Slow boost

[rogerch]

The boost is taking way longer to build pressure than it used to. It eventually boosts up and takes off.

This indicates an air leak to me but I can't find one. The problem is how to get max boost with the car stationery ?

Any ideas ?

[910Esprit]

Does yours still have an external wastegate? In which case, a leak causes it to fail in the max boost position (as does a torn diaphrgm). Maybe the wastegate walve is simply 'sticky'. (or its another fault entirely unrelated to the turbo/wastegate) I think a rolling road/dyno would be the only way to see max boost stationary, anything else would be a disaster waiting to happen!

[Mike6]

Hi Roger

 

Presumably you have checked out the vacuum pipes. Also look at that black/white one way valve which is very basic and when it fails boost pressure is allowed to go into the crankcase. They were obsolete for a while but SJs have them in stock.  

[rogerch]

Yes I've checked everything I can think of, though I suspect the next stage is to dismantle from the turbo to the plenum, I'm not expecting to find anything.

So, if the wastegate were not seating (sealing) correctly what might the symptoms be ? this is what I'm thinking.

[rogerch]

It gets stranger and stranger. Fuel pressure from the pump is 4 psi, dead on spec.

However, (on a private road of course) I gave some big wely, hit 160-180, probably 3-4 psi on the gauge @ around 6000 rpm, lift right off and immediately back on absolutely nothing, just like I ran out of gas. It recovers quickly, but I'm not sure what it's telling me.

I haven't check yet to see if the air filter has collapsed but it's a K&N so I'm not expecting so, neither do I suspect the hose from the air cleaner to the turbo has collapsed.

Is there any way I can check pressure in the turbo, ie, how can I confirm the wastegate is closing and sealing ?

[sanj]

The elephant trunk has been known to delaminate and collapse internally, might be worth a look.

[Mike6]

Roger. Have you had a word with Sparky. Some time ago he had a pump which looked like a bike pump with a gauge. He attached this to the wastegate and measured the pressure at which the wastegate actuater started to move. He then adjusted the wastegate as necessary. At the time I remember he checked about 6 of our cars at a meet.

[rogerch]

Thanks Sanj, a good thought I will inspect in the morning with fingers crossed.

Mike I have a similar arrangement that I use ti set wastgate pressure, it's set at about 11-12, I know, I know it's a bit high, but it's fast !

I currently have the air filter, air box, plenum and all the ducting off, and have found no reason for reduced boost, nothing obvious leaking. Going back to basics I did a compression test 138-140 across the board, so it's not that !

So, unless Sanj's idea of the trunking collapsed internally, I'm very much afraid it' turbo off time.

I can see the induction side impeller spinning with the engine running, So I'm thinking either exhaust impeller (doubtful) or wastgate not sealing.

Any drawings or info on whatever Garrett it is on my 88 Turbo would be welcome. I think I've just found something to keep me occupied over Christmas/

[Mike6]

Roger

 

I wouldnt start stripping the turbo just yet. Have you removed one or two vacuum lines to check there is some suction ie is the vacuum pump working properly. You can probably tell if the brake servo is doing its job and whether you need extra pressure on the brake pedals. The servo is fed from the vacuum pump as you know. Also check under the panel back right of the car where the small black line from the pump joins with the rubber vacuum pipes. Mine was perished at this point meaning no vacuum was getting anywhere.

 

If you do strip the turbo, as I am tempted to do at some stage, its a T3 model and you can get service parts. Molemot is the expert on these turbos. I believe the place to get the kits is 'gpopshop.com'

 

Good luck 

[Trevsked]

I've not read all the thread but have you checked the wastegate actuator? As Sanj suggested the intake trunking is also a suspect.

Trevor.

[Sparky]

Prime suspect for me is the trunking.  It's possible for this to look fine, but lose integrity under load. I assume your wastegate's closed at rest?  Can you check boost pressure at the plenum using a a decent gauge?  I presume plenum gaskets are all OK?

[rogerch]

Thanks for the suggestions guys, I've checked the trunking both to the airbox and to the turbo, neither show any sign of degradation.

Basic checks, compression good across all 4, timing spot on, vacuum advance working normally. Fuel pressure 4 psi, from the pump and each of the regulator outlets.

When I attache a gauge to the outlet for the waste actuator, the best I see revving the engine is 2 psi. This leads me back to my original gut feel, damaged wastegate.

Of course the same symptoms could also indicate a blocked exhaust.

[rogerch]

Next question, can I get the wastgate off without disturbing the turbo ?

[DanR]

Have you done a run with the hose to the wastegate disconnected? Be careful not to run it too hard or you'll get overboost with leanout=dead engine. Just play with it to see if it feels more responsive.

[rogerch]

160 flat throttle, max boost on the gauge = 2 psi.

Tomorrow I'm taking the exhaust off to have a look at the wastgate and exhaust impeller, I'm expecting to see a broken valve.

I can't see how I might get the wastgate housing off without removing the turbo, any ideas ?

