mbohn said:
Yes, the secret seems to be use Hondabond HT sealant. On the previous forum I posted a description of how I fixed mine after the dealer's fix failed. Search for that pdf file or I'll find the link later for you. My repair failed too so I recently started over and changed from Permatex Ultra Black to Hondabond HT. The document I wrote explains how to get at the mating surfaces and get them really clean - I think that is another important issue. I think the procedures are right, its just the sealant I recommend changing.

I've only got 3 months and about 500 miles on this repair, I think you need a couple thousand to really be sure it is working, so I was waiting to say anything on the forum, but so far it looks really good.

Also, I removed the front cover on my '98 R11R, had it powdercoated and replaced it using Hondabond HT and it sealed the first time. This cover is functionally the same as the K12RS timing cover.

Mark
This leak is a bitch to fix long term because the chain tentioner is mounted in the cover not in the main engine case like the earlier 1100 and 1000 engines. The oil pressure forces the oil out of the joint between the main case and the chain cover. They did this to make adjusting the valves easier but didn't allow for the pressure increase at the joint. If you were able machine a groove around the small hole that carries the oil to the tentioner and install a o ring, would be a permanent fix but would be out of the reach of most people.
Have fun
H
 

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popeyebedford said:
Has anyone ever tried a serious cure for that problem? For example milling an O'ring groove into the cover?


Anyone know of a permanent fix?
Permatex "Grey" Silicone gasket sealer. Remains rubbery forever, and has high resistnace against oils (unlike many silicones). I used it after an engine teardown on my old K100 3 years ago, and there isn't the slightest hint of oil anywhere.

Just be sure to clean all surfaces with an aggressive solvent like lacquer thinner then make sure they are bone dry before applying the bead of Permatex. If there is a gasket, you can continue to use it, but clean it well first too. Allow the stuff to cure for 24 hours before use.

Bob.
 

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HGP3 said:
This leak is a bitch to fix long term because the chain tentioner is mounted in the cover not in the main engine case like the earlier 1100 and 1000 engines. The oil pressure forces the oil out of the joint between the main case and the chain cover. They did this to make adjusting the valves easier but didn't allow for the pressure increase at the joint. If you were able machine a groove around the small hole that carries the oil to the tentioner and install a o ring, would be a permanent fix but would be out of the reach of most people.
H
HGP3, Do you think the space beneath the chain cover can become pressurised when it should be vented to a breather, same as the main engine case or is the space under the cover at oil pressure?



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It's not crankcase pressure, it's actually main oil pressure, the same oil pressure that lubes the crank and everything else. Can be really high when you start up cold, especially with heavy weight oil. I think the leak happens when the engine is cold but I can't prove it. I reasealed mine a couple of times using all the factory and urban legends to no avail. (98model) I do use 15 x50 mob1, probably part of the problem. Doesn't do any more than weep and I can't see it unless the fairing lower is off. It never drips. And I sold it so it isn't my problem any more. The K12S doesn't leak or burn any oil.
H
 

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HGP3 said:
It's not crankcase pressure, it's actually main oil pressure, the same oil pressure that lubes the crank and everything else. Can be really high when you start up cold, especially with heavy weight oil. I think the leak happens when the engine is cold but I can't prove it. I reasealed mine a couple of times using all the factory and urban legends to no avail. (98model) I do use 15 x50 mob1, probably part of the problem. Doesn't do any more than weep and I can't see it unless the fairing lower is off. It never drips. And I sold it so it isn't my problem any more. The K12S doesn't leak or burn any oil.
H
How has temperature got anything to do with oil pressure? There is a pressure relief valve in all motors that opens well below 100psi.

Bob.
 

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Cold temps and thick oil are going to cause high pressure. Not high flow, just high pressure. A hot engine generally fails due to low oil pressure, as the viscosity of the oil is close to water (very thin), and the oil pump can't deliver the volume needed. That pressure relief valve is only worth anything when it is dealing with an engine at operating temperature, the oil pump is efficient, and the bearing surfaces are within tolerance. Otherwise, when cold, it's going to relieve the oil pump with no consideration to upstream demands, and won't help when the oil pump starts cavitating when the oil is too hot and too thin.

Turbo can probably explain it much better, though. :)



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Oil pressure per se is not such a simple thing that you can say is good or not good for an engine. The property of oil is such that it should get to the parts that need the lube and not break down under extreme pressure of the mechanical parts. So a hot engine with lower pressure and the lube getting everywhere, is better than a cold engine with thick oil at high pressure. That's why most engine wear occurs with regular cold starting, running and foolishly racing the motor when not up to temperature.

Fortunately I haven't been into my K's lube system for repairs yet, but most gasoline engines have to maintain oil pressure with a regulator close to the pump outlet incorporating a bypass to stop the pump failing with cold thick lube. It's not uncommon to find gasoline engines running for many years below the set regulated pressure when hot, particularly when low viscosity oils are used.

Back to the K's timing cover, if it really is at oil pressure somewhere from 40 to 60 psi, that does surprise me, because even the slightest leak would piss oil and you could have no oil and a burned out motor in minutes.



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tensioner?

HGP3 said:
It's not crankcase pressure, it's actually main oil pressure, the same oil pressure that lubes the crank and everything else. Can be really high when you start up cold, especially with heavy weight oil. I think the leak happens when the engine is cold but I can't prove it. I reasealed mine a couple of times using all the factory and urban legends to no avail. (98model) I do use 15 x50 mob1, probably part of the problem. Doesn't do any more than weep and I can't see it unless the fairing lower is off. It never drips. And I sold it so it isn't my problem any more. The K12S doesn't leak or burn any oil.
H
I've attached two photos. 870s shows one of the oil return passages that allows oil inside the cover to drain back into the crankcase. This passage is very large and it would take an enormous oil flow rate into the cover to create pressure inside the cover.

The second photo, 879s, shows the inside of the cover with the chain tensioner housing (lower edge about 1/3 the way from left to right edge). It is supplied oil from the galley you can see just above the tensioner. Any oil that flows past the tensioner piston or leaks past the tensioner housing / timing cover seal would undergo major pressure drop and would have a very difficult time pressurizing the timing cover.

In simple terms: The oil flow path from the pump to the tensioner piston and back to the crankcase has two resistances in series. The first is the tensioner piston and is a large resistance. The second resistance is the oil return passage and this resistance is very small relative to the tensioner flow resistance. It would be very difficult to generate a high pressure between these two resistance.

Mark
 

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Excellent Mark! Just what I'd expect. Your photos show a pretty clean wide mating face and one which I'd expect to be sealed with the right spec. of gasket (cork and rubber recommended to me) Can you think of any reasons why BMW don't or can't use a gasket? Is there any part of the cover which fits around an oil seal/shaft/bolt where a gasket wouldn't work?

I can also see from your photo that the face could be milled to fit O ring section, but gasket must be a first and cheapest option. If a gasket is good enough for a sump cover, it should work for this. Thanks - Vox



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Voxmagna:
My timing cover photo was taken just after I applied the Hondabond HT. If you look carefully you'll see two holes in the cover that are not part of the mating flange - these must be sealed and you'll see Hondabond on them. With your method you would need to machine o-ring grooves in those surfaces or just make small circular gaskets for them.
Mark
 

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Thanks, I see them. Yes they're at the same surface level so 2 gaskets from same thickness sheet should work.

I didn't add earlier for others interested, that where I've use sealants on aluminium covers I've usually sand blasted the surfaces with a standard air line grit gun. You get a damn good key, at least on one side. But you MUST remove all traces of blasting grit afterwards.



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mbohn
It is my contention that the oil pressure in the oil gallery pushes or warps the timing cover and as I remember ( I'm old remember) the cover in the picture looks different than my early 98. I thought the oil came thru a hole just under the tentioner. My cover had 2 set screw like plugs to seal the drillways to the oil gallery, one in the main case and one in the timing cover. these were right at the gasket surface. What year is yours?
H
 

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I once met a cage cylinder head (VW Golf) which gave perennial oil leak problems at the head/block interface because they fed the oil at high pressure to the valve gear, then metered the pressure down dooogh! There are tricks done with composite copper cyl head gaskets such as screen printing a bonding a rubber bead around high pressure connecting holes, also O rings in annular grooves are common.

It seems we have to separate possible high oil pressure leak from the usual mating cover with possible distortion scenario. The latter is definitely fixed with a surface plate check and a gasket. But the former needs more investigation to determine the oil gallery routes and whether the space behind the cover could in the event of breakdown of a gallery seal, push a large amount of oil into the timing cover which can't drain away quickly.

The best solution for oil connecting galleries under pressure, is to fit a thin wall stainless tubular insert in one connecting half with a circular O ring groove milled around the outside, the tube projects to fit the mating cover. The tube stops lateral pressure bursting the O ring.

Your photos seem to show oil galleries cast in the cover and I'm guessing that that's how oil is fed to the chain tensioner, so sealing the galleries must be addressed first. I seem to remember an archive post that picked up on the tensioner not working and much rattle because of an oil pressure leak or problems with the tensioner piston - can't remember which.

The more I look at your photos, the more I think Goo of any brand is not the fix and forget solution for the life of the motor. You've just got to get right what BMW got wrong. You can often smell bad design rats when there are plenty of cautions and details in a service procedure.



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Interesting discussion. I'm one more with the recurring oil leak.
Hey Mark, mine was done with Hondabond by my ex-dealer (now defunct), and leaked reappeared after within 3K miles (it was there when I changed the oil 3K miles later). Not a lot, and not a drop on the belly pan, but an oily mess all over the engine.

Interesting concept the oil pressure. I still think it's more a matter of surface preparation than anything else, as several owners are leak-free even after thousands of miles. My dealer took several days to do the job in a winter, and let it cure for 2 days, so yes, I was surprised of the leak.

Finally, I read on the old site several covers were defective, and I had arranged for my dealer to order a new one and attempt to fix it again, but when I called to take my bike just before the warranty expired, they gracefully notified me they were not a BMW dealer any longer (nice gesture!). So I'm on my own, as the now closest dealer is over 300 miles away, and with no loaner bikes for out of staters (like me). Hey Mark, did you find your instructions?? I'd like to tackle the job sometime soon. PM me if you need my Email.
JC
 

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HGP3 said:
mbohn
It is my contention that the oil pressure in the oil gallery pushes or warps the timing cover and as I remember ( I'm old remember) the cover in the picture looks different than my early 98. I thought the oil came thru a hole just under the tentioner. My cover had 2 set screw like plugs to seal the drillways to the oil gallery, one in the main case and one in the timing cover. these were right at the gasket surface. What year is yours?
H
Hgp3:
With the design you describe I can now understand the leak path you describe. Do you have a photo of this earlier timing cover so we can see how oil is delivered to the tensioner?
Mark
 

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revised writeup

BLACK_03_K said:
Hey Mark, did you find your instructions?? I'd like to tackle the job sometime soon. PM me if you need my Email.
JC
JC: The revised writeup is 1.7 MB which is too large to upload. I don't recall how I uploaded the first version. PM me your email and I'll send it directly to you.
Mark
 

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mbohn
Unfortunately, I sold it without ever taking pics of the cover. I had it off in 2002 for the last time and just ignored the seep.
H
 
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