changed glow plugs-- new problem - Page 2 - PeachParts Mercedes-Benz Forum

winmutt · #16 11-16-2007, 06:03 PM

Pulling the injectors requires replacing the heat shields.....

BIGRED · #17 11-16-2007, 06:19 PM

Quote:

Originally Posted by Brian Carlton

You know what I'm thinking...........I'll bet that he blew the relay fuse somehow.

Pull the cover from the relay..........there is a solid strip of metal that is sitting below two Phillips screws. See if it's damaged in any way. If so, that's your issue. If not, it still may be compromised. Use an auto jumper cable to bridge the two terminals and repeat my aforementioned test.

Report back with results.

That was my thought...but then it started with a 2nd try. Thinking short or broken wire......but diagnostics is the only solution.

Document your steps and the results and take pictures if you can. Might be worth taking the knucklehead to small claims on principal.

darkman · #18 11-16-2007, 06:56 PM

I checked the strip fuse. I read somewhere about them getting
brittle or something so I pushed on it and tried to move it from
side to side. It is firmly set and just a little sloped downward.

I tried to start the car. There still is no glow light but it "clicked"
then started.

I turned it to the #2 position (since it clicked before) opened the
hood and listened until I heard the "thunk".

So... i guess if it clicked AND thunked, the relay must be working
enough to perform the voltage test-- which I'll do ASAP since the
light isn't working and there's no guarantee it'll start again.

Question:
Could manipulating the fuse have done that??
How?

........
BigRed... we're on the same wavelength for sure. The last thing
I picked up when the tow truck came this a.m. was my camera.
........

Brian Carlton · #19 11-16-2007, 07:05 PM

Quote:

Originally Posted by darkman

Question:
Could manipulating the fuse have done that??
How?

Yes.

The fuse can be cracked.........but you cannot see the crack.

darkman · #20 11-16-2007, 07:28 PM

I always LMAO when I see this on the forum.

"I don't understand what happened..........it was running fine
yesterday..........nothing like this has ever happened to
me before......and now it won't start......what should I do???

...............pray to the M/B gods.........

And post to the Diesel Discussion forum!

I really appreciate these insightful tips.
Tried to start again. This time it took 3 tries.
Still hear the preglow.

I'll report back as soon as I can do the voltage test.
Thanks everybody.

JimSmith · #21 11-16-2007, 08:17 PM

I am a bit lost. The solution has to explain all of the events that have been described so far, and then some.

First, what were the symptoms the car showed to convince you the glow plugs needed replacing, and how long did this condition exist?

Next, as I understand it, the new glow plugs did not stimulate the system to light the dash glow cycle indicator light, but, if the glow plug circuit was turned on with the key, and you waited, just like the indicator lamp was working, you could get the engine to start.

Next, after more than one apparently successful use of the glow plugs following the pretend the dash indicator light lit method, suddenly that method stopped working at all.

You called the AAA guys to tow the car to the shop and have the car reworked.

After a day, the shop made no progress, you fished the old/original glow plugs out of the trash, one or more was broken, the mechanic started the car with ether or something like that, and you drove home.

You pulled a plug and looked at the identifying numbers, and wrote them down.

I have some added questions, the first being, what were the original symptoms that inspired you to have the plugs changed.

Next, when you got the ones out of the trash, and two were broken, what visual evidence of them being broken did you discover, and can you describe that, and possibly surmise how they were broken?

When you check the resistance of the plugs from the threaded body to the electrical connector on the outer end (also threaded), what do you get for the original plugs and what do you get for the new plugs? The new plugs, if they are still installed, can be tested by pulling the plug inside the relay housing on the fender and checking between the connector socket and a clean metal surface on the engine or the fender. Measure and record the electrical resistance (Ohms) you get. Do this by setting your digital multimeter to a relatively low Ohm setting and putting one (the red one) lead in the plug socket and the other lead (the black one) to ground. If you get the colors of the probes mixed up it makes no difference when you are reading Ohms. Once you have measured resistance readings, sort the plugs into groups - there will be good ones with resistance readings near approximately 1 Ohm, and then there will be bad ones with zero Ohms or very high values. Put the plug back into the socket/pin connector in the relay housing. Replace any "new" plugs that are bad with "old" plugs that are now known to be "good."

