Hello,

I have changed the filters and the strainer; I have rebuilt the turbo; put in a new radiator and water pump; I have put in a new chain and injectors. I have adjusted the injection pump and valves.

The car has 200,000 miles on it. It has some blow-by.

But why does it slow so much on an incline? Why does the temperature rise on hills or when it goes above 80? Why is there so little kick-down? Are some engines simply born weak and others strong?

If I need to rebuild this engine, is a valve job enough or does it need to come out for rings and pistons...

You list all kinds of problems and seem ready to bite into a big job. How about settling down and do a simple compression test and if possible a leak down test. Then we could all come up with some good answers. A valve job is consider a maximum tuneup, not a rebuild.

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Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

^ Yeah and go over the fuel system, see if the ALDA is getting a proper signal too.
Good luck and let us know what happens next.

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83 SD

84 CD

Thanks for the help. I have a compression gauge.

Where would you suggest attaching it? To an injector or glow plug hole and do I need a special mercedes adaptor??

Either place, just be sure to remove all of either and if you use the injectors, have a set of new heat shields.
Most gauges have an assortment of adapters that will fit.

__________________
83 SD

84 CD

Have someone sit in the drivers seat and press the accelerator pedal to the floor (car off). Look at the throttle stop between the injection pump and block and make sure that the linkage is bottoming out on it. A lot of cars i have tinkered with where slow because the linkage was sloppy, and not giving the pump full throttle.

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1979 240D with a 617 turbo diesel.

Nothing you mention necessarily indicates a mechanical problem.

Have you had other benz turbodiesels?

All of these things if not excessive could be within the normal operating of a 300d motor. If excessive though could be indicative of a problem.

A compression test should give some good information.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Hate to ask an obvieous question but did you clean out the boost signal line on the back of the intake manifold?

How steep of a hill? Time the car from 0-60 on flat ground. A real strong example will be in the 12.5-13 second range if everything is working right.

The engine only has 125hp! How fast are you *expecting* it to be?

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

When you are finished with the standard or normal things. Close off the return line from the injection pump and report any change on this site.

No change at all means you have really low fuel supply pressure in the base of the injection pump. . You cannot hurt the car with this test.

If car goes much better the relief valve spring is possibly very weak. At that point you should get a thirty pound liquid filled gauge and check the actual pressure. Your ideal target is 19 pounds but around fifteen is okay with the return line open and not the major issue. With the return line obstructed and a lift pump in good shape the gauge should go to the peg at thirty pounds.

In my opinion there are many of these cars running with very little base fuel pressure in the injection pump.

Thanks guys for all the help. I guess Im asking how worn my engine is: blow-by, temperature rising under load, some smoke at idle, not much torque or top speed. When does the moment come to pull the engine and freshen it up.... ??

Yes, that missing compression test will probably tell you all you need to know.

__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!

Blowby does not mean much unless it is hard to start cold or has low compression numbers. Temp rising under load means a cooling system problem. T-stat, water pump, or radiator (or all of them). A bit of smoke at idle is normal for a 617, they tend to be smoky.

__________________
-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

Ok

I did a compression test and all five came in at 220 to 260 PSI. Is that very low?? I thought stock was up around 425. Could explain the smoking and blow-by ??

Yeah, that's low. But adjust the valves and check again.

Then maybe a leak down test to determine where the problem lies.

__________________
83 SD

84 CD