New Project Truck. 92 250 4x4 Manual.

bumblebeer

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Well, much to my wife's dismay, I've bought another idi.

This one is a 92 250 4x4 extended cab zf5 with a really nice cm flatbed. 4.11 gears and 285/75r16s on aftermarket bullet holes. Painted in the always timeless Rust-oleum flat black. Not a clean truck, but exactly what I was looking for. I'll post some pictures later.

It was used on a cattle operation to haul a feeder back and forth between the barn and field. Ran every day, but short trips. Supposedly has a rebuilt engine in it with roughly 100k on it, but I'd take that with a huge grain of salt. The injection pump has been rebuilt, and the story roughly matches the milage displayed. Although the psom had a blown fuse when I bought it so who knows? The PO seems like he kept up oil changes and fuel filters and that's about it...

I've been steadily going through it.

The wiring is atrocious. Some due to rodents some due to the PO. Completely rewired all the lights, and I've been steadily rewiring in sensors. It was missing pretty much everything but power to the fuel shut off solenoid, oil pressure, temperature, and tach.

Changed all the fluids. PS pump had ATF, trans had gear oil, don't think the rear diff had ever been changed. I've got some AutoRX and Delo in the crankcase, and synthetic everywhere else.

Smoked like a freight train when cold. Turned out to be a bad glow plug. Went ahead and replaced them all. Was very happy to see they were motorcraft. No more smoke after that.

The transmission makes a weird noise when getting started in first or reverse, but I think it's got a SMF so that'd make sense. But other than that it was running really good. And getting great fuel mileage. I was touching 20mpg if i took it easy.

Figured I'd pull the injectors and pop test them just to confirm they were good. And that's when things went downhill...

They were not good. Like at all. Leaky but no drip. Atomization was terrible, and they didn't really have much of a pop, and no chatter at all. Just kinda pissed out when the pressure was high enough and then stopped when it wasn't. And that pressure was on the low side for all of them. Around 1600.

So I decided to rebuild them. And that really sucked. A lot. Like one of those old hoovers with the bag they use in schools and hotel rooms. I understand why good injectors are $400+ Anyway... after spending way more time on it than I wanted to, I got it done. 8 injectors popping at 1850 (+/-)50 with good spray pattern and nice chatter.

So I got them installed. And of course the next step was to time it with the newly rebuilt injectors. Got the DTI meter hooked up and went to 2000 to get a baseline, and holy hell! It was running at 11.5 btdc. I can't even imagine what it was before with the lower pop pressure injectors. So I set it down to a reasonable 9.5.

Next morning, it was back to smoking like a freight train at startup. It smoked a bit after warming up as well, but it was very whispy. And fuel economy was suffering. Down to about 16. Spent a while running down various rabbit holes, air intrusion, leak back over night, bad glow plugs or controller, etc. Finally decided to do a comp test.

I don't have the results in front of me, but 5 of 8 cylinders were 425-475. The other three were under 400 with the worst being 350. Ok, not great. But not the worst either. Least they all had some compression.

So I buttoned it back up and got it running. Cracked the injector on the lowest compression cylinder, #7 btw, and after a second or two, no smoke. Changed injectors with another cylinder just to be sure, and yep, problem stayed with the cylinder even with a different injector. Opened it back up, put a little 15w-40 down the glow plug hole and let it sit a half hour or so. Turned it over for a few seconds, then did another compression test. Got 425. So sounds like bad rings and or a grooved cylinder. I'm assuming due to washdown from the previously bad injectors.

So now I come to the actual reason for today's post, and thank you kind soul if you've stuck with me this far. I monkeyed around with the timing this evening, and I found that if I bump it up to 11 which is technically within factory spec of 8.5 btdc (+/-) 2.5 Although it seems an argument could be made that with ulsd the base of 8.5 should be bumped up to 9.5. Anyway... The smoke nearly disappeared! Just barely a hint of greyish smoke. Of course the engine was already warm, but it was still a noticable improvement over the more retarded timing.

I know the solution here is to replace the rings and possibly sleeve the cylinders, or pull the other 7.3 I have and swap it out. But I don't have room for any of that at the moment. I've got a couple other projects taking up space in the shop that will have to be finished first. Assuming I'm planning to pull the engine at some point anyway, what would I be risking by advancing the timing and continuing to run it as is now until I'm able to get to fixing it properly? Would probably have to wait until fall.
 
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Cant Write

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I’m not an expert, but advancing it and getting near 20 mpg sounds great to me. Gives you time to button up other projects. And work through other things that need attention.

You’re already armed with knowledge of the likely problem. So you’ve already prepared for rings or sleeves at a later date. Maybe it’s stuck rings....

Heck when you wrap up others, pull your other IDI and build it, then engine swap.

All I know for sure is by advancing your timing, you’ve done killed off your mosquito fog machine, and you’ll need that this summer. County might even pay you!!
 

bumblebeer

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Pictures as promised.
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captain720

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Run it, you know what’s wrong and your ready plus it sounds like it’s running rather well good for you.
 

bumblebeer

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I’m not an expert, but advancing it and getting near 20 mpg sounds great to me. Gives you time to button up other projects. And work through other things that need attention.

You’re already armed with knowledge of the likely problem. So you’ve already prepared for rings or sleeves at a later date. Maybe it’s stuck rings....

Heck when you wrap up others, pull your other IDI and build it, then engine swap.

Run it, you know what’s wrong and your ready plus it sounds like it’s running rather well good for you.

I wish it was just a stuck ring, but I don't think I'll be that lucky. I'd think that a stuck ring without any washdown or cylinder polishing, would cause excessive oil consumption. But I haven't noticed any. Although I haven't put enough miles on it yet to get a really good idea.

