Wastegate

[tirpsesutol]

I have never heard the relief pressure sound from my 87 HCi's wastegate. Is this normal?

[Evil_Dr_Fish]

Sounds like you may have a sticky wastegate?

Have you heard other people's Cars of a similar era?

When you lift off when boosting the car you should get a chattering sound... and when at full belt almost a dump valve type sound when you lift off...

Or do you mean that you havent heard anything while your foot is down? (and nor should you - well except Darth Vader over your right shoulder and vrooooom!!)

[Guest teigan]

it sounds like a very loud boat style outboard motor sputtering. depending on how your car is tuned, it may not kick in most of the time. you should be able to force it to dump when you quickly pull off the accelerator in lower gears.

[nello]

Check your Boost Gauge? If the dial goes allthe way round the clock - the Wastegate is stuck? Normally hits about 12-1 o'clock (cannot remember the actual boost reading without sitting in my car?!) at max boost............

[molemot]

Don't confuse wastegate with dump valve. Wastegate discharges exhaust from turbine input through the silencer; dump valve dumps excess boost input from plenum chamber on overrun. Max boost should be about 7 to 9 psi; if much higer than this, the wastegate is U/S - probably a holed diaphragm. These are obtainable - at a price(!) - and require the wastegate to be removed and dismantled to change. Broken studs. drilling. tapping...all that good stuff. The nice waffly sound from the overrrun comes from the plenum chamber dump valve which is the silver thingy mounted at the rear of the plenum near the fuel pressure regulator.

[dodgy]

while my gearbox is out, ive benn cleaning and checking things.

that dump valve on the back of the plenum chamber, had a BLANKING PLATE fitted in between the valve and the chamber! wont know why that was done for a few weeks yet, but isnot that valve a backup vent incase of overboost?

i have took the plate out now and will have to wait and see the outcome.

the gearbox is almost ready to go back in after the CWP broke.

should definately hear a flutter sound from the wastegate, i always drive with the window down to make sure i can hear it what a loverly sound !!!!!

(from what i can remember! )

[DrieStone]

while my gearbox is out, ive benn cleaning and checking things.

that dump valve on the back of the plenum chamber, had a BLANKING PLATE fitted in between the valve and the chamber! wont know why that was done for a few weeks yet, but isnot that valve a backup vent incase of overboost?

The dump valve is for throttle lift to prevent wear and tear on the turbo, if you have an aftermarket blow off valve fitted then you don't need it. The blow off valve does the same job, but is more elegant. You could leave your dump valve attached and functioning, but it should never actually do anything unless you're running more boost than stock.

The dump valve is a valve with a spring that opens at a certain pressure (a couple psi over normal boost). When you lift the throttle and the throttle butterfly closes the turbo is still spinning and therefore creating boost. In this case now you have the turbo making boost and the throttle closed. Pressure builds and the dump valve "dumps" it. The problem is that even with a dump valve in place the pressure still acts like a brake on the turbo slowing it down. A blow off valve uses the pressure differential between the two sides of the throttle butterfly to open. Therefore it takes a lot less pressure to open a blow off valve than the dump valve (and therefore less braking action on the turbo). Theoretically with a blow off valve your turbo is free wheeling and when you get back into the throttle you get boost sooner. With the dump valve your turbo slows down a lot more and it will take longer to get boost.

It's doubtful you hear the wastegate.

[dodgy]

if i have no aftermarket dump valve fitted, what is the sound that i hear when i change gear then?(chattering) as my dump valve on the plenum chamber was blanked off!

this sound i have heard on almost every other turbo.

i can only asume it has to be the wastegate working.

can anybody throw some light on this subject?

[USAndretti42]

It's the sound of the compressor stalling as the air has no where to go because the throttle is closed. This makes the pressure downstream of the compressor shoot up until the compressor slows down.

[tirpsesutol]

Check your Boost Gauge? If the dial goes allthe way round the clock - the Wastegate is stuck? Normally hits about 12-1 o'clock (cannot remember the actual boost reading without sitting in my car?!) at max boost............

<{POST_SNAPBACK}>

Boost climbs steadily and slowly but not all the way around. I dont drive my car very hard so maybe that is the reason for not hearing the dumping sound. Car is in the shop getting some much needed repairs done but will try pushing her a little harder next time and listen for it.

[slade]

sigh... alright, I'm confused. I thought that most turbocharged cars (including the esprit) had a wastegate to limit boost, and some turbocharged cars (not the esprit) had a dump valve or BOV to save wear on the turbo.

