123 Diesel
 

I just bought a 1977 300D that has been sitting for a year. I changed the glow plugs because they were bad; drained the old fuel and filled it with fresh diesel, changed all the filters and fuel lines; tested the fuel pump and all electrical circuits. The engine turns, the glow plugs light up but it does not fire and start. At first I did not have enough oil compression so after getting different pieces of advice, I used about 6 oz of transmission fluid poured down the injectors to build up the engine compression. The engine started knocking, but still no fire. Any other ideas?

Thank you in advance.

Try adjusting the valves, always a great place to start on the 61* series diesel angines.

:cool: :cool:

OK, how do I do that? I have not taken an engine apart before.

I don't understand how you can pour transmission fluid down the injectors.
For a diesel to run (cold) you need compression, air and fuel at the right time with hot glow plugs. Have you tried cracking open the line to an injector to make sure you are getting fuel? I'd check that before chasing down a compression problem.

I am getting fuel through the injectors - I took them apart and fuel spilled everywhere - I think I ran afoul of several EPA standards. I poured transmission fluid down the opening in the air filter housing and that bought up the compression. Up to that point there was no nise coming from the engine. After the transmission fluid was used the engine was turning and knocking, but not igniting.

I am at a loss. I think I might put in on a flat bed and take it to the dealer.

did you use the hand pump to get all the air out, this pressurizes the fuel system

yes I did

If you know the car ran when it was parked then I would check the timing as if it has a lot of miles and the chain was not changed and the chain tensioner is stuck you timing might be off enough to cause problems, mine had 180000 and the timing was almost 10 degrees out

Tools needed: 3/8-13mm socket, 3/8-6" extension, 3/8-ratchet, feeler gauges (appropriate thicknesses for your engine specs found on the label on the radiator support) 2-14mm (specially bent wrenches for adjusting valves on an MB diesel) and the valve holding wrench. You may want to check with your friendly neighborhood MB shop and see if someone will "Rent" the special wrenches to you, or if you have an extra 80+ dollars you can add them to your collection.

1) Remove valve cover
2) Adjust valves starting with cylinder 1 and work back
3) Cam lobes should be 180 degrees opposite of rocker

:cool:

The '77 had loop type injectors, but may have been converted to pin type.

If they are loop type, replacing them may not solve your glow problem. Crud builds up around them shorting them to ground, thus not transferring current down the line to all glow plugs.

Also, you MUST put all the insulators and links on properly or you will have a short.

Using a DC voltmeter, ground one lead, turn on the ignition to glow and check voltage at each glow plug. Start by measuring at the rear one. If there is no voltage there check the bar fuse in the fuse holder at the firewall. To find it just follow the wire from the rear glow plug. If you have about twelve volts there go from plug to plug and you should drop about three volts at each plug as you move forward. If you have say only about 1 volt at the middle plug, you need to remove all the plugs and clean the crud out with a wood stick or the fancy reamer that is available. If the crud is shorting the plug to ground it is your problem.

Summary, check fuse not by sight but with meter. The fuse can look good and be bad. Secondly make sure the voltage drops gradually plug to plug.

Good luck,

Expected MPG
 

OK, the car has been running for a year now. I am having problems with the AC - leaking and even though the fan is running overtime, it is barely cooling. I am suspecting a leak at the expansion valve and maybe old compressor. I test drove a 1983 and with the AC at maximum I froze in about 5 minutes. Anyway what is the expected MPG on a 1977 non turbo 300D with automatic tranny? If I get 21 mpg I am having a good day.

yup, 21 and less in city to 25 highway.

so what was wrong with the engine start up last year?? you never let us know.

Thanks for the post. Now I feel better.

There were couple things wrong with the engine. Once I poured some transmission fluid down the injectors and rechecked the glow plug connections it started right up. It has been running ever since. On occasions it does not start the first time but it starts on the second crank.

The problem I am having with it right now is with the climate control. I replaced the auxiliary water pump, the servo, the AC amplifier and the climate control cabin sensor. The heat worked great for a while but the AC never quite cooled. I had the AC checked by 3 different mechanics and got three different diagnostics. First told me that the dryer needed to be replaced even though it was brand new. It was leaking Freon at the dryer because of a loose connection. Once the connection was tightened the leak stopped. The second told me that the compressor needed to be replaced because it was soaked in fluorescein – the yellow dye used to test for leaks – on the bottom. The third told me that the compressor was fine, but the evaporator was leaking. I did not see any dye in the condensation released under the vehicle, however there is a lot of dye around a yellow metal box under the dash – I am assuming that is the expansion valve? Actually it leaked so much that it melted the insulation around the pipes under the dash.
So my question is who is right? Also how cold is supposed to get in a 77? My AC never cooled even when it was fully charged. Will I be better of replacing the whole system? I priced the parts at around $450 plus labor.