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83 Turbo Esprit Wastegate diaphragm

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83 Turbo Esprit.  The waste-gate diaphragm split so, as expected, it wasn't regulating the turbo pressure.  I have a new diaphragm from JAE but can't figure out how to get the old out of the "cup",washer, diaphragm sandwich.  Do the two aluminum parts just separate or are they threaded together?

Thanks for your help!


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Hey Rich,



The diaphragm just separates, can be replaced right in the car.


Back the bolts out until the are each held by a couple threads, then separate the top & bottom of the wastegate body (bolts shown on the images below, either side of the data plate) then the top & bottom can be released. Be cautious as there are springy bits inside...

Just gently pry the upper and lower halves apart, no threading.


For sure, it might require some prying.



Atwell Haines

'88 Esprit

Succasunna, NJ USA

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  • 1 year later...

Hi Guys You may be interested in this, which i have just posted in the Esprit Chat Forum page.


Lotus Esprit Turbo S3 HC
Turbo Charger Wastegate Sticking Problem and Its Once & For All Fix
Ever had this problem.
After period of not using the car all seems fine when it starts up, idles and rev’s fine with no load on the engine.
But take it for a drive and all is not well. If you apply anything other than light throttle the boost rises rapidly/exceeds the normal max/the boost limiter kicks in chopping the ignition and due to over fuelling/excessive boost the engine back fires with a very loud bang and a sudden/harsh loss of power/acceleration.
The same fix can be applied to all versions of the Garrett/Ham Standard wastegate.
The attached details the problem and the once and for all fix.

Wastegate From Parts List.jpg

Turbo Charger Wastegate Sticking Problem and Its Once And For All Fix.pdf

Edited by Brian Harvey
Additional wording
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Using nickel anti-seize lubricant on the valve stem is also good.

Note early Turbo Esprit didnt have any boost limiter, when the wastegate sticks the pistons melt and engine blows. Lotus had to replace several engines under warranty on early cars owing to this.

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  • 1 month later...

Thanks Atwell for the photos of your wastegate.  I have recently taken mine off and replaced all the gaskets and diaphragm. What I find a little confusing in the different size spacers between the top and bottom of the wastegate.  Yours appears not to have a spacer at all.  I have seen 4 different size spacers on these wastegates. 6mm, 8mm, 15mm and 28mm.  Mine has a 28mm spacer. Steve from SJ says there were 5 different sized spacers.

The different size spacers should change the boost pressure due to the preload on the spring.  I read one forum entry that had the spring size as between 105-110mm.  My spring is 114mm. Does anyone know that if there were different size springs and different resistance used in these wastegates?


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Our wastegate was modified by the previous owner, who removed the spacer #14, I know. Not aware of anything else that was done.


It still boosts to ~ .65 BAR according to the dash gauge (no overboosting!).




Atwell Haines

'88 Esprit

Succasunna, NJ USA

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