New Project Truck. 92 250 4x4 Manual.

bumblebeer

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Compression check would be my starting point.

James
Apparently my compression tester has given up the ghost. It'll read, but won't hold pressure. I threw it on there anyway. Doesn't look like I have any totally dead holes. The needle was topping out around the 300psi range for each cylinder. Obviously not super accurate, but they are at least making compression.

I'm also getting a decent amount of smoke all the time now. So I fiddled around cracking the injection lines. Cylinder #7 is still slacking on the job, but I crack the line and it's still smoking, tighten it back up and the smoke increases. I guess the extra smoke could be from the oil control ring on my old friend #7 crapping out. Cause she is drinking the oil pretty good now, but that would also be a sign of a worn guide. :dunno Otherwise everything responded as expected.

I'm going to get a working compression tester, and I could get some real compression numbers. And pull the valve covers and look for gunk buildup. Pull the rockers and wiggle the top of the valves, but I'm not really sure I see the point. I'm not in a position to tear into it right now, so I'd probably just keep running it in any case. What are the chances it would be something like a bent rod on an intake valve, or a broke spring, or something else that can be fixed without pulling the engine or heads? Pretty slim I figure.

I'll let it warm up tomorrow, and get some readings with the infrared thermometer to see if anything is already in dire straights, but otherwise will probably just let it be and try to get started on an engine rebuild as soon as I can. :fan:
 

Dirtleg

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Not sure if your A/C is still holding but I found with mine after it was converted to 134, the R12 to 134a adapters would cause the refrigerant to leak out very slowly. I'd get a summer out of it but then next year, low on refrigerant again. Was maddening. I did find while trying to locate the leak, that my 6 month old compressor was leaking at the body seal. Then I thought everything was fixed when I replaced that with a new Motorcraft compressor. Nope.

Solution? Take the 134a adapters off after charging the system. Has been 3-4 years now without issue. Blows plenty cold. Also black truck.
 

Nero

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I have the exact same issue. I might try taking my fittings off next time I recharge it... Good tip.
 

bumblebeer

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Not sure if your A/C is still holding but I found with mine after it was converted to 134, the R12 to 134a adapters would cause the refrigerant to leak out very slowly. I'd get a summer out of it but then next year, low on refrigerant again. Was maddening. I did find while trying to locate the leak, that my 6 month old compressor was leaking at the body seal. Then I thought everything was fixed when I replaced that with a new Motorcraft compressor. Nope.

Solution? Take the 134a adapters off after charging the system. Has been 3-4 years now without issue. Blows plenty cold. Also black truck.

Also make sure your schrader valves are in good shape.

Yeah, it's still holding up really well! But I did notice a leak from the low side fill port valve. The conversion fittings I had on here are really ******. I just tightened the Schrader valve and it seemed to stop the leak. But I'll keep that in mind and will probably remove the fitting if it gives me any more trouble. And I'm still not sure why, but the high pressure cutt off switch will occasionally kill the compressor when reving above 2600 rpm. But if the rpms drop, or stay stable, it will kick right back on after a second or two. It's cooling really well and hasn't popped the relief valve so I'm still considering it "fixed" lol.
 

bumblebeer

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Oh and I did some more investigation on the chuff and smoke issue. Turns out it's not a valve after all. It was a timing issue. She was extremely retarded. Like 4.5* ATDC! :eek:

I think I know why and now I'm just hoping I haven't killed the injector pump.

The PO said that they haven't used the front tank in years. So I've just been using the rear as well. I pumped the front tank and got out about 10 gallons of nasty brown diesel. I poured some tank cleaner and a couple gallons of diesel in there then drove it for a few days and pumped it back out. Repeated this a few times until it came out nice and clean. I should have just dropped the tank cause that ended up being expensive, but I was feeling lazy...

Anyway, been running that front tank for the last couple of days and I think there is an air intrusion somewhere between it and the selector valve. Driving around today I noticed if I swapped to the rear tank the smoke cleared almost completely after a couple minutes. Swap back to the front tank and it smokes like a freight train.

Looks like the ip has been sucking a lot of air. Just hope I'll be able to adjust it back in time and it isn't too far gone. I'll update when I know more.
 

bumblebeer

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I've adjust the pump about as much as I can without removing the injector lines. It's got it from 4.5* ATDC to ~3* BTDC.

I came across this post in another thread.

