loop style glow plug question
 

this should be simple for you guys, 78300d quit starting, from the #5 plug to #4 plug the resistor wire glows red, same for #4 to #3, the remaining resistor wires do not glow red, but they do get hot. i pulled plugs 1,2,&3 and they look ok, no broken loop, and resistance testing seems to indicate that they are ok. Bad resistor wire ? plugs bad anyway ?, any suggestions would be appreciated.

If the resistor wires are glowing at all that means it's a complete circuit.

Narrow down "quit starting" for us. How did it quit starting? Did it fun fine then decide to not start the next day?

Is there any exhaust smoke while it's cranking?

Does it try to start at all? Coughing, sputtering, etc?

started getting harder to start, would have to let glow longer and longer, then one day it wouldnt start, after trying for some time the batteryseemed to go down, so i hooked up the jumper cables to my truck, the mercedes started up pretty quick with the cables attached. ran and started good for a week and now no start period, cables or no, i plugged in the block heater for a couple days - no start, not really coughing or sputtering when cranking maybe a tiny bit just for a second. no smoke that ive noticed while cranking.

Have you tried changing the fuel filters? Take off the fuel tank cap and listen for a rush of air which could mean a plugged tank vent.

Pump the primer handle a bunch (Like 50+ times) and see if it makes it any easier to start.

with the jumper hooked up, does it sound like the crank speed is the same as last week when it was starting? a bad battery will make it very difficult to crank these 22:1 CR motors. it sounds like either your starter has gotten weak, or your battery is failing. another possibility is that the loops are inadequate to heat the PC enough to aid ignition. new loops could get the band aid going a bit longer, but conversion to pencil plugs will make a MUCH bigger difference. is it worth 100.00 to find out? your call. get a fully charged type 49 battery in there and see if the plugs and starter work better. if no change, you might wanna look into conversion...

I suggestion you take this opportunity too switch to the new style GPs, you wont regret it. :)

This is excellent advice... do it!

Your problem may be simpler than you think, and cheaper than retrofitting to the new style plugs. Take off all the wires between the glow plugs and at each end (even the end that grounds to the engine itself) and give them a good cleaning with a wire brush until they are nice and shiney. Do the same with the glow plugs themselves. Clean any metal connection that makes electrical contact. Then reattach everything and give it a try.

Recently bought a car that would not start. Tried everything, including ether. Wouldn't even hit. Turned out one of the connections on the glow plugs had corrosion and excessive resistance. Once the connections were cleaned, the engine started right up. I would never have thought that could make so much of a difference, but it did.

good point KCM, but he has pulled the plugs, and reinstalled them, it's unlikely there is still some resistance from corrosion or whatnot... still, not a bad idea. a wire brush, or some sandpaper wouldn't hurt.

i only pulled the plugs out after the point where the resistor wires werent glowing, the first three, cleaned everythinh real good. starter sounds like it always did when the cables are attached. im pretty sure its getting fuel, but i will crack the nuts at the tops of the injectors and crank to see if fuel comes out. I have hand primed a bunch - no help. Should all of the resistor wires be glowing red ? I would think so, and they are not leading me to think glow plug issue. I think i will upgrade to the dieselgiants plugs that do not require any changing of the relays or any of the other related jazz. but i was hoping to get the car started this weekend.

can i just go buy some pencil type plugs from the napa and wire them up like on the diesel giants site http://www.dieselgiant.com/mercedesdieselloopglowplugrepair.htm, or are those some kind of special plug.

They're a special plug. The series plugs have larger diameter threads so it's a pencil plug with series threads. They are available invidividually but you'll need the exact part number, a standard pencil plug for later engines will not fit.

While it does sound like symptoms of glow plug issues, he did plug in the block heater. {providing it works.....}
That makes it sound more like the weak battery, slow starer scenario.......
I agree about upgrading the glow plugs, as that needs to happen whether it's the problem or not.

anybody got a part number for those pencil type with series threads plugs ?

jimmyL, ought it to start when it's being jumped. cranking sounds right. block heater seems to be working, the valve cover was hot to the touch. what about these non glowing resistor wires ?

I think the wires closest to the source of power glow the most. As long as they are hot, I think they are working. This is by recollection since I converted my 77 to pencil type years ago.

well if thats the case, seems like mine are working correctly. i verified that there is fuel by cracking the #1 injector line at the injector and cranking, and there was fuel that came out. when I am cranking now i am having the car hooked via jumper cables to my truck b/c i have been cranking so much lately, starter souns fast and like it always has. no smoke while cranking from exhaust, someone had asked earlier. that being said whatelse does she need to start, fuel & heat. ran pretty much fine, parked, then would not start the next time i went to drive ??? and here we are, going nowhere.

I have a '68 or so Ford 3000 diesel tractor, and it does not have glow plugs. Sometimes it fools me and I think something is wrong, when in fact the battery is just weak and needs some help. I can't always tell by listening to the starter. It sounds very similar, but the cylinders can tell.....;)

put the battery in from my 85td - no go. tried putting some wd40 down the intake - didnt even try to start in the least. fuel is getting to the injectors while cranking. resistor wires closest to the electric sorce glow red - so i take this to mean that all the glow plugs are ok because if any one had failed - none would be working and no resistor wires would be glowing. What do i check next, compression test ?