Does the Esprit have a dump valve/bov or not? I was almost sure it didn't, though Driestone seems to explain all that a bit differently...

Also, I do have the fluttering noise, I always assumed it was the wastegate somehow . I thought it was more of a whooshing, rice rocket/semi truck sound if you had a BOV.

slade

Edited October 13, 2005 by slade

[Guest teigan]

your esprit has a waste gate and a blow off valve. read your service manual. people often fit more robust ones though.

[DrieStone]

A wastegate is different than a blow off valve or dump valve.

A wategate is a valve that allows exhaust gases to circumvent the turbo. A lot of turbos have a wastegate integrated as part of the turbo (in fact only the giugiaro cars have an external wastegate). You can see the waste gate on the Esprit, it sits between the exhaust manifold and the turbo just forward of the driver's side rear tire (on the US cars). The wastegate only opens when the turbo is making the preset amount of boost (so you're probably WOT climbing through the revs,) it's also so low in the engine bay I doubt you'd ever hear it. The wastegate is a heavy (usually) cast piece that is subjected to extreme heat and controls huge amounts of pressurized exhaust gases.

Our cars were fitted with a dump valve, which is used to bleed off the excess boost when the throttle closes. Some people fit a blow off valve instead, but either way, it does the same thing. The dump valve is what you hear when you get off the throttle and the car "chitters". The chittering is the valve opening and closing very quickly. A blow off valve sounds more like a whistle (depending on the valve you've fitted), because the valve stays open and you're hearing all the excess boost rush out of the system. The blow off/dump valve on some cars are flimsy little plastic things.

Edited October 14, 2005 by DrieStone

[lwasson]

A wastegate is different than a blow off valve or dump valve.

A wategate is a valve that allows exhaust gases to circumvent the turbo. A lot of turbos have a wastegate integrated as part of the turbo (in fact only the giugiaro cars have an external wastegate). You can see the waste gate on the Esprit, it sits between the exhaust manifold and the turbo just forward of the driver's side rear tire (on the US cars). The wastegate only opens when the turbo is making the preset amount of boost (so you're probably WOT climbing through the revs,) it's also so low in the engine bay I doubt you'd ever hear it. The wastegate is a heavy (usually) cast piece that is subjected to extreme heat and controls huge amounts of pressurized exhaust gases.

Our cars were fitted with a dump valve, which is used to bleed off the excess boost when the throttle closes. Some people fit a blow off valve instead, but either way, it does the same thing. The dump valve is what you hear when you get off the throttle and the car "chitters". The chittering is the valve opening and closing very quickly. A blow off valve sounds more like a whistle (depending on the valve you've fitted), because the valve stays open and you're hearing all the excess boost rush out of the system. The blow off/dump valve on some cars are flimsy little plastic things.

<{POST_SNAPBACK}>

[lwasson]

I am now driving my '83 Esprit and have just a few interior carpet issues to complete and I am finished with the ground up rebuild of the car.

I thought I was just about finished. Ha!!

Now that the car is motivating a whole new adjustment cycle begins. Tweak this a little. Tweak that a little more.

The wastegate is not working and my boost shoots up to 15psi. Not good. This is disappointing because I can't stand on the gas to see what she will do. The dump valve is working properly and makes the wiffy sound between shifts.

So, why is the wastegate stickiing? I have loosened the adjustment screw almost all the way out. Still over boost happens quickly. I took the wastegate off and I was able to push the valve in by hand so not much force required to move the valve. While the wastegate was off I inspected the valve seat in the adapter between the header and turbo. It has cracks so what I thinking is that valve is not seating and exhaust gases are leaking past the valve. But why does it build over boost so quickly if the seat is cracked??

Even with small cracks in the seat it seems like the valve would open just a little at 15psi?? After driving the car I can put my hand on the exhaust pipe coming off the wastegate and its just a little warm. So if gases were leaking past the wastegate valve seat you would think that pipe would be hotter than just warm.

Last is the sound it makes starting around 12psi of boost. Its a shrieking sound that is constant. Like air is leaking from around a seal. It does not flutter. The sound increases in level as the boost increases. Very annoying.

I'm still driving the car but I never allow the boost to go over 8psi. This corresponds to about 1/3 throttle.

Next step is to take off the wastegate and take it apart to look inside.

Any other suggestions?

