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Discussion Starter · #1 ·
I just bought a '95 GMC W4 box truck with the Isuzu 4BD2T engine. I'm looking to swap it into my '95 Jeep Wrangler. The truck needs to have its engine heater plugged in to start at temperatures lower than about 40 degrees F. I would have thought that the glow plugs could handle that... I mean, 40 degrees isn't that cold!

The truck has 220,000 miles on it, so maybe something is just worn out. What could it be?
 

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glow plugs do fail. How is it running otherwise?
 

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I think you should run a compression test.I've never plugged mine in, and I lived in Minnesota most of the time.Good Luck.
 

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Discussion Starter · #4 ·
The engine runs and sounds great! However, there is a reasonable amount of blow-by out the crankcase vent tube. Maybe the rings are worn and it can't generate enough compression (i.e. air temperature) at startup?

Also, I noticed that the glow plug indicator only stays on for two or three seconds after turning the key to ON. I would have thought that it would take longer for the plugs to heat up.
 

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My plug indicator light only stays on for a few seconds also.Low compression sounds like the culprit.I think with that many miles you would want to do a valve job in any case before you do a swap.
 

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Being indirect injection, the 4BD2 is never going to start as easily as the direct injection 4BD1.
Can you put a voltmeter on the glowplug rail and earth to see how long they're getting power for? I suspect it's quite a lot longer than the few seconds the lamp is on.

220,000miles is nothing if the engine has been looked after. A compression test could be worth it for piece of mind.
 

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Discussion Starter · #7 ·
Thanks for the suggestions. I'll check the glow plug circuit and see what I can find. I gotta pick up a compression tester for diesel engines, too.
 

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Discussion Starter · #8 ·
I pulled the motor for my project, so I can't run it anymore... but I did have a chance to check the glow plugs. All four work, but they take about 10 seconds to glow. After 15 seconds, nearly the whole tip is cherry red. (This was in 60 degree weather.) The glow plug light in the truck only illuminated for about five seconds, regardless of the outside temperature. Perhaps the timer circuit was bad?

I haven't gotten a compression gauge yet, so I still need to check that.
 

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I pulled the motor for my project, so I can't run it anymore... but I did have a chance to check the glow plugs. All four work, but they take about 10 seconds to glow. After 15 seconds, nearly the whole tip is cherry red. (This was in 60 degree weather.) The glow plug light in the truck only illuminated for about five seconds, regardless of the outside temperature. Perhaps the timer circuit was bad?

I haven't gotten a compression gauge yet, so I still need to check that.
The glowplug light does only burn for about 5 seconds. But I think the circuit stays on for longer to keep them on while the engine is cranked.
 
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