Poss overboost problem

[Smithy111]

When I was last out in my Turbo Esprit I noticed that on full acceleration the boost kicks in as expected and then theres a sound of a massive release of pressure and stabilisation of the boost pressure (this is before lifting to change gear). Does this sound like a stuck waste gate and the manifold release valve blowing off? If so what parts do i need? Im thinking wastegate diaphragm/some sort of service kit?

[esprit22]

Yep, does sound like the wastegate is sticking, gonna need to take the wastegate assembly off the manifold and strip it down. Simple to strip it down, not so simple to remove it from the manifold though..

[Smithy111]

Right I’ve taken the waste gate assembly off (was surprisingly easy!) the valve stem was stuck solid so bit of ac90 and it’s running smooth now.

Cleaned and inspected the diaphragm and is in good condition, so my only question before reassembly and refit - should the valve stem be lubricated with anything? There seemed to be a very small amount of black oil in it?

 

[Smithy111]

Anyone? Going to reassemble and refit to car at weekend.

[910Esprit]

Fabian has been wrestling with the same issue on his rebuild thread.     Until I deleted that wastegate, I just used a smear of synthetic engine oil on assembly and used the car regularly.  Never had an issue with the wastegate sticking, but that was probably because it was so worn!   I certainly wouldn't use any sort of lube, such as a grease, that could dry out

Edited April 30, 2020 by 910Esprit

[jonwat]

58 minutes ago, 910Esprit said:

 I certainly wouldn't use any sort of lube, such as a grease, that could dry out

What about a dry lubricant like graphite? 

[910Esprit]

Sounds reasonable!  

My assumption is that the manufacturor would have selected construction materials that could run without any effective lubrication over an extended service life, as there is extreme heat, no reservoir of lubrication and no service process specified.

Edited April 30, 2020 by 910Esprit

[C43]

I don't think you would find anything that would withstand the heat. I guess now we would apply a coating to the shaft. Ask a turbo supplier perhaps?

BTW shouldn't you have heat proof wrap on your chassis legs?

cheers

C43

Edited April 30, 2020 by C43

[Smithy111]

I was thinking of using copper slip grease as that’s good up to 1100c otherwise engine oil.

its never had anything round the chassis rails? What’s recommended? Reflective foil tape do the job? Or maybe exhaust wrap?

[andydclements]

It's good to at least 200c, but because its flash point is going to be the same as grease 1100c in the absence of oxygen, I think the grease element of it will just burn away in the wastegate exhaust gasses.  Could you not chemically remove the rust, and so just return it to the bare metal as per original spec?

[Smithy111]

That’s not the problem it was the shaft that was stuck but no wear in it 

[AndyPG]

Whatever you lubricate it with, probably won't still be there after a few days of use. It's such a harsh environment.

I'd go with jonwat's graphite suggestion. It stands the best chance.

Failing that, a bit of copper slip and get it back together.

Andy.

[Smithy111]

Ok ill do that if it burns off no harm i guess.