K12 timing cover - Why they leak - K-Bikes.com - Excellence in Motion
Reply
 
LinkBack Thread Tools Display Modes
post #1 of 16 (permalink) Old Jul 13th, 2007, 9:59 am Thread Starter
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
K12 timing cover - Why they leak

There have been many posts about this problem, much discussion about sealants and in some cases people get leaks fixed. In other cases the leaks come back. It seems strange that so many different people, some with good wrenching skills, still get the problem.

So I have the opportunity as I've always promised to get my '97 perfectly oil tight. Most of us who've 'been there' know that BMW rely on a bead of silicon gasket sealant placed in the right places to make the seal. It is vitally important that the sealant is applied to a grease free surface and in most cases the sealant is allowed sufficient time to cure - which could be up to 48 hours. When this work is done at the front, with oil in the bike and a motor in the frame, getting oil free mating surfaces can be very difficult. In fact on my own '97 KRS, most of the oem sealant was pushed away from the cover and block surfaces with very little actually sticking.

I was once puzzled when a previous champion of timing cover leaks posted that there was a lot of oil behind the cover which puzzled me a while since you would only expect splash oil feed at low volume. you might get the kind of leak that stains the case at the edges, but reported bad oil leaks surprised me.

Before I started my rebuild, I acquired some 20thou Nitrile rubber sheet, and some high performance glass fibre based 10 thou gasket material. I aim to use the nitrile sheet to make a re-useable gasket on the timing cover. The glass fibre material is for use elsewhere.

Now I've had a big shock which might be the real cause of all the timing cover leaks. The main oil feed gallery from the oil filter carries oil at very high pressure. It passes into the timing chamber and then connects via a milled land to oil lines cast in the timing cover. These meter oil at a lower pressure to the timing chain tensioner and valve gear. With the motor horizontal, oil returns to the sump via large holes in the block at the far end opposite to the crank. Too much oil around the top end will aggravate the smoking problem at start up as more oil will hang around the valve stems.

If the main oil gallery connection to the timing cover leaks, The timing cover will get filled up with a much larger volume of oil than normal, since this is the high pressure side before metering. I hate to dwell on this scenario, because it has the potential for reducing oil pressure where it's needed most - at the crank bearings.

I've posted 3 photos. 2 photos show the large round part of the casting and the oil hole. Note on the block photo how the hole is off centre in the land.

The first photo shows the result of a 'print' after my timing cover was coated with engineers blue and mated to the block. You can see how the oil gallery misaligns badly and in fact the hole centres in the timing cover and the block are misaligned a whopping 3mm. You can see in the third photo that the area of contact to achieve an oil seal is very poor at the top edge.

I don't know how many other bikes are like this, but the next time you remove a timing cover, just check where those hole centres sit. I'm not enamoured by the fix either, which is probably to fit a threaded ali plug, drill a new hole and re-face the surface.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
Attached Thumbnails
Click image for larger version

Name:	K12 Block-main oil feed small.jpg
Views:	211
Size:	55.1 KB
ID:	5578   Click image for larger version

Name:	K12 Timing cover main oil supply small.jpg
Views:	182
Size:	52.8 KB
ID:	5579   Click image for larger version

Name:	K12 Block-timing cover contact for main oil gallery small.jpg
Views:	236
Size:	68.6 KB
ID:	5580  
voxmagna is offline  
Sponsored Links
Advertisement
 
post #2 of 16 (permalink) Old Jul 13th, 2007, 10:25 am
Addict
 
carnadero's Avatar
 
Join Date: Dec 2005
Location: Sillycon Valley, CA, USA
Posts: 645
Out of curiosity, did any of the older Bricks have this problem?

Black 2002 K1200RS - "The Beast" (over 100k miles)
carnadero is offline  
post #3 of 16 (permalink) Old Jul 13th, 2007, 11:41 am Thread Starter
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
Mine KRS is a '97 so that must be one of the early one's. First you might just spot the oil drilling off center, but working with the motor in the frame, you might miss it. Then you say, OK it's a bit off center in the block, but perhaps they got the hole in the cover lined up. Not so with mine. The timing cover hole centre is south and the block centre is North!

I'm probably going to fit an ali plug threaded M12 into the 10mm block hole, then re drill the 8mm oil hole on the correct center. For good measure I'll be fitting an 8mm sleeve. But I'm not looking forward to any of it. K's don't have oil pressure gages, so how would you know if this joint leaked? I suspect the timing cover leak shows first so as luck has it, you probably get away with any reduction in oil pressure if the cover is re-sealed fairly quick.

