BMW K bikes (Bricks)

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1Back to top Go down   Engine case and cover tolerances Empty Engine case and cover tolerances on Thu Apr 05, 2018 9:52 pm

FreyZI

FreyZI
Silver member
Silver member
Left the K sit all winter and did a bit of work on the Guzzi instead, but mostly just mourned the crappy weather in central Pennsylvania (still mourning).  I'm getting reinvigorated to finish this project and get the old girl back on the road.  So, today I drained the oil so I can address a leak.

I did the whole top end (er, left side end) in the fall (an effort to address smokiness).  Upon reassembly, I noted that there was a bit of an offset between the engine case and the front cover -- not much, maybe a fingernail's thickness.  Despite a liberal spreading of ultra black, I ended up with an oil leak -- probably several drops a day -- apparently right where that offset is, below the timing chain.

Engine case and cover tolerances Img_1542

Now, admittedly, I rushed and tightened down the case cover before letting the ultra black cure a bit.  So, the questions:  Is this gap anything to worry about?  Should I just give it another go with the ultra black and allow proper time for cure before tightening down the cover, or do I need to do something more involved, like filing?

Cheers,

Frey

    

2Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Thu Apr 05, 2018 10:45 pm

TacKler

TacKler
Life time member
Life time member
The gap is just how it is made and the sealant you applied is what is required.  However the manual says to apply the bolts to the correct torque values as this avoids distorting the seal.  

However, looking at the photo, the bolt to the left of the indicated area looks to be loose.  Could this be the problem?


__________________________________________________
Red 1991 K75S
    

3Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Thu Apr 05, 2018 10:55 pm

Laitch

Laitch
Life time member
Life time member
@FreyZI wrote:Despite a liberal spreading of ultra black, I ended up with an oil leak -- probably several drops a day -- apparently right where that offset is, below the timing chain.  . . .allow proper time for cure before tightening down the cover . . .
Curing isn't the problem. If the surface is not perfectly free of oil, you'll have problems. Did you reuse the old gasket?

Like TacKler, I was wonder what was happening with that screw, too.

Engine case and cover tolerances Wassup10


__________________________________________________
1995 K75 73,000 miles
Engine case and cover tolerances Usa-lo10
    

4Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Fri Apr 06, 2018 12:12 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
A trick we use in the boatyard is to tighten down on sealant in two stages.

Put the sealant on the surface you want to seal and then assemble, tighten the fasteners only enough to get a bit of sealant to squeeze out all the way around the joint, then stop.

Let the sealant cure for at least a day, longer if possible, then tighten to the proper torque.

What you have done is used the sealant to form a thick gasket that is compressed when it has hardened enough so that it doesn't all squeeze out.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

5Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Fri Apr 06, 2018 1:30 am

RicK G

RicK G
VIP
VIP
The crankcase end cover probably has been put on incorrectly which makes the other end sit out a bit the best way is to remove the crankcase cover then position the front cover so the ends are flush then once the front cover is tight the crankcase cover and cam covers can be put on without that uneven surface. Just a very small dab of sealant then tighten the cover bolts finger tight, let the sealant cure the tension the cover bolts to 8-10ft/lb.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

6Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Fri Apr 06, 2018 10:33 pm

FreyZI

FreyZI
Silver member
Silver member
Indeed that bolt was loose.  Another duh moment in this project.  I'll try re-aligning the timing chain cover before putting the valve cover back on.  So, what's the best way to get the old ultra black and the oil off the gasket so I can get a good seal?

    

7Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Sat Apr 07, 2018 8:15 am

robmack

robmack
Life time member
Life time member
Careful scraping with razor blade to get the large portions off being very careful not to gouge or scratch the surface. Then follow that with a cloth wiping with acetone. You want to remove all remnants of old sealant so that will take time and effort. Don't be tempted to rush the job and use abrasive scrubs.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

8Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Sun Apr 08, 2018 4:52 pm

FreyZI

FreyZI
Silver member
Silver member
@robmack wrote:Careful scraping with  razor blade to get the large portions off being very careful not to gouge or scratch the surface. Then follow that with a cloth wiping with acetone.  You want to remove all remnants of old sealant so that will take time and effort.  Don't be tempted to rush the job and use abrasive scrubs.
Carefully cleaned.

Questions: Per Haynes manual, "Apply smear of sealant to stick in cover groove."  Is there a sealant that's easily removed the next time I have the cover off?  When they say, a "smear", what exactly is that?  Is it really necessary?

    

9Back to top Go down   Engine case and cover tolerances Empty Re: Engine case and cover tolerances on Sun Apr 08, 2018 5:07 pm

Laitch

Laitch
Life time member
Life time member
@FreyZI wrote: When they say, a "smear", what exactly is that?  Is it really necessary?
It's a smidge that's been spread out by downward and lateral pressure. As far as being really necessary, don't do it and let me know. I'm a slave to instructions.


__________________________________________________
1995 K75 73,000 miles
Engine case and cover tolerances Usa-lo10
    

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