OM606 Glow Plugs Again?? - PeachParts Mercedes-Benz Forum

treetops · #1 10-10-2016, 10:48 PM

Hey all,

So I replaced all 6 GPs on my E300 in March of last year and now my GP and CEL are lit up, so one or more is out. This does not sound or feel right to me.

Now, I have been using the car for work which is about 6-8 stop/starts, sometimes more, per day with the engine stopped for anywhere from 20 mins to 2 hours. My crude math calculates thats about 2200, or more, starts/glow cycles since 3/15 assuming the GPs cycle on hot starts as well.

I used Bosch DuraTerm GPs and according to thier tech sheet says overheating due to controller failure is the leading cause. Continual cycling, which given my use of the car maybe the case, is listed too. BTW, these GPs are designed for a 3 min after glow as well.

Im not sure if the OBD/CAN would throw a CEL for a controller failure but I am sure my driving use of the car is a factor here.

Any thoughts or do these GPs just die after a certain # of cycles. Not looking forward to doing this again.

mach4 · #2 10-11-2016, 06:44 AM

I don't know if it's wise or feasible on a 606 engine, but on my 617 I've gone with a totally manual system - just a momentary switch on the dash and a Ford solenoid to activate the plugs. Under normal SoCal weather conditions, about 3 seconds of glow is all I need. If it's colder, add a few more seconds. And if I'm traveling and it's freezing, maybe 20 seconds and a little after glow until it smoothies out. If the engine has been run in the last hour or two, I don't use any glow.

Assuming glow plug life is roughly proportional to cycle time, I may never change a plug again.

Might be something worth researching....on the otherhand, stuck glow plugs on a 606 is not a fun proposition, so maybe it makes good sense to replace them frequently to prevent this.

mikemass1221 · #3 10-11-2016, 07:43 AM

They should last for well over one year. 2200 cycles is not a lot. It is possible one of your wires is not making a good connection. But checking this still requires removal of the Intake Manifold.

How does the car "feel" after a cold start? Especially after this morning's cool weather in our area. If one GP is not heating up, it will be very noticeable after you start it. If no symptoms as such then GP's may indeed all be functioning. Before I ruined my 606 due to a broken GP I used to get an occasional CEL only for it to go away after the next few starts. (This was when all 6 GP's were working properly).

And Yes indeed. What Mach4 said. Broken GP's no fun. I am the poster boy on this forum for completely botching a removal job.

shertex · #4 10-11-2016, 08:10 AM

While this doesn't answer your questions, I would ditch Bosch and go with Beru. I was pretty disappointed with the short life span of the Bosch plugs on my 91....have heard nothing but good things about Beru.

dtf · #5 10-11-2016, 11:19 AM

it might be that the glow plug harness insulation has cracked. I had all my GPs working this spring but now the GP light only lights up after I start it telling me that the system has a problem.

The mechanic told me my harness was toast. Do the Resistance test on the plugs first before you pull them again?

Diesel911 · #6 10-11-2016, 11:33 AM

This is aproximately what is in the Mercedes Manual: The life of a Glow Plug depends on a considerable extent on the Injection and combustion sequence. Injection Pressures (pop pressure) that is too low, binding nozzle needles, coked and dripping Nozzles as well as too early begin of injection.

I also believe that carbon build between the Cylinder head and the heater element on the Glow Plub causes the Glow Plug to pull higher amperages for a longer time. I based that on a test I did that shows as the Glow Plug heats the amperage drops. Carbon build up would allow the heat from the element ot be conducted into the cylinder head and coolant keeping the heater element cooler longer and pulling more amps for a longer period.
Reaming the Carbon out of the Glow Plug holes takes care of that issue.

tjts1 · #7 10-11-2016, 12:11 PM

Remove the intake manifold, start the engine and bring it to operating temperature, stop the engine and immediately hit each one with the impact gun. They will all come out easily.

ESchwab · #8 10-11-2016, 02:08 PM

I have a '98 e300, which I have owned for 9 1/2 years and has 138,000 miles on it; I have complete service records. The car has had glow plug problems four times. The first was about 80,000, when two glow plugs were replaced. The second was about 93,000, which was about 11 years ago, all glow plugs were replaced. The third was at about 120,000, about 4 years ago (all replaced). I now have one bad one and will replace them later this month.

