Use of Copper Gasket Spray On Cylinder Head

[Leptons]

I'm in the process of replacing the head gasket on my car (it's a 328i Sport). It's my first head gasket change actually having done pretty much every other type of repair! The head is off at the engineers getting skimmed and pressure tested.

I've stumbled across a few posts online about coating the block face with various things to aid sealing on reassembly. Obviously when the block has not been decked there can be minor imperfections/pitting.

Anyone have any experience of it?

TIA

[Leptons]

Thanks for the replies, looks like a no then! I was planning on using an OE gasket, seems to be made of some kind of composite with steel rings around the actual cylinders.

[Leptons]

kev b said:

Is this one of the engines that has a problem with the threads in the block stripping if it has been overheated?

A mate had a 325 and the bolts pulled the threads out when tightened up.

Yes it's not got a great reputation! As far as I know it hasn't overheated though (it was pressurising the cooling system)so fingers crossed!

[Leptons]

robinessex said:

An over heated engine won't make that happen. Unless the block was cherry red at some time!!

It's pretty well documented. They're an alloy block and the bolts are Torqued to the equivalent of around 80NM.

[Leptons]

motorhole said:

Yep, 40 Nm then two steps of 90 degrees is correct. Believe me, that second 90 degrees is pure stress bundled up into 14 discrete packages.

I managed it without pulling any threads. My advice would be as follows:

1) Make sure all threads in the block are impeccably clean. A clean head bolt should be able to be loosely wound into its hole by hand until it bottoms out (without the head in place). If it doesn't, threads aren't clean enough.

2) BMW specify using oiled bolts. Use regular engine oil. Too much oil is bad and can result in hydro lock in the threads. Use a drop of oil under the bolt heads and on both sides of the washers. A dribble of oil on the bolt threads. Then leave to drain on a sheet of card or paper.

3) Leave at least 20 minutes between torque stages to allow the bolt to stretch. I left it 30-40 minutes between each stage.

4) Hope for the best. Have wife/friend/pet to hand ready to console you if it goes tits up. If it goes to plan, you'll need a seat and a brew before you do anything else!

Edit: I also thoroughly cleaned all the new bolts and washers with carb cleaner and left to dry prior to oiling.

Thanks for the wise words, sounds like dirty threads and losing track of which one you've torqued up are a big cause of stripping them. I had actually read a lower initial torque figure of 32nm. Also heard a few people leaving out the final 90DEG or using one figure of 50lbft!

[Leptons]

paintman said:

Once you've done the initial torque put a thin line on each bolt head all pointing in the same direction - I used a paperclip & a tin of white paint I'd got knocking around when I did my RRC V8 recently. Trick I've used for years after being told it a long time ago!
Then when you do the angle tighten you can see which ones you've done & which ones you haven't.

ETA You don't need a fancy angle gauge to see when they've been turned 90 deg either!

Edited by paintman on Friday 28th July 14:13

So simple but genius! Thanks