I'm about to do a headgasket job on my 93 945 turbo. The car has made it to 290,000 miles on the original gasket, and the car is still very much drive-able; even though my coolant has quite a lot of oil in it, I'm getting exactly the same performance and mpg as I did when I bought the car 12 years ago with, with 200k fewer miles on it! I must say I find this a testament to the incredible engineering of these cars. But of course, I can't put off this necessary repair for much longer.

The head has had a few valve adjustments over the years, and the engine runs smooth as silk. For this reason, I'd rather leave the head alone and just clean up the gasket surface so I can get everything put back together as quickly as possible. Does anyone have any tips for doing this well and with basic tools? I was thinking of perhaps using a soft wire brush with a drill, and maybe some steel wool to finish things. My main concern is of course getting particles/dirt/grit stuck all over the oily head, and I don't have too many thorough cleaning options available, since this will be primarily an 'on the street' job; no driveway or garage available, unfortunately...

Any tips or shared experience would be greatly appreciated. Thanks!

You will have to see how it looks once its off. On my 940 it looked pretty good with several spots of corrosion. I chose to play it safe and had the head surfaced as it did get hot a couple of times. At 290 Kmiles, I'd think it would be a bit out of flat, but what do I know.

Mike

After removing the head on the 83 I noted the head's gasket surface was quite clean, but I attacked a couple of dodgy spots with an acetone-soaked rag (outdoors, plenty of ventilation) and a plastic pot scraper. Did the job.

The block deck was a different matter, bits of gasket stuck on. On this cast iron surface I was comfortable with carefully using a sharp, 3/4" woodworking chisel to scrape away the gasket residue. I plugged all water jacket holes and the small oil passage with paper towelling, and used big wads of paper towel in the cyl bores.

I figured any tiny bits of the paper towel remaining would either degrade into mush, or get combusted and blown out the exhaust.

Somewhat like Spook's technique, I used a powerful shop vac both before and after removing the paper towel wads, wiped the cylinder walls with oil, and gave the block deck a wipe with an acetone-soaked rag to ensure a totally oil-free, clean and dry surface for the gasket. IIRC, I used an Elring gasket set from FCP.

When I do a job like this, I fill the cooling system with plain old tapwater only, and run the engine for a few minutes to check for leaks - or test with a cooling system pressure tester. If it leaks, you don't have glycol coolant all over the place and you have not wasted money. If no leaks, I drain, and put in 100% antifreeze/glycol to 1/2 the system capacity, then top up with distilled water.

--
Bob: son's XC70, dtr's '94-940, my 81GL, 83-DL, 89-745(V8) and 98-S90. Also 77-MGB and some old motorcycles.

Dear benfingland,

Hope you're well. While I've not yet had to do a head change, I've done a few waterpumps. These require cleaning the front of the block, to remove any residues from gaskets. I think of this cleaning as akin to preparing a wall to receive paint. To get the best job, I want the surface to be perfectly clean, i.e., no dust, grit, stains, etc.

Key point when doing a head-gasket: avoid scratching the aluminum of the head's underside. To that end - and to ensure a surgically-clean surface - I'd use methyl ethyl ketone (MEK) or dimethyl ketone (DMK or acetone). These powerful solvents - very flammable and carcingonenic - dissolve all oil-based materials. Be sure to wear heavy duty nitrile gloves, while handling these solvents.

To keep dust/grit out of the cylinders, I'd pack the cylinder with clean plastic bags (which do not shed fibers or dust). I'd again rely on solvents to remove most head-gasket residue, stains, etc. As the block is cast iron, you can safely use a brass wire wheel to remove anything that the solvents don't remove.

Before removing the plastic packing, I'd pass a vacuum cleaner hose over the top of the block. I'd use a couple of fingers to hold-down the plastic packing, so that the suction can remove all dust, grit, etc. As a final precaution, I'd wipe the top of the block with a tack cloth. This is cheesecloth, with a rosin coating, that is sticky. To it will adhere all dust, grit, etc. Painters use tack cloths to ensure a defect-free finish.

After you remove the plastic packing, I'd again wipe the cylinder tops and walls with a tack cloth. Just before seating the head, I'd coat the cylinder walls with clean oil.

My guess is that once you make the final pass with the tack cloth, it will be perfectly clean.

Hope this helps.

Yours faithfully,

Spook

Thanks, Spook, for the great ideas. Especially the tack cloth - I haven't used one in years, and would never have thought of it otherwise. I replaced the headgasket in my '92 NA last year, but found I also had to replace the entire head, since the car had overheated several times, and the surface was also badly corroded due to substantial neglect by the previous owner. So this will be my first experience (hopefully) re-using a well-cared-for head. Your advice is most appreciated!