F650 Head Gasket replacement problem

**Cactus Bob** · #1 23 Jun 2008

Greetings BMW tech gurus ...
I need some advice. I just finished putting the engine back together on my wife's 2000 F650ST after a nasty overheating experience. Long story. I had both the head and the mating cylinder faces re-machined. Head vacuum tested. New head gasket. Meticulously reassembled. Adhered carefully to torqueing procedure, yada yada ... She started up on the first kick, ran beautifully for several minutes and then slowly started blowing steam. I'm obviously getting coolant into the cylinder. Clymer recommends loosening and re-torque of all the external head bolts in this situation but I'd appreciate any additional perspective on this. Can I "over-torque" the 4 primary head bolts? Thanks in advance.

**Cactus Bob** · #2 26 Jun 2008

I followed the procedure outlined in the manual to relax and re-torque the "external" head bolts. Didn't help. Next step will be to pull the cams and re-torque the main bolts.

**Cactus Bob** · #3 26 Jun 2008

I Re-torqued the 4 main head bolts to 60Nm. After about 2 minutes of running the F650 started to blow a bit of steam again, but when she hit temperature everything settled in. Tested the bike with a 1/2 hour ride last evening. Good to go!

**Bill Ryder** · #4 26 Jun 2008

By blowing steam do you mean steam coming out of the exhaust pipe? If you had a previous problem where there was coolant coming out the exhast with antifreeze smelling exhaust fumes your muffler will have residiual coolant in it. On japanese bikes I repair the exhaust can steam for miles and miles. I make sure I run them a lot before I give them back . If on the other hand you have bubbles in the radiator....that is a problem.

**Cactus Bob** · #5 27 Jun 2008

Yup - white exhaust (steam) coming out of the tail pipe.
Unfortunately, checking for bubbles in the coolant would be difficult on the F650 with the gas tank in place ... but I was so certain that coolant was slowly getting into the cylinder past the new head gasket. Now I'm not so sure. After the initial damage there was a LOT of coolant pushed into the exhaust system and you're probably right that it took time to clear itself. Didn't even think of that. Kinda wish you had weighed in on the subject a week ago ... but everything is good. She runs clean beautiful now.
Thanks for the comments.