Headgasket UV/ozone protection - PeachParts Mercedes-Benz Forum

bgiovan · #1 01-03-2011, 08:05 PM

In reading the FSM on a 617 head R&R, they refer repeatedly to not opening the head gasket until just before use as it is affected by "light and ozone". HBOL makes no such reference as far as I can see. Is this a big deal and why. Sorry if being obtuse...first time doing one of these. Thanks!

barry123400 · #2 01-03-2011, 08:18 PM

Well what does it hurt really to follow the old instruction. Chances are the head gasket may have been changed since that was written. Or different sealing material . All I can think of is that light and air may start some gasket adhesive on the gasket hardening as soon as air is present.

bgiovan · #3 01-03-2011, 08:27 PM

Agree completely Barry. Thing is the Haynes book has you taking the gasket out and tracing it on cardboard to put the head bolts in exact sequence. That by its very nature means you are taking it out at least a few hours early if you are only doing the gasket and are quick. Most are sending the head out and well, days..weeks. Just didn't know how bad it was to pull it out early as implied by Haynes.

barry123400 · #4 01-04-2011, 02:26 AM

Draw a simple pictorial of the bolt layout on cardboard and punch some holes. You can get by without a really accurate template.

ForcedInduction · #5 01-04-2011, 03:12 AM

The headbolts are stretch bolts. Being of that type and several decades old with thousands of heat cycles, I wouldn't be reusing them.

At $3.50/ea thats $91 but for a job that occurs once every 20+ years its cheap insurance.

bgiovan · #6 01-04-2011, 06:26 AM

Well when you put it that way Forced...

Thanks for the help guys. Just wanted to understand the rationale.

Happy New Year!