timing a '75 240D - PeachParts Mercedes-Benz Forum

harrygrey382 · #1 11-07-2006, 12:20 PM

Hi, still new to this forum, so please bare with me for a second.
I've just bout a W115 240D off ebay. I knew it had timing problem. It's at home right now, and I'm back this weekend to work on it.
It starts (reluctantly) and runs smoothely. But it's totally gutless, barely enough power to move. Not much smoke, no knocking.

Aparantly after someone replaced the head it took them so long they forgot where the timing marks were. They replaced the head because it blew a head gasket and found the head was cracked. They used a "good second hand head" and the bottom end was in "good nick".

I've just bought the Chilton's 1974-1984 sedans/wagons manual. However, the timing section is useless. It does tell you how to do it or what marks to look for. Either in the camshaft section or the IP section. It assumes you are taking apart a correct and complete motor.

So I have a couple of questions. Do I start with timing the IP? If so, what marks am I looking for/what is the best method? How do I find TDC assuming the chain is incorrect so I can't look at the valves? Will I need to remove an injector and shine a torch in? Or do I start with the valves? Again what's the procedure?

Sorry for the huge post. I am disappointed in Chilton's though. I'd get a Haynes but it doesn't cover 115's. But is the 240D similar enough throughout to use the same manual?
Thanks guys
Harry

kalpol · #2 11-07-2006, 03:19 PM

I had a 85 300D so some of this may not apply...in fact it all may be wrong for a 240D but maybe it will give you a place to start....

There should be a TDC peg on the crank pulley with degree marks scribed. The camshaft should be marked with timing marks (a notched washer behind the pulley and a line on I think the cam tower), easily seen if you remove the valve cover. The IP is timed in a couple of ways, the easiest way is to get the locking tool to lock the pump at its TDC point, so you can remove the pump, lock it, time the engine, and then reinstall the pump.

The fact that it runs without blowing up makes me think the valve timing is more or less correct, so your injection pump timing is probably way off, or it's possible the compression is so bad that it has no power (but I was always under the impression that if the compression is good enough to get a diesel started, it will run fine).

I do miss my 300D

harrygrey382 · #3 11-08-2006, 01:27 PM

yeah I kind of agree, it running must mean valves can't be too bad. Haven't comp. tested but the starter motor sounds healthy laboured when it's cranking. So where do I go about getting one of these IP locking tools (I'm in UK btw)? Would a local garage have one?

dkveuro · #4 11-08-2006, 01:54 PM

Revised......Remove the fuel lines to the injectors.
Remove the #1 i/p element and remove check valve and spring.
Refit the now empty element holder.
Roll engine over to 24 btdc on comprssion stroke for #1.

If equipped with manual fuel pump...unscrew top and operate plunger.
No fuel should spill/weep out of element.

Roll engine to 22 btdc...pump fuel and a little fuel should now begine to leak out of element.

Roll engine past 24 btdc again and pump fuel...no fuel should leak out of element.

If you can...pump fuel while rolling engine towards 24 btdc from way before ...say 45 degrees btdc....fuel should quit spilling from element as you reach 24 btdc.

The injection pump metering plunger closes off at 24 btdc to begine fuel ( BF.) pressure to injector. This presuposes the pump is timed okay.

If fuel weeps out after 24 degrees you need to advance the pump timing.

If it stops weeping out before 24 degrees you need to retard the pump.

All rolling over of engine must be in direction of normal rotation otherwise the chain slack will give you incorrect spill timing.

.

harrygrey382 · #5 11-08-2006, 06:52 PM

great, sounding good so far. Although how do I measure 24 btdc? Is the best method to find tdc to look at a timing mark on the crank and the cam shaft lobes for #1 piston?

dkveuro · #6 11-08-2006, 10:13 PM

Because it calls for timing of 24 btdc....the crank pulley will be marked for it...
some of the European diesel engines had other marks like BF 'Begin Fuel' or 0/0 for tdc..SD, 'Start of Delivery'......etc.

The cam front tower has a pointer to line up tdc...it usually is a notch in the cam thrust washer and a pointer on the tower.

.

harrygrey382 · #7 11-09-2006, 12:56 PM

what about disconnecting any throttle linkage? And what if mine has an electric pump? Sorry for asking these basic questions, I just won't have a huge lot of time and want to try and get it done this weekend without having to ask these sort of questions in a rush.

nhdoc · #8 11-09-2006, 02:34 PM

Quote:

Originally Posted by harrygrey382

...It starts (reluctantly) and runs smoothely. But it's totally gutless, barely enough power to move...

LOL, sounds normal for that car!

Seriously, since you don't know where the problem lies don't dismiss what could be mis-adjusted throttle linkage or even a slipping transmission or frozen brakes. I assume you have tried to turn all the wheels by hand and none are stuck?