How long has it been since it ran? If it has been long enough to dry out the rings you might try squirting a bit of ATF or oil on each glow plug hole... this will wet the rings and increase compression. I had to do this to get my 220d started after it sat for several years.

i took it to the grocery store 1 & 1/2 weeks
ago.

Cycle your g;ow circuit and read the voltage drop across each plug. There is a small chance a plug has shorted internally giving you a shorter glow plug series string.
Or even simpler is to read the drop across the number one plug at the front of the engine. Should be a voltage drop of a volt or so. Some diesels just do not like to start with a couple of glow plugs missing.
The hot connecting resistance wires closer to the firewall do not mean the whole circuit is properly active. You could still have a plug with a short to ground in there.
If the glow plugs check out I wonder about bad fuel but it did not catch on wd40.

Day and night difference on my 1976 300D between old loop series style glowplugs and the new pencil Duratherm type. Ordered from Autohauz arizona. great place.
I used Echlin 80 Amp solenoid. Solenoid is powered by the original glow plug feed wire.
It starts after 4 or 5 seconds glow.
The orig glow light is now defunct but it is not needed. I just count to 4 and crank. No problems. Don't waste you time with the mythical Fast Glow kit. First of all it is not plug an play and second of all it costs $98 even if you could find one. I returned mine to Autoparts warehouse for credit. Instructions with it do not show my vintage hook up.
Good luck if in fact it was your glow plugs giving you the hard start condition.

oh no, still wont start, with the old glow plugs i measured voltage at plug closest to firewall and got 8.5 volts, the second one was like 3 volts and every one after that was in order of .28 volts, so i bought diesel giants pencil style retro fit kit, installed this afternoon, big fat goose egg. cranks and cranks no start. just to recap, fuel is getting to the injectors while cranking, i have tried to start with the battery from my running 85td, no start with wd-40 (with old glow plugs) down the intake with the airclear cover off, i sprayed for 2 seconds at most, maybe not enough wd ? it was running fine, parked, next day and every day since then no start. the only thing i did not mention previous is that 2 weeks before it quit starting i was getting extremely loud injector nailing, i though i had broken a connecting rod, but i swapped out all the injectors with those from a running parts car, after that no more nailing noise, when doing the replacements of injectors i did not replace the heat shields like is reccomended on the diesel giant page - but ran great for two weeks after injector replacement ?

bummed out
John

Something's wrong with the glowplugs if you're only getting 8 volts. Have you checked the new plugs to make sure each one is getting 12 volts?

nope, will do first thing in the morning

I would think that checking too see if the GPs were getting juice when you changed systems would be part of the job:rolleyes:

glow plugs are all getting 10.5 - 11 volts. i put the battery on slow charge last night so she was good and juiced up this morning. put some wd down the intake while my wife cranked - nothing. anthing else to try before i go buy a compression tester, which i need anyway.

WOW, that is strange.
have you adjusted your valves?
a compression test and even a blowby test may be needed.
try this, pull the injectors, and arrange the lines in the engine bay so you can see the spray pattern. then crank the motor, and verify you are getting fuel and spray out of them.

have not adjusted the valves. ill verify that the injectors are spraying. but shouldnt it have done something with the wd down the intake even if the injectors werent spraying ? would compression go from drivable to undrivable overnight ? if the compression was that bad wouldnt i have noticed lack of power ? I thought it was peppy compared to other non turbos ive driven especially after the new used injectors i just installed a couple weeks before it quit starting. but again shouldnt it have fired even a little with the wd ?

Glow plug for older 617 engines
 

Pencil glow plug for loop-style engines is Bosch 80035; available at NAPA for $18.83 ea.

If you test injector spray pattern, be careful not to inject fuel into your fingers or any part of your body - it's BAD. Steve

When you read different voltages across the first two plugs it meant the first two plugs had gone high resistance internally compared to the ones that read .8v. That would mean the plugs further upsteam would not get hot enough. Your .8v sounds about right as most voltage is dropped across the resistance wires. Yet in my mind it should have been about 1.3v.
If glow plugs after the number two read .8v their voltage was being dropped across the number one plug. With the number two partially responsible as well. In otherwords current flow was less than normal with only the number one plug getting really hot and number two warm if any really where. That was your original problem I believe.
Since I assume you did not throw the plugs away measure their individual resitance. If they all are the same then you had a bad connection at the point you were reading the 8.5 volts.
Now I do not know why your new plug setup is not producing but I think somehow or other something is wrong in your glow setup. Can you describe what you did when you converted over? I know it sounds stupid but it might point somewhere.
The car was not starting earlier and it is completly understandable why. It should be starting now in my opinion unless something or other in the new system is messed up.

the conversion is pretty straight forward. they are pencil style plugs with loop stlye body. installation details here... http://www.dieselgiant.com/mercedesdieselloopglowplugrepair.htm

previous poster said i could test the new ones by testing the voltage at each new plug and that i should be getting 12v at each plug, im getting 10.5 - 11 and assuming that is ok.

Yes that voltage reading does sound about right. I really still think that if your earlier readings were right it was the glowplug circuit that caused the no start. May be wrong though if your engine has great compression it would still function with a marginal glow plug circuit.
Why it is not now starting is beyond me. Your hand primer pump is not leaking badly? I assume you have pumped up the fuel since you got into this. Have you done anything else?
Will it at least make some commotion with a little wd 40 sprayed down the intake now with the new glow plugs? Apparently not as I just reread your last posts. I also wonder if you picked up some really bad fuel. Not common but happens once in awhile. Thats why I only fuel at truck stop places.
Maybe you should also consider doing the compresion check now. Although as you said usually the compresion failure overall is gradual in nature. Certainly not over a week or two. You also might want to consider dumping the contents of the fuel filter into a glass jar looking for a lot of water or anything strange. This situation otherwise is not making a lot of sense.

barry, pulled the injectors just for fun. they sprayed, it was pretty neat to watch. (note to others who may read and not know, careful not get in the way of a popping injector you will get blood poisioning, lose digits, or worse ). the engine has 290k burns oil around 1 qt in 500mis which i feel like is a fair amount but it has always felt strong. as for bad fuel ive been running off the current tank for quite a while but i did go get a small can of fresh diesel to stick under the hood havent done it yet though. ill pick up a compression tester from harbor freight tomorrow maybe, and check it out. looked through the oil filler while my buddy cranked watching for cam movement making sure the timing chain didnt somehow become disengaged its ok. dont know if compression could go like that overnight. its baffling.

When you had the injector out did you look in to see how bright the glow plug was when activated? Since you did not really seriously overheat the engine I still cannot see a sudden loss of temper of the rings. That is about the only way to loose general compression rapidly. Other than something failing generally affecting one cylinder only. Since it was getting harder and harder to start over a very short period. If all of this occured on that same tank of fuel it could still be the fuel.

Flooded
 

If you have flooded the engine I would guess this could be part of your problem after remediations / improvements have been done.
I also put a 4 gage redundant ground wire from battery negative post directly to engine block.

thought about flooding - would it evaporate dissapate like gas, what would the time period be on that - overnight sufficient ? yesterday i cranked a bunch with all the injectors out to verify that they were spraying. looked down the holes and saw plugs glowing. today i hooked a can of fresh diesel straight to the injector pump - nothing. just to recap : good fuel, injectors spraying, new updated glow plugs (glowing), starter sounds like it always had (pretty fast), wd straight down intake while cranking - nothing, its like it knows i bought the 85td to replace it and it wants revenge, but i would like to have sold it (running) for something, shoot i might have kept it. i have too much other stuff i want to do, if i havent figured it out by this weekend we may see if anyone wants it as is on the craigslist or its going to the scrap yard. Thanks for all your help

Too bad, Out of curiosoty I would borrow a diesel compression gauge and check the compression if I did not own one. If still high the car will bring more money usually.
Also if good compression is indicated you will probably solve the problem. I know I would take a chance and pay more for an unrunning engine with high compression.
I have never flooded a diesel but anything is possible in this world. I always figured if a diesel had excess fuel oil in the cylinders it would slowly drain down past the rings in a reasonable time. From what you posted the engine should be running. At this point I would want to know the compression numbers.

Simple serial process of checking finite number of contributors to find root cause
 

1: fuel (good fuel) quality, quantity, spray quality, timing
2: air: unobstructed air supply
3: compression: leakdown test, compression test, cylinder balance (compare all cylinders)
4: fire: amp draw on each glow plug. get rid of series plugs if you have not already done so
5: Clear previous conditions like FLOODING.
All of these elements need to be examined. You will find the root cause or combination of causes. Do not scrap the car because of one little obstacle. You will be successful!:)
Just shooting from the hip quickly now but hope this helps encourage and direct you in your quest for fire!!!

gonna do a compression test tomorrow, adjust the valves and then take another compression reading. ive never adjusted the valves before, everthing seems clear except the part that talks about getting the cam lobe at about 1 o'clock. ive looked at the diesel giants guide http://www.dieselgiant.com/valveadjustment.htm ,pretty good but its still vague about where the cam needs to be to check the clearance. with something so precise with such small clearances, seems like there would be a more accurate way of placing it, haynes manual is vague too, so i guess close is ok, just seems weird

By pointing the high part of each individual cam lobe to ~ 1-o'clock you are getting the shallow side of the lobe in line with the clearance check point. The lobe has a fairly good portion of its circumference at or close to the "shallow" dimension, so if the lobe was pointed to 12:50 or 1:10 it really wouldn't make much difference.

what do you think about these compression readings : 80 100 100 275 200 , adjusted the valves, 100 200 120 275 200 too low to run ? was running great one day, the next no start, doesnt make sense, feel like i have tried everything. tried some ether w/o glowing - nothing.

I would verify those numbers... if those two low pots could be brought up to the others, you MAY be able to get her running. 100 and 120 are impossibly low. the 200's are really too low to reliably start. you may have waited too long to adjust the valves, and burned a few. next step is an pressure test to see where the leaks in compression are from.