Glow Plug Upgrades for W124 300D - PeachParts Mercedes-Benz Forum

i-osprey · #1 10-17-2009, 11:18 PM

Are there any upgrades available and recommended for the glow plug system on a 602.962 engine?

I am talking glow plugs and/or relay upgrades.

Also, do the 190D 2.5(602.961) and the 300D 2.5(602.962) use the same OEM glow plugs?

I have tried to find this out but nothing definitive has come about.

babymog · #2 10-18-2009, 12:20 AM

The glowplugs should both be available in the Buy Parts button/catalogue above for comparison.

Both the '87 190D Turbo and the 300D 2.5 Turbo had the "aftergow" relay and plugs, not sure if there was any improvement available other than fresh Beru plugs.

i-osprey · #3 10-18-2009, 01:52 AM

Quote:

Originally Posted by babymog

The glowplugs should both be available in the Buy Parts button/catalogue above for comparison.

Both the '87 190D Turbo and the 300D 2.5 Turbo had the "aftergow" relay and plugs, not sure if there was any improvement available other than fresh Beru plugs.

Has anybody used the new Bosch "Duraterm" plugs with the shiny chrome finish?

Beru is what everybody recommends but I am having a hard time finding out anything about the new Duraterms.

Apparently there have been some knock-offs pretending to be Bosch that have made their way into the market.

Either way I think I will go with the Berus.

I think the ones I have now don't afterglow enough.

At startup the engine starts and runs fine but after about 5-10 seconds it starts running much rougher and smoking more.

I plan on replacing all glow plugs and injectors in a few weeks so I am open to any suggestions on that front(or any other front for that matter).

While I have the intake manifold off I plan on replacing a part that is leaking oil that is on top of the injection pump but I don't know what it is.

I has a green or black plastic top with some kind of a "teeth and groove" plastic fastener holding it on the pump.

It's on the engine side on the top of the injection pump.

I am leaking oil from there and have been for some time.

I may also replace the gaskets on side and bottom of the IP since they are leaking oil too and have been for a while now.

I figure that while I have the IM off I should get all of this done at once.

NJ300sdl · #4 10-18-2009, 07:14 AM

I would not expect the 1987 to have afterglow, believe 1990 was first year. It could be converted.

oldsinner111 · #5 10-18-2009, 09:32 AM

I love my Duratherms.After 3 sets of different brands and reaming,the Duratherms are good.

Jeremy5848 · #6 10-18-2009, 11:30 AM

Quote:

Originally Posted by i-osprey

. . . At startup the engine starts and runs fine but after about 5-10 seconds it starts running much rougher and smoking more . . .

How long are you glowing? Until the light goes out is not enough for an OM603 engine unless it is already warm from running. A good 10-15 seconds is better and if it is cold outside the full 30 seconds (or whatever) is recommended until the relay clicks off.

Home-made afterglow can be added to a non-afterglow preglow relay for the cost of one simple relay. See this thread for the details of how to do it. Although the initial installation of the extra relay was next to the preglow relay, I later moved it to the fuse/relay box where it is invisible.

I also added an "AFTER/GLOW" light to the instrument cluster so I can see when the preglow relay times out. When warming up the car, I wait until this light goes out (30 seconds) and then drive the car. The AFTER/GLOW light also acts as a warning -- if your preglow relay sticks in the ON position (very bad -- burns out glow plugs and runs down the battery) the AFTER/GLOW light will not go out.

You can also change to an after-glow relay ($$$), especially if you can get one cheap from a junkyard. Be sure that you have the right part number when you go junking and have the correct engine block temperature sensor for the new relay (others will know the details).

Jeremy

i-osprey · #7 10-19-2009, 11:56 PM

This is on a 1993 300D.

babymog · #8 10-18-2009, 10:57 AM

Afterglow was standard and original in 1987 on the 190D 2.5 Turbo.

Oldwolf · #9 10-18-2009, 11:10 AM

I just replaced GP #1 with a Bosch Duraterm (made in France). The old one that failed was a Bosch also. Not Duraterm I don't think.The old one said "Made in France" also. The old one had a Mercedes symbol stamped on it too. I wonder if could have been the original factory installed unit? Can't be sure of that though I guess.