That's what I has hoping to hear about being able to run it, just didn't want to risk damaging something else other than what I already know needs work. I most likely will pull the other 7.3 and do a full build on it before dropping it in when I get the time.

However...

I've got the timing adjusted to 11.5, and that's as far as I'm willing to push it. There is still a good amount of smoke on cold startup, but a lot less than it was at 9.5. And there is still a slight haze once it warms up that does not change with rpm. Well the volume increases with RPM, but that makes since cause more RPM means more displacement across the same amount of time, but it doesn't seem to increase in proportion or quality if that makes sense. I don't think I was able to notice it last night because the sun was asleep.

I did pull the glow plugs and shot some compressed air in the cylinder. I couldn't tell when it was at tdc or the bottom of the stoke so I just keep bumping it over and pumping air. Air was alternately pushed out the intake and exhaust as you'd expect for the intake and exhaust strokes. I eventually got it to land on a compression stoke, and with the reg set at 90psi it turned the engine. So I knocked the reg down to 20psi and tried again. I did get a bit of air coming through the oil filler hole, but then I tried it against a high compression cylinder and it seemed to do about the same.

So all that makes me think that the cylinder isn't totally dead cause otherwise it shouldn't respond to changes in timing or engine temperature. But it definitely isn't achieving full combustion.

I remember the PO said the pump was "turned up" when it was installed. The cover plate doesn't have a paint mark, so I can't confirm that one way or the other, but I think I'll turn it down a flat or two and see if that improves the smoke situation. I mean it seems to run okay, but smoke out the tail pipe = money out my wallet. :frustrate
 

bumblebeer

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Your question - you’re not going to hurt it at 9.5

11, or now 11.5 not 9.5! I set it to 9.5 and that's when it started smoking. It improves with more advanced timing, but I'm not willing to go further than 11.5 . when I bought it before replacing the injectors and timing, I figure it was at around 13° btdc.
 

hacked89

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11, or now 11.5 not 9.5! I set it to 9.5 and that's when it started smoking. It improves with more advanced timing, but I'm not willing to go further than 11.5 . when I bought it before replacing the injectors and timing, I figure it was at around 13° btdc.
I’ve tried from 3 to 16 for fun and honestly it’s a resilient engine for being off spec. I ran one at 11 for awhile and noticed hard hot restarts and I pulled it back. But if you have no issue then run it for now.
 

IDIBRONCO

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Well, much to my wife's dismay, I've bought another idi.
Addictive aren't they. In a good way though.
I know the solution here is to replace the rings and possibly sleeve the cylinders, or pull the other 7.3 I have and swap it out.
That's not the only solution,only the "ideal" solution.
I wish it was just a stuck ring, but I don't think I'll be that lucky. I'd think that a stuck ring without any washdown or cylinder polishing, would cause excessive oil consumption. But I haven't noticed any. Although I haven't put enough miles on it yet to get a really good idea.
You never know.
I’ve tried from 3 to 16 for fun and honestly it’s a resilient engine for being off spec. I ran one at 11 for awhile and noticed hard hot restarts and I pulled it back. But if you have no issue then run it for now.
Each pump is different. Maybe this one likes more timing advance than others?
 

bumblebeer

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So I've got the beast tamed just a bit. Turning the fuel down 2 flats seemed to really help. Smokes for a minute or two right after a cold start, but clears up quickly. Then it puffs out some light haze after the cold timing advance clicks off until it warms up. When it gets to full operating temp no smoke or haze at idle. It's still give a bit of a puff when lugging at WOT, but that's to be expected. Fuel mileage on the next tank will be the real tell.

It's driving and shifting a lot better too. I had to really baby her to get good smooth shifts before. And upshifting above 2000 rpm was rough no matter what. Now it's smooth sailing and I can really wind it up and still get a good clean shift. It is a bit more docile, but still seems to have plenty of power. Which makes sense assuming it was getting a lot of excess fuel before.

I did pull the valve covers to replace the gaskets cause I had a small oil leak on the passenger side. I noticed the push rods had some rust on them, so I'm assuming it's spent some time with the covers off or has had a blown head gasket or oil cooler rings in the past. But I haven't noticed any coolant in the oil or oil in the coolant, and other than a bit of rust everything under the cover looked fine. I'll post some pictures this evening so y'all can take a look. So of course, I did the only reasonable thing and slapped the valve covers right back on lol. I'll pull them again after the next oil change and I guess we'll see how AutoRX works on rust.
 

captain720

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Surface rust on lifters is in my opinion no big deal at all, mine had some just from sitting in a hole in the ground for ten years. The surface rust went away into the oil and never caused a problem.
 

Nero

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I had some on mine, and I drive mine maybe once a month, it's definitely no issue.
 

asmith

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Just so you know a lot of guys run gear oil in their ZF5s to quiet down the gear rollover from a SMF, if I remember right I think 30w is what was mostly used. and ATF is commonly used for power steering fluid, again I seem to remember type F ATF is actually speced by Ford for their power steering.
 

bumblebeer

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Just so you know a lot of guys run gear oil in their ZF5s to quiet down the gear rollover from a SMF, if I remember right I think 30w is what was mostly used. and ATF is commonly used for power steering fluid, again I seem to remember type F ATF is actually speced by Ford for their power steering.

You're dead on about the ATF type F. I managed to track down a manual and that is the recommended fluid from Ford.

I've read about folks running non detergent straight 30 in their zf5s but I my case I didn't notice any additional noise going to ATF and shifting was a lot smoother. Now granted that is with a good quality full synthetic ATF so ymmv.
 
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