Turbo guru - 1987 300D wagon turbo has no boost.

[ah-kay]

Car has no power going up hill. Okay on freeway or level road.

I connected a boost gauge to the inlet manifold of the wagon. There is no boost or very little ( pressure ) at all even going uphill. I removed the front turbo accordion looking boot and try to check/feel the turbo fan. The fan spins okay, no side or lateral movement. I don't want to remove the turbo yet, what else can I do to further diagnose the problem?

If I start the car, would I see the turbo fan spins?

[87tdwagen]

Check the line to your wastegate see if disconnected or has a leak. Also apply vac to the line and verify that the diaphragm and rod on turbo are operational and or not stuck.

[ah-kay]

This is what I have done so far.

1) started the car and I can see the turbo spinning. No unusual noise so the turbine wheel should be ok, right?

2) pull vacuum to the wastegate control and heard it pop opens. I presume it is good?

3) I don't know much about turbo. My understanding is that the wastegate is controlled by pressure, is it right? The vacuum controls a diaphragm which allows pressure within the turbo to open/close the wastegate. Is my understanding correct?

I have not removed the turbo yet and checked for blockage or wastegate stuck open. The wastegate is spring loaded to be closed? The chance of it stuck open is low, right?

I don't know why there is no boost. Any help or information is appreciated.

[87tdwagen]

Yes the control side of the Westgate is operated by pressure, my bad, try blowing into the hose looking for movement on the rod and the exhaust bypass valve. These can get stuck open. Typically you would see low manifold boost, but depending on how you are reading, if while driving vs revving parked etc.

If your compressor wheel is moving at significant speed and increases accordingly with revs, it is attached and driven by the exhaust wheel. It should be making boost.

Can't see why none is made if that holds true.

One large possible leak area, could be the connecting pipe exiting the turbo feeding the crossover pipe. Big green O rings, but still, would hiss like crazy and still make boost

The only other thing that comes to mind would be a clogged or nearly, air filter or intake obstruction possibly not allowing enough volume in.

Otherwise no more suggestions to offer. Hopefully someone can help

[ah-kay]

I can't check easily turbine wheel speed relative to engine revs. It is not the air filter box as it is removed plus the accordion boot. I will take all plumbing out and check for blockages, if any. I am stumped.

[87tdwagen]

You've got me stumped as well. Barring any massive air leaks, which I;m sure you would notice, if the wheels are turning, there should be boost. It is possible that the wheels are disconnected along the shaft, possibly the exhaust or the impeller side, that's why assessing the speed of the impeller relative to engine rpms. The impeller could move on its own slowly due to intake air flowing over it feeding the engine, but if it is driven by the exhaust wheel its speed will react accordingly to engine speed.

Let us know what you find out, this is an odd one in my book. Best of luck in the diagnosis.

EDIT:
Looked mine over again for some other possibilities that could apply to you:
EGR valve if you still have one, sits right in the boost pipe off of the turbo. Possibly, clogged, with crud build up? Easy to unbolt and check. Also start at the top, disconnect the crossover pipe, this will expose the turbo air charge outlet and gives you a clear view into any obstructions in the charge air path.

EDIT YET AGAIN:
One last thing, is exhaust obstruction. I recall when my Cat on the wagon finally clogged up at 275kish miles it exhibited similar, very low boost. I could see that on my gauge along with the increased EGTs and therefore was easy to pinpoint to the Cat. Once freed up, good as new. Without the exhaust flow it wont be able to produce much boost, and if you still have your CAT installed, it's quite likely clogged with soot.

[ah-kay]

Originally Posted by 87tdwagen

You've got me stumped as well. Barring any massive air leaks, which I;m sure you would notice, if the wheels are turning, there should be boost. It is possible that the wheels are disconnected along the shaft, possibly the exhaust or the impeller side, that's why assessing the speed of the impeller relative to engine rpms. The impeller could move on its own slowly due to intake air flowing over it feeding the engine, but if it is driven by the exhaust wheel its speed will react accordingly to engine speed.

