Changed Glow-Plugs, cold starts now weak, flashing glow plug light -HELP NEWBIE-

Started by WrightSounds, 20 May 2013, 04:27 PM

WrightSounds

Had some work done at a reputable shop and will be heading back there but first I was hoping to get some of your opinions so I, an engine newbie, can have an idea as to what is up.

On Thurs the 9th I took my 1980 300SD in to have the brakes bled, to have a fuel hose at my tank replaced, and to have new glow plugs installed. I supplied the glow plugs, Bosch, that I bought new from Autohaus.

The car started and ran fine when I picked it up and for the next 4 days I drove it. Then I didn't drive it for two days. When I went to start it the engine didn't crank well, or evenly, like it was missing and it needed gas. It did start up but it was weak and shaky for a few seconds. Also, almost right after turning the key to start it, during the shaky start, the glow plug light indicator started flashing and continued to do so for half a minute or so.

It started fine the rest of the day. It started fine the NEXT day and day after. Then I didn't drive it for a day and a half. This morning, same weak, shaky start. It's been fine since.

The only thing I checked is the clear fuel filter and it's nice and clean. I've read about testing the glow plugs and the relay but I'd rather not mess with anything at this point.

I'm going to call the shop but like I said wanted some of your opinions of a possible problem so I'm a little more educated when I talk to them.
Thanks!
Matt

WrightSounds

I've attempted to measure the glow plugs from the relay with my multi-meter. I found the relay mounted to the side wall under the hood. I slid the cover off. I could see the main power wire bolted on, the strip fuse, the connection to the ignition, and the larger connector to the glow plugs themselves. I attached the negative side of the multi-meter to the negative terminal of the battery. I then put the other multi-meter pin into each glow plug harness slot and with it set to 200 ohms I got the following:

Hole 1: 1.9 ohms
Hole 2: 1.8 ohms
Hole 3: 1.8 ohms
Hole 4: n/a (no connection there)
Hole 5: 1.9 ohms
Hole 6: 260 ohms
Hole 7: 24 ohms
Hole 8: 1.1k ohms

Not sure what hole corresponds with what but it seems like one of my glow plugs is defective. From what I've read the glow plugs should measure between 1 and 2 ohms. Well, looks like four of them do.

Taking the car back in on Thursday morning.

JasonP


I never messed with my glow plugs, but there seeems to be a lot of good info out there on the internets if you have the time.

Here he talks about carbon build-up in the glow plug holes:

https://mercedessource.com/node/8556

As far as troubleshooting the wiring, I wouldn't know. I think it is a pretty simple job. Perhaps if you have time over the next couple of days you could save yourself some $ and fix it before Thursday. I doubt the shop would even know about the carbon build-up.

Good luck.

1979 300SD
Color: 623H "Light Ivory"
1979 300SD
Color: 861H "Silver Green Metallic"
1977 280 E
Color: 606G "Maple Yellow"
-------------------------------------------

WrightSounds

Quote from: JasonP on 20 May 2013, 09:56 PM

I never messed with my glow plugs, but there seeems to be a lot of good info out there on the internets if you have the time.

Me neither! I mean, I bought the new plugs with the intention of installing them myself but after popping the hood and giving it a go, twice, I decided to have professionals do it.

Quote from: JasonP on 20 May 2013, 09:56 PM

Here he talks about carbon build-up in the glow plug holes:

https://mercedessource.com/node/8556

I doubt the shop would even know about the carbon build-up.
I actually asked if they ream the holes for carbon and he said, "definitely". Also stated it right on the invoice.

I'm guessing that one of the glow plugs is defective. So now I feel like one of the "smart guys" that brings me parts they've supplied for me to work on their guitars only to find out they're the wrong brand, size, type, or, they're broken or defective  :o
Needless to say I'm a bit annoyed because if I bought the plugs from the shop then it would be on their dime to fix it. Well, probably not now  :(

WrightSounds

So jack #7 corresponds with glow plug #5. Since the reading on my multi-meter was off for that glow plug I went and visually inspected it and noticed the nut that holds the o-ring connector/wire back to the relay, was TOTALLY LOOSE therefore making intermittent contact. I tightened it and so-far, so-good.

