GTA headgasket

[clee]

The one I thought was OK would appear not ....It keeps overheating but only after about 20/30 mins and then will cool down of it's own accord
I have now tested it when very hot and get a positive reading on the gas analyzer .It looks like it might be leaking out the side of the LH head as well .....No white smoke to speak of just an occasional puff .Could it be sometimes going in the pot and then sometimes out the side ?
Warped head ? Bolts not down fully ?

[paul b]

bugger.........don't sound good Lee.......

is there any extra pressure build up in the cooling circuit or blowing dipstick out etc...

or, can you feel the exhaust gas being blown out, not just oil or water dripping onto the head and burning off quickly, giving the puff of smoke

[clee]

Difficult to say Paul ...I might need a 'Professional's' opinion .
It is definitely pressurising but only after about 20mins on a good run ...In the garage it stays fine for ages and cools down with the fan .

[paul b]

is it using/losing coolant at any rate??????.....

[clee]

Yes, but most is coming out the expansion cap and that is new ...Very little white smoke just the odd big puff when very hot .

[paul b]

how long does it take you know to check the head bolts.....

just incase you find 2 or 3 gone loose...sounding very head gasket like....sorry

[clee]

Not long ...but with the angle settings I don't know what they should be in Nm anyway .It might be obvious though .
I also have this oil pressure issue when hot so I wanted to check that and compression before I pull the lump .
That's what it was over here for anyway ...I just thought the dude had got lucky and it was just the cap and fans playing up .

[paul b]

oh I see, thought it was on yours...sorry...

yes, they are angled...rule of thumb is start low on the torque settings..., set, click,set, click....until you reach a torque when you feel it just start to "pull"....

on the setting up just check 2 or 3 separate bolts so you get a real figure..then go around them in sequence..

oil pressure, a number of things ....
definetly check compressions when you can..


cooling maybe something as silly a water pump vane fell off...but it doesnt sound like it..

[clee]

Yes, going to ref the wrench on my lump then test his
Pretty sure the head gasket is dodgy ...fluid went green after 5 pumps when the engine was hot after a run out ....Std GTA's feel very slow to me now

[TrickyDicky]

Have you had the head pressure tested whilst it was off? could be cracks opening under thermals more when hot. If the heads coming off and you dont have APT facilities (Air decay test is the best method) then try dye penetrant testng the combustion chambers in head - may show something indicitive.

hth

Tricky

[clee]

The heads were not touched at all I believe . Just the pistons/liners replaced .
I've suggested we get the heads at least checked and skimmed .I have some more heads lying about that I know are good .

What with this and the very low oil pressure I'm suggesting he has a 'word' with the guy that rebuilt it .It's only done 150 miles since then .
Will do a comp check and take it from there .If anyone has a oil pressure test kit I could borrow for an hour I'd be grateful .

[TrickyDicky]

[quote=clee;92505]The heads were not touched at all I believe . Just the pistons/liners replaced .
I've suggested we get the heads at least checked and skimmed .I have some more heads lying about that I know are good .

quote]

You say the heads weren't touched? we are talking Ally heads, it is good practice to budget in a skim everytime they are removed, clamping pressures and constant thermal expansion/contraction can encourage material to move (ie warp) without boiling. to be fair you can get away with it most times, however a full diagonal and traverse straight edge check for flatness to factory spec. (probably about 3-4 thou on them heads) is an absolute must.

hth

Tricky

[MFaulks]

Lee, I think if you do it on straight torque it should be around 90Nm std, but I'll need to look at my wrench and I'll remember It's very easy not to torque these up if the block threads aren't cleaned up, and nice bolts threads, and oiled threads and washers etc

not really sounding good is it... I think the chap needs to get back to his supplier asap before anything gets stripped, 150 miles down the road must be covered.

As Tricky says could be warped heads, but also the liner setup heights if these are way out, who knows... do you know why the engine was originally stripped, I know you mentioned the chap had been told it was a blown piston, but what was the real circumstances before this, apologies if you already told me, my brain seems very selective these days laugh

[TrickyDicky]

I know you mentioned the chap had been told it was a blown piston, but what was the real circumstances before this, apologies if you already told me, my brain seems very selective these days laugh

If a Piston's blown a hole through itself due to Detonation etc the Heads should be skimmed as a matter of course and if there was overheating also it should have been pressure tested also a matter of course.

Your only in the Mids Clee, somewhere like Bilston Head centre would have the Heads and refurb them completely and trustworthily.

[clee]

He was told a piston was blown but it wasn't it turns out .I'll try and get an idea of the symptoms before it went in .All I know for now is that it was running like a bag of ****e when he bought it but why change all the pistons and liners
Bit of a minefield really as it could be one of half a dozen things on the rebuild ........
Compression check today and see if that shows something .