My car starts a bit rough in the morning when cold (at least two tries before it fires up) and takes time to smooth out... I wanted the check the GPs, so last night I checked the relay, checked the fuse, checked the juice, etc. The one and only GP I pulled was German made, tested ok and it glowed real nice - looked good, so I got some questions now:

Question1: Since the fiirst GP seems new is it worth pulling ALL of them out one by one and testing them individually? The problem is that it took my almost 2 hrs to pull, test and reinstall the fist one - there just isn't any room to work...

Question2: Should I pull the high pressure liness off of each Injector to make more room to work?! I'm really leary of doing that but I see no other way to get my hands/tools in there - please advise as it seems real risky to me to take these off... never done that before.

Question 3: The battery only tested at 9.5V with the engine OFF - didn't test with the engine on, but it seems low - could this be a problem with rough starts as the GPs probably like the juice?!

Finally - is there a way to test the overall health of the alternator - if the battery is low, maybe the ALT isn't doing its job...

Lots of questions - sorry, I'm a newbe...

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

Several things I'd consider:

1. Glow plugs do not have to be removed to test. Disconnect the electrical connector at the relay box and take an ohm meter to each terminal. Good plugs will read about 0.6 ohms cold. If you get a bad one, the connector is marked as to which glow plug it goes to.

2. Battery does seem to be low. If it's more than five years old, I'd replace it.

3. Brushes in the alternator are cheap and easy to replace and also wear out. Wouldn't hurt to check them or just replace them and keep the old one for an emergency spare if needed.

Lots of this info and much more of it is in the archives via the search feature.

Len

Merc,

What kind of juice are U talking about? Tomato juice, apple juice, orange juice, pear juice?????? BTW, how did U check the "juice"? A juicemeter? LOL

Battery voltage is way too low, but battery might discharged. Charge the battery and check the voltage again. Voltage should be about 12v and then voltage should goto 14+ volts when the engine is running 1000 RPM or more. If the voltage reads 14+ volts, the alternator is probably OK.

How long do U leave the GP on before U crank the engine? Wait longer before U engage the starter, even if the dash GP light goes out to see if it starts easier.

P E H

1: As mentioned, don't pull them out to test them, just test the resistance across them with an ohmmeter when they are cold. Short circuit is dead, as is infinite resistance. Around .6 is good, greater than 1 is marginal.

2: You can remove the injector lines if you want, assuming you need to actually replace some of your plugs, many people find it faster to remove those lines, then remove the glow plugs. I've got small hands and a ratcheting box wrench set, so I don't bother. If you remove the lines, mark the metal lines so you remember where they go, and start all the nuts by hand, you do NOT want to crossthread on your injection pump.

3: Your battery is in bad shape. Get it tested, but plan on replacing it. Engine on should be around 13.8-14.5V. If you are getting that, then your alternator is doing its job.

peace,
sam

__________________
"That f***in' biodiesel is makin' me hungry."

1982 300TD Astral Silver w/ 250k (BIO BNZ)
2001 Aprilia SR50 Corsa Red w/ 5.5k (>100 MPG)

2 hours to test and remove one?.. all you need is some PB soak them in PB and use the correct wrench to remove each.. careful not to break them off in the head

If the glow plugs all check out good and the battery is fully charged the duration that the glow plug relay contacts stay closed may be too short. IF the glow plug relay contacts open up too soon the glow plugs will not get hot enough to help start the engine. My glow plug relay went bad so it would only stay closed for a total of 6 seconds while the glow plug lamp would only light for 1 second at all temps. The glow plug relay is supposed to stay closed for around 30 seconds total which includes the time the glow plug lamp is on. The time the glow plug lamp stays lit is dependent on the glow plug relay temp on the OM603, but I'm not sure about the OM617.

-Steve

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1987 300TDT smoke silver w/ burgundy leather interior
2000 VW Passat wagon indigo blue w/ beige leather interior
1985 Mustang SVO
1970 Chevrolet K10 fleetside, shortbed

Yes - tood me a long, long time and it was a real PITA because there just isn't enough room to work in there - I couldn't get my hands in there especially with a wrench and I was to timid to taking off the high pressure lines...

What's PB stand for?!

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

PB blaster, a very good penetrating spray. All I've used since I tried it. The glowplug system only gets 11V, not 12.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

dont be intimidated by the hard lines.

i always take them off to do the glows.

loosten the clamps that keep the lines from rubbing on eacy other but leave them attached. then loosten all the 17mm fittings on each end of each line, then lift them off as a unit. when you put them back on be sure they turn freely with your fingers and get them down to resistance then tighten them down. they take a lot of torque so dont be afraid to tighten them. after being sure the threads are correct.

then you can remove the glows easily. be careful with the wires. they want to spin and if you let them you will damage them. really not hard once you get the swing of it.

i could change all four in prob not much more than a half hour so a beginner should be able in 2 hours i would think.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Thanks for all the info everybody. Any idea on what I should torque the 17mm fittings to when I'm done?!

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

you got some way to get a torque wrench on them?

a special socket?

i just use my box/open craftsman wrench and pull about as hard as i can.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Ah, thanks - good tip - I've disconnected the plug at the relay and measured the resistance on all 5 - yep, one of them was open circuid (#5) - went ahead and measured directly at the engine and the measurement there was about .6 Ohms, so I concluded that it's the wire from the relay to the plug itself that's broken...

What kind of wire should I use to replace? I know there's a lot of 'juice' going to those plugs while cranking... (guessing around 80A) - so I want to use the right guage wire.

Also, measure the battery again with a better voltometer and it seems fine -car off around 13.6V (seemed a bit strange that it would be above 12...) - measured 3 times - got all readings above 12... Did not yet test with engine on...

Thanks,
James

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K

James "Juice",

The GP circuit uses about 75 amps so each GP wire from the GP relay conducts about 15 amps. So a 14 gauge wire from the connector on the GP relay to the GP will be sufficient.

Wires rarely break in the center so first check the connections on each end. Check the resistance from the GP connector in the relay to the connection that screws on the GP. U might be able to use the wire and repair the connector. I would suspect the connector that goes on the GP first.

P E H

Use the pictorial to help you with the glow plugs.

http://dieselgiant.com/glowplugrepair.htm

__________________
1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

I'm almost certain now that the #5 plug is bad - the wire itself tested OK when I measured it with my Ohmmeter after disconnecting it from the plug...

My ohmmeter then started to malfunctioned last night so I couldn't complete the testing, but I'm fairly certain that one of the plugs (the last one) has a short in it...

Question: is it a good idea to just replace ONE of the plugs and keep the rest in place if they test ok (around .6 ohms)?! Or should I replace the whole set?

Also, I probably will go with Bosch plug and rent the GP reamer for the job... How/where can I rent it?!

James

__________________
1987 Mercedes 300SDL; SOLD
1985 Mercedes 300D; SOLD
2006 Honda Pilot - wife's ride; 122K;
1995 Toyota Land Cruiser - 3X locked; 182K