[dodge1979]

I use a tyre inflator gauge attached to the airline with the end adapted to fit to tge wastegate, that way I can see the pressure at wich the wastegate opens and then measure its travel as per factory manual...quite simple setup really..id be tempted to agree with previous thought regarding the adjustment of the actuator...and your coment previously regarding the boost being turned up but it goes well always makes me.cringe when I hear people say that...its just not healthy and is only a short term, quick shortcut to more power and lower engine life...its not a proper tuning process. That aside, I would suggest you look at the less obvious alternative to where your boost could have gone...leaking out of the gasket and clamp seals...this is something I doubt youd notice unless you test for it...i did a thread the other month in Esprit chat on rolling road results and the realistic results from tuning...give it a read. I found a fair amount of boost was leaking out of new gasket and clamped hoses...but as this was on a dyno run we were able to deduce this and start to amend it. As a home test, get the backend up in the air securely, put it in gear and run the car up, having covered your plenum and all.boost hoses, joints gaskets etc with a soapy water solution...if you have boost leak youll see bubbles clearly. I found even though all my assembly was new and fresh I still had leaks, which I then attended to meticulously aftetwards....

[rogerch]

 

Found it !!

 

Wastgate valve not seating, not even close to seating, that's as close as I've got so far but the shaft could be bent, I'm really curious it's a good couple of mm out of alignment.

But I'm happy that's not too serious, I've broken one stud so far.

[rogerch]

I was happy this morning when I found the problem. Now i'm really, really p155ed off, This morning I had only broken 1 stud, easy to get to no drama. Then I came to take the turbo off the exhaust, 2 more broken studs, and one I absolutely cannot get to, the only option, separate it off the manifold, 3 more broken studs, and another one I absolutely cannot get to.

Before you ask yes I have taken absolute care, working slowly counter clockwise and clockwise, plenty of WD40 most done overnight.

Now I'm stuck, I really really don't want to take the manifold off, that looks like a engine half out job.

 

The intermediate casting, the bit between the manifold and the turbo, detaching that from the manifold, are there any secrets to getting to the top inside bolt ?

 

What else would you do on Christmas day ?

[ramjet]

[CHANGES]

Roger

Stick at it,  I know it is a pain but they just have to come off. Do what ever it takes

to remove the nuts even if its a bit crude, boot floor out helps, if not already removed.

Sheared studs not an issue.. people who do this work regular make up spanners to do

the job... and experienced people who remove their turbo's quite often change the studs

for cap head bolts and s/s lock nuts. This method saves a ton of time... and back ache , not to

mention the frustration factor.

If you attempt to take the manifold off you will find you will be going into a very dark place, as 

this is equally as bad... if you crap out on that its engine out time and you don't want that...

Once you get the turbo off you might as well go for full reconditioning with 360 brg and maybe

a hybrid upgrade. This does not cost any more and does have performance advantages....

    It will eventually come off and the cuts on your hands will heal ..stay positive,,

Good luck and have a good Christmas.

 

Dave

[rogerch]

I'm not complaining, oh well, OK, I am complaining, but from the history of the car the turbo and exhaust have remained untouched since 1991, 21 years, under the extreme heat of an exhaust manifold and turbo, so none of this surprises me, which is exactly why I don't want to take the manifold off. (apart from it looks a bitch of a job) it's going to add to the total of broken studs, all the ones so far I can drill/easyout, no so the manifold to head.

 

I'm going to see if I can get a short 17mm 1/2" drive socket and a wobbly extension. If I could get in there with a grinder I'd just cut it, but not enough clearance.

 

Thanks for the encouragement Dave, when I put it back I'll use Alan head bolts and stainless nuts as you suggest.

 

I'll keep you posted.

Edited December 25, 2012 by Roger the Dodger

[CHANGES]

In the past I have used a Dremel or die grinder to weaken the nut then split it.

fiddly and crude but does the job..

[Mike6]

Good luck Roger. Must admit thats one job I haven't had to do yet. Most of the tools in my garage have been adapted one way or another - last time was to remove the water pump.

 

Oh by the way Happy Christmas - its pouring here and my submirsable pump is working overtime getting rid of the flood in the garden, imagine you will be throwing a few kangaroos on the barbie later. 

[rogerch]

Well it's out and on the bench, hoo bloody ray !!

A short socket and a wobbly extension did the trick, I got the socket on squarely even with the bend of the exhaust got a wobbly extension on it and a burly neighbor.

I'm intrigued to know how this happened, the whole spindle and bush appear to have moved, but seem disinclined to move back, the spindle may also be bent.

Anyone know how to get the wastgate valve out, and subsequently a new one back in ?

 

I'm busy now drilling the old studs out, 1 done 7 to go, 4 of which are under thew car on the end of the manifold.

[sailorbob]

I doubt whether the spindle is bent, there isn't anything to exert that much force on it. I suspect it's moved due the the spindle and bore wearing. It could probably be repaired by sleeving the spindle and boring the housing but if the housings are cheap enough it may be better to replace the housing.