The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: tomtit on August 23, 2010, 05:29:56 AM
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Hi guys need some advice, Started the bike up today and looks like the R/H head gasket has blown so my question is how hard is it to change the head gasket as in do I need special tools also would the head need to be machined and if so would that mean the L/H head will need machining also. Any advice would be greatly appreciated.
Tom
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Out of curiousity, what does a blown head gasket sound like?
Removing the head is actually quite easy. But you will need to remove your exhaust first - Sounds obvious. But if you have never removed your exhaust, I would recomend you cut the collars off and renew them.
They have a habit of corroding and when not touched for years at a time. When you then remove them, you run the risk of stripping the threads off the head also. This will be expensive to repair. And is entirely avoidable - As Clint once said - "Are you feeling Lucky?"
But going back to your original question, when you take the rocker cover off, you will see four nuts that hold down the rockers, these re your head bolts. Undo them and slide of your head (after removing the card and exhaust). You might need to tap the head with a rubber mallet to unstick it though. It really could not be easier - thats why we like them.
You will need a torque wrench to do them nuts up again.
Good luck
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What symptoms lead you to think that the head gasket is blown out?
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Thanks for the advice Steve, I've worked on bikes and cars previously just was not sure if special tools were required. In regards to cutting off the exhaust collars I don't quite follow as if you cut the collars off how do you get the threaded part out of the head ?.
Bob when I put my hand to the front of the head near the exhaust I can feel a small amount of compression escaping plus I can hear it which drew my attention to it in the first place, Nothing major but no doubt will get worse. Looks like the long ride home took it's toll.
Tom
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If you can determine if the gas that is escaping is coming around the exhaust itself, there is a seal on the header pipes, I believe the R65 is the only bike that has these .
Next time you start up the engine, have a spray bottle with water in it, spray it on the area before it gets hot enough to boil the water off, see if you can narrow down the area of leakage before taking anything apart .
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Or, if your bike is post 1980 and has the US- Pulse-air system (metal tubes conencting from airbox to just under the exhaust ports on the head, you might be feeling pulses of air/exhaust out of them if the compression bolt on the head end of the pipe isn't tightened sufficiently.
It may also be that the compression ring/sealing ring that goes round the header pipe (it fits inside/under the big finned exhaust nut and should be compressed/squeezed as the nut is tightened to help seal things up) could be put on backwards, which would cause it to not compress/seal effectively. In any case, if those big finned exhaust nuts do not EASILY come off - IMMEDIATELY stop trying to turn them, get a hacksaw or rotary cutting tool and carefully cut across it between the fins - go slowly and carefully so that when you get down near the threads of the exhaust port on the head you STOP! Then use a cold chisel or pry bar to break the nut apart. I usually make a cut on the top side and underside as best I can to facilitate splitting the nut (only done it once myself, though).
If you force the exhaust nuts off and the threads have seized, you'll basically strip the alloy threads off the cylinder head with the buggered up exhaust nut and then you'll be looking at ~ $200 repair job to have a machine shop weld it up and cut new threads, per head. Or alternatively, there are some specialized clamps made in Germany, but I suspect they'll set you back at $200 as well.. IT is a YEARLY ritual to unscrew the threads (once you know they are OK), clean them and put on fresh anti-seize to keep these 'healthy'.
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Worth posting occasionally:
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F83811490%2Foriginal.jpg&hash=6c820e9d2f082135407da42e85f6772f3cce0cf1)
I tried it - it works!
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Thanks for the tip Bob I tried this and the leak seems to be coming from around the exhaust area so maybe a seal.
Rob will try the mix of lapping compound and oil when I check the exhaust seal.
Thanks to all for the advice, It is really appreciated.
Tom