Turbo problem? - PeachParts Mercedes-Benz Forum

Gordo · #1 10-10-2006, 11:57 AM

My 85 300TD Turbo is prety slow. I have adjusted valve lash, checked timming chain strech (about 2 degrees), checked Inj timming (drip method about 24 degrees BTDC), the alda is maxed out with little or no smoke. I put a boost gauge on it and there was only 8psi, so a took the hose off the waste-gate. The boost went to 12psi. It seems like it should be more? I live at 8000ft above sea level and need the power in the mountains. Also I am only getting about 20mpg. Can anyone help?

rrgrassi · #2 10-10-2006, 12:15 PM

Have you cleaned you banjo bolts on the ALDA and the intake yet? How are the lines between the the ALDA and the intake? Have you checked your turbo switch over valve? Mine was frozen shut, and the PO bypassed it instead of replacing it.

Gordo · #3 10-10-2006, 12:29 PM

Banjo bolts and lines are all clear. By turbo swich over valve I assume you are talking about the relay looking thing in the middle of the line that goes from the intake to the alda. I bypassed that and there is no change in performance.

rrgrassi · #4 10-10-2006, 12:42 PM

Yes, that would be the relay thing, and you should be getting about 15 to 17 psi of boost IIRC. It is possible that the waste gate is not closing all the way, or a seal is leaking.

Also, when was the last time the air filter was checked/replaced. Just trying to run down the simple list first.

If all checks out, you will need to check your turbo as a next plan of action.

Gordo · #5 10-10-2006, 12:48 PM

Brand new air filter. All the pressure likes look good. The difference in boost from 8psi to 12psi with the wast gate hose off did not change the performance. Is this because I have a fuel problem? How do I check the turbo? Do I need to remove it from the car? Thanks for your help. IIRC?

rrgrassi · #6 10-10-2006, 12:59 PM

IIRC If I Remember Correctly.

I have not had messed with my turbo yet, as I have not had the need to, but I do need to change the U -Tube seals, so I'll be doing the spin test and the lateral play test by hand.

Engine needs to be turned off, and cold, or slightly warm. With the U-Tube off, spin the blade of the turbine and it should spin very feely. Then see if you can make the turbine move back and forth on it's axis. You do not want it to move laterally. If it does not spinn freely, or if you see broken or cracked fins, it is time for a rebuild or replacement.

If you do run the engine, with the U-Tube off, you run the high risk of having something sucked in, including your fingers. Turbo fins make nice slicers.

Johnhef · #7 10-10-2006, 01:05 PM

almost. boost pressure sounds about right from a car of that age. depending if yours was a california model or not, factory boost was around 12-13psi, unless cali and then I believe those were set to 8ish.

I didn't see anything about fuel filters. if you have plenty of boost and no power its more than likely a fuel issue.

rrgrassi · #8 10-10-2006, 01:43 PM

Good call on the checking the fuel filters. I did notthink to ask that, since Gordo seems to have knocked out the simple stuff.

Gordo · #9 10-10-2006, 01:46 PM

It is a CA motor. The fins on the intake side look okay (have not looked at the exaust side yet), and the turbine has no play but might be a little stiff to turn. It spins easly by hand but it stops right away when I let go of it. As far as I can tell it sounds normal when it spins up under load. New fuel filters.

rrgrassi · #10 10-10-2006, 01:56 PM

The turbo should not stop right away after you release it, according to all the reading on Turbo info posted on this forum. It should come to a gradual stop

Search the forum, as it sounds like either the bearing are wearing out, or some how oil flow to the turbo has become restricted, resulting in bearing accelerated wear and possible turbo lock up.

How many miles are on the car. It is possible that the turbo is just wearing out.

Gordo · #11 10-10-2006, 02:07 PM

The motor has 258K on it.

TheDon · #12 10-10-2006, 02:45 PM

Quote:

Originally Posted by Gordo

It is a CA motor. The fins on the intake side look okay (have not looked at the exaust side yet), and the turbine has no play but might be a little stiff to turn. It spins easly by hand but it stops right away when I let go of it. As far as I can tell it sounds normal when it spins up under load. New fuel filters.

dont worry about the exhaust side... by spinning the compressor your also spinning the turbine.. unless you want to check the fins go ahead.

Gordo · #13 10-10-2006, 02:54 PM

I gess I should have a look at the fins on the exaust side. I wonder if there is a way to flush the turbo with fresh oil with out taking it off and taking it apart. Do you think that might loosen it up? It is only very slightly stiffer to turn then other turbos I have worked on.

rrgrassi · #14 10-10-2006, 02:56 PM

Mine has 222,500 now. How well was the engine maintained? I think mine was fine, but the PO and ham fisted shop the PO used, did a lot of not so good short cuts, like using RTV on the oil filter seal ring, splicing the high pressure side of the A/C line going to the compressor, etc.

Usually improper maintenance or engine oil used, failed intake seal that lets dirt in, etc can result in the turbo not spinning freely.

There was a posting on this forum that told the turbo should spin feely with out any drag on it. I am looking for it to refer you, but no dice yet....

Gordo · #15 10-10-2006, 03:07 PM

I will look too. It is a salvage yard motor and I don't know what the PO did or didn't do. I do know however that the PO was enough of a hack to put the harmonic balancer on 180 out making it confusing to find TDC. That is taken care of though. As far as the motor condition goes there is no blowby, no compression check yet.