From the past posts I've read, the timing cover leak seems to be either there and cosmetic, or dripping and real bad. It's the latter case I think might be caused by the oil gallery leak.

Years ago the first VW Golfs were known to leak oil at the cyl. head and in some cases sieze on the crank journal furthest from the oil pump. They'd used the head gasket to seal the high pressure oil to the valve gear and when the head overheated and warped you got oil leak and low oil pressure. At least on that motor you could see it. On the K brick it's all covered up. If you think about it, that oil gallery dripping oil will be the most difficult to get sealer to stick on and the 2 cover hold down screws are not too close either.

If somebody with a motor in pieces can check theirs, we might find out whether mine is a one off, or there are more.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
voxmagna is offline  
Sponsored Links
Advertisement
 
post #4 of 16 (permalink) Old Jul 13th, 2007, 10:15 pm
 
Join Date: Jun 2003
Posts: 221
Quote:
Originally Posted by voxmagna
There have been many posts about this problem, much discussion about sealants and in some cases people get leaks fixed. In other cases the leaks come back. It seems strange that so many different people, some with good wrenching skills, still get the problem.

So I have the opportunity as I've always promised to get my '97 perfectly oil tight. Most of us who've 'been there' know that BMW rely on a bead of silicon gasket sealant placed in the right places to make the seal. It is vitally important that the sealant is applied to a grease free surface and in most cases the sealant is allowed sufficient time to cure - which could be up to 48 hours. When this work is done at the front, with oil in the bike and a motor in the frame, getting oil free mating surfaces can be very difficult. In fact on my own '97 KRS, most of the oem sealant was pushed away from the cover and block surfaces with very little actually sticking.

I was once puzzled when a previous champion of timing cover leaks posted that there was a lot of oil behind the cover which puzzled me a while since you would only expect splash oil feed at low volume. you might get the kind of leak that stains the case at the edges, but reported bad oil leaks surprised me.

Before I started my rebuild, I acquired some 20thou Nitrile rubber sheet, and some high performance glass fibre based 10 thou gasket material. I aim to use the nitrile sheet to make a re-useable gasket on the timing cover. The glass fibre material is for use elsewhere.

Now I've had a big shock which might be the real cause of all the timing cover leaks. The main oil feed gallery from the oil filter carries oil at very high pressure. It passes into the timing chamber and then connects via a milled land to oil lines cast in the timing cover. These meter oil at a lower pressure to the timing chain tensioner and valve gear. With the motor horizontal, oil returns to the sump via large holes in the block at the far end opposite to the crank. Too much oil around the top end will aggravate the smoking problem at start up as more oil will hang around the valve stems.

If the main oil gallery connection to the timing cover leaks, The timing cover will get filled up with a much larger volume of oil than normal, since this is the high pressure side before metering. I hate to dwell on this scenario, because it has the potential for reducing oil pressure where it's needed most - at the crank bearings.

I've posted 3 photos. 2 photos show the large round part of the casting and the oil hole. Note on the block photo how the hole is off centre in the land.

The first photo shows the result of a 'print' after my timing cover was coated with engineers blue and mated to the block. You can see how the oil gallery misaligns badly and in fact the hole centres in the timing cover and the block are misaligned a whopping 3mm. You can see in the third photo that the area of contact to achieve an oil seal is very poor at the top edge.

I don't know how many other bikes are like this, but the next time you remove a timing cover, just check where those hole centres sit. I'm not enamoured by the fix either, which is probably to fit a threaded ali plug, drill a new hole and re-face the surface.
The oil is supplied to the chain tentioner at full oil pressure, and I believe this pushes the cover away from the crankcase. The older (K100, K1100) engines didn't leak here and the tentioner was on the main crankcase. I think the reason they changed it was to make it easier to align the locking pin for valve service. Remove the cams to adjust the valves. If they had put bolts on either side of the hole, or counter bored it and used an O Ring, no problem
I noticed this in 98 when mine started leaking.
H
HGP3 is offline  
post #5 of 16 (permalink) Old Jul 14th, 2007, 1:02 am
Addict
 
carnadero's Avatar
 
Join Date: Dec 2005
Location: Sillycon Valley, CA, USA
Posts: 645
Quote:
Originally Posted by HGP3
TThe older (K100, K1100) engines didn't leak here and the tentioner was on the main crankcase.
Yeah, this is why I inquired about the older Bricks. I was at the local dealership a week ago, and there was an old Brick parked out front, one of those that wasn't fully surrounded by plastic, and I noticed the timing cover was absolutely devoid of any oily spots (altho it had a fair amount of road dirt on it ).

