Mercedes-Benz Forum banner

New E300 owner with questions.

1235 Views 4 Replies 3 Participants Last post by  Moth
I picked up a 1995 model E300 for what I think was a good deal the other day. I'm going to try and fix it up best I can. I have never owned a Mercedes before. I was wondering what I should address on this car if anything? Also had a few issues I could use some advice on: (I'm going to order a Bentley manual, I just need to resolve these issues asap).

Does the car have an electric fuel pump to supplement the IP or does the IP act as the fuel pump?

The temperature gauge will start out normal but then jump all the way to 120C as if it is getting a poor signal. Where is the temp sensor located so that I can make sure it has a clean connection? Or will this require that I replace the gauge?

It leaks a lot of diesel which makes it hard to start if it has been sitting. From what it looks like I will have to remove the intake manifold to get to the fuel tubes. Are there O-rings or something in there? VW fuel pipes don't have O-rings but I'm assuming this car does or it wouldn't leak so much. Any idea where I can find these parts?

The factory radio requires an anti-theft key to be entered and I do not have the owner's manual. Can the dealer supply this key if I give them the VIN?

The tachometer doesn't work. How do I verify it is hooked up correctly?

The vinyl in the interior is coming apart in several areas. Is there any type of glue that is recommended to put it back together?

Also, If anyone has a website that sells little odds and ends parts for a good price it would be appreciated. Thanks all.
1 - 2 of 5 Posts
No electric fuel pump, just a mechanical lift pump by the IP. If it's old or has a lot of miles, replace with a new BOSCH pump.

Temp gauge sender unit is located on the cylinder head, which will require intake manifold removal to get to. HOWEVER, your symptoms appear to be likely caused by the dreaded eco junk wiring MBs from this era were plagued with. Look for the 2 wire connector by the upper radiator outlet on the engine side. If the insulation is cracked or missing you'll need a whole new engine wiring harness. Without a solid harness, these cars are almost impossible to troubleshoot. At least you have a diesel, which simplifies things a bit but there is no avoiding the eco junk if it has not been adressed yet.

See this link. Same car different engine, but similar symptoms.
PeachPartsWiki: W124 Engine Wiring Harness Replacement

Fuel leaks are not unknown on these cars. Simply replace all the fuel lines with new MB parts, and update the IP fuel lines around the IP as needed with the banjo bolt type connection. Not very expensive and will last a very long time.

The dealer can get you the radio code key IF your car still has the factory installed unit with the appropriate s/n#. There is no one master code that unlocks all radios.

For the tachometer, start by replacing the OVP relay with a new genuine MB or KAE(hler) relay. Also replace ALL the fuses in the fusebox with the updated copper core fuses. Again, this is needed to establish a solid electrical baseline.

The vinyl does delaminate, especially around the door pockets. Can be reglued using 3M automotive adhesive and some plastic clamps bought from Home Depot or Lowe's.
See less See more
Re-soldering the OVP is a band-aid approach at best. The internals wear out. Just get a new relay. The ABS & SRS light issue is probably indicative of a bad OVP relay..

Change the trans fluid & filter every 25K using conventional non-synthetic dexron-III fluid. Chevron and Valvoline Maxlife are very good. Be sure to drain the torque converter too.

Do engine oil & filter at least every 5K using diesel rated 15W-40 such as Chevron Delo400.

There is no warning buzzer or light if you overheat. If you do overheat a diesel, start crying, so make sure all your gauges work.

The oil pressure gauge, with the engine at full operating temp and at idle, should indicate about 1.5-2 bar on the dial. The critical measure is that full 3+ bar must be established before 1500rpm. Perhaps your oil pressure sending unit (or the wiring) are bad.

Use part sites like,, among others.
1 - 2 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.