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  #1  
Old 02-12-2002, 08:19 PM
turbodiesel300
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Expected performance of a 300 SD

I had recently replaced both fuel filters and now notice an improvement of top end performance. However, when climbing a medium incline, say 6-8% it will very slowly accelerate from 60 to 65 taking about 10 seconds at full throttle in top gear. Also this is usually the top speed for the car on such slopes. When climbing it used to surge before the new filters and actually decrease in speed, but not anymore. There is plenty of power on the flats though, it seems like it could reach a 110, but I've never tried to for fear of stressing the engine. It does pull strong past 90. Is this a typical performance profile of an 85 SD? Or does my car seem to be underpowered for some reason?

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  #2  
Old 02-12-2002, 08:30 PM
turbodiesel300
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No, I've never seen those before. Where is the banjo fitting? Maybe I can get them looked at. The car has 220,000mi. and runs very well, i.e. starts on the first crank in 20 degree F.
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  #3  
Old 02-13-2002, 01:38 PM
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Location: Chattanooga TN
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This tube that you described, where it connects on the left side, can you explain that connection. Is the dial looking contraption what you are calling the banjo bolt? Does the cap just come off or is this a dial that adjusts pressure somehow. I am afraid to mess with it before I understand it cuz with my luck it would be some sort of sensative pressure adjuster.
thanks
Eric Z
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  #4  
Old 02-13-2002, 02:28 PM
turbodiesel300
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Well, I think I found the banjo bolt, if it's hollow and has 3 oval holes at the head? Anyway, I dismantled it and took the car for a spin to see if there was any noticeable difference in performance. There was none that I could detect. The bolt had a little soot in it but not too bad to cause any restriction. The plastic tube was also clean. So, I cleaned both out with carbeurator cleaner and tightned the banjo bolt back on. Then I made sure if there was any vacuum coming from the end of the tube. There is a little vacuum pressure when the car is reved, and when the throttle is released the air flow is reversed and is bled off. Is that what's suppose to happen?
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  #5  
Old 02-13-2002, 02:58 PM
turbodiesel300
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Well, maybe it's just me any my car is performing fine. Will a zero-60 time give me a good idea if its running ok? If so what kind of a time should I expect?
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  #6  
Old 02-13-2002, 03:35 PM
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my 83 300SD will kick down into third when going 60 if I floor it, if it stayed in top gear those speeds may be normal, i would look at your tranny shift points/kick down.
R
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  #7  
Old 02-13-2002, 03:39 PM
turbodiesel300
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Yes the car will kick down every time. The car can handle shallow slopes well, but is the medium hills (20-30 degree incline) where it needs to be wide open to hold 65.
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  #8  
Old 02-13-2002, 08:32 PM
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Turbodiesel:

You are not producing full horsepower. You should be turbo boost and more fuel climbing hills, with a considerable increase in power with load. Sounds like your car running like a non-turbo with fuel delivery problems!

You have one of three things wrong

1. You ALDA is miss-adjusted (it is the big metal "can" on top of the injection pump with the hose connected to it). This can be adjusted -- search for postings that describe your specific model

2. You have a bad overboost switchover vavlve or broken or clogged boost line between the intake manifold and the ALDA. Try connecting the two hoses that go to the overboost protection switchover valve together with a peice of vacuum line to bypass the valve. If you get power back, this is the problem and can be fixed by replacing the switchover valve or the sensor switch on the manifold.

3. You aren't getting any boost from the turbo. Alas, I suspect this is most likely your problem, as you should have pressure on the manifold above idle, not vacuum. There are several causes of boost failure, from a broken boost control (wastegate control) spring (fairly cheap) to a siezed turbo (not cheap.

There are several posts about turbo diagnosis -- the best thing to do is get a presure guage hooked up to the boost line and see what kind of pressure you get under load -- if you get pressure, look at the ALDA and boost controll lines. No pressure, you have a turbo problem.

A quick check of the turbo is to take the inlet hose off and spin the wheel by hand ENGINE OFF, PLEASE. If it won't turn easily, there are rough spots in the rotation, or any axial play, it is shot and needs rebuilt.

DO NOT operate the engine with the turbo compressor wheel exposed -- it will eat your hand if you touch it, and if anything solid gets sucked it, scrapnel will come flying out, very dangerous, to say nothing of expensive.

Peter
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  #9  
Old 02-14-2002, 10:21 PM
turbodiesel300
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Well, I bypassed the switch-over valve and connected the pipe from the banjo fitting directly to the ALDA. The performance remained the same. I also rechecked the pressure at the manifold by removing the banjo bolt, and placing a finger over the hole and there is definetly negative pressure above idle. Why would this be? I think the turbo is working because I can hear the distinctive whoosh along with an increase in acceleration as it spools up.
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  #10  
Old 02-14-2002, 11:52 PM
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Hey Turbo,

I found this to be informative. Check "turbos" and "fuel system".

Senior members please advise.

Take care,

Matt

http://www.mbz.org/info/articles/
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'83 300SD
'85 Celica
'98 Harley Springer Softail
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  #11  
Old 02-15-2002, 12:02 AM
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Hey Turbo,

I found this to be informative. Check "turbos" and "fuel system".

Senior members please advise.

Take care,

Matt

http://www.mbz.org/info/articles/
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'83 300SD
'85 Celica
'98 Harley Springer Softail
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  #12  
Old 02-15-2002, 12:18 AM
turbodiesel300
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Does an 85 SD have a Garret or KKK turbo
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  #13  
Old 02-15-2002, 01:06 AM
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Look At the Turbo for Manufacturer

Greetings Turbo,

If you have looked at the Bayler sheets concerning adjustment of your wastegate, turbo, etc. you'll have to look at your turbo to see what the manufacturer is. As mentioned, both companies were used, so it's up to you to look at the manufacture name on the turbo. I would also use great care in any adjustments they reccomend, as you'll be buying the new engine, not them, should you get too zealous with your adjustments.

Charles
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'84 300SD 256,000 Gold on Brown (Mileage Award)
'86 300E 246,000 Blue on Tan
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  #14  
Old 02-15-2002, 03:17 PM
turbodiesel300
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I hooked up a hose from the switch-over valve to the drivers side window, and indeed there is positive pressure at load. The only problem is that I don't have any idea what is the p.s.i. I can't find a pressure gauge anywhere. The local performance shop has 60 dollar mountable gauges. But these go up to 30 p.s.i Does anyone know where to find a simple gauge to measure 10 p.s.i.?
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  #15  
Old 02-15-2002, 03:47 PM
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Join Date: Feb 2001
Location: Atlanta
Posts: 63
Search under "boost gauge" and you should find a couple of posts with links. Someone had suggested JC Whitney. I haven't gotten one yet but it looks like you'll want one that goes to 15psi.

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'83 300SD
'85 Celica
'98 Harley Springer Softail
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