Turbo woes? Wastegate sticky? Other?

[tedtaylor]

43K miles, unmodified, all original. Just finished a 3,000 mile vacation (see separate post under Touring) and car ran great.
I suspect turbo wastegate sticking? not certain, but here are the symptoms...
Previously, car ran great, turbo boost kicks in, boost gauge reads, neck snapping action, everything fine, HOWEVER....
while accelerating hard, and turbo kicking in, suddenly loss of boost, gauge drops, and loud thrust noise coming from exhaust. Any further acceleration is hindered with no boost and thrust noise from exhaust. I have to depress clutch and rev motor couple times, let idle down, then let clutch out and drive again. Usually it cures the problem, return of boost and turbo action. More frequently however, initially get boost and turbo action, but cuts out with same problem above = loss of boost and thrust noise from exhaust.
I've never tackled engine work and read some posts on sticky wastegate and i'm tempted to try and take off heat shield and remove wastegate actuator and clean or lube or work it free. Hopefully it won't be a big problem.

NOTE: One other symptom noise was weird and just before turbo lost boost, a shrill blow up the balloon noise occurred. Not trying to be funny, but imagine the Disney cartoon "Junglebook" where the elephant parade inspection had one of them blowing their trumpet horn trunk, only to be tied in a knot and that stifling trumpet stopping noise is heard. That's what I heard with my turbo losing power under hard acceleration. It could have been an "in-between" situation where the turbo was functioning properly, then the problem came about (making that funny noise), then not working at all (thus the other symptomatic signs).

sorry to be wordy, but I NEED HELP and direction as to what to do.
thanks

[Brit-Car-Nut]

Ted: Based on your earlier posts regarding the changes in the sound during your trip and now this post, I think you need to check the pre-cat and "real" cat for failure. Sections will overheat, fuse and then break off. When under pressure, they will gather together and plug the exhaust flow. Coming off the throttle, they bounce away from each other and flow is restored until a higher flow gets them back together again.

The MGBs with a cat did this at a regular rate nd most people jut replaced the cat with a "test pipe"

Does NJ Inspection still tailpipe test the M100? If so, can you find out what the passing grade is?

I believe you can get away with only 1 of the two, but it really depends on what limits the inspector is looking for. I have a few pre-cats as spares, but if you need one, we can work something out. The "real" cat is a little bit more difficult and having been paying attention to the posts from others that have replaced bad cats with magnaflo weld-ons only to have them fail within a year or so, I bought a spare from Lotus when they were on the sell-down list and I was bringing in a cargo container of parts, so shipping wasn't a problem.

There is a company that occasionally lists the Federal and S2 Cats for around the price Lotus charged for theirs on the aftersales list, but shipping will probably be pretty steep.

If NJ doesn't test the car, then gut the pre-cat if it shows signs of fusing and replace the "real" cat with a "test pipe" but remember to leave the pinched section in place. You will understand when you look at the "real" cat as the front pipe is flattened.

Any chance you are going to this year's LOG? I am a few hours away, but if you are that close, you could look at the parts here to get a better idea of what you might need. If you want to "talk about this" my number is 704-395-2949

[HJ2]

Hi Ted,

Is it possible that a connection of one of the hoses Turbo - Inter cooler - Inlet manifold is a tad loose? If it builds up pressure and then starts leaking, it could explain the problems / sound you have as well.
Also do a visual check on the compressor wheel (just take the hose off between turbo and air filter to have a peek.Whilst you are in there: Feel if the compressor wheel if it has any excessive play A little axial play is OK (approx 0.5 mm) but radial play means your bearing is knackered)

All simple to do!

[steve matthews]

Ted, + 1 on what hj2 posted. Rule out turbo inlet side first.

+ 1 on what john says as far as direction for exhaust. Start your
budget for an exhaust system. Heat up the exhaust and put cardboard in
front of the exhaust tip. Rev engine to high rpm. If you have pieces of metal
stuck to the cardboard you know what to do.

Steve

[Enright]

First step, do a paper-clip test and report back your fault codes.
You don't have to open the bonnet or even start the engine for that.

[HJ2]

[tedtaylor]

I just checked and I have NO codes present.
now does that say no turbo issues present and probably more physical issues like the cat?
Or does that just say nothing that happened tripped any fault code only?
just tapping the vast experience network out there that may have gone this route with these symptoms.
thanks

[tedtaylor]

Good news! I checked the air intake at the turbo turbine and spins smoothly and no discernible play or wiggle on the shaft. I then started hitting the exhaust with a rubber mallet and no rattles in the cat, however the muffler was rattling. I looked inside and could see metal pieces from the baffles laying inside. I did a surgical enema from the tail pipe and was able to remove two large pieces of baffle. I'm hopeful this was my problem thinking that at times, they would block the exhaust passage and create the symptoms I previously described. Time will tell. Since i have the car up on stands, i'm going to change the oil and filter. I'll take it for a test drive later and report back my findings.
thanks

[HJ2]

Sounds plausible!

Hope you'll be back soon with a positive report

[tedtaylor]

SUCCESS! Final result is good. Test drive reveled no abnormalities. Boost gauge up to just above .05, very responsive and peppy.
Muffler sounds slight booming as before, consistent note. No more boost loss or thrust sounds.
Sooooooo, it seems all along that old rusty baffle metal material loose in the muffler may have caused intermittent blockages in the exhaust? Time will tell for sure. I'm just happy nothing major was broken or needed fixing.
thanks for all your leads and suggestions everyone!
Happy motoring!