DrCharles
Full Access Member
I bought my '93 F250 nonturbo 7.3 with 186k miles less than a month ago, so I'm still learning about the IDI and everything that's been neglected or "repaired" badly on this truck. It had the run-five-seconds-then-die problem, which I fixed with a Facet 40285 electric lift pump. Starts great in warm weather now. However, when the temp dips to 40F or below, it was hard to start (some cylinders firing intermittently but a good 20-30 seconds of cranking to get 'er running). At 32F it took several prolonged attempts before it stopped "sneezing" and actually ran.
The glow plugs would come on for maybe five seconds, then start clicking. Turning the key off and back on would not start another cycle, just immediate clicking. After reading many worrisome threads about broken-off glow plug tips, with considerable trepidation I decided to attempt replacement today with genuine Motorcraft ZD-9 plugs.
Allegedly the glow plugs had been replaced within the last few years. Unfortunately they had installed Autolites.
But I got lucky and all eight came out easily. I first blew all the crud from the areas surrounding each glow plug, then applied generous amounts of ATF/acetone mixture from a refillable aerosol can. That's the best penetrating oil I have ever found - you just need to shake it up immediately before applying, since it tends to separate into two layers.
The trick to getting these unscrewed is to use a 1/4"-drive ratchet, extension, u-joint and a deep socket (3/8"). The 1/4-drive socket is shorter than the 3/8-drive and there's just enough room to get it over the plug that is under the injection lines on the driver's side. Moving the line clamp helped too.
One plug needed a little working back and forth with another application of penetrating oil. Another unthreaded but didn't want to slide out with finger pressure, so I shot a small amount of oil mix along the barrel of the plug, let it sit a few minutes, worked it up and down and spun it in the hole, then it came out with a small vice grip and a firm pull.
An examination of the removed Autolite plugs showed little carbon deposits, so maybe they're even newer than I thought. But two of them showed small but visible swelling already. Looks like I got to them just in time. Measurement of resistance was also instructive: three showed about 0.6 ohm, one was 1.6 ohm, one 28.3 ohm (basically open), two nearly dead shorted (maybe 0.2 ohm in addition to the resistance of the test leads themselves) and one completely open!
:***:
No wonder it was hard to start and the controller was confused! With the new ZD-9 plugs in place, I turned the key on. This time the WTS light stayed on for a good eight seconds (50F temp), and when I hit the starter, within two revolutions it fired right up
I also replaced the heater blower while I was under the hood. Next is to replace all the busted plastic stuff and the headlights (basically everything between the radiator support and the bumper).
The glow plugs would come on for maybe five seconds, then start clicking. Turning the key off and back on would not start another cycle, just immediate clicking. After reading many worrisome threads about broken-off glow plug tips, with considerable trepidation I decided to attempt replacement today with genuine Motorcraft ZD-9 plugs.
Allegedly the glow plugs had been replaced within the last few years. Unfortunately they had installed Autolites.
But I got lucky and all eight came out easily. I first blew all the crud from the areas surrounding each glow plug, then applied generous amounts of ATF/acetone mixture from a refillable aerosol can. That's the best penetrating oil I have ever found - you just need to shake it up immediately before applying, since it tends to separate into two layers.The trick to getting these unscrewed is to use a 1/4"-drive ratchet, extension, u-joint and a deep socket (3/8"). The 1/4-drive socket is shorter than the 3/8-drive and there's just enough room to get it over the plug that is under the injection lines on the driver's side. Moving the line clamp helped too.
One plug needed a little working back and forth with another application of penetrating oil. Another unthreaded but didn't want to slide out with finger pressure, so I shot a small amount of oil mix along the barrel of the plug, let it sit a few minutes, worked it up and down and spun it in the hole, then it came out with a small vice grip and a firm pull.
An examination of the removed Autolite plugs showed little carbon deposits, so maybe they're even newer than I thought. But two of them showed small but visible swelling already. Looks like I got to them just in time. Measurement of resistance was also instructive: three showed about 0.6 ohm, one was 1.6 ohm, one 28.3 ohm (basically open), two nearly dead shorted (maybe 0.2 ohm in addition to the resistance of the test leads themselves) and one completely open!
:***:
No wonder it was hard to start and the controller was confused! With the new ZD-9 plugs in place, I turned the key on. This time the WTS light stayed on for a good eight seconds (50F temp), and when I hit the starter, within two revolutions it fired right up
I also replaced the heater blower while I was under the hood. Next is to replace all the busted plastic stuff and the headlights (basically everything between the radiator support and the bumper).
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