TRD head gasket, gone or not?

TB2 · Post by **TB2** » Sat Jul 02, 2011 1:12 pm

Hello everyone,

I just came back from a few months in Asia and now I really need to take care of that nasty problem I have with my TRD:

Quite frequently, the red and yellow + STOP lights are flickering, especially when accelerating or going uphill. Until now, they never stayed on but I didn't force it. (well apart from the two times one and two years ago when the engine actually overheated because the fan had fallen off)

I've only got one temperature sensor on the thermostat housing (my manual says there should be two, one with a grey, and one with a yellow cable), but this sensor looks like new to me and the connections are very clean.

I've let the engine running with the water filler cap off and if rev the engine, very small bubbles start to appear and the water level inside the water tank rises. Here's a video:
http://login.icu.uzh.ch/~archer/20110701_003.mp4

With this happening at just over 60° water temperature after running for 10 minutes, can I safely assume that the cylinder head gasket needs to be replaced?

If yes, how do I know which thickness I need - my shop is selling two types, 1.54mm ("two notches") and 1.64mm ("three notches"). Also, what other bits should I get and replace when doing the head gasket?

Thanks for the help!

Post by **mat_fenwick** » Sat Jul 02, 2011 1:56 pm

Sorry, I haven't time to download the video (slow connection) but it certainly sounds conclusive that you have gases leaking into the cooling system, the usual cause of which is the HG or head.
Gasket thickness relates to piston protrusion at TDC, but in practice a lot of people either fit the same thickness gasket (if the head doesn't require skimming) or simply put the thickest one on.
It would obviously be worth changing the cambelt, probably the cam seals and it's easier to do the metal braided hoses to the heater whilst the head is off. Head bolts will be the stretch type on yours, which can be re-used if under the length limit. For peace of mind I replace them with new, but I have re-used once before. You'll need a T55 Torx bit to undo them.

themildbunch · Post by **themildbunch** » Sat Jul 02, 2011 1:57 pm

Sorry to see you've got bubbles there... My TZD had a much milder version of that that I missed when buying the car last year..

The conclusive test was that less than a minute after a cold start taking the cap off the expansion tank gave a distinct hiss showing pressure build up caused by the HG leaking...
I ended up using a local specialist as I needed to use the car quickly - it still cost around 3 times what I paid for the BX initially!
Not really worth taking short cuts with this kind of work I think - the head should be skimmed and that would determine the thickness of replacement gasket...
I'd definately change the waterpump, tensioners, cam belt while this is all apart unless they're very new. You'd also get good access to the braided heater and coolant hoses / heater valve / Doseur / clutch cable... All worth checking or renewing when there's easier access.
I also had the fuel heater bypassed which is worth doing as it's a common area to leak..

Good luck..

TB2 · Post by **TB2** » Sat Jul 02, 2011 2:19 pm

Thanks for the hints.

I will of course change all the belts, rollers and the waterpump. What about the valve stem seals?

Also, how do I know if the head needs to be skimmed? Is it enough to clean it carefully and properly and then use a straight metal bar to check if it's level all around? If it needs to be skimmed, is it just the head or the engine block?

Post by **mat_fenwick** » Sat Jul 02, 2011 3:39 pm

A straight edge and a set of feeler gauges will enable you to check for flatness - there is a tolerance but not sure what it is offhand. I'd advise against skimming if it doesn't need it, as there is a chance you will uncover porosity in the head.
If there is any warping, it's usually in the head although I have known the area around where the head bolts screw into the block to be slightly raised, and need dressing down.
It's also a good idea to have the head pressure tested, if you have access to someone who could do that for you. Valve stem seals will probably come as part of a gasket set, so makes sense to fit them really.

citronut · Post by **citronut** » Sat Jul 02, 2011 7:28 pm

if the head has been cooked it will need skimming, but first get it presure tested,

also it is best to check the condition of the valvel face's and the seats,

you should also check the depth of the valve's below the head face especialy if you have the head skimed,

regards malcolm

Oscar · Post by **Oscar** » Sat Jul 02, 2011 8:34 pm

I have a new in packet head gasket, set of seals, and set of bolts that I bought for my TZD just before I scrapped it. If they're the same as you need, you're welcome to make me a silly offer for them - say half of retail, plus postage? They're just sitting in the cellar now.

TB2 · Post by **TB2** » Sun Jul 03, 2011 11:40 am

Thanks for your offer, Oscar. I The TZD, was it non-turbo? I'm not sure if the gasket is the same. At least, the shop where I usually order sells two different items for the turbo and non-turbo engines. The gaskets look slightly different as well, although the holes are almost the same:

turbo:

non-turbo:

The other seals and bolts have different part numbers as well. I don't have an account for GSF so I can't check their retail prices but my shop sells the gasket + a set of seals + the bolts (made by ELRING) for just over £ 200. Does that seem right?

About that pressure testing, that's just for the head, when it's off, right? To see if it's cracked, or what is the purpose of this?

citronut · Post by **citronut** » Sun Jul 03, 2011 5:29 pm

exactly to check if it has any internal cracks or any for that matter,

aparently the turbo heads are more prone to this,

regards malcolm