I drive pretty often (almost every day) but never very far. I drive between 4 and 5 thousand miles a year. I think the glow plugs would last longer if I took longer trips and drove more as carbon build-up is a likely problem. The car had Mercedes plugs until I used Bosch the last time they were changed. I used a reamer when I did the replacement four years ago.

It may be a good idea to change the glow plugs every time the intake manifold is removed. I had it off in May; should have changed them then.

treetops · #9 10-11-2016, 02:24 PM

Thanks for the response is folks. I was going over my mileage records and see that I put on approximately 35000 miles since March of last year. These are all fairly short trips to and from different stops no more than 15 miles between each one.

I would say that my injectors probably need a thorough going-over given that there's no record of them being changed from the PO and my driving habits.

Tjts1, did you leave the intake on loose or just take it off and start the engine to bring it up to temperature? There's some concern of a errent dustball flying into the intake that I don't want to have happen.

Jeremy5848 · #10 10-11-2016, 09:28 PM

(1) An intact EGR system will exacerbate any problems due to or blamed on carbon build-up. Carbon definitely makes the glow plugs harder to remove.
(2) A piece of window screen over the intakes will keep much if not all stuff from being sucked into the cylinders.
(3) In my experience, Bosch or Beru glow plugs last 40-50,000 miles. YMMV.
(4) Always have the engine warm before trying to remove glow plugs; use penetrating oil for a few days beforehand on the glow plug(s).

Jeremy

EDBSO · #11 10-11-2016, 10:40 PM

Quote:

Originally Posted by shertex

While this doesn't answer your questions, I would ditch Bosch and go with Beru. I was pretty disappointed with the short life span of the Bosch plugs on my 91....have heard nothing but good things about Beru.

X2 for me, Beur is the answer.

I have the electronic EGR delete and still got extremely short life out of Bosch.

treetops · #12 10-17-2016, 06:17 PM

Well luckily only the #1 GP was bad, so I went ahead and changed it out. I ended up undoing the intake lower bolt from underneath, the pesky EGR collar and then took the IM off to see whats what. When ready, I put the IM back in place with about 6 of the bolts in tightish and ran the engine back up to temp.

The GP did come out without too much trouble although my HF 18 V impact gun didnt do the trick, so loosened the GP by hand....sloooowly. Yup it was carbon'd up good and put up a fight even when fully unscrewed.

I was able to ream out the GP hole with my home made version, got the new one in and back in business. The most fiddy part was that damned EGR collar. Not sure if it makes a difference, but screwing the lower IM bolt back in before tackling the collar made it easier.

Gotta do the EGR delete. Curious about where the EGR vapors go if not into the manifold...out the exhaust?

Diesel911 · #13 10-18-2016, 03:34 PM

EGR vapors go into the intake manifold.

barry12345 · #14 10-19-2016, 08:59 AM

Quote:

Originally Posted by treetops

Well luckily only the #1 GP was bad, so I went ahead and changed it out. I ended up undoing the intake lower bolt from underneath, the pesky EGR collar and then took the IM off to see whats what. When ready, I put the IM back in place with about 6 of the bolts in tightish and ran the engine back up to temp.

The GP did come out without too much trouble although my HF 18 V impact gun didnt do the trick, so loosened the GP by hand....sloooowly. Yup it was carbon'd up good and put up a fight even when fully unscrewed.

I was able to ream out the GP hole with my home made version, got the new one in and back in business. The most fiddy part was that damned EGR collar. Not sure if it makes a difference, but screwing the lower IM bolt back in before tackling the collar made it easier.

Gotta do the EGR delete. Curious about where the EGR vapors go if not into the manifold...out the exhaust?

Yes out the exhaust as the egr vapors sent into the intake manifold are some of the exhaust components.

oldsinner111 · #15 10-19-2016, 09:41 AM

like spark plugs,I remove mine cold,but when I used wvo as fuel,i was changing GPs every 9 months,even though I reamed my holes out.Its been 3 years now on diesel,same GPs.