4age head gasket - lend me your thoughts

**mattysshop** · 15-01-2010, 02:26 PM

what sort of gasket are you using?

**oldcorollas** · 15-01-2010, 04:23 PM

pitting in piston 3, and also in the head on that cylinder, is "foreign object damage"

ie.. part of spark plug ceramic busted off usually.

**predator** · 15-01-2010, 08:16 PM

Plugs that are in presently look ok, so must have been previously.

Originally Posted by mattysshop

what sort of gasket are you using?

ACL Monotorque.. although by the sounds of things that wasn't a good idea :-s, but I don't have time to get another now. Although on reading I found something interesting - ACL says Monotorque gaskets already have a Hylomar type coating. While the gasket is seating for the first few km, it is recommended to use water for coolant, as glycol coolant can interact badly with the initial gasket sealant. Maybe this is the reason for the some of the failures?

JP · 15-01-2010, 09:29 PM

put it off and use a genuine gasket. Dont use the ACL Monotorque unless you want to be replacing it again very shortly.

**thechuckster** · 15-01-2010, 10:01 PM

i concur - even an OEM-copy off eBay would be better than monotorque (they invariably fail early and despite your best efforts to get even torque settings on all the headbolts, you'll end up randomly loose head-bolts).

**predator** · 16-01-2010, 10:07 AM

That bad huh..

why the hell they still sell them for all if they are known to be that bad?! f'ers..

I will try and grab one from Toyota today. think the parts place is open till 12.

**predator** · 24-01-2010, 06:52 PM

Here is the head cleaned before I put it back on.. As you can see the inlet valves seem quite good, but the exhaust ones are very rough. Maybe the inlets were replaced but not the exhaust side some time.

Proper Toyota gasket installed ($110 from Toyota - 2 day turnaround). Looks like what was on there previously. Sprayed Hylomar either side.

Also noticed the cam caps were all mixed up. I nicely ordered them when taking them off, but putting them back on I noticed the E's and I's were mixed up, arrows wrong way, a few in the wrong order

So whoever last worked on the engine clearly wasn't too careful. I um'ed and ah'ed about whether to leave it as it left the factory, or the way it was, but went back to factory, figuring as it had probably worn in the majority of the km the right way. No problems yet.

Wednesday I got the car back together. Let it idle up for 15 minutes, drove it for 15 minutes, seemed to be okay. Then today I decided I would test it out by driving 300km to Toowoomba and back to dump a replacement 20v engine + gearbox in the back (170kg or so) in 31 degree heat

Anyhow, this was a little crazy, however seems to be running fine, no overheating issues. With new platinum plugs, various new gaskets and the cleanup, seems to be running smoother than it ever has. Will see how long it lasts. At least I now have the 20v there ready to go in if it does blow.

**BLACKCAT** · 24-01-2010, 08:07 PM

If you have to rebuild another head just spin up all the valves in a drill while cleaning with a strong wire brush. The exhaust valves are always full of carbon due to the extra heat on that side.
Its also a good idea to lap the valves as most second hand ones will leak quite a bit.

**TERRA Operative** · 25-01-2010, 04:44 PM

Yea, I clean my valves on the bench grinder with a wire wheel attachment. The deposits on the exhaust side are as hard as concrete!

The exhaust valves shown above have the buildup still on them, can be up to 1/2 a mm thick.

**predator** · 25-01-2010, 08:46 PM

At the time, I wasn't too sure whether they were that way due to hardened carbon buildup, or the exhaust valve material itself. So I left it alone, didn't want to damage any valves. Sounds like I should have given it a go like I did the inlets. Anyhow, one for next time, thanks though.

**oldcorollas** · 25-01-2010, 10:21 PM

Originally Posted by predator

Plugs that are in presently look ok, so must have been previously.

ACL Monotorque.. although by the sounds of things that wasn't a good idea :-s, but I don't have time to get another now. Although on reading I found something interesting - ACL says Monotorque gaskets already have a Hylomar type coating. While the gasket is seating for the first few km, it is recommended to use water for coolant, as glycol coolant can interact badly with the initial gasket sealant. Maybe this is the reason for the some of the failures?

could even have just been a passing rock......

nah, old plugs for sure.

the sealant on them is Viton (if it is the bead you are thinking of)
if the head and block are CLEAN then it should seal well..

funnily enough, for K engines, Monotorques are the gasket of choice (as long as you retorque/check after running in a bit