'99 E300 Cold Start Difficulty - Page 2 - PeachParts Mercedes-Benz Forum

sokoloff · #16 12-11-2006, 08:16 AM

You can check the plugs with everything in place by taking an ohm meter to the glow plug cable at the relay box. Good plugs will read about 0.6 ohms cold.

Len

mdisav · #17 12-11-2006, 08:19 AM

Just test them at the harness at the glow plug relay and get the ohm reading. No need to remove the intake to test. When was the last time they were changed?

mdisav · #18 12-11-2006, 08:20 AM

Like he said. Diddo!

BioPOWER · #19 12-11-2006, 11:18 PM

Okay, I'll test them at the harness; I don't think it's a glow plug related problem anymore, the GP light still goes on indicating no faults in the system (although it's probably time to do the work anyway and change them all)

As far as I know they are all original unless the dealer changed one, I've never had a problem with them.

nhdoc · #20 12-12-2006, 06:18 AM

Quote:

Originally Posted by Carleton Hughes

That and loose O rings on your fuel lines,particularly the pre-filter.

Know all about it,went thru it all.

Check what Carleton said...the pre-filter o-ring can cause this! Is it worse when the tank is less than 1/2 full? Do you park on an incline?

BioPOWER · #21 12-18-2006, 02:47 PM

Yes, the starts are definately harder when the tank is less than half empty...
I'm guessing this is caused by the level in the tank being less than that around the filters and allowing fuel to drain back overnight? I don't park on an incline but I suppose it would make the symptoms better/worse depending on the angle.

Today I'm going to run some diesel purge through to clear up some heavy knocking i hear; I'll check the lines and filter seals while I'm under the hood.

TMAllison · #22 12-18-2006, 03:14 PM

Try leaving it outside on the driveway for one night. Back it in so it is nose down and see if the hard start and stumbling in the morning goes away. If so, it is air and the stumbling is caused by the IP evacuating the air that seeps in overnight.

If your driveway is perfectly flat stick a 2 x 4 or 4 x 4 under the rear tires.

F18 · #23 12-18-2006, 06:47 PM

Correct me if I'm wrong....but you should be able to check the resistance of each Glow Plug right at the muti-pin socket on the GP relay without removing anything including the Exhaust manifold. One lead of the OHM meter in one of six connections in the plug (which are usually number 1 thru 5 or 6 depending on which engine) and the other lead grounded on the engine block or frame. As Len said....the good glow plugs should have a resistance of 0.6ohms. I used this technique on the 84 and 87 SD I use to have all the time.....but have not had a GP problem on the 98 E300TD yet!! So don't remove the manifold or anything before you check them out.

If GPs check out with the right resistance then double check for air leaks at the lines, pre-filter and O ring for the shut-off valve on the side of the IP. The O rings for the pre-filter and shut-off valve run about $2.50 each so it would be good preventive maintinance to change them anyway....

aklim · #24 12-18-2006, 11:39 PM

I thought the only true way to test GPs is to do a load test?