I am new to the forum, so let me introduce my diesel. I have a 1980 Mercedes 300 SD Turbo in my 1974 Ford Super Cab. Intersting vehicle though it is, I bought it this way.

Around Thanksgiving I drove her home, about 45 miles, and parked her as normal. She has not started since.

I have replaced and checked the glow plugs - there is a frost plug heater, whcihc works, and an aux radiator hose heater, that works. Engine temp is moderate, as the truck is in my garage.

To start I usually hit the plugs for 10-15 seconds and she fires right off. To kill, I hit a vacuum button for 3-5 seconds and off she goes.

Right now, I cannot even get here to fire. Fuel is present, makes exhaust, but refuses to start.

Anyone have any ideas I could try? I'm thinking perhaps there may be a vacuum leak, brought on by the temp change?!?

Any ideas will be appreciated. I would like to have both a running vehicle and the garage space, again.

Thanks,

Joshua L. Coder

If there was a vacuumm leak the engine should start and just not shut off. Firs make sure that the "vacuum shutoff switch" isn't sticking shut the second step would be to verify that the shutoff valve attached to the IP isn't stuck.

I will check the vacuum switch this evening. It is actually a switch from an air ride seat - pretty straight forward.

I beg your patience, what is the IP?

Thanks,

Joshua L. Coder

Welcome.

IP = Injection Pump

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92 300D 2.5L OM602 OBK #59

I think Brian wants to know if you checked to see if the plugs were getting 12volts when they should be glowing and whether you checked the resistance of each plug, and if so, what was the resistance.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Welcome to the forum.


Please describe exactly how you checked the glow plugs.

Did you perform the test after glow plug replacement?

I checked the plugs after replacement. I replaced 3 of the 5, only because I thought they needed replacement.

I checked voltage at the plug and had 12 volts there. I attempted to check resistance, but my meter leaves a bit to be desired - so the results were not conclusive. I did not pull the plugs and put voltage to them, as I have little reason to doubt they are working correctly.

Thanks,

Joshua L. Coder

A bit more on the set-up. When I want the plugs to "glow" I hit a button, installed in the dash, that pulls in a solenoid. This solenoid, very similar to a starter solenoid, has wires that run to each of the plugs. When the button is pressed, the plugs glow. Likewise, when not pressed there is no voltage going to the plugs.

A wire is off the load side of the solenoid back to a light in the dash that alerts to voltage present on the load side.

Not sure if anyone wanted/needed to know that, but there it is.

How long have you owned this vehicle?

Did you own it last winter?

Where are you located? It would be preferable if you put that in your profile.

What brand glow plug did you purchase and install?

Since June.

No.

Green Isle, MN (SW of the Twin Cities of Minneapolis and St. Paul)

NAPA - Which I've since decided was not the best choice - as far as I can tell from the reading I have done.

You need at least 100 rpm, fuel, air, compression and heat to start these babies. If one isn't right then no start. Check each conditions and make sure you have them. IE pull the hard line to see if fuel is actually going to the engine, check the voltage of the battery while cranking, check the air cleaner ect. If everything is right it will start.

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1977 300D Lost coolant while someone else was driving
1983 300D Can't run without oil
1985 300SD (gone but not forgotten)
1990 300TE 4matic Sold
1991 Yamaha Venture
1975 Kawsaki 250 triple
1974 Honda 200CL
1951 8N Ford
2008 Wildfire 650C

I would check the resistance on each plug before doing anything else. Digital multimeter is good for this, perhaps even necessary as an analog scale is probably too hard to read to be as accurate as needed.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Compression - I cannot imagine the compression has changed, drastically - though I have not tested that.

RPM - I feel is good - I keep the battery on a charger.

Air - Just changed the filter, all looks fine there.

That leaves fuel - which may be the culprit. I filled up at H@liday Station Store, not by choice, but rather necessity. I thought since I was making exhaust, that I have fuel, but I have not physically pulled the line.

Thanks Again for all of the suggestions.

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That's All I Got
Joshua Coder
Green Isle, MN
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1980 300SD Turbo In a 1974 Ford SuperCab Pickup
1964 Parts Car

You mentioned that you installed "NAPA" glow plugs. However, NAPA is just a retailer. Did you happen to notice the manufacturer of the plug? Certain plugs don't have a good reputation and, if you've got such plugs, you really need to perform a resistance check of the plugs...........now.

Compression could be an issue if you leave the vehicle out in the cold and try to start it. But, if it's got a block heater and is inside a relatively warm garage..........we can dispense with that possibility.

So, that leaves the issue of fuel. You questioned the condition of the fuel at this new station..........and, therefore, it's time to pull the secondary fuel filter and carefully pour off the contents. Look for contamination and/or water. The filter will collect some of the water, but, if the problem is massive.........water will pass to the IP and prevent a start.

How far did you drive the vehicle after filling up at this "questionable" station? If it's more than 10 miles, fuel is not likely the issue.

Which brings us back to glow plugs...................

Bosch - I was not aware they sold any others.



Block Heater, yes. Heated Garage, no.

Holiday does not have a great rep in these parts. I prefer not to use their fuel, but had allowed the tank to get to a level that prevented me from going much further - not empty, but less than 1/4.

About 45 miles.

Indeed it does. I will pull the plugs and check the resistance. I should be able to hit them with 12 volts and see if they glow as well, while they are out. #4 and #5 are a real pain to get to without significant disassembly - which is why I have not replaced those. I do have replacements for them.

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That's All I Got
Joshua Coder
Green Isle, MN
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1980 300SD Turbo In a 1974 Ford SuperCab Pickup
1964 Parts Car