A question about EGT's

Gareth · Post by **Gareth** » Tue Mar 20, 2007 9:03 am

Very certain it is the gasket at fault here. For some time (and without me realising what it was) there would be a loud high pitched noise from the turbo area when the car was restarted from hot after about 10 minutes. after a few more minutes running it would disappear.

It turns out that this noise must have been a gap between the turbo and manifold so its no wonder the ally gasket couldnt take the heat (it melts at anything about 750/800C.

It's only now as the performance has very gradually got worse that i've noticed there being a problem.

I've ordered a SS gasket from the states and will be using a belt and braces approach when the turbo comes off.

Gareth

duncan · Post by **duncan** » Tue Mar 20, 2007 9:04 am

Sounds like it has been gradually getting worse Gareth - annoying I bet, but good that you have diagnosed it now and have a plan to fix it :thumb:

rowdyburns · Post by **rowdyburns** » Tue Apr 03, 2007 9:12 am

borgue wrote:or it could be you are using too much ignition advance at low boost.

High EGTs are caused by too much ignition retard, not advance. Think about how you are shifting the burn time in the combustion cycle.

Gareth · Post by **Gareth** » Sun May 06, 2007 11:27 pm

Hi guys, a brief update to this saga.

Managed to remove the turbo/manifold today, and its definatly been leaking on that join. Not as bad as i had expected it to be, but enough to cause a problem. The gasket was still in one piece but thin and had started to erode at the rear which explains the dust, the nuts holding the turbo onto the manifold were not mega tight.. but more worrying was the evidence of a crack on the turbo outlet flange where it mates with the manifold. Its right where the gasket sits, not alot i can do about this aparet from replace the turbo, with a new stainless gasket it will take the heat better, new locktab washers and a good clean up with some emery cloth in a block should clean it up enough, but its a good excuse to get a T34 in the future!

Gareth

Gareth · Post by **Gareth** » Sun May 13, 2007 2:28 pm

Pleased to say the car is now back on the road and better than ever. EGT's are 150 F cooler! Time to get the boost up again, as its sitting at 13-14psi, its never been as smooth but then again i did do a number of things at the same time like replace the gearbox and clutch (resolving the sticky gearchange, oil leak from the casing and dodgy mount at the same time), better driveshafts and a good clean up elsewhere. I've also removed the dump valve so the only clue to its performance is the exhaust..

Gareth

borgue · Post by **borgue** » Sun May 13, 2007 4:44 pm

rowdyburns wrote:
borgue wrote:or it could be you are using too much ignition advance at low boost.
High EGTs are caused by too much ignition retard, not advance. Think about how you are shifting the burn time in the combustion cycle.

incorrect, it could be either to advanced or not advanced enough, there is a window to aim for.

too far EITHER way will result in a higher than desired egt.

Ollie