Jump to content
Sign in to follow this  

Hydro Locking head bolts?

Recommended Posts

Does anyone know if the DRZ400 head bolts are bottom tapped and prone to hydro locking and popping the block if there is coolant or oil in them when you torque your head bolts? I heard some interesting sounds when torquing my last head bolt on the first pass to 18ft pounds, realized I forgot to check and make sure those holes where dry! I pulled that bolt and the bottom looked good and dry but also extended beyond the threads.  Could have been one of the other bolts I suppose but I would have heard a crack upon torquing those bad boys and I don't feel like puling them all and compromising my HG. I have done car heads before and when you are torquing 80+ lbs you hear crazy stuff that makes you feel like you are in the titanic, at 18ft pounds though it just didn't seem right to hear any tinging. I guess I won't know what those sounds where for a while. It resembled the sound an exhaust header cooling down on a cold day after a hot run, PING!

Share this post


Link to post
Share on other sites

1: Yes they are a blind hole

2: Sure if you mistakenly left oil or coolant in them you may have caused issues,, never seen it, but it would be a bad idea non the less.

3: 18 ftlb?  You do know the suggested head bolt tq is 43 ftlb yes? 

Share this post


Link to post
Share on other sites

18ft lbs is service manual's recommended first pass, then continue to 34. However, 43-44ft lbs seems to be the recommended torque spec for final pass. Since I drained the coolant, only the high pressure port for the coolant had any fluid in it, which is the closest to the head bolt that I was tightening when I heard then ping, When I pulled that bolt though, and looked down the hole, it was dry as a bone. Guess I'll just throw this baby together once I get my MCCT and see what happens. Who knows until then. At least it ain't my truck and I only dropped 800 bones for it.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×