The car you have is normally pretty guttless...0-60 in 20-25 seconds but it should move...however something as simple as frozen parking brakes can drain those 60 HP right down and cause the car to be a real slug!

vox_incognita · #9 11-09-2006, 03:12 PM

Hi,
you may also want to have a look at these pdf`s:
http://mb.braingears.com/114_115_Disk1/program/engine_74_4d.htm
and buy a set of Hazet valve adjusting wrenches,you`ll need them one day...

dkveuro · #10 11-09-2006, 05:48 PM

Quote:

Originally Posted by harrygrey382

what about disconnecting any throttle linkage? And what if mine has an electric pump? Sorry for asking these basic questions, I just won't have a huge lot of time and want to try and get it done this weekend without having to ask these sort of questions in a rush.

I/P is has it's own pump...there's no electric pump.
If your taking off the cam cover you will need to remove the linkage to the pump.

Remove the injectors too...this will allow you to turn the engine over by hand so much easier...you'll need a 27mm deep throat socket.

.

Mike D · #11 11-09-2006, 06:59 PM

1 and 1/16" socket will do if you don't have a 27mm. The same size is needed to pull the injectors. You might as well go out and buy some new injector return hose. A meter will do. I guarantee you the old stuff will split or leak when you try to put it back on.

If you don't want to pull the injectors then pull the glow plugs. The contacts probably need to be cleaned anyway.

Unless you want to do the timing check just to get familiar with the engine I'd suggest you take the car to any reputable injector pump shop or indie Benz place and pay the $50 they'll want to check it for you. After you've done a few, they're easy. The first one you do, you are never sure if you got it right.

It ain't exactly a glorious, fun-filled task and that back nut on the pump is a real booger to get to. With the proper wrench (about $25) it's easy but without it trying to finagle the combination of extensions and swivels is a real pain.

The actual procedure calls for a "drip" tube. You remove the valve from #1 injector line, install the drip tube, apply fuel pressure to the IP, rotate the engine until the flows stops (with "A", ONE, drip within 10 seconds). Where the pointer is located is the IP timing. Obviously this is on the #1 compression stroke.

If the pump is indeed out of time, you bring the engine to 24 degrees BTDC on the #1 compression stroke and rotate the pump until you achieve the "drip".

Gravity pressure on the fuel is sufficient. I use an old transmission fluid quart bottle with a hose stuck in a cork in the opening. I cut open the bottom and fill it with whatever, tranny fluid, diesel fuel, WD-40 etc. I can tape it or clamp it to the hood structure. It's out of my way and I can pinch the hose to shut off the flow.

Have fun.

harrygrey382 · #12 11-10-2006, 06:50 AM

great, thanks miked. Should I remove all the IP-injector lines? I think I'll just remove the glow plugs for compression loss. Is there a fuel tank shutoff? If I disconnect the pipe from the tank fuels going to flow out right? I assume if it's incorrect how to rotat the pump is obvious?

nhdoc, I towed it 80 miles, felt very free. No breaks jammed on. It won't go into second gear so this is not right. IMO the amount of work required for timing the IP is less than the hastle of finding an IP shop and towing the car there. But this could be a last resort.

One more thing, I also have a 240D out of a 1979 TD. It is meant to be good running condition with about 200000 miles on it. Can I get timing marks off this? If the worst came to the worst, would it drop straight in?

nhdoc · #13 11-13-2006, 10:07 PM

Quote:

Originally Posted by harrygrey382

nhdoc, I towed it 80 miles, felt very free. No breaks jammed on. It won't go into second gear so this is not right. IMO the amount of work required for timing the IP is less than the hastle of finding an
IP shop and towing the car there. But this could be a last resort.

You towed it 80 miles? Is it an auto tranny?

Others may know better than I but I think this is a big no-no with these cars. You can fry the transmission towing them in neutral for long distances...maybe that's why it won't upshift now.

dkveuro · #14 11-14-2006, 10:12 AM

Quote:

Originally Posted by nhdoc

You towed it 80 miles? Is it an auto tranny?

Others may know better than I but I think this is a big no-no with these cars. You can fry the transmission towing them in neutral for long distances...maybe that's why it won't upshift now.

WRONG.

Early automatics, up to around 1983/4, have TWO pumps...one driven by the engine the other driven by the output shaft.....

.

harrygrey382 · #15 11-14-2006, 03:36 PM

It is a manual. Unless my entire grounding in everything mechanical is at fault, this is fine. The gearbox steel feels nice anyway.

To update incase anyones interested - I found the IP to be 9 degrees late. It's now correct (24 btdc) and runs heaps better. Now for a full filter and fuel replace - the stuff it's running on is nasty. Feel guilty starting it.

Breaks are jamming though, brother just brought over a nice master cylander from australia so am hoping that'll help. Otherwise it's caliper inspection...