How to clean headgasket sealing surfaces?

[wasfishing]

What's the best way to clean the head gasket sealing surfaces? Engine was recently rebuilt (60km ago) but had to remove the head and send it back. The head just has stains from what looks like we're the headgasket was. From my understanding it has to b perfectly clean for the multilayer metal gasket to seal properly. Anyhrlp would be great thanks.

[andrew_mx83]

If going to a MLS gasket you really need to have the block surfaced by a (good) machine shopto get the correct RA finish.
Ive seen blocks that have been decked by a crappy shop that were weeping water to oil after 5000km.... 60k since rebuild, you've got no chance.

[dnegative]

Ive seen blocks that have been decked by a crappy shop that were weeping water to oil after 5000km.... 60k since rebuild, you've got no chance.

Ergh without seeing it I wouldnt say no chance but I wouldn't bother trying to be honest.
We have done headgaskets at work (MLS with whatever coating they seem to come with) on well used motors without any issues but they have been cast heads and blocks.


A regular headgasket will work however.......

[wasfishing]

Woops not 60k I meant 60km as in I drove it twice! So block n head have both been resurfaced very recently

[Rodger]

Make a scrapper from a length of old Power hacksaw blade to use on the block or sharpen a stiff palett knife. Scrape so that if you do create a light gouge it is not heading between bores or water or oil passages. Use something like carb cleaner and a brass wire brush to loosen and clean off any "glue" from block and head. With only 60km the surface finish will still be there and usable and the "glue" may not have fully set up.
If worried about the head then when it is back at the machine shop ask them to scim it again.

Regards
Rodger

[trd_st184]

I wasn't sure that the brass wire brush would be a good idea as I heard they could score the metal, especially if any of the brush wires were to come off in one of the oil galleys. Please correct me if i'm wrong.

[Rodger]

Brass is softer than the cast iron block and soft enough not to score the alloy head.

Keeping the oil gallery and water passages clear of debris is always a concern and it can take some effort if you wish to be maticulous.
The critical bit as you allude to is to keep the debris out of the oil pressure passages and the return to sump passages, so you could block them off with bits of rag or masking tape.
Keep what oil is left in the sump and drain it after the block is cleaned to help flush away the debirs and any added cleaning fluid.
Material will need to be cleaned out of the bores and from off the pistons as best can be with a soft rag. Anything "soft" or even the odd brass wire missed during clean up will not harm the motor if left in the bore as it will quickly get burnt away.

When the head goes back on the water passages can be flushed out.

[HAVABEER]

+1 for the hacksaw/reciprocating saw blade

get them from mitre 10 etc, and use a bench grinder to sharpen a point on 1 end. wrap the other end in a bit of cloth and duct tape to make it easier on your hands.

there's also a few spray on gasket removers from auto shops, i used one and it worked OK, nothing special but did help to looses up an old old old baked on gasket, got it on my skin and burnt like hell after a while. there's a product from 3M we use at work called 700 which is an adhesive and solvent remover (use it to clean just about everything) the best thing about it is it dries to nothing so does leave a residue.

[woggin]

how bout micarta scrapers?

[wasfishing]

Cool I've got a hacksaw blade scrapper already ( there Awsome) Wots the best way to clean the head? I've already got it back from the shop and they didn't touch it....

[Rodger]

Try the carb cleaner or the 3M product Havabeer mentions (that I have used in my line of work as well).

Scotch bright green pad and elbow grease. I do not believe you need to get it back to clean alloy finish. If the stain does not come off with a reasonable attempt then it can be considered to be bonded into the alloy and should not impede the bonding of a new gasket.

Regards
Rodger

[MorGo]

Doing the industry maintenance work benefits some carbide blades;just go and see what the local paper mill can give ;-) Very handy things to scrape surfacec clean..

The 2JZ-heads have absolutely horrible finish but still they seal.

Never ever put anything abrasive to the block or head! Even if you get the surface clean is it straight?
Last yoer I have a "rebuilt" Volvo engine.Yeah,the deck was clean but when surfacing it the narrow cylinder to water channel was grinded down 0,3 mm compared to other deck.. (it was a nightmare every way;the hone was done crank in the block and no effort to clean the hone debris.Rings just put on the pistons;no measuring or filing the ring gaps) Customer was VERY happy when I show the pics where hone shit was on the block (that was assembled block;ready to run..)

[dnegative]

3M roloc discs if you have experience and know what your doing (and only ever on cast!)
Scotchbrite, scraper and a oil stone otherwise

[MorGo]

If not recently done the machine skim!! if it take 0,2 mm to have clean cut it have to done!
Or fool yourself and are happy to save something by not doing it..

Most heads are reasonably straight but the blocks.. In any build get the block deck machined!! Do you read;get the block deck machined straight!I repeat;get the block grinded straight at somewhere place that is known for good job.

Did I make myself clear;the block IS not straight! It's a little wonder to see how distorted blocks still seal! Grinding the deck that's the first 0.05 mm..then next.. still there is untouched deck.. 0,2 mm ..still something that the grind wheel has not touched..! 0,25mm and still not absolytely clean..

I am sorry if I made someone just get engine built (or somewhere assembled) have bad dreams but...

When enough blocks been on the machine one start to see big picture.Bolt holes rise,ridges between cylinders drop and the important cylinder bore-water channel sunk.

Whenever you have the block apart have it decked!

[andrew_mx83]

^^^^^

This man is on the money, its a shame i can only rep him once.....

The last few blocks i have sent in for machining have needed in the order of 0.020" (0.50mm) taken off which is a lot in engine speak.

I havEnt checed the block of the bhg i pulled apart last night yet, but the one from a week ago has corroded so badly around the water jackets im not even going to bother taking it to the shop for surfacing as there would be no deck surface left! New block ,decked (of course) is the only way i will give it back to the customer confident that it will seal.