If you find some "new" plugs that are bad and replace them with "old" plugs you have measured and know they are good, you have to verify now that the wiring is ok. So, recheck the replaced plug once it is installed following the procedure above using the plug receptacle as this test checks the wire from the plug to the glow plug too. If you find a formerly "good" "old" plug is now no longer good, the wire is suspect between the relay plug and the glow plug. Check the plug you took out, alone, and see if the plug you tested with the wire and decided was bad is really bad, all by itself. If the "bad" "new" plug is now good when measured out of the car, the wire is likely bad. Check the wire at that point, and if it is bad, replace it.

If none of that Charley Chaplin "new" "old" "good" "bad" stuff turns out to be confusing, and all the new plugs are good, no bad wires, etc. you have to look into the glow plug relay box.

Once you have the relay housing cover off and the plug that has the lines to the glow plugs that you took out and have now reinstalled, you can also check the fuse. Unscrew the two Phillip's head screws (I believe they are Phillip's head screws, they may be regular slotted heads though) and take the relay fuse out. Give it a good twist with your fingers to make sure it is not actually already broken but holding together with corrosion products. If the fuse is ok, you have to check whether power is getting to the fuse.

Have someone turn the key to start the glow plug cycle while you measure voltage with your meter between the two holes the screws came out of, and see if it is not near 12 Volts (the glow plug line plug must be reinstalled). Record the voltage reading.

Put the fuse back in, and tighten the screws down pretty firmly.

Try the system once it is all restored. If the light doesn't come on on the dash, there is a problem in the relay, most likely. In some instances when a thing like this is on its way out, well, not all functionality is lost .at the same time and you get weird responses. It may work, it may not. My old 1982 240D would not light up when one glow plug was burned out, but if I cycled the key from zero to glow and back to zero and then on to glow again, the light would come on and behave normally. If two plugs were out, it never came on until I fixed them (I never fixed just one...)

The system draws a lot of current when it works, and if the light isn't going to work for whatever relay circuit reason, but the glow plugs do, rather than listen for noises, just turn the overhead interior lamp on. When the glow plugs cycle on the lamp dims slightly (but noticeably) and then, when they cycles off, it brightens up a bit. Very obvious. One it cycles off in cold weather I usually just turned the key back to zero and back to glow, light dimmed and then I fired the starter.

Anyway, I am very curious about what the original behavior was, and what the condition of the removed plugs might be. Good luck and I hope this helps. Jim

raslaje · #22 11-16-2007, 09:21 PM

Quote:

Originally Posted by Brian Carlton

Set it so that's it's on suitable scale........15V DC or 25V DC should do it.

Touch the black lead to the + battery terminal and the red lead to the - battery terminal. Confirm that the meter reads approx. 12V.

If it does........continue:

Put the tip of the black lead on the tip of one of the glow plugs (leave the red lead on the - battery terminal).

Have another person turn the key to the #2 position.

Observe the meter...........it should read about 11V..........and should stay at 11V for about 35 seconds..........when it will go to zero and you'll hear a "thunk" from the relay.

Report back with results.

Brian: Do you have the red and black leads mixed up?

Brian Carlton · #23 11-16-2007, 09:34 PM

Quote:

Originally Posted by raslaje

Brian: Do you have the red and black leads mixed up?

I don't.

vstech · #24 11-16-2007, 10:27 PM

brian, if you are posting black to ground, and red to positive, which lead is connected to the - position on your meter? most meters I have used, have a black circle to indicate where the black lead goes into the meter, and a red circle to indicate where the red lead goes. in this instance, if red goes to the + location and black goes to the - location on the meter, then the voltage you were measuring would be -12VDC

right?

darkman · #25 11-16-2007, 11:23 PM

Clarification for Jim,

I knew during the summer that a glow plug was out because the
light had stopped working and I got the unburnt fuel smoke and
a brief rattling start on the first startup of the day.

Because of the onset of winter (I'm in Chicago now) I wanted to
have them done before the actual winter temps set in.

I was able to start the car in the shop although neither the shop
owner nor his mechanic could do so. I overlooked his asking me to
start it but it's something I confronted him with today. He reminded me
that I started the car at least twice after they "repaired" it.