The next step is calling the shop and yelling at them. This is the 2nd reputable shop I've taken the car to. I can't stand not being able to trust or have faith in mechanics. I would try all this stuff myself except I lack tools, money to buy tools, space to work on the car, the knowhow, and most importantly the BALLS to just give it a go myself.

Not sure what I'm expecting from the shop. Some of my money back for having to finish their job?

John Hubertz

Quote from: WrightSounds on 21 May 2013, 10:03 AM
So now I feel like one of the "smart guys" that brings me parts they've supplied for me to work on their guitars only to find out they're the wrong brand, size, type, or, they're broken or defective  :o the shop then it would be on their dime to fix it. Well, probably not now  :(

I know, that is always the problem with Mercedes ownership - you want to acquire your own bits and pieces so you know the price is right and the quality is proper; but then the mechanic looks at you like you're a drunk Irish pallbearer for bringing your own parts. 

You know, I wouldn't mind paying a fixed premium - say $50 or whatever, to make up for "their" parts markup, but don't treat me like a redheaded stepchild just because I want reasonably priced OEM quality parts.
John Hubertz
"When the going gets weird, the weird turn pro."
(Hunter S. Thompson) 

1977 450SEL (Max Headroom)
[img width=68 height=73][url="http://i48.photobucket.com/albums/f248/fullhappyfish/max.jpg"]http://i48.photobucket.com/albums/f248/fullhappyfish/max.jpg[/url][/img]

JasonP

Quote from: WrightSounds on 21 May 2013, 12:29 PM
I can't stand not being able to trust or have faith in mechanics. I would try all this stuff myself except I lack tools, money to buy tools, space to work on the car, the knowhow, and most importantly the BALLS to just give it a go myself.

Yup. I hear ya, brutha.

I once picked up my car and decided to ask the mech where my starter was. So we popped the hood and all the clips on my air filter were undone.

I don't understand that mentality. I just don't understand how people can not give a shit about their job, or other people's property. But it is everywhere.

The more you work on your car, the more your confidence will increase. And you always have forums like these to help you out.

1979 300SD
Color: 623H "Light Ivory"
1979 300SD
Color: 861H "Silver Green Metallic"
1977 280 E
Color: 606G "Maple Yellow"
-------------------------------------------

wbrian63

I don't know how folks that can't work on their own cars keep anything running beyond 100,000 miles.

Used to be, manufacturers used planned obsolesence to make sure consumers would only keep a car for a relatively short time.

Now, cars are more durable, and mechanics are the reason why consumers only keep cars for a relatively short time.

The very few times I've taken my W220 S55 in for service, I've come away feeling pissed off/on. Last time the car was in for service, I had an ABC (active body control - car has a hydraulic suspension similar to 6.9) "take me to the shop" message on the cluster. Turns out the plastic tank that holds the fluid for the suspension had developed a leak. While it was in for service, I asked about a problem with the rear suspension - it seemed overly bouncy, and occasionally, I'd get flash of red in the cluster when I went over a large dip in the road. Plus there was a banging noise from underneath in the rear when I'd encounter large bumps in the road.

Got the car back with a $1,400 bill (what kind of plastic tank costs $800!?!!?!). Both of the other issues I reported were noted as "unable to reproduce" on the work order.

Within 1/4 mile of the dealership, I encountered both the warning flash and the thud from underneath...

Had I not already been pi$$ed about the cost of the tank (this MB dealer won't honor my MBCA 10% discount on service, but they'll sell parts to me at wholesale when I'm doing my own wrenching) and late for an appointment, you'd have read about me on the evening news as I drug the service manager down the road by his nose-hairs.

I invested in a computer setup to allow me to run the diagnostics on the car myself. The red warning over large dips was a failure in the rear suspension control valve ($1,300). No more warning lights. While I was under the car getting covered in very expensive pentosin oil, I also replaced all of the pressure spheres - both the front and rear main units were completely exhausted - full of fluid. I'm not certain if these units play a role in the ride and handling of the car like they do on a 6.9 because I didn't really notice any change after replacing them, but still to have them present in the design and not at all functional can't be good for the overall health of the system.

