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Wastegate Stuck Shut 82 Turbo Esprit - Induction/Turbo/Manifold/Exhaust - The Lotus Forums Jump to content
robington

Wastegate Stuck Shut 82 Turbo Esprit

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Hi all,

Took the car out today after it had not been used for 2 Months and noticed the wastegate appears to be stuck shut.

It used to open at around 7lb but today it spun straight up to 15lb!

I noticed straight away and came off the throttle, so no damage done. Continued to drive to see if it will clear, being careful and coming off throttle as soon as it hit 10lb, but no difference.

I suspect the diaphragm, but is there anything else I should be checking before I jump in?

Thanks,

 

Robin.

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First easy check. Undo the pipe from the turbo compressor to the waste gate...stick a bit of rubber or plastic tube over it..and blow down it. You shouldn't be able to....if the diaphragm is intact. If you can blow and keep on blowing and not reach a point where your eyes bulge and the earwax flies out of the aural orifices...then the diaphragm has split. This is usually what happens...but it is a;so possible that the wastegate valve has jammed in it's valve guide. I always lubricate mine with engine oil (Castrol Edge 10-60) when I assemble it. When I was doing the bodywork and paint, she sat for years and the thing corroded. 

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Can the wastegate valve be released while its in situ at all?

I'm wondering if all that salt that got in when I drove in in Feb has corroded it shut and that perhaps a lever and wiggle on the spring will free it off.

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Have look at my thread ,'Turbo#3'  ,my waste gate pivot was corroded and worn and i err 'slightly' over boosted and popped my turbo.

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It's a different system on the earlier turbos...it's a cartridge that goes underneath the manifold. In it there is the valve, which goes upwards and engages on the valve seat which is part of the manifold. This is held shut by a spring. It is opened by a synthetic rubber diaphragm, the top of which is fed with pressure air from the turbo compressor. When the pressure gets high enough, the diaphragm moves downwards against the spring and the valve opens. The valve runs in a guide which is part of the cartridge, and this can corrode and stop the valve moving...or the diaphragm splits and the system won't work. When I first changed the diaphragm in 1999 (?) it cost me £140...for a rubber disc....(!). It's an aircraft part, and the necessary traceability costs. They are cheaper these days!!

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So I started looking at this today - I am sure it has seized shut. 

DSCF3679_zpsgpzjdylx.jpg

 

 

DSCF3682_zpsxxhbbagp.jpg

 

I undid the 4 10mm bolts to separate the unit, being careful to make sure it did not spring out when the last bolt was removed. I did that by supporting the wastgate with a scissor jack. One bolt was really difficult to get at so I ground down a 10mm  spanner to suit and that did the job!

 

DSCF3686_zpsjeughagj.jpg

 

DSCF3688_zps8jl6yuyi.jpg

 

 

DSCF3683_zpslhu3ngyp.jpg

 

When I got it apart the diaphragm was revealed along with a disc with 2 nuts in the middle. Its stuck solid. I assume its the valve assy, so is it all supposed to slide out or does undoing those nuts release the unit?

 

Thanks in advance.

 

Robin.

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You need to take the wastegate assembly off, completely. Take off the two nuts that hold it to the manifold, the pressure sensing pipe to the turbo and the exhaust pipe coming from the wastegate to the silencer. The diaphragm seems ok...but there may be a tear underneath the big washer that you can't see. Or the valve could be seized in the guide. The nuts showing in the middle of the diaphragm fit on to the valve...the valve runs in a guide in the upper part of the wastegate. The valve head itself fits into a seat on the wastegate adaptor above the wastegate...it shuts going upwards, so the seat is above the valve. The valve will not come out from where you are at the moment...the valve head is above the guide, so you can't pull it out! Does the thing move? Grab hold of the nuts on the valve with a decent pair of pliers and give a tug. It ought to move downwards...thus opening the valve, which would allow the exhaust gases to bypass the turbo and limit the boost. If it won't move, then it is seized......

 

You're already a lucky boy...none of the studs broke!!! Let us hope your luck continues... All of mine snapped and I had to rotate the wastegate and drill and tap new holes....

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Thank you John

I have had a wiggle and it wont move! so I assume its seized.

 

The exhaust pipe you can see in the picture is attached to the wastegate adaptor, so I don't think I need to remove those..

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All done!

A bit of a job to get the wastegate off, but its off now and yes, the valve was seized solid. Some cleaning and WD etc has sorted that out ant the wastegate is re-assembled ready to go back in next week. I have double checked the diaphragm and its fine.

 

Having now done the job I think its easier to take the wastegate off in the first instance if anything needed to be done to it because its only 3 nuts and I think it would be really difficult to try to put that spring assy back in while its fitted to the car.

 

Do you think I will need to replace that gasket/spacer that goes between the wastegate and the adaptor?

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I wouldn't bother to do anything with the spacer and gasket...the thickness of the spacer sets the maximum boost pressure, thinner spacer gives more boost as it increases the spring loading on the valve/diaphragm assembly. As long as the upper part of the wastegate is sealed ... where the pipe from the turbo compressor goes...and the valve is free to move...all should be fine, given that your diaphragm is good. Below the diaphragm it's open to the atmosphere via the hole in the bottom, anyway.

 

You are, of course, quite right inasmuch as the exhaust pipes don't need to be interfered with to remove the wastegate. Haven't had mine off for some time.... I would recommend lubricating the valve stem and guide with some synthetic oil to prevent future seizures..mine has been fine since I did this and it's been unmolested for many years, doing 3 to 4 thousand miles a year.

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Its worth having a peer into the seating to check the condition of the valve seat in the manifold adaptor. 

 

On the dry sump car I used to own, this was in poor condition, with a chunk missing and caused sluggish build-up of boost pressure.

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Do not lubricate valve stem with any oil. It will burn or coke.There is a special Nickel anti-seize paste good up to 2000F, Jet-Lube Pure Nickel Extreme Anti-Seize and Thread Lubricant (from the Amazon).

 

If you notice an excessive stem to housing bore clearance, re drill the housing and press in a steel valve guide with the clearance 10 thousands.

.

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Correction: My new stem to guide clearance is 0.007"

 

See post No. 112 here

 

  http://www.lotustalk.com/forums/f164/1986-88-bosch-cis-k-jetronic-injected-esprit-specific-items-101095/index6.html

 

.

Edited by MrDangerUS

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Nice to know some "super trick" lube exists for the valvestem/guide interface. Mine had a spot of synthetic Castrol Edge 10w-60 a good few years back, and no sign of any trouble yet...don't think synthetic oil is prone to the burning or carbonising thing to any extent. Of course, talking standard engine here....(!)

When I fit my new exhaust manifold I shall sort out the wastegate valve properly, this time.

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