Quick glowplug questions/OM603 (sorry) ...

[BodhiBenz1987]

... sorry for the new thread, since I know there have been numerous on this topic in the past few days ... I simply have some quick questions that I need quick answers for, and figured some of the old threads might not get read:
I've read all the old threads thoroughly and want to go ahead and check my 603's glows ... I'm heading to Advanced Autparts and to the dealership to stake out needed tools/parts and I want to make sure I get or order everything I need. So ...
1) To test the glowplugs, what is the simplist thing I can do to at least get a rough idea if I have an issue? From a previous thread I understand you can do this with a multimeter without even removing the plugs? I'm buying a multimeter anyway, so this would be easy if someone could give me the rundown on that.
2) If I decide to go ahead and replace them, what do I need to prepare for. Removing the intake seems like the road to take, because I don't want to get in a battle with the innards of my car and break something while trying to squeeze around in there. I have no idea how to remove the intake or what tools to use (I might not have the needed tools). What do I need? To remove the intake, I need to remove fuel lines, correct? Do I then have to prime the pump afterwards ... how hard is that and how do I do it?
3) In one of the posts there was a link to a good tutorial for a 603, I think at DieselGiant ... I lost it ... anyone got it on hand?

Again I apologize for the re-post on a well-worn topic. I'd hate to go to the store and return short of something I really need. It's freaking freezing, I'm on a crutch (stress fracture) and I'm trying to be as efficient as possible.

[WANT '71 280SEL]

The best tool you'll need which you may not have would be allen sockets. Look at the bolts holding the intake on and you'll see what I mean. You'll want L wrenches and allen sockets. Some are hard to reach one way or another. If you can, try to find some in 1/4" and make sure you have an assortment of etensions and wobble sockets.

As far as checking if the GPs are good or not. Pull the harness off the relay and put a multimeter on the end of each GP. If you have infinite resistance then it is bad.

The cheapest place for GPs for this car is believe it or not, Autozone. They are Bosch brand and like $11.00 or $15.00/each. It is cheaper than the dealer or an online place and they'll probably have them in stock, mine did.


Let someone else get on here and give you more details on checking the GPs, I don't remember mmuch else about doing it or how best to do it since I'm in college and away from my baby.

Thanks
David

[P.E.Haiges]

Bodhi,

Get an digital electronic multimeter. The easiest way to check the GP is to measure their resistance, it should be from 0.5 to 1.0 ohms.

Pull the GP cable out of the GP relay. Then test each of the GP by plugging one lead of the meter in the female holes of the connector you just removed. The other lead of the meter goes to a good ground on the engine.

I have a 603 engine but have not done any work to it yet, so I can't help with the mechanical end. But check the GP resistance first and you may not have to do anything else.

P E H

[Brian Carlton]

You can always ask us for help. Help is what we do here.

First, I think you should verify that the plugs are bad. You really don't want to do this job in the cold if you don't have to. This is especially true when you are new to wrenching.

So, let's check them first to see what condition they are in.

The meter will have the capability to measure resistance in ohms.

Set the meter to the lowest possible setting that you can. If it has a X1 scale, use it.

Find the glow plug relay on the driver's fenderwell and unplug the connector from it. The connector will have six sockets. The sockets will have small numbers on the plastic housing corresponding to the cylinder numbers.

Put one probe from the meter in the #1 socket and connect the other probe to the negative battery terminal. Read the meter and record the value.

Repeat for the other five plugs.

You are looking for values below 1.2 ohms. So, the scale must be small enough to accurately read this value. A $10.00 meter will likely not be good enough for an accurate determination.

Report back with results before attempting further work on manifold.

[PRCBD]

I have done this job w/o removing any fuel lines - just popped off the connection between lines and injection port for two cylinders to make turning the wrench easier. It would definitely be easier to get at stuff with all the fuel lines gone, I was just leary of putting all that back. You will definitely need a driver with a pivot head and hex "sockets." Good old fashioned allen wrenches (various lengths) worked well too.

sorry can't help with the multimeter diagnosis - If I remember you are looking for small voltage drop in series or ~1 ohm resistance - sounded to me like you needed a darn good meter.

good luck!

edit: oops - brian snuck in there with diagnosis while I wasn't looking - at least we agree that you need a good meter...

[Pete Burton]

check the ACCURACY of your ohmmeter by holding the 2 test leads together, then take your resistance measurements. If for example your meter reads 0.3 ohms with the leads together and your plugs read 0.7, 0.8, 1.0, 1.2, 0.7, 12.5 then your actual values would be 0.4, 0.5, 0.7, 0.9, 0.4, 12.2. Check the REPEATABILITY of your meter by periodically retouching the leads. If you keep getting 0.3, 0.2, 0.4 that should be fine. If it's all over the place, then the meter won't tell you much. You can get a surprisingly decent digital meter these days for $20. It won't measure DC current over 10 amps, but hey, a $80 meter usually won't either.

[dlssmith]

I changed my glow plugs last night. I didn't test them, other than to determine if the 80 amp fuse was ok and there was power to them generally. I knew some were bad, probably 4 of them, and so I just changed them all.

I removed the injector lines, which is very easy, and the intake manifold. I had a new gasket for the intake, crossover etc. Not a hard job, but the 6mm allen head socket with a swivel is essential. I started out to do it without taking the injector lines off, but ended up taking them off to make the intake removal easier. You will also probably have to remove the injector line brackets and clips, which are fragile.