The bump under the rear floor is still there. I've checked everything that can thump and I can't find any evidence of non-chassis parts making contact with the body. Since I've had it in for this problem before, my plan is to find a stretch of road where I can reproduce the problem with a passenger in the car, then return to the dealer and take the service manager "for a ride..." Then I'm gonna hit him with the "since I had this in before and your MB-qualified mechanics couldn't find the problem, you get to find it for me for free and I'll fix it myself..."

We will see how far I get with that...

Another story -

I had my '92 300SE in a shop because the head gasket was leaking. Typical problem for the M-104 engine, and the person I'd bought the car from had just had the gasket replaced before I purchased the car. Turns out he did a real hack job, because when they pulled the head, they discovered he'd left the washers off the head bolts and had ruined the casting when he torqued the bolts down at reassembly. So to add to the already expen$ive list of parts being replaced, I had to purchase a good used head from a wrecking yard. Good & used are sometimes at odds, so I think the final price was $350 or $400...

The total cost for this effort - and I wasn't willing to cut corners - I wanted to keep the car for a long, long time - was (if I recall) nearly $5,000. WAY more than I paid for the car, and WAY more than the car was worth.

I had expected about $3,500... WOW!!!

Here in Texas, we call this "getting screwed without getting kissed".

I did notice that the car idled more smoothly than ever before, but was a little down on power at the top end. I also noticed that the temperature gauge wasn't working.

The connector that attaches to the temperature sender at the front of the motor is the same shape as the connector that attaches to the camshaft advancement solenoid (car has variable timing on the intake camshaft).

Surprise, surprise - the wires were switched. Bigger issue is that the wire that belonged on the cam solenoid carries voltage to the solenoid when the signal comes from the computer to change the cam advancement, and the wire that works the sender doesn't.

So, when I'd step hard on the gas, the computer was sending voltage to a place where it could do damage... No evidence that any damage was done - reversing the wires restored the performance and the gauge started working. It was VERY obvious that the wires weren't attached to the right places, one of them was very slack, and the other was stretched almost to breaking. Putting them where they belonged made everything "just right."

Also - after getting the car back, I noticed a tick noise when cranking the motor. One or more teeth on the starter ring gear are damaged. This wasn't there when I took the car in for the head work. I think the shop used a device to fix the ring gear so the motor wouldn't turn during the R&R of the head and forgot to remove it when it came time to start the car. Repeated attempts by some Jr. Mechanic resulted in a damaged ring gear.

Of course, when questioned, the shop insisted the noise was there when the car came in for service....

When I mentioned the reversed wires they did ask me why I didn't return the car to them. "Why should I return to your shop to allow you to fix a problem that should have never occurred in the first place? Nobody noticed the temp gauge wasn't working? I'd think you'd be VERY interested that the temp gauge wasn't working when starting the car back up after a major service like a head gasket job. Would you just wait for the coolant to boil before realizing there was a problem, when the gauge would warn you that things were getting too hot? If the gauge wasn't working when you put the car back together, if you had bothered to check the reassembly, you'd have found your own problem. If you had failed to find the problem, you could have called me and I would have told you that the gauge was working when the car was dropped off, and that as that device wasn't part of the service requested, that likely you'd done something to break it and you'd best get cracking trying to fix the problem you caused."

Needless to say, they don't get my business any more...

I have often thought that one could make a more than decent living by being a careful, accurate and honest mechanic. Sadly, for every one customer like me, that would be willing to pay reasonable $ for careful, accurate and honest service, there are probably dozens that want to patch, not fix and don't want to pay what the service is really worth, then expect you to honor your warranty when their decisions before and actions after the service are the reason why the car is back in the shop again...

No thanks - I'll turn my own wrenches as long as I'm able.
W. Brian Fogarty

'12 S550 (W221)
'76 450SEL 6.9 Euro #521
'02 S55 AMG (W220) - sold
'76 450SEL 6.9 Euro #1164 - parted out

"Bond reflected that good Americans were fine people, and most of them seemed to come from Texas..." Casino Royale, Chapter V

1980 300sd Turbo Diesel

Just changed my glow-plugs myself and did a pretty good job. Even reamed holes with a reaming tool supplied by www.mercedessource.com put new glow plugs in and purged system and after a little hesitance started fine. I took it for test drive and it drives great. I also changed all filters the day before.
YouTube is a wonderful source also for help with repair knowledge on the car.