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whats inside the external wastegate?

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Hello all

I think my wastegate is not working perfectly, although it doesn't seem to be seized. The diaphragm is airtight, cos it can hold a vacuum if I attach a pipe to the hole at the base. So, I was wondering how the seal is made where the shaft of the valve enters the body of the wastegate. Is there a 'wearing/replaceable' part there?

(I suspect the wastegate, as the revs are not immediately falling away when lifting-off, but there is no other evidence of an air/vacuum leak at the carbs/mainfold - the servo is also feeling less effective). I also cant remember hearing the wastegate 'fluttering' when I was last out (although I was not driving hard).

cheers Steve

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here you go i hope this helps.

open it up and make sure your diaphram isnt on the way out, one common mistake when people rebuild them/take them off is to forget to put on the thermal gasket on the top of the wastegate before bolting it back on the aux manifold, and they also forget the seperator gaskets that go either side of the diaphram to protect it from heat and sticking to the metal.

the spigot recesses into the wastegate manifold/aux manifold and is attatched by two nuts with a mika gasket inbetween, this stops thermal transfer between the manifold and the wastegate, and prevents the diaphram edges from melting.

there is a valve face inside the aux manifold that the valve presses against.

when you undo your 4 bolts that keep the diaphram together you will find a spring pushing the valve up, it is possible this spring is broken and it is also possible your diaphram is stuck closed and wont open. if its seald then it may be that its stuck shut and the valve isnt opening, you can undo the 4 bolts with it on the car, its easier to get to the two rear ones if you undo the turbo to sump pipe thats next to it, dont worry no oil will come pouring out. undo the bolts and make sure you have hold of the bottom of the wastegate cup as it will spring right off otherwise. when off try pulling the vlave gently down if it doesnt move then thats the problem, if it moves but its stiff etc, then undo the locknuts, take the washers anddiaphram off carefully and pull the vlave down gently, then with some fine wet and dry say 2800 grit, rub the sides of the valve stem and then wipe off, then give it a little copper grease and push it up and down a few times, it should free it up in the hole then, re-assemble and re-try it.

dia.jpg

WASTEGATEINFO.jpg

DSCN3839.jpg

here is a close up of the top of the wastegate here you can see the small stepped spigot that recesses into the aux manifold.

DSCN3840.jpg

this is the valve face in the aux manifold on my old one.

DSCN3842.jpg

Edited by bigsi

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Thanks Si

I cant see your picture, can you have another go please.

The thing I still dont understand is whether there is a valve guide or gland where the valve enters the wastegate. If so does it wear?

cheers Steve

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Yep,just goes into the casting. Designed in a way to collect all the crud, rust and eventually sieze. This seems to be the common wastegate failure mechanism if the car is not run on a regular basis. When I re-built mine, a friend drilled it out and fitted a phosphor-bronze guide for the valve to run in. Its been fantatsic ever since

cheers

Mikey

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Yes this is the BIG problem for cars that are not used much. The key here is to not just turn the engine over now and again - you really need to actually actuate the Turbo to ensure the wastegate is kept moving. Fuel carbonisation goes a long way to sticking these. I had some problems in my early years with my car but ended up turning the valve with a drill and free up and found a brand new diaphragm (

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Hi Nello,

Could you please tell me where you got your wastegate diaphram from as its far cheaper than ones i have looked at?

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