Lack of power, how to test turbo? - PeachParts Mercedes-Benz Forum

jugganaut · #1 06-18-2008, 10:51 AM

I bought a non-running 1981 Turbo Wagon for $350 and after some fiddling found out that it was just a clogged fuel filter that made it "non-running". Engine sounds great, but driving around it has zero power. Changed the air filter, glow plugs, has new fuel (and filters). Starting to think that it may be the Turbo (manufactured at the tail end of '81 and does have turbo).

My question is how do I test the turbo to see if it's actually working?

Thanks!

tangofox007 · #2 06-18-2008, 10:58 AM

You might try cleaning the line from the rear of intake manifold to the ALDA (via switchover valve). If the line is not clear, fuel delivery will be inadequate and performance will suffer significantly.

bgkast · #3 06-18-2008, 10:58 AM

Plugged Banjo bolt? You can check the turbo by removing the U tube and trying to spin the turbo. It should spin freely and "coast" a revolution or so when you spin it. Also try gently moving the shaft side to side and in and out. There should be minimal play.

BoostJunkie · #4 06-18-2008, 11:16 AM

Quote:

Originally Posted by tangofox007

You might try cleaning the line from the rear of intake manifold to the ALDA (via switchover valve). If the line is not clear, fuel delivery will be inadequate and performance will suffer significantly.

On my 82 300SD I cleaned out the lines and the bolts and still had no real power. Make sure to check the switch over valve for blockage too. Once I cleaned it out I more zip back in my engine.

ALSO, Check over your vacuum system. A nice tight vacuum system will make your car run better. Replace any broken or leaking lines, fittings, etc...

jugganaut · #5 06-18-2008, 11:18 AM

Quote:

Originally Posted by tangofox007

You might try cleaning the line from the rear of intake manifold to the ALDA (via switchover valve). If the line is not clear, fuel delivery will be inadequate and performance will suffer significantly.

Oh yeah, I forgot about that... there's a good pictorial on Dieselgiant for doing that...

tangofox007 · #6 06-18-2008, 11:19 AM

Quote:

Originally Posted by BoostJunkie

A nice tight vacuum system will make your car run better.

It will make a lot of things work better. But the engine isn't one of them.

#7 06-18-2008, 02:34 PM

If the filters were so plugged as to prevent the engine from starting you should clean the tank strainer as well and check for collapsed hoses.

777funk · #8 06-18-2008, 02:37 PM

My old 84 300d had the transmission's cable disconnected on the valve cover. It would shift so soon that the turbo wouldn't ever get the chance to spool. Took me a few days after buying it to notice that that's what it was. After that, fast as it should have been and a very nice car.

tyl604 · #9 06-18-2008, 04:23 PM

If the vacuum switchover valve is bad, you will have very little power. About a $35 fix if DIY.

johninva · #10 06-18-2008, 04:25 PM

incredible deal on the wagon, got some pics ?

#11 06-18-2008, 04:26 PM

Quote:

Originally Posted by tyl604

If the vacuum switchover valve is bad, you will have very little power. About a $35 fix if DIY.

Overboost switchover valve, not vacuum. It wouldn't be that. Even with no boost enrichment it will still have 88hp, plenty to move the car around decently. Zero power means lack of fuel or mechanical failure.

JHZR2 · #12 06-18-2008, 04:46 PM

I'd clean the banjo bolt and then buy a cheap boost gauge to plumb in at the boost control on the firewall (the line from the banjo bolt goes there) with a three-way vacuum connector.

You need to drive the car, you wont get boost revving it in neutral... See what you get. Optimum is about 10-12, I dont exactly recall the best value.

JMH

winmutt · #13 06-18-2008, 05:55 PM

11psi was factory. 12psi is about all you will get out of it with by adjusting the wastegate with a stock spring.

JHZR2 · #14 06-18-2008, 06:56 PM

With a boost controller (dawson boost controller was it???), it seems that one can go quite a bit higher - longevity suffers of course.

Supposedly the wastegate springs get tired and soft.

JMH

winmutt · #15 06-19-2008, 12:04 PM

Quote:

Originally Posted by JHZR2

With a boost controller (dawson boost controller was it???), it seems that one can go quite a bit higher - longevity suffers of course.

Supposedly the wastegate springs get tired and soft.

JMH

Anything over 12 is pointless unless you add more fuel. T3 tops out at 15psi, the KKK is like 11. After that they become heat pumps.