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Do Waste Gates "talk"?

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As I become more familiar with the car I am beginning to "pick up" on sound nuances not previously noticed. The car is, and has been, running flawlessly (touch wood?) since I picked it up about three weeks ago. However, I have occasionally heard what I would describe as a muted "thunk" when first accelerating from standstill, and sometimes just after selecting the next higher gear---not during the actual gear selection, but as adding accelerator travel once in gear. Do waste gates function at the lower RPM's or only at higher RPM's to govern boost? Would the dreaded "sticking wastegate" produce such sounds? The car will soon be on a "lift" to repair an intermittent fog lamp, and at that time I will be looking closely at suspension fittings, engine mounts, etc., but rough pavement (when at a constant speed) does NOT produce the noise, nor do I detect any "slippage" in the drivetrain. I realize that trying to respond to a "post" like this one is "a shot in the dark" without actually driving the car. Still, it's at least possible that this is one of those Lotus "quirks" that others have already experienced.

Thanks,

John


Being second is to be the first of the ones who lose.

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It's difficult to discuss sounds verbally!

I doubt you would get that from the wastegate - a flutter maybe, but not a thunk.

Most of the others problem you mention (engine mounts, suspension) would produce a more metallic clang. In your case it sounds (excuse the pun) more like this:

http://www.lotusespritworld.co.uk/EGuides/...kheadPlate.html

I had exactly the same problem last year and the sound was more a dull clunk. Also, it didn't happen on rough roads, only when nailing the throttle in a low gear.

It's easy to fix but does mean taking a craft knife to your carpets (thankfully behind the seats!)

Edited by neal

May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

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Thanks, Neal. I went to the LEW link and read the complete procedure. Sounds like something I could attempt. Will first take a look at other possibilities when car is on the lift. If nothing jumps out at me, I'll consider the "mod".

John


Being second is to be the first of the ones who lose.

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You could also check the pivots at the end of the radial arms, there's only 2 little bolts that hold the shims in. If one of these comes loose it can clonk, but only during a transition between accelerating and overrun, on bumpy roads you wouldn't notice a thing.


Hey, can anyone smell fuel?????

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You could also check the pivots at the end of the radial arms, there's only 2 little bolts that hold the shims in. If one of these comes loose it can clonk, but only during a transition between accelerating and overrun, on bumpy roads you wouldn't notice a thing.

Thanks, Colin. That's exactly the sort of thing I'm going to be looking for when the car is on the lift. You described my "symptoms" to a T.

John


Being second is to be the first of the ones who lose.

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My one did 'clonk' occassionally on fast departures, lower gears.

Discovered the rear suspension arm bushes were totally shot (especially the upper ones).

All quiet now.

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My one did 'clonk' occassionally on fast departures, lower gears.

Discovered the rear suspension arm bushes were totally shot (especially the upper ones).

All quiet now.

Reference "Paranoid Newbie" thread: now that your car is parked in your Living Room (aka REALLY fancy garage), I would imagine that your new bushings should last into the next century, eh Pete?

Cheers,

John


Being second is to be the first of the ones who lose.

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I would imagine that your new bushings should last into the next century, eh Pete?

Cheers,

John

We'll see B)

Many have commented that the standard rubber bushes can have a short life (ie 10k miles!) Given that the inner toplink ones are just between the turbos and the cats, they get heat-cycled to death. Replaced them with polybushes.

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This sounds like it could be the wooden firewall clunking around.

Mine had this and made clunking noises at the same times as you describe. It is a common problem and very easy fix with these cars and hopefully that's all it is. Just search the forum for this problem for further detail

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This sounds like it could be the wooden firewall clunking around.

Mine had this and made clunking noises at the same times as you describe. It is a common problem and very easy fix with these cars and hopefully that's all it is. Just search the forum for this problem for further detail

There is a guide to solving this problem on LEW:

Bulkhead mounting fix guide

Cheers,

Mike S


1996 Esprit V8, 1998 Esprit V8 GT, 1999 Esprit S350 #002 (Esprit GT1 replica project), 1996 Esprit V8 GT1 (chassis 114-001), 1992 Lotus Omega (927E), 1999 Esprit V8SE, 1999 Esprit S350 #032, 1995 Esprit S4s, 1999 Esprit V8 GT (ex-5th Gear project), 1999 Esprit V8SE ('02 rear)

1999 S350 #002 Esprit GT1 replica

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Thanks, Bob and Mike. Neal had already directed me to the LEW link, which I read. What still mystifies me a bit is that the LEW "fix" is predicated on the problem occurring on "rough or bumpy roads". I don't have the problem (no muted clunks) while driving at a constant speed over rough pavement, only on acceleration (and sometimes on deceleration as well). Bob, can you elaborate on the cause(s?) of your symptoms? Was it on rough roads as well as accel/decel?

I finally had the car up on a lift recently, and the Lotus mechanic (who has 23 or so years of experience with other vehicles, but only a year with Lotus---but seems to be "a quick study") and I had a very thorough look at the suspension and engine mounts. He took the time to check the tightness of every bolt/nut he could reach. Only one moved so much as a hair. You could see that the bushings were no longer brand new, but they appeared to be "servicable". The clunks I get are not particularly brutal, more of a "nuisance" really. At least I now know that the wheels aren't going to fall off! If the "shifting bulkhead" problem can cause noise on accel/decel, but not necessarily on rough roads at a constant speed, then maybe the LEW fix is in order. Not sure that I would want to commit to polybushings all around at this point, especially if they are not the cause. Where's a crystal ball when you need one?

Aaarrrggghhhhh!

John


Being second is to be the first of the ones who lose.

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The noise from my bulkhead happened more on accel / decel; however ultimately it did start to happen on rough roads as well.

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The noise from my bulkhead happened more on accel / decel; however ultimately it did start to happen on rough roads as well.

Thank you, Bob, for the additional input. Do you happen to know what model year Lotus began welding the bolts to the interior side plates? I.E, with a '99 am I looking at a "one man job" or will I need someone to hold the bolts in place while I tighten the engine side nuts(when reinstalling)? If mine are not welded, would a pair of vise grips (perhaps taped down to the carpeting) be sufficient to keep the bolts from turning?

Regards,

John


Being second is to be the first of the ones who lose.

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Thank you, Bob, for the additional input. Do you happen to know what model year Lotus began welding the bolts to the interior side plates? I.E, with a '99 am I looking at a "one man job" or will I need someone to hold the bolts in place while I tighten the engine side nuts(when reinstalling)? If mine are not welded, would a pair of vise grips (perhaps taped down to the carpeting) be sufficient to keep the bolts from turning?

Mine weren't welded (car's a 98MY) but I had no problem doing it myself. I am 6'1" but as I recall it wasn't a stretch. Used a circle spanner to hold the nut in the engine bay (as with all things in the V8 engine bay, access is minimal) and a wrench to tighten the bolt from the interior.


May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

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Mine weren't welded (car's a 98MY) but I had no problem doing it myself. I am 6'1" but as I recall it wasn't a stretch. Used a circle spanner to hold the nut in the engine bay (as with all things in the V8 engine bay, access is minimal) and a wrench to tighten the bolt from the interior.

Thanks for orienting me "the right way 'round", Neal. Yes, it would make more sense for me to immobilize the engine bay side (due to the aforementioned minimal access) and do the turning from the interior side.

Regards,

John


Being second is to be the first of the ones who lose.

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