Let us know what you find out, this is an odd one in my book. Best of luck in the diagnosis.

EDIT:
Looked mine over again for some other possibilities that could apply to you:
EGR valve if you still have one, sits right in the boost pipe off of the turbo. Possibly, clogged, with crud build up? Easy to unbolt and check. Also start at the top, disconnect the crossover pipe, this will expose the turbo air charge outlet and gives you a clear view into any obstructions in the charge air path.

EDIT YET AGAIN:
One last thing, is exhaust obstruction. I recall when my Cat on the wagon finally clogged up at 275kish miles it exhibited similar, very low boost. I could see that on my gauge along with the increased EGTs and therefore was easy to pinpoint to the Cat. Once freed up, good as new. Without the exhaust flow it wont be able to produce much boost, and if you still have your CAT installed, it's quite likely clogged with soot.

I don't understand the CAT part. Where is it? The car drive okay just lack of power.

I think it is the turbo. I removed the cross pipe and put a ballon over the turbo outlet. The balloon was inflated. When I increased the rev the balloon got bigger so the turbo was producing boost. I did the same with another car the balloon got bigger much faster and blew off at a much lower engine speed. So the bottom line is that the turbo is producing boost but just not enough to be useful. The turbo is coming out. It could be the wastegate stuck open. The turbo was an used one so it could be a dud.

[87tdwagen]

Good idea with the balloon test, creative.

The Catalytic converter is about 5 or 6 feet down the exhaust pipe from the turbo. A hexagonal unit about a foot long itself. Approx under the passenger seat floorboard.

The best way to test, since you have things apart, is to disconnect the down pipe right at the rear of the turbo. Then perform your balloon test again. If it pops off quickly like the other car, building up boost, then the Cat is clogging. It can create enough back pressure to keep the turbo from generating stock max boost 12-14psi.

Check this first to save you from pulling the turbo if not needed. If no change, then the problem is in the turbo itself.

You can also test the wastegate with everything still installed, apply pressure to the control pod, look for the rod at the rear to the Wastegate for movement, or grab the rod or wastegate end and see if you can move it. You can also hit it with penetrating oil.

Hopefully this will get you going. These turbos are very simple, no variable vanes or anything, just a simple finned exhaust wheel and impeller wheel on a shaft. It would take some serious damage to either for them not to move air. My guess is the exhaust restriction. Your car can still run fine at say 30% flow, but your boost and overall power will be limited and doggy at less than full flow.

You mentioned that it is a used turbo. How long have you had it on the car? Any problem after first installing? Was it weak on power right after installation?

[ah-kay]

Originally Posted by 87tdwagen

Good idea with the balloon test, creative.

The Catalytic converter is about 5 or 6 feet down the exhaust pipe from the turbo. A hexagonal unit about a foot long itself. Approx under the passenger seat floorboard.

The best way to test, since you have things apart, is to disconnect the down pipe right at the rear of the turbo. Then perform your balloon test again. If it pops off quickly like the other car, building up boost, then the Cat is clogging. It can create enough back pressure to keep the turbo from generating stock max boost 12-14psi.

Check this first to save you from pulling the turbo if not needed. If no change, then the problem is in the turbo itself.

You can also test the wastegate with everything still installed, apply pressure to the control pod, look for the rod at the rear to the Wastegate for movement, or grab the rod or wastegate end and see if you can move it. You can also hit it with penetrating oil.

Hopefully this will get you going. These turbos are very simple, no variable vanes or anything, just a simple finned exhaust wheel and impeller wheel on a shaft. It would take some serious damage to either for them not to move air. My guess is the exhaust restriction. Your car can still run fine at say 30% flow, but your boost and overall power will be limited and doggy at less than full flow.

You mentioned that it is a used turbo. How long have you had it on the car? Any problem after first installing? Was it weak on power right after installation?

