Grease for head gasket and bolts??

[pagoda]

I'm amazed that the cylinder head bolts are only torqued up to 10 Nm. That's much less than a spark plug and one could do easily achieve it with a 10mm ring spanner.

Richard

If i recall these bolts are M6 in a hard cheese alloy . Very easy to twist off by heavy handling. A ring spanner will (over) do it by how much? Use a torque wrench on head bolts always.

 

[DownWest]

I'm amazed that the cylinder head bolts are only torqued up to 10 Nm. That's much less than a spark plug and one could do easily achieve it with a 10mm ring spanner.

Richard

Read the first post... Little engine. Bolts prob 6mm.

 

[RichardS]

If i recall these bolts are M6 in a hard cheese alloy . Very easy to twist off by heavy handling. A ring spanner will (over) do it by how much? Use a torque wrench on head bolts always.

But I've never suggested not using a torque wrench.

Richard

 

[RichardS]

Read the first post... Little engine. Bolts prob 6mm.

I've already read the first post. My subsequent observations remain unchanged.

Richard

 

[sparkie]

I've already read the first post. My subsequent observations remain unchanged.

Richard

Hi chaps, yes they're v.small (6mm) bolts into soft(ish) alloy, and I was lucky to get them out in one piece, hence my intent to do a good job when I re-build. I've even bought a new (smaller) torque wrench as my present one won't read that low. What with the price of the gasket and thread sealant etc as well I've nearly spent as much as I paid for the engine in the first place...

 

[gordmac]

Surprised an alloy block would use bolts rather than studs. Rough calc gives the torque about right for 80% proof load on grade 8.8.

 

[sparkie]

Surprised an alloy block would use bolts rather than studs. Rough calc gives the torque about right for 80% proof load on grade 8.8.

Yes studs would have been preferable, if not as tidy. Thanks for the check on torque- reassuring.

 

[Poignard]

It may just be the application of the old maxim "An engineer is someone who can do for 10 pence what any fool can do for a quid” .

If bolts will do the job, as they obviously do, there's no point in using studs and nuts.

 

[rszemeti]

Copper grease would work very well in this situation, it is very widely used as an anti-seize in marine applications.

 

[VicS]

Copper grease would work very well in this situation, it is very widely used as an anti-seize in marine applications.

Why would anyone use "copper grease" when the manual says Loctite 572?

 

[rszemeti]

Why would anyone use "copper grease" when the manual says Loctite 572?

If you had read the original post, that would be obvious. He was lucky to get them out in one piece, as there was considerable white corrosion.

 

[VicS]

If you had read the original post, that would be obvious. He was lucky to get them out in one piece, as there was considerable white corrosion.

IF you had read the entire thread you would know that I had read the original post because I referred to it in my reply at #7 where I directed Sparkie to the workshop manual which specifies Loctite 572.

He was probably able to get the bolts out without damage because they had been coated with Loctite 572, or an equivalent thread sealant, when originally assembled. What he believes was white corrosion may well have been the cured Loctite. If there had been a lot of corrosion he probably would not have got them out.

 

[thinwater]

Copper grease would work very well in this situation, it is very widely used as an anti-seize in marine applications.

In fact, if you look at the marine anti-seize products from Locktite (LB 8023) and others, they are copper free. That is one of the key characteristics of a "marine" anti-seize.

LB 8023, one of the best in marine applications, in independent testing:
"Black, metal-free, brush top lubricant and anti-seize made from graphite, calcium, boron nitride and rust inhibitors. ABS approved. "

 

[sparkie]

Well I never thought I'd get such a variety of different views... all very interesting and informative. Point taken about the white "corrosion" Vic, and it quite possibly was old sealant, but there was a considerable difference between the four bolts, and the one with the most deposit was the hardest to remove... anyway, my brand new tube of 572 has just arrived in the post, and my new torque wrench arrived yesterday, together with the new gasket, so re-build here we come..wish me luck! Thanks to all contributors. Sparkie.

 

[anoccasionalyachtsman]

I'm sure it's been covered (I've read it all, but that was days ago) to clean the holes, either a tap or use an old bolt with a longitudinal slot cut through it with a thin cutting disc.

 

[VicS]

I'm sure it's been covered (I've read it all, but that was days ago) to clean the holes, either a tap or use an old bolt with a longitudinal slot cut through it with a thin cutting disc.

Good idea ( I dont think it's been mentioned)

Probably need a plug tap rather than a tapered tap though

 

[Malish]

Good idea ( I dont think it's been mentioned)

Probably need a plug tap rather than a tapered tap though

3rd post

 

[anoccasionalyachtsman]

3rd post

It's the interweb, and if a tip's worth passing on it's worth doing it twice. Or thrice.

 

[RichardS]

But post #3 was "Yes that was one of my reservations. Options are copper, white (calcium), or LM (petroleum). Did think about zinc chromate paste but have found this tends to set very hard over time" so I don't understand what that has to do with the type of tap needed to clean the threads anyway?

Richard

 

[VicS]

3rd post

#4 actually but I missed it whatever number it was

It was 4 days ago .... memory's not that good.