I would point out that two of my injector lines broke within two weeks a while back. I ended up replacing all of them under advice from members of the forum. I suggest being careful with the lines if they've not been replaced since they are subject to cracking after many years of service.

If you plan to remove the intake manifold have a new gasket ready. I'm glad I did since the old one was in such poor condition.

Adjust your ALDA now and lubricate your throttle linkage too, when the intake is off.

[BodhiBenz1987]

Wow, you guys are saints ... saints, I tell ya. I'm going to go fetch a multimeter and will report back with the findings. Should be fun ... I haven't used one of these since high school physics!

[WANT '71 280SEL]

Once again, about the injector lines breaking. It ONLY happens when the car has been used for long periods of time without the proper clips. Just make sure they're all there and holding when you change the oil and you will never replace a line. I've never heard one person say the lines broke for no reason. I'll bet someone has been running it without the clips. I assume you replaced them when you replaced the lines?

Thanks
David

[speedy300Dturbo]

The best tool I've come across for removing the 6mm hex bolts is this:

http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=1315&group_ID=154&store=snapon-store&dir=catalog



It's pricey but well worth it, IMO. Coupled with a 6" extension, all bolts can be removed in less than 5 minutes.

[dlssmith]

I wish I'd had that 6mm ball hex socket last night, it would have made the job way easier and well worth $15. A set of those might be in order for my Christmas present to myself...

By the way, regarding the broken injector lines. Mine were run for probably many years without the clips. That's probably why they broke and from what I've read, the clips are known to break, so maybe a lot of cars are running around out there with a potential problem that only takes a couple of dollars to fix.

[BodhiBenz1987]

OK, the results are in, after much shopping, shoveling and waiting:

I ended up getting readings of .6 ohms for plugs 2-6 and a .5 reading for plug 1. The consistency leaves me a little doubtful of my methodry. I clamped the black probe to the negative terminal on the battery using a plastic clamp (the probes are like pins, not the clamp type I've used in science classes). My multimeter seems to be a decent one ... it's a $25 Craftsman and the guy at Sears said it should be able to accurately read values under 1 ohm. I did the accuracy ad repeatability test ... it reads .2 ohms on accuracy and is very repeatable. The only thing I noticed was that the reading jumps all over jibip if the probes are jostled or moved at all ... is it supposed to do that? Forgive me for being negative, but I have a hard time believing that all six of my 19-year-old glow plugs are still perfect!

[dlssmith]

I doubt they are 19 year old glow plugs, probably changed at some point in the car's history.

I will describe what mine sounded like when starting with some (not sure how many) bad gp's. Crank, crank, sputter, sputter firing on 2 or 3 and then gradually coming around to firing on all cylinders. Pretty rough at first, no matter what temp outside. Quite a bit of unburned fuel smoke.

Now with new gp on all six cylinders. Crank, maybe one rev, perfect combustion on all six, right from the start. Other than the usual clattering noise that any diesel makes, it runs perfectly from the start now and smokes very little - and we're talking 5 below zero the other day.

[Pete Burton]

Originally Posted by BodhiBenz1987

OK, the results are in, after much shopping, shoveling and waiting:

I ended up getting readings of .6 ohms for plugs 2-6 and a .5 reading for plug 1. The consistency leaves me a little doubtful of my methodry. I clamped the black probe to the negative terminal on the battery using a plastic clamp (the probes are like pins, not the clamp type I've used in science classes). My multimeter seems to be a decent one ... it's a $25 Craftsman and the guy at Sears said it should be able to accurately read values under 1 ohm. I did the accuracy ad repeatability test ... it reads .2 ohms on accuracy and is very repeatable. The only thing I noticed was that the reading jumps all over jibip if the probes are jostled or moved at all ... is it supposed to do that? Forgive me for being negative, but I have a hard time believing that all six of my 19-year-old glow plugs are still perfect!

same results I got on my used glowplugs. I also had 2 with open circuits and one about 10 ohms. I had 10 plugs (from 2 engines) The rest were 0.3 to 0.5 When I rebuilt my engine I put in these used plugs and I know they are all still good. Yours are too. I'm sure you must have something that DOES need fixing, right?

[BodhiBenz1987]

Originally Posted by dlssmith

I doubt they are 19 year old glow plugs, probably changed at some point in the car's history.

I will describe what mine sounded like when starting with some (not sure how many) bad gp's. Crank, crank, sputter, sputter firing on 2 or 3 and then gradually coming around to firing on all cylinders. Pretty rough at first, no matter what temp outside. Quite a bit of unburned fuel smoke.

Now with new gp on all six cylinders. Crank, maybe one rev, perfect combustion on all six, right from the start. Other than the usual clattering noise that any diesel makes, it runs perfectly from the start now and smokes very little - and we're talking 5 below zero the other day.

I'm pretty sure they weren't changed ... my dad owned the car since new and kept pretty good records. There's no documentation of a change, and he says he's never had them changed. You never know though, he does forget now and then

My starts sound somewhere in between the ones you describe. It starts right up instantly when I turn the key, but kind of hacks, jumps and struggles in its first few moments of idle. It then smooths out and is clear sailing. I did notice the last time I drove it that the light goes out before the relay clicks off ... so I've been ignoring the light shutoff and waiting until I hear that relay click ... it seems to start smoother that way. I'll try it a few times and see if this is the trick. I'll also test the relay and strip fuse.

LOL, Pete ... I guess it is possible they're still good ... it just doesn't seem right ... I mean, come on, shouldn't there be something wrong with everything?