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85 F250 Once Over

1210 Views 7 Replies 6 Participants Last post by  cdnsarguy
It's nothing short of a miracle that I stumbled across this sight. I have been pouring over it and learning new things as fast as I can click from thread to thread.

I've got an 85 F250 2WD w/170,000 miles that I've owned since 2000. Previous farm/ranch truck for another owner who I don't think took good care of it. It's always smoked at start (gray like a jet engine lighting off) and under load (black). It also surges once I get to the lower half of the aft fuel tank so I try not to use that tank since I'm sure it is filthy. About a year ago I started having a problem with the engine starting and immediately dying followed by running fine after a little cranking to get it started. A shortage of time/laziness kept me from looking further into it. A few days later I noticed a strong fuel smell and upon investigation one of the fuel injection lines cracked so I replaced that. Everything was fine for a couple months then it did it again with another injection line which I replaced. After replacing that line I still had a diesel smell and found fuel seeping from the top of the injectors at the feed Ts and return lines. Of course, I was still having the starting difficulties. About that time I left for Iraq so the truck got parked. Since getting back I've finally gotten around to looking in more depth and found this website where I've learned about air intrusion etc. Also, just as I was starting to research for info online I decided to disassemble everything from the IP downstream and see if there was anything obvious. I hadn't learned about the trouble with the feed Ts yet, but when I pulled them off I thought, "this has to be the problem." I've now gotten the fuel injectors out with much strain as they were more or less frozen in. Most of them have some sort of hard deposit built up just below the threads, a few pretty bad. The passenger side bank doesn't look as bad, but on the driver side the further back you get the worse they look. The aftmost (I can't remember the cylinder # now) seems to be coated in what appears to be oil. Anyway, I'm going to replace them, test the glowplugs and replace them if required. Suppose I'll do a compression test while I'm at it. Also going to pull the valve covers and see what I find. The oil on the one injector makes me a little apprehensive. Probably going to replace the lift pump too. I'd like to avoid replacing the IP.

If you've made it through my book, thanks. Any insight and hints would be great. I've always worked on my own cars but getting this in depth with a diesel is new. Not looking to boost performance, just want a good running stock truck.
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Thanks for all the tips and the thanks you've expressed. You may be surprised how much a simple thanks means.

Well, I am sure having fun with this truck. I've always liked to take things apart and put them back together. When I was 4 or 5 I did that with an alarm clock. Unfortunately, I didn't unplug it first! Well, I finally got around to getting the valve cover off on the driver side of the vehicle. This was the side with the dirtier injectors. I didn't see any problems (yet) that could be allowing oil to migrate into the cylinder. Upon closer inspection I realized that the oily part of my injectors is within the tube between the threads and the copper gasket. If oil in the cylinder is getting to the injector then it would have to get past that gasket. Otherwise, the only way in is past the threads.

I pulled the CDR off just to take a look. I did have a lot of oil in the intake with the appearance of it running out of the CDR. I don't know how visible the diaphragm in the CDR should be, but all I could see/feel was the spring. All the "conflicting" information on the CDR that I've run across on the site has led me to do a bit of reading on it's purpose. Basically, what I've found is that it is to maintain as close to static pressure differential as possible. I believe the numbers were 4 to 6 inches. Seems like a simple design to perform a simple function. Usually that means a part that should last and last.

I also pulled the intake manifold off just so I could give it a good cleaning, and I was curious about how much gunk I may or may not find underneath it and the valley pan. I'm having a little trouble with the valley pan. All bolts are removed but I can't seem to find the valley pan drain plug which apparently needs to be removed. Is this something obvious or something you'd have to know where to look? I don't want to bend it up getting it out.

Next question is should I pull the heads? Part of me wants to just to do it and the practical side of me wants to so I can take a good look at the valve seats and cylinders. Of course another part of me wants to leave it alone lest I find some horrible stuff going on!

Like I said, I'm having fun with this! I haven't checked the glow plugs yet or (obviously) the compression.
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It is only curiosity. But then, curiosity killed the cat; will it kill my truck? Maybe I had better rethink this!
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