So as stated above cylinder 7,2,and 3 have low compression so the truck wont even turn over. The shop that it was taken to says that it would be cheaper to get a new motor cause that labor to either fix the piston rings or to check the valves would be the cost of a crate motor. So my question is how hard would it be for me to do it. I've never messed with an IDI before. Also could it possibly be caused by the cdr valve. the motor has 360,000 miles.

 

How low are we talking? An IDI will run on 5 cylinders, and it'll probably start firing on the other 3 once it runs for a minutes.
When you say, "won't turn over," do you mean it won't crank or it won't start?

 

Yes, please explain. If the shop did a compression test that means the engine can crank.

If you need to get an engine you'll have to get one from a salvage yard. I don't think 6.9l or 7.3l IDIs are offered as a crate engine anymore.

Use this search engine to find an IDI in a salvage yard near you.

http://www.car-part.com/
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So it barely cranks. Has 2 Relatively new red top batteries. Compression is low to mid 200s

 

if it just barely cranks i would look at battery cables, starter, and batteries themselves.
if it indeed has low compression, it would spin over very fast.

 

yeah so it struggles to spin over really at all. So whenSi bought the truck I replaced the sending unit on the rear tank replaced the fuel filter proved the system and it ran drove it about a mile and slowly died. Tried to reprise it but I couldn't get any fuel through. But the shop says it's a compression issue

 

me thinks the shop may be trying to sell you a $8,000 engine and replace a $120 starter.

 

i do agree with that thought. so ill check the cables and starter. and i guess the fuel pump cause its not getting any fuel

 

not getting fuel could be a few different