87 300e Turbo Hard Starting

[SoCal Diesel]

I am getting an 87 300e Wagon Turbo Diesel tomorrow. My friend is the original owner and has owned a few diesel Mercedes over the years. He said the car was gradually getting harder to start until one day it wouldn't. He thought it might be the glow plugs. He towed it to the shop and since it has been there 5 months since the breakdown, the shop foreman cannot remember what exactly is wrong and the work order cannot be found. He vaguely remembers the problem as possibly injection pump timing because he said it DID run but was very hard to start. That is all I have to go on. I would love a few suggestions of what to check upon initial inspection when I get it to my house tomorrow. The car has 234k and has had timely services during its life. A member on BenzWorld suggested delivery valve seals on the pump, but could timing chain stretch also cause the pump to be WAY out of time it will not start?

[kerry]

Glow plugs.

[Jeremy5848]

It's a 300D Turbo. The 300E is a gasser.

X2 on glow plugs.

[SoCal Diesel]

Is there a shop manual available online for information? Is the procedure the same for checking glow plugs on the 124 chassis and the 123? I had a 240d for some time and am familiar with the procedure on that model.

[engatwork]

Go to startekinfo.com, workshop resources and find the link for the w124 manual.

If you have been under the hood of the diesel 123 then you will feel comfortable under the hood of the diesel 124.

[vstech]

Originally Posted by SoCal Diesel

I am getting an 87 300e Wagon Turbo Diesel tomorrow. My friend is the original owner and has owned a few diesel Mercedes over the years. He said the car was gradually getting harder to start until one day it wouldn't. He thought it might be the glow plugs. He towed it to the shop and since it has been there 5 months since the breakdown, the shop foreman cannot remember what exactly is wrong and the work order cannot be found. He vaguely remembers the problem as possibly injection pump timing because he said it DID run but was very hard to start. That is all I have to go on. I would love a few suggestions of what to check upon initial inspection when I get it to my house tomorrow. The car has 234k and has had timely services during its life. A member on BenzWorld suggested delivery valve seals on the pump, but could timing chain stretch also cause the pump to be WAY out of time it will not start?

if regularly serviced, it's unlikely to be the timing chain stretch. most likely is glow plugs, or glow plug relay/fuse, but I'd imagine any shop would check that first... My 87 TD (technically, classed as an E300 TD) has a problem with air getting in the pump via the fuel temp thermostat leaking... simple fix, but I just park with the nose down, and it starts up every time.
another possibility is the shutoff valve has failed, and it's keeping the car from starting. ya check that by starting the car and watching the stop lever for motion... if it flutters, it's likely the valve.
aside from those simple checks, ya'd have to have the car and tell us some symptoms first...

[SoCal Diesel]

Thanks for the ideas and suggestions. Is the procedure for checking the 124 glow plugs different from the 123?

[Jeremy5848]

Same procedure, just remember to check all six -- don't stop after four or five! Easiest to pull the plug at the preglow relay and check each pin to ground. You should get no more than an Ohm or two, depending on the accuracy of your meter. New glow plugs generally measure about half an Ohm. Measuring at the plug also checks the cable and all of the connectors along the way to the glow plug.

If one or more measure many Ohms (hundreds or even infinite) then you have a possible bad glow plug. The potentially bad ones need to be rechecked at the glow plug connector to eliminate the wiring as the cause.

If all of the glow plugs appear good, you need to check each one for 10 Volts or so during preglow. That makes sure the relay and wiring is good.

Removing the glow plugs and testing them individually with a battery and heavy wire is the last choice as it's a lot more work.

Jeremy