Power Loss in a OM617

[RichardLSU]

Hi everybody. I'm the proud owner of a 1985 300SD. This car has served me very well during the last 3 months and almost 10K of ownership. Yes, I put alot of miles on this thing and have little to no complaints with it.

However, while driving to Shreveport, La. from KC, Mo. I set the cruise control like I always do and everything was fine until I noticed that I was starting to lose speed going up hills (something it has never done). I turned off the cruise control thinking that was the problem, it wasn't. By the time I got home (about 160 miles later) I was convinced something was seriously wrong. On some big steep hills through Arkansas I thought my car was going to sputter out and die by the time it reached the top.

My engine seems to be running at lower RPMs and it almost feels like I can't feel my turbo anymore. There was a few spells where things seemed to get back to normal while I was driving home but it never lasted very long.

Did I lose a vacuum line somewhere? Is my turbo shot? I've visually inspected everything and nothing seems out of order. Perhaps I just missed it.

Any input from you experts would be much appreciated! Thanks!

Before you panic, replace both fuel filters. That type of power loss is a classic symptom on clogged fuel filter(s).

[LUVMBDiesels]

I agree. I would change both filters and also check the lines from the intake manifold to the cut over switch and from the switch to the ALDA.

The lines go from the rear of the intake to a switch on the firewall and from that switch to the ALDA on top of the Injection Pump. take them off very carefully (don't remove the end fittings) and blow them out with carb cleaner

These lines get blocked and cut off pressure to the ALDA no pressure = no fuel enrichment

If you have a boost gauge I would plumb it into the line from the switch to the ALDA and drive. You should get 9psi on a stock turbo

[RichardLSU]

Thanks for the tips.

The fuel filters would make sense. Where are they located?

Originally Posted by RichardLSU

Thanks for the tips.

The fuel filters would make sense. Where are they located?

Left side of the engine, the primary (small) filter is in the fuel line just before it enters the injection pump. The secondary filter is located near the left front of the engine. It looks like a small "spin on" oil filter. Do you have any spare filters available?

[BoomInTheTrunk]

one main pull filter is the little thing down on the side of the Injector Pump its inline. the other is that can that is screwed on right next to the power steering pump.

[LUVMBDiesels]

Originally Posted by RichardLSU

Thanks for the tips.

The fuel filters would make sense. Where are they located?

The primary is a clear plastic filter inline with the fuel line coming from the rear of the car. It is near the injection pump

The secondary is near the cruise control actuator and looks like an oil filter

There are posts detailing how to replace them. but in a nutshell. you need to unbolt the secondary filter from above (19mm) I think. You need to unclamp the primary as it uses hose clamps.

Fill the secondary with fuel or diesel kleen as it helps to have it filled when you prime the pump.

Put everything back together and pump the primer (located on the engine block near the injection pump) pump the primer until you hear a hissing sound.

Then you should be good to go


Good luck!

[RichardLSU]

Thank you all so much!

I'll head down to the parts store tomorrow and pick up some new filters. The process sounds pretty strait-forward. I'll go have a look under my hood and check it out. Hopefully that will fix my problems.

[RichardLSU]

Upon further inspection I found a vacuum line for the transmission that had completely come apart and disconnected itself from the module on the front of the firewall. I went to the dealer and ordered a bunch of connectors and misc vacuum lines, along with both fuel filters and new o-ring gaskets.

I'll keep you all posted if it makes a difference.