I reminded him that neither he nor his mechanic have been able to
start it since they worked on it. Although they could start it to drive it into the garage bay. He said he asked me to do it because sometimes people have personalized ways of starting their cars. (Anyone's intelligence offended yet??)

My position is that if it's really fixed then anyone who has the key should be able to start it.

As I look back I think that the starts are due to the warmth of the
engine. Once the engine was cold-- nada!

I retrieved the GPs and 2 tips were broken. I've read in the forum
about the possibility of breaking plugs when you extract them. Now
that the "repair" is paid for and unsatisfactory, I'm looking for evidence
and I still need my car fixed fixed-- maybe more than jus GPs.

I got the Bosch box out of the trash too. That's how I got the part #
Also (trying to give the guy the benefit of the doubt because he ordered
the plugs from somewhere other than hsi regular warehouse) I was leaving
room for the possibility that the wrong GPs were sent/installed. And to
give him a face-saving excuse.

(I'm thinking he wants to rectify this for the sake of "customer lifetime value". You know, wheel alignment, brake flush, 4 oil changes/year. Okay-- duh).

This a.m when I tried to start there was no sign of the glow cycle.
Aside from the GP light there were none of the other signals
that you normally get. The only sound was that of the starter spinning
but nothing to hint at an engine trying to start.

I had it towed back to the shop and after a couple of hours I asked if
there was anyway he could start it. He said he could do it with fluid.
I said-- "do it. I want my car back." This is after getting no feeling that
he was trying to rectify yesterday's work but, instead, to find some other
billable work. Needless to say I was getting more psssd by the minute
because of the casual (guiltless) approach he was taking.

The events after returning with the car are the last few posts.

I haven't been able to do the voltage test and won't be able to until
daylight. I'll be on the job, though, when the sun comes up.

Brian Carlton · #26 11-17-2007, 12:13 AM

Quote:

Originally Posted by vstech

brian, if you are posting black to ground, and red to positive, which lead is connected to the - position on your meter? most meters I have used, have a black circle to indicate where the black lead goes into the meter, and a red circle to indicate where the red lead goes. in this instance, if red goes to the + location and black goes to the - location on the meter, then the voltage you were measuring would be -12VDC

right?

I've always used black in the + socket and red in the - socket........but, clearly, you can do it any way you please. If the meter calls out for the opposite polarity.........then that will surely work for you.

darkman · #27 11-17-2007, 12:03 PM

O.k.

I'm getting ready to voltage test. In the daylight I can see where
the mainifold was reattached incorrectly.

Here are pictures of the mainifold re-installed down inside the injection
lines. Could these bent lines have an effect in what we're trying to
solve?

JimSmith · #28 11-17-2007, 12:11 PM

Originally Posted by vstech :
brian, if you are posting black to ground, and red to positive, which lead is connected to the - position on your meter? most meters I have used, have a black circle to indicate where the black lead goes into the meter, and a red circle to indicate where the red lead goes. in this instance, if red goes to the + location and black goes to the - location on the meter, then the voltage you were measuring would be -12VDC

right?

In this type of trouble shooting the "absolute value" is the number you care about. Polarity is fixed when the minus terminal of the battery is connected to the ground on the car (the frame) and the positive terminal of the battery is connected to the power distribution system/fuse box/starter. All you care about is the number, the polarity is not of interest so the color of the meter leads is not important in this exercise. Jim

JimSmith · #29 11-17-2007, 12:13 PM

Quote:

Originally Posted by darkman

O.k.

I'm getting ready to voltage test. In the daylight I can see where
the mainifold was reattached incorrectly.

Here are pictures of the mainifold re-installed down inside the injection
lines. Could these bent lines have an effect in what we're trying to
solve?

I can not make out what I am looking at specifically. I would say if any of the lines are broken or crimped significantly, you may have an issue. But your primary problem is getting your new glow plugs to work. Did you fish any of the not broken old glow plugs out of the trash, and, did the entire broken tip of each of the broken ones come out?

Jim

darkman · #30 11-17-2007, 12:20 PM

Yes I have all the old glow plugs.

The broken tip is the outer end that the wire attaches to.