87 300SDL Power Loss, Smoke - Page 2 - PeachParts Mercedes-Benz Forum

Gregory · #16 10-25-2008, 02:11 PM

I could not feel any side-to-side play in the turbo wheel. There could have been a slight amount of front-to-back movement, along the length of the turbo axle. The wheel turned quite freely.

LUVMBDiesels · #17 10-25-2008, 02:23 PM

Get a boost gauge and plumb it in the line going from the manifold to the ALDA. Check the boost pressure as you drive the car. You won't see boost revving the car in the driveway. Let us know what happens...

Gregory · #18 10-25-2008, 05:34 PM

I sprayed some WD-40 into the hole in the intake manifold where the line comes out, going to the ALDA switch. The engine revved a bit and pre-detonated until the WD-40 was burned.

I made a boost pressue gauge tool from a tire gauge and misc. parts for $20. (see photo) I ran it up to 60 mph, with the RPMs getting up to 4000, the needle never lifted off the zero stop of the gauge.

There is a new and not-good sound coming from the engine. I used a 2" tube as a stethescope to try and isolate where the sound is coming from. It sure seems like its coming from the turbo, perhaps the rear turbo bearing is shot. It does sound like a bearing race grinding.

After the motor cools a bit, I'll take the air tube off the front of the turbo again and test the rotor for play again. If I can move the rotor in and out, or forwad and back, along its axle, does that mean its toast?

LUVMBDiesels · #19 10-25-2008, 07:45 PM

You should be getting at least 8psi on the road. With the turbo exposed, start the car and see if the turbo starts spinning. If you rev the engine the turbo should spin even though it is not producing much boost. If it does not spin freely you probably need to replace or rebuild it. If it spins, check the waste gate to make sure it is not stuck open.

Good luck

Gregory · #20 10-25-2008, 07:57 PM

I posted a photo of the linkage to the waste gate arm. Can you tell from the photo if it open or closed?

LUVMBDiesels · #21 10-25-2008, 08:51 PM

Quote:

Originally Posted by Gregory

I posted a photo of the linkage to the waste gate arm. Can you tell from the photo if it open or closed?

I will look at my car tomorrow morning. I will compare it to your picture

guage · #22 10-25-2008, 10:06 PM

Sounds to me like a clogged spin on filter.

Jeremy5848 · #23 10-25-2008, 10:18 PM

If the turbo was not producing boost (due to either an internal failure or a failed-open boost gate) ALDA would not allow the IP to inject more fuel to cause smoke. So the smoke is probably not a turbo problem. I'm concerned that your tire gauge may not have enough low-end sensitivity to measure the pressure in the intake manifold, which is usually no more than 13 psi or so.

Could you invest in a "real" boost gauge? Should not be expensive and is a good diagnostic tool to own. One option would be to buy a Mityvac, which is a good tool to own if you have a diesel Benz. Get the metal version and the one that can measure both vacuum and pressure.

Jeremy

sixto · #24 10-25-2008, 10:46 PM

A hose and a whistle?

Sixto
87 300D

GRIESL · #25 10-26-2008, 10:12 AM

A boost guage is cheap and useful. But you could also just disconnect the feed in the cabin from the tire guage and put your finger on the end of the hose just to see if it's producing any pressure. The feed line from my boost guage popped off in the cabin and produced a lot of hissing noise. To quiet the noise and put my thumb on the end of the hose, and you could feel the pressure. I have my turbo turned up to 11 psi, but I would imagine you could still feel 8 or 9 psi on the hose. Good luck!

Gregory · #26 10-26-2008, 02:58 PM

Boost guages at CarQuest were over $60.

I took the air tube off the front of the turbo again, there is no play in the turbo wheel. Holding a mirror and a light so I could see into the hole, the turbine was not spinning at idle. I couldn't hold the light and mirror in one hand to ramp up the RPMs, and see if it started spinning.

However, after I put it all back together, I drove to the end of the block and back, smoking like crazy. When I returned, there was a large puddle of oil where the car was parked overnight, about a 12" circle. I looked under it with the engine idleing, and engine oil was drip-drip-dripping out of the hole in the exhaust pipe that the muffler shop drilled yesterday to test for back pressure. I guess he didn't weld it shut properly.

So now we know the smoke is probably coming from oil, instead of fuel. What could cause so much oil to get into the exhaust, and why would there be a power loss?

babymog · #27 10-26-2008, 03:09 PM

Turbo should spin at idle.

sixto · #28 10-26-2008, 03:35 PM

See if you can remove the turbine section feed pipe. The part that used to be a trap oxidizer. If that's oily, you might have lost a valve guide or seal. If not, it has to be the turbo.

Sixto
87 300D

Gregory · #29 10-26-2008, 03:43 PM

The other day, when I first took a look into the turbo, there was a small pool of oil in front of the blades.

Today when I was trying to see if the turbo was spinning at idle, I was looking at the center nut, not the turbine blades. The center nut wasn't turning.

Gregory · #30 10-26-2008, 05:01 PM

I took off the ERG valve and made a swab with tie wire and a paper towel to probe the length of the turbo section feed pipe.

The paper towel came out with a lot of dry soot, no oil.

How can the turbo dump so much oil into the exhaust pipe?

The oil level is down 1/2 quart. I've driven it maybe 20 miles since I last checked it, it was full then. It's blown out a lot of oil in a short time.