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Premium Member
2006-2009 Range Rover MkIII / L322
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100 Posts
Discussion Starter #1
Hi guys


I’m doing a head gasket replacement on my 4.6 and at the stage when the heads are back from the machine shop and I’m about to refit them. I know I need to clean the block face really well before putting the gasket and heads on, and was going to use fine wet & dry sandpaper.


But … how fine should the paper be? The finest paper I have from B&Q is 600 grit but it seems really course - I’m worried that I’ll score the hell out of the surface and ruin the block.


My other problem is cleaning out the head bolt threads - where the hell do I find a thread chaser for 7/16 threads in the UK?? Or do all us Brits have to make our own out of standard bolts & an angle grinder?

Hope you can help :)

Cheers
John
 

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Banned
1995-2002 Range Rover P38A
Joined
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3,952 Posts
Or do all us Brits have to make our own out of standard bolts & an angle grinder?
That's what I use. An old bolt with a slit along it's length made using a 1mm cutting disc in an angle grinder. The slit allows any water or oil laying in the hole to be pushed out as the bolt is screwed in so you don't get a hydraulic lock when you put it together for good.

Wet and dry soon clogs on aluminium but 600 grit is a bit course, I'd see if you can find some 800 or even 1200 if you can (if B&Q don't have it, try Homebase or dare I say it, Halfrauds). In saying that, once you start it will be a lot less course after it's been run over the top of the block a couple of times. Wrap it round a cork block or piece of wood so it is flat and just work from end to end making sure you cover the whole width. Keep going until the surface feels like glass......
 

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Banned
1995-2002 Range Rover P38A
Joined
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135 Posts
An independent shop manager suggested that I use Scotch Brite Ultra Fine and WD-40. I manually turned the engine and got all of the gunk out. Another Professional suggestyed that I spray the head gasket with Permatex Copper Spray-A-Gasket and let it become tacky. I did both and it has been trouble free for two years.
 

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Premium Member
2006-2009 Range Rover MkIII / L322
Joined
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100 Posts
Discussion Starter #4
Cheers folks, I'll get ordering and see if I can get her back together by the weekend :)
 

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Banned
1995-2002 Range Rover P38A
Joined
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3,952 Posts
I'll second Scotch Brite Ultra Fine but I've never seen it in your local DIY in the UK. I can get it from a friends bodyshop where it's used for preparing surfaces before paintwork and the only place to buy it is from the specialist suppliers.
 

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FOUNDING MEMBER
1995-2002 Range Rover P38A
Joined
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488 Posts
Method I've used for many head gaskets, without subsequent problems, is as follows:-

1. Place clean rags loosely in each bore.

2. Use compressed air line or can of pressurised clean air (used for cleaning electronics) to blow out the bolt holes.

3. Screw bolts back into bolt holes finger tight.

4. Soak old gasket material on block face with Autoglym Intensive Tar Remover (this really is good stuff for loosening any old gasket material).

5. Use plastic (must be plastic) kitchen spatula to scrape off well soaked 'crud'.

6. Finish off any stubborn bits with 'Scotchbright' pad (the ones used for washing dishes by hand).

7. Pull rags out of bores bringing any 'crud' with them.

8. Blow out bores with compressed air.

9. Remove bolts.

10. Polish block face with rag lightly soaked in Autoglym Intensive Tar Remover.

11. Final blow out of bolt holes and bores with compressed air.

12. Final polish and dry of block face with clean dry rag.

13. Use new head gasket with no added 'goo' unless specified by manufacturer.

Jobs' a good 'un.
 
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