Installed a boostgage and observed peak boost around 8.5-9 psi.
Out of curiosity, I clamped shut the hose to the wastegate. What a difference. The car came alive even at low to medium boost because the boost came up faster. Not to mention a brief run when boost is at 15 psi. Yahooooooo!

I suspect that the wastegate is a leaky device at least in my car. Don't know it is by design (leaky valve) or it developed some leak.
Anyway, an adjustable pressure relieve valve (non-leaky type) will be installed in-line with the wastegate sooooooon!

Another observation. The turbo has very tight coupling with the exhaust and intake manifold, the "lag" is minimum. Wonder if intercooler will significantly increase the lag?

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Shane83SD

Why do you think you have a leaky wastegate?

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'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

No, wastegate works perfectly, since you have full boost (and then some) with the actuator control line clamped shut.

What you have is a tired control spring -- it's too soft, so that the wastegate opens to early, restricting boost.

There have been several posts on what to do about this, from just adjusting the spring to replacing it with another controler with an external adjustment.

What you want is NO MORE than 13 psi (you can get more, but engine reliability goes down fast with more).

Worst cast you will have to remove the turbo and take it to a diesel injection shop and have them replace and adjust the wastegate controller spring.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

For a perfect non-leaky pressure relief valve, the action is like an on-off switch. As pressure is lower than rated, the air path is 100% blocked.

Operating under the rated boost, there should be no difference whether the hose is clamped or not if the waste gate is non-leaky. The fact that the boost can be built up faster indicates the waste gate is a leaky device. Weak spring mentioned by psfred is one form of "leaky" device.

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Shane83SD

Wastegate here isn't leaking, it's being opened too soon by a weak spring. Most 617 engines were set fairly low at the factory (10-11 psi boost) and the spring is going to allow lower boost as it ages.

When the boost line is clamped shut, the wastegate won't be opened, and since the turbo produces more and "faster" boost under that condition, the wastegate is fine. The wastegate actuator is opening the gate too soon.

Note that a wastegate is NOT a pressure relief valve -- it opens to "waste" the exhaust around the turbine. If it won't seal, the boost will be low from excessive flow around the turbine no matter what the actuator is doing. Usually a poppet type valve, so flow is proportional to opening amount -- this allows a constant pressure in the intake with variable flow through the turbine.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I tried the clamping test and I also noticed a hugh difference, but then I suspected a warnout spring.

Anybody have a turbo repair place they like? Any idea on the price? My other thought was to buy a rebuilt turbo from Performance Products when they have have their 15% sale. Still would be $600.

Craig

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1994 E420, Pearl Black/Black. 2.82 rear diff., AMG front spoiler, painted lower half. SOLD

1972 & 1974 BMW 2002tii's.

Look up Diesel Injection Service in your phone book. Or call some independent shops in you area and ask them who they use. Any injection service will also work on turbos -- the only reason for asking for recommendations is that some are better or more familiar with MB turbos that other.

You don't need anything else done, right? Just a weak spring? This won't be any 600 bucks!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!

I remember someone posting a place in Texas a long time ago. I think when I called them they wanted around $400. Seemed high to me. Maybe they were going to go through the whole thing and put in new bearings. I'll check the phone book, but I'd rather have a shop that knows these turbos.

Craig

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1994 E420, Pearl Black/Black. 2.82 rear diff., AMG front spoiler, painted lower half. SOLD

1972 & 1974 BMW 2002tii's.

On my 300d, I am sure my wastegate is "leaking". I assume that the control is no longer being closed by the spring. On a gauge, I am getting about 5psi but that was using a high pressure gauge so it was difficut to read the low #s accurately. I know it is below spec though. I installed a valve in the line from the turbo and eventually closed it completely with no increase in boost. Is it likely that this can be fixed by removing the cover from the wastegate control and cleaning/ replacing the spring? How does that clip come off? What are other possible causes or ways that boost can be "leaked"? Anyway, I sold this car to my father to make room for my next project (MB diesel in one of my Scouts) so I will be passing this information on to him.

Use the search on 'adjusting the wastgate spring' or something like that and you'll find plenty of info there. Not a bad job, I was able to do it in about 20 minutes. I think what most run into is that the spring can only be adjusted so much, then it bottoms out and can't go any further. I think the only solution is a new spring. Where to get the spring is the big question.

Craig

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1994 E420, Pearl Black/Black. 2.82 rear diff., AMG front spoiler, painted lower half. SOLD

1972 & 1974 BMW 2002tii's.

Since I blocked the pressure from the turbo to the wastegate control w/ a valve and the boost did not change, I don't think that twisting the spring to adjust it will help. I haven't taken it apart but my guess would be that the spring is broken or something is stuck.

I'm assuming that you've cleaned the banjo fitting. Maybe your switchover valve is venting everything to the atmosphere? You must have bypassed this when you tested your turbo, so did you notice a change when you hooked it back up? Since you're getting some boost, the turbo must be spinning.

Craig

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1994 E420, Pearl Black/Black. 2.82 rear diff., AMG front spoiler, painted lower half. SOLD

1972 & 1974 BMW 2002tii's.

Yes the banjo fitting is clean. The gauge is teed in to the line and will be replaced by a proper gauge soon. If you are talking about the overboost protection valve (you may have to forgive me for my use of terms), I removed it because it was blocking the boost signal to the aneroid. Yes, the tubo is spinning and the car is not without power so I figure that the lack of boost is not because of an engine problem but a wastegate problem. The issue here is that the boost is not increased when the line from the tubo to the wastegate is completely block.

Where can the spring be obtained?

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N. Hodges
1994 S350
1987 300 SDL (for sale)