Well my 240D glow plugs failed this morning - Page 4 - PeachParts Mercedes-Benz Forum

vstech · #46 02-25-2015, 09:30 AM

the readings you are reporting leave me to think all your plugs are bad.

they should be reading approximately .7 ohms if they are good. all are either .3 or less, and one is reading some odd number... change them all.

pj67coll · #47 02-25-2015, 07:05 PM

Quote:

Originally Posted by funola

Glow light in dash not indicates one or more burned out glow plug (read your owners manual). Replace #1 and go from there.

Maybe you had the glow plug connector connected when yous measured 1.5 ohms on #1? To proof to yourself why it's important to disconnect the connector is measure the 4 pins on the glow relay, you'll see they are all connected together. That means (if the connector is plugged in) when you take resistance measurements, all you need to 1 good glow plug to get good readings on the rest, i.e. the readings are not to be trusted.

I did have the plug connector connected initially so that makes sense. Looks like at least one bad plug then.

- Peter.

pj67coll · #48 02-25-2015, 07:06 PM

Quote:

Originally Posted by vstech

change them all.

I may well do that. Probably all new plugs and ream out the chambers while I'm at it.

- Peter.

Stretch · #49 02-26-2015, 01:42 AM

If you are taking them out then you can check them individually

pj67coll · #50 02-26-2015, 08:02 AM

Quote:

Originally Posted by Stretch

If you are taking them out then you can check them individually

Yes. I'll do that soon as I can order some. Strange thing is I'm pretty sure I saw a reference to glow plug replacement a few years ago in the previous owners records but looking thru them all last night I can't find anything about it. Might have been imagining it I suppose but I really did think they were done. Anyway. Like I said I guess it's time for new ones.

I'm considering doing a manual conversion like Funola's. I like the idea of the simplicity of that solution. I'll explore the various options. Might have to wait for the next pay check though.

- Peter.

funola · #51 02-26-2015, 08:23 AM

Quote:

Originally Posted by vstech

the readings you are reporting leave me to think all your plugs are bad.

they should be reading approximately .7 ohms if they are good. all are either .3 or less, and one is reading some odd number... change them all.

He had the glow relay connector plugged in and it showed all the glow plugs were good, that means at least one glow plug is good , or 2, or 3, or all.

Another fact is that ohm meters cannot measure low resistance accurately and discern differences accurately to the right of the decimal point. If you want any kind of accuracy, measure the current draw of the glow plug.

funola · #52 02-26-2015, 08:24 PM

Quote:

Originally Posted by pj67coll

.............
I'm considering doing a manual conversion like Funola's. I like the idea of the simplicity of that solution. I'll explore the various options. Might have to wait for the next pay check though.

- Peter.

I have 2 left, converted manual glow relays- plug and play (just add a momentary push button to switched +12 V.
$40 + shipping.

Or you can send me yours, $25 to convert + shipping.

pj67coll · #53 02-26-2015, 11:10 PM

Quote:

Originally Posted by funola

I have 2 left, converted manual glow relays- plug and play (just add a momentary push button to switched +12 V.
$40 + shipping.

Or you can send me yours, $25 to convert + shipping.

Did you convert these yourself or are they off the shelf?

- Peter.

funola · #54 02-27-2015, 09:36 AM

Quote:

Originally Posted by pj67coll

Did you convert these yourself or are they off the shelf?

- Peter.

These are used Mercedes glow relays that I converted to manual. It has one wire (6 ft long) coming out of the relay which you snake through the firewall grommet next to the brake booster, connect wire to a momentary switch, connect other terminal of switch to keyed + 12V (cigarette lighter is convenient) done! - can't get easier than that. The glow plugs and cluster glow light are powered as long as the momentary switch is held down. Hold it down as long as you need based on temperature, or not at all if the engine is warm. If you need after glow when really cold out, just hold it longer after the engine has started.