Oldwolf · #10 10-18-2009, 11:11 AM

Depending on temperature the 602 can afterglow for up to 60 seconds. Have you seen the timing chart I am speaking about?

bobodaclown · #11 10-18-2009, 11:22 AM

I only replaced 1 bad one I had with a Bosch from Autozone. No problems yet. Haven't seen any upgrades for the OM 602.962 as far as plugs. The factory system is pretty good.
Looks like Afterglow was incorp in 1989.

There is a temp sensor that will determine afterglow time.

It basically works like this.
Glow system turned on 30 amps to each glow plug, Heats glow plug very rapidly Amps drop to approx 8-15 amps. After 9 secs glow plug reaches 900 deg C temp, 1180 deg C max after 30 sec.

When glow system is switched on. Preglow indicator lamp in instrument cluster lights up. Glow durations is determined by temp sensor. Preglow indicator goes out indicating that the engine is ready for starting.
AFTERGLOW TIME:
When temperatures are below approx 0 Deg C Max after glow time is 60 seconds.
These are approx time periods.
30 Deg C No Afterglow
25 Deg C 10 Sec Afterglow
20 Deg C 20 Sec Afterglow
15 Deg C 30 Sec Afterglow
10 Deg C 40 Sec Afterglow
5 Deg C 50 Sec Afterglow

Overall seems like a reliable well designed system on the W124 OM 602.962.

FAULTS:
Before 1988: Preglow indicator fails to light up when key moved to #2 position.
As of 1989: Pre glow indicator lamp fails to light up when key moved to #2 position. in addition: the preglow indicator lights up for approx 1 minute when engine is running.

Possible faults:
Interrupt in cable connection to terminal 30
Preglow time relay faulty
interrupt in one or several cables to the glow plugs or glow plugs
short circuit in system.

Pre 1989 systems have 80 ampre fuse built in. could be bad.

Check out this link: http://www.peachparts.com/shopforum/archive/index.php/t-246719.html

Jeremy5848 · #12 10-20-2009, 01:16 AM

Ah, I missed that, sorry. You should already have an after-glow relay in your '93. I suspect (but do not know for sure) that all 602 engines will have the same glow plug -- and possibly the 603 as well. You can confirm that in EPC, the Mercedes Electronics Parts Catalog, available free to USA residents here.

If new glow plugs (they do wear out) do not fix your problem, you might try measuring the current to the glowplugs, see if they are getting their rated current. If not, the relay contacts in the preglow relay may have gotten burned.

Another possibility is that the after-glow circuitry or the temp sensor has failed so that you are no longer getting afterglow. Quick way to check this is to wire a small 12 volt bulb to any one of the glow plugs and run the wires for the bulb into the passenger compartment so you can keep an eye on it. If the bulb is lit then the glow plug is getting voltage (whether it is drawing sufficient current is another question).

If the engine is cold, the bulb should stay on for at least 30 seconds, depending on the afterglow timing for the '93 model-year. If it does not stay on for at least 30 seconds then you may have an afterglow failure. If the bulb stays on but the engine still stumbles then you may have bad glow plugs or bad relay contacts.

i-osprey · #13 10-22-2009, 03:33 PM

I have ordered new Beru glow plugs that should arrive by this weekend.

I have been having harder and harder starts as it cools and the other day something happened that hasn't happened before.

I had just turned off the car to go into a convenience store and when I got back I let it glow as usual until the light went out.

I started it and it ran very poorly especially considering that I had just turned it off.

Then about ten seconds after I drove away the glow plug light came back on.

It has done this now three different times.

What exactly does this indicate?

Could it be just bad glow plug(s) or does this situation indicate something else?

bobodaclown · #14 10-22-2009, 06:36 PM

bad glow plug or plugs.
check this out. http://www.peachparts.com/shopforum/showthread.php?t=247850

babymog · #15 10-22-2009, 10:45 PM

It probably indicates a bad #1 or any two of #2-#5 are bad.