Typically, when a pump is totally unusable, it's because the head/rotor clearance got high enough that it won't start when hot(requires complete replacement of head/rotor, the expensive internal parts). This is a true 'failure'.
A more typical "failure" is when the timing gets stuck fully retarded. Not entirely sure why this happens, but over time, the pump will become more and more retarded, or simply 'jump' much more retarded - resulting in blue or even white smoke, crummy performance.
When I have a pump that otherwise works fine, but is doing this, I just pry up the IP gear cover and skip the IP gear a tooth ahead. This gives about 7 degrees of advance, generally enough to get it back into the normal "adjustment range" by rotating the pump. It's a cheap fix that seems to work fine, though sometimes you need to adjust the light load cam from there if it's too advanced down low.

One other failure that I've heard about but not seen myself is the head/rotor actually siezing together. This would be due to a lack of lubrication in the tight tolerances, or some sort of metal getting in the wrong spot. When this happens, the "tang" breaks off internally and the pump drive spins freely. This IP core is basically spare parts and not practically rebuildable.

You also have seals leaking/weeping diesel, which isn't a 'failure' per se, but becomes one of those things you want to replace. Again, something that ordinarally would need replacement, but it's possible to swap seals without too much hassle, especially if it's one that's easy to get to.



Any failed bearing material would be in the housing, not in the pressure side of the pump. It would get returned to the tank and filtered through the fuel filter before getting to the injectors.
Pretty much the only thing that would send material to the injectors would be the inlet vane pump on the input of the IP.

We shall see. Fortunately, it's a thrust bearing, not a side bearing, so there should be no wear on it - I'd expect the only real issue would be destroyed seals if it slid too far out. Remember, the shaft comes out that way, so there's no bosses or other diameters to catch on things and wear.


No, you don't need any special tooling. Just need a vice, hand tools and allen wrenches. The only 'special tool' that you are supposed to need, a tool for removing the inlet cone on the back, well, a open end wrench worked just fine. At least on the pumps I took apart, it wasn't on there that tightly. You could even leave the brass adapter from the inlet hardline still attached to the IP, for added strength there.


I've done it several times. Never had any issues. In my case, it was simply a matter of tearing it down far enough to replace the shaft seals(which is /past/ the thrust washer portion), which I did. Seriously - you don't *have* to take apart every single screw and plunger buried deep in the head or housing - just need to get the main parts out, which limits what you need to put back.
There's also settings like the guide stud in the back which will work "ok" at pretty much any position you physically can put it in; it will just affect drivability - so you can adjust and drive and get it good enough again.


Would it? Most people don't even want to mess with the pump at all, let alone tear into and rebuild one. Instructions are out there, and, well, I followed(most) of it and succeeded... but that was just a re-seal job.
The real problem is that to affect performance and actually make one new, you tend to need new parts or at least a flow bench to modify some of the settings. Otherwise, you just have a fixed, but still worn IP.

I think that's pretty close to what happened here. May or may not have anything to do with the air intrusion, but otherwise seems identical. So my questions are:

1. Y'all think I should remove the hard lines and rotate the pump, or jump a tooth?
2. Assuming I can get it properly timed at 2000 rpm, I want to make sure the cam advance is working properly. What should I be reading for timing at idle and redline when I'm 9.5* at 2000.
 

IDIBRONCO

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1. Y'all think I should remove the hard lines and rotate the pump, or jump a tooth?
Even though some people do, and Mac Robb is one of them, I never recommend skipping a tooth on the IP gear. I'd loosen, not remove, the injector lines and rotate the pump some more. All you have to do is loosen the lines enough that they no longer hold tight to the pump.
 

bumblebeer

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I was able to get it back in time without jumping a tooth. I did have to remove the injector lines from the back of the pump. I honestly do not see how it would be possible to just loosen the lower lines without removing the top ones first. Moved it nearly all the way to the end of the adjustment range towards the passenger fender. Put it back together and was too far advanced, but I had enough play to retard it back to 9.5* without needing to fiddle with the lines again.

It's running good again, here's hoping it'll hold up.

I believe it should be most advanced at idle and most retarded at redline. Which mine is, so I think everything is working correctly, but I would still love to get some numbers for what timing readings should be across the rpm spectrum.
 

IDIBRONCO

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I honestly do not see how it would be possible to just loosen the lower lines without removing the top ones first.
Use a crow's foot on a short extension. I believe that you do have to remove the line from the fuel filter too do this but may be wrong since it's been years since I've done this.
 

Nero

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Banana wrench. Or make one with a little torch magic.
 

bumblebeer

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So I guess my injection pump has failed?

It's went retarded again. I'm going to adjust it, but I don't think it's going to have enough adjustment left to get back in time.
 

bumblebeer

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Well a bit of good news with the bad I reckon. Just found a 7.3 locally that's already been pulled. Price seems fair, so I'll more than likely get it.

I was thinking I'd have to wait until fall to start a rebuild cause I don't have enough room in the shop right now to pull an engine from a donor truck. But with it already being out, I would be able to go ahead and get started! :cheers:
 
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