Sounds like you have only 1 bad glow plug. If you buy one, I'll throw in a good used glow plug for free.

pj67coll · #55 02-27-2015, 08:36 PM

Quote:

Originally Posted by funola

These are used Mercedes glow relays that I converted to manual. It has one wire (6 ft long) coming out of the relay which you snake through the firewall grommet next to the brake booster, connect wire to a momentary switch, connect other terminal of switch to keyed + 12V (cigarette lighter is convenient) done! - can't get easier than that. The glow plugs and cluster glow light are powered as long as the momentary switch is held down. Hold it down as long as you need based on temperature, or not at all if the engine is warm. If you need after glow when really cold out, just hold it longer after the engine has started.

Sounds like you have only 1 bad glow plug. If you buy one, I'll throw in a good used glow plug for free.

That's a nice offer. Thank you, but I've already decided to replace all my plugs and not the relay - at this stage. I bought four plugs and reamer from Kent and they should be here Wednesday. This car was run on bio-diesel for a few years while in Phoenix and I think it may have had some WVO in it too. I've heard that this can increase carbon build up and premature plug failure. In any event I want to not have to get back in there again any time soon and decided to replace all of them and ream out anything that might be in the chambers at the same time.

I recall seeing something in the cars documentation about changing out glow plugs from the PO but now I can't find it. I know I'm not imagining things but now I'm not sure what was done so I've decided to simply remove all doubt by renewing them all. If the problem persists I'll know at least I have four new ones and can rule them out and I'll consider other options thereafter.

For the cost fo the plugs I'm not too worried about going this route and I'd like to keep it stock if possible - assuming it's the plugs and not the relay or something else of course.

I hope to be able to change them out next weekend so we'll see what happens then.

- Peter.

pj67coll · #56 03-04-2015, 09:50 PM

Well. My glowplugs arrived this afternoon. I'm planning on starting the change out early Saturday morning. I'm not certain I want to remove the injector lines even thought it provides better access. Never having done this before I'm a bit nervous of screwing them up.

- Peter.

toomany MBZ · #57 03-07-2015, 07:45 AM

I don't remove the hard lines, but you do need to contort your hands, especially the rear two.

If you decide to tale 'em out, remove the entire rack. Loosen the connecting clamps a bit.

pj67coll · #58 03-07-2015, 10:55 AM

Quote:

Originally Posted by toomany MBZ

I don't remove the hard lines, but you do need to contort your hands, especially the rear two.

If you decide to tale 'em out, remove the entire rack. Loosen the connecting clamps a bit.

I'll be starting this job within the hour. So. I'll see how I feel about it when I get in there.

- Peter.

Diesel911 · #59 03-07-2015, 12:44 PM

If you remove all of the Fuel Injection Lines when you re-install them leave tighten the Injector end of the lines by hand and then back them off a bit. It is OK to tighten the Fuel Injection Pump end.

Crank the Engine till Fuel comes out of them and then tighten the Fuel Injection Line Nuts at the Injector and attempt to start.
If you don't do that there is a chance of Air getting inside the Fuel Injection Lines and if you tighten both ends the Air gets trapped in there and when you crank the Engine the Air compresses but does not move the Fuel towards the Injectors very Much. That means it takes a lot of cranking to get the Air out.

By having the Injector Nuts at the Injectors a little loos the Air is not trapped and has a place to escape.

pj67coll · #60 03-07-2015, 04:49 PM

Thank you all who participated in this thread. All advice was appreciated. Took me almost three and a half hours as I was going slow and being careful, never having attempted this before.

I now have four new Monark glow plugs in the motor and it's glowing fine.

I followed Kent's procedure to the letter using one of his online video's. Most useful having my laptop right next to me and being able to pause and retrace steps etc.

There was almost no carbon in my chambers from what I could tell. None the less I reamed each one three times just to be sure. I was able to install all the new plugs by hand right up till they bottomed out and only a final tightening with the wrench was necessary.

I removed the fuel injector hard lines and I'm glad I did. I don't see how I would have managed trying to work around them Had a couple of towels sacrificed to the diesel spill when I tried pumping the air out of the lines at the end. I will have to replace the hand pump with one of the newer ones.

Anyway. Once again. Thank you all. This forum is the greatest.

- Peter.