Thanks for the info.

This car is rarely used, only for Home Depot trip or hauling small load, less than 1k miles per year. I can't remember whether it had power when I bought it in 2014. The oil pump in the sump had a hole caused by a ball bearing and starved the turbo with oil. The turbine wheel shaft snapped so the old turbo was definitely bad. I think the ball bearing was from the vacuum pump failure before my ownership. I replaced the turbo and still has no power but it drives ok so I never bother. The turbo was bought from fellow forum member awhile back. The shaft turns okay so I just installed it. Basically the failure mode wasn't a sudden thing but I decided to fix it once and for all.

[87tdwagen]

You're welcome.
The background, helps, being not all of a sudden. Really leaning towards a exhaust restriction, as it was on mine, it progressively got weaker.

Disconnecting the downpipe at the turbo will confirm this. I chose to straight pipe the Cat, but I have no emissions testing. If you have testing, I would recommend hollowing out or getting a generic unit. The OE units have been NLA for years now.

If found to be a exhaust restriction, it needs to be addressed. It will only get worse. The biggest detriment being the extra 300-450 degrees increase in EGTs stressing the head.

Best of luck

[vstech]

Ok, exhaust restriction, enough to affect turbo would be very difficult to drive at all.
My bet is intake clogged.
Get a 5mm Allen and remove all the bolts on the intake, and check for blockage.
The egr can completely clog the intake. I’ve seen it so clogged ya can’t fit a pencil in…
Also, clogged fuel filters will do this… since, fuel is needed for enough exhaust to build boost…
A quick check for exhaust cat clog, is remove the brass plug in the exhaust and see if the car has boost.
Fuel filters are the most common cause.
Followed by clogged intake, then clogged cat.

Of course, this assumes the wastegate is closing.

[vstech]

And IIRC, the 87 has a vacuum controlled wastegate…

[ah-kay]

Originally Posted by 87tdwagen

You're welcome.
The background, helps, being not all of a sudden. Really leaning towards a exhaust restriction, as it was on mine, it progressively got weaker.

Disconnecting the downpipe at the turbo will confirm this. I chose to straight pipe the Cat, but I have no emissions testing. If you have testing, I would recommend hollowing out or getting a generic unit. The OE units have been NLA for years now.

If found to be a exhaust restriction, it needs to be addressed. It will only get worse. The biggest detriment being the extra 300-450 degrees increase in EGTs stressing the head.

Best of luck

I have turbo boost.

Removed exhaust from the back of the turbo ( 3 nuts) and now I have turbo boost. Drive around for 5 minutes ( too loud, everyone is turning heads ) and the boost shows psi similar to the 300D sedan. There are 3 boxes in the whole exhaust, need to figure out which one is the catalytic converter or blocked.

[vstech]

Originally Posted by ah-kay

I have turbo boost.

Removed exhaust from the back of the turbo ( 3 nuts) and now I have turbo boost. Drive around for 5 minutes ( too loud, everyone is turning heads ) and the boost shows psi similar to the 300D sedan. There are 3 boxes in the whole exhaust, need to figure out which one is the catalytic converter or blocked.

Nice.
That is an easier fix than the intake for sure.

[87tdwagen]

Awesome news!

Here's a picture of your exhaust system:
The red circled unit is the Cat and the most likely clogged. You can disconnect the flange after the CAT (if yours has one) to verify that is your clogged unit vs the remain 2 mufflers. If your boost is limited after the CAT, then it's definitely the Cat. Very likely to be the case given it's tight honeycomb ceramic mesh insert. From a design perspective, it's too far from the manifolds to heat up sufficiently to completely burn off the soot and or oil build up.

If you straight pipe it, I recommend that you keep one of the flanges in that location so that the exhaust can be split. An exhaust shop might just be tempted to cut fore and aft and weld in a pipe, leaving you with a long cumbersome exhaust system to remove for repairs otherwise doable with removing only a shorter section of the exhaust.