She is a wonderful handling car. I am not disappointed in getting this project car and spending 2.5 years in the rebuild. Good to get another G-car back on the road.

Many thanks!

louis

[DrieStone]

Louis,

At the risk of sounding stupid here, you did hook up the boost line to the wastegate actuator didn't you? It sounds like that the problem may be that the actuator isn't reading the boost so it's not opening.

[lwasson]

Louis,

At the risk of sounding stupid here, you did hook up the boost line to the wastegate actuator didn't you? It sounds like that the problem may be that the actuator isn't reading the boost so it's not opening.

<{POST_SNAPBACK}>

No not a stupid question. Esprit2 said to look at that first and check for cracks in the line.

The problem was a torn diaphragm (sp?). The nut that holds the wastegate valve to the diaphragm disk was loose. The valve stem wallowed out the disk causing the diaphragm to move to one side were it got pinch and a large hole was the result. An easy fix but the diaphragm is a little pricy.

Thanks!

louis

[Guest teigan]

hi. you've made a lot of progress since last we spoke. you should start looking for a replacement waste gate unit. not sure what you describe can be repaired. also suspicious is that it shoots up to 15 psi. that sounds a bit high for your engine, even with a closed wastegate.

[DrieStone]

The guys at JAE suggested replacing the manifold with the 88+ version and swap in a turbo with an integrated wastegate. They mentioned that the stock manifold has a habit of cracking on the 81-87 turbo cars.

[AJay]

The guys at JAE suggested replacing the manifold with the 88+ version and swap in a turbo with an integrated wastegate. They mentioned that the stock manifold has a habit of cracking on the 81-87 turbo cars.

<{POST_SNAPBACK}>

Careful!!!! the later manifold does not position the turbo in the same place. Therefore work is needed to line up the plumming for the Turbo( so i have been told).

Also the exhaust system will need changing from the down pipe to the tail box. the standard box does not fit so it will have to be a bespoke system.

I will be carrying this out when my manifold crack as i happen to have the latter turbo and manifold stored away, but it won't be a cheap fix!!!!!

[WayneB]

I noticed a few years ago that my auxillery manifold had developed cracks in the valve seat area.

Boost taking longer to come up is a symtom of this.

After pricing new manifolds and dying of shock $$$$$$$$

A race car engineer friend of mine came up with an economic sollution by welding in a new valve seat .

Its been working OK for 2 years now

[lwasson]

I noticed a few years ago that my auxillery manifold had developed cracks in the valve seat area.

Boost taking longer to come up is a symtom of this.

After pricing new manifolds and dying of shock $$$$$$$$

A race car engineer friend of mine came up with an economic sollution by welding in a new valve seat .

Its been working OK for 2 years now

<{POST_SNAPBACK}>

I agree. A new valve seat could be welded. When that time comes is looks like a straight forward job.

Thanks Wayne

[TurboEsprit1987]

On my 87 HCI, the bolt on the spring end of the wastegate valve is missing. What is it's function? It appears to control the tension on the valve spring. If that's it, then no bolt means the valve probably opens too soon.

-Nick

[lwasson]

On my 87 HCI, the bolt on the spring end of the wastegate valve is missing. What is it's function? It appears to control the tension on the valve spring. If that's it, then no bolt means the valve probably opens too soon.

-Nick

<{POST_SNAPBACK}>

Hi Nick

You are correct. Is you boost pressure building up to 8 or 9psi? If not the the wastegate is opening too soon.

louis

[Richard S3T]

I replaced both manifolds last winter -- not pleasant work, but this is what I understand you can do.

Wastegate. You could adapt a race wastegate into the existing intermediate manifold, or I was considering machining my own, drawings not yet finished. Perhaps use a solid piston with a PEEK ring which can withstand reasonable tempratures and high PV (load/speed) factors with low friction.

Main exhaust Manifold. Early ones are longer lasting than the thin later ones for the later turbo set up. Lotus still supply them so no other was available in the UK. I bought mine and all fixings from SJ sportscars.

Intermediate manifold. Try South West sports cars, who get them cast in SG (ductile), 420/12 iron. Longer lasting than the original.

Alternative solution. Steve at SJ offered to supply me with a kit that includes later manifold type but in SG iron, Later turbo with integral wastegate, New exhaust and blanking piece to match up with existing silencer. I would have done this, but had already purchased a new intermediate manifold and my wastegate is now in acceptable condition.

Richard