Black 2002 K1200RS - "The Beast" (over 100k miles)
carnadero is offline  
post #6 of 16 (permalink) Old Jul 14th, 2007, 3:27 am Thread Starter
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
HGP3,

I would go with what you said. I already commented that the nearest 2 cover hold down bolts are not very close to that high pressure gallery. Combine the low hold down pressure with poor alignment of the oil gallery faces and oil at 70(?) psi will pee into the timing cover pretty quick, then with the timing chain and timing gears wanging around at 4000 rpm, you have an 'oil pump' and oil just wanting to get out.

There are 2 surface mated oil feed points in the cover. The one I described is important because the hole is large and misaligned compared to the amount of metal left to seal. There's a much smaller feed hole used to get oil into the cyl head and rockers. here they have a 4mm drilling in about a 12mm dia. face, which should be OK.

I don't think it's oil pressure at the gallery hole that pushes the entire cover apart at the edges. There are too many fixings around the edge and there are a lot of reinforcing ribs cast in its roof. One of the solutions to the VW car problem was to fit a tubular sleeve, similar to the dowel used for alignment in this cover at the edge. I'm considering this for both oil feed points. When I think they milled out the water connection flanges and fitted O rings at the pump and cyl. head water connections for water at max 20psi, this leaves me a bit cold.

Anyway, I appreciate that most of us probably never look inside the timing cover. I'm just suggesting that if a timing cover leak is really bad with more than a trace of oil around the edges, there could be a possibility of lower oil pressure, so get it fixed quick. When the time comes to have the cover taken off, get the shop to check the alignment of the hole centres with engineers blue on both oil feed points with the cover in position.

I was wondering if this might be one of BMW's best kept secrets, what could they do as a fix, and could they have changed something at a later date. Since my off center drilling was in the block and they would have mady many to the same template, you can't fix this with just a new re-designed timing cover. The hole in the block is aligned with the gallery tube feeding it, but the casting shape around the hole was off center with insufficient metal to match my cover.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!

Last edited by voxmagna; Jul 14th, 2007 at 3:35 am.
voxmagna is offline  
post #7 of 16 (permalink) Old Feb 26th, 2008, 10:45 am
 
Join Date: Aug 2007
Posts: 165
Mine always had some oil seeping from the cover...but it never leaked so bad until I took it to the dealer to have him fix it under warranty. Now it is pissing oil all over the inside of the belly pan. The dealer fixed me up good!
BigHausLittleFalsy is offline  
post #8 of 16 (permalink) Old Feb 27th, 2008, 9:20 am Thread Starter
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
I wouldn't be so hard, although you are right to be upset. There are many here that have done the job a couple of times at least and only a few who have claimed a success for many miles.

You probably have a good case to get the work done properly and it just might be that when the dealer works out the cost of getting it right for you a second time, they may pay more attention. Good Luck!



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
voxmagna is offline  
post #9 of 16 (permalink) Old Feb 27th, 2008, 9:41 am
 
Join Date: Aug 2007
Posts: 165
The thing is this.....not everyone can do this type of work even I know that. The dealer probably can do it...but they have to WANT to do it first. The reason it didn't get done right is because it wasn't important for them to get it right. This is what seperates a good mechanic form a mediocre one. You say that I might want to give them a second chance to get it right? Ok....there's a saying we have here in America....."fool me once...shame on you....fool me twice...I'll blow your brains out!"
BigHausLittleFalsy is offline  
post #10 of 16 (permalink) Old Mar 1st, 2008, 3:15 pm Thread Starter
Addict
 
Join Date: Mar 2004
Location: , , UK
Posts: 3,750
Some had the dreaded timing cover leak during their new bike warranty, others when dealers did it.

If the factory make the bike and it leaks, you can't have much confidence in the oem service instructions or the design and then you have to think outside the box for a better solution.

Fool me once and I look for the design flaw and try to fix it myself forever.



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
voxmagna is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the K-Bikes.com - Excellence in Motion forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Parts are in. Need help with the timing cover. ELP_JC K1200RS/GT (Classic) 2 Aug 19th, 2006 9:04 am
Hit a snag on last step to remove timing cover. Help!! ELP_JC K1200RS/GT (Classic) 2 May 22nd, 2006 10:35 pm
Valve Cover Leak bluestreak K1200RS/GT (Classic) 3 May 16th, 2006 9:00 am
Questions On Timing Cover Leak And Valve Check. ELP_JC K1200RS/GT (Classic) 6 May 8th, 2006 12:22 pm
Timing chain cover drip solution popeyebedford K1200RS/GT (Classic) 23 Dec 16th, 2005 6:30 am

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome