Well I finally got to dive into my 1985 F-250 w/ 6.9L Diesel. Recently, even in warm weather 55f and up to about 70f the truck does not want to start, so I have had to run the engine block heater for about 1-2 hours to at least get it to start. Once it starts it is not happy, and it shuts off after like 5 seconds, and I start it again and it finally starts to run normally. Alright, so I think it is the glow plugs. Apparently, last year my dad had the GP wire harness, glow plug controller, and the glow plug relay replaced, including all new glow plugs (Autolites-)

So today I removed the air cleaner and dove in. I first tested the Ohm's for each plug with my Multimeter, and I never got a reading on any of them. I also did the light test by hooking a test light to the positive post on the battery and to the metal flange on each GP. Anyway, the light never lit up on any of the 8 GP's. Could they all be so damn dead already? I sprayed PB Blaster to loosen them up b/c I know GP's can break off, but once I got them out I realized they were all Autolites, and one of them was a really old Autolite. 4-5 of them were heavily sooted/blackened, 2-3 were very ashy white color, and the one on the right rear and the 2nd one on the right were saturated in diesel fuel and possibly oil. The left rear GP was hard to get out and was definitely becoming bulbous/swelling b/c it got really tight at the end when I was trying to pull it out. I think I got lucky here on getting them out?

I am going to order all new Motorcraft ZD1A glow plugs, and install them to at least eliminate the GP's as a problem. Is there a way to test the GP controller and or the GP relay via the light trick or using a multimeter?

Also, I am confused about the engine block heater process. If the block heater has been plugged in for 2 hours and the truck starts right up, doesn't that mean the GP's are ok and are actually functioning? If that is true, then why don't they work correctly when I turn on the truck with the key and try to start it without using the engine block heater? Also, why don't the GP's light up the test light or my multimeter since the truck will start when using the engine block heater? I guess I am thinking too much, but something doesn't sound right.

 

the engine block heater and the glow plug systems are not related in any way. when you plug the block heater in, the truck will start because the engine is hot enough to not need the glow plugs to light off the fuel.

as for your question as to why the plugs will not light up, they are autolites. one of the biggest piece of crap glow plugs made, rite next to champions.

 

Block heaters put heat into the engine, makes it easier to reach 500 degrees in one compression stroke so the fuel will ignite.

Glow plugs put the heat into the precombustion chamber so it is easier to reach 500 degrees on one compression stroke and ignite the diesel fuel.

Glow plugs and block heaters are two different routes to the same destination, enough heat in the engine for it to start.

I have seen posts here where people only got 2 or 3 starts out of Champion or Autolite glow plugs before they died.

 

Stupid me. Thanks for the clarification Dave.

Is it safe to assume that once 1 plug goes, the rest are not far behind? I assume the other ones start to fail b/c they have to work harder due to additional resistance or less resistance? If these are such crummy GP's it wouldn't surprise me if they fail quicker once one or two are dead already.

 

once one plug goes, there is move power going to the others, burning them out faster.

as dave said, there have been guys here only get one or two starts out of autolites and champion plugs before they all burn out.

they blame the controller and other things, instead of the garbage glow plugs they put in to save a few bucks. but little do they know, that up till last year, the junk plugs cost $5 more than the ZD-1A's.

 

Oh, that is funny. Once some of these dealers get back to me to confirm that the ZD1A's that they sell are actually the Germany ones, then I will be ordering the new plugs this week, hopefully tomorrow (Monday). Then I can get this beast running again.

 

i went to autozone 3 years ago for the ZD-9's for my 88. they kept on trying to give me the autocraps and chumpions for $19.95 each.

my response was, "the ZD-9's are $9.99 each. why should i pay $10 more for garbage"??

they had no answers for me besides trying to tell me the ZD-9's were the wrong plugs, and the other crap was better than the ZD-9's.

i finally told them to "just give me what i asked for, not what your computer says i should use."


i would not worry too much about the made in germany tag on the plugs.

 

I couldn't even get Beru plugs at Autozone a coupl'a months ago. Went for Bosch but decided not to use them and took them back.
Paid too much at the Ford dealer (18-20 bucks) but they work and don't break off in the combustion chamber.

 

Well I thought you had to check on this b/c there are a lot of motorcraft GP's that were not actually made in Germany and are not as good as the Germany ones. Isn't this correct?

 

that is a toss up. the ones in my 88 are not tagged made in germany, and it has been 3 years now without any problem.

and the ones i put in the 89 12 years ago were not tagged made in germany also. and they are still working fine.
i sold the truck to one of my employees, and i do all the work on it, so i know they are still in it.

 

I like your "hiding from the stupid" people sighn.

Reminds me of a shirt my parents bought me: I could agree with you but then we'd BOTH be WRONG!

 

Well I ordered my Motorcraft ZD1A plugs tonight. I can't wait to get them and test them, and then start the truck. Yippee.

 

I know how you feel. Getting something to work right sure does warm the cockles of your heart.
Plus it ends the FIGHT you've had with it.

 

if you have power to everything in your truck but your glowplugs still wont work chances are its the relay they go out all the time in these old fords if it is then instead of paying thirty bucks for one take some wire and rig up a push button in the cab it bypasses the relay and doesnt cost too much either

 

The relay is working, and the plugs are certainly dead. So new GP's are on the way. I do need to find out how to make the GP system a manual system with a switch in the cab, b/c that would be nice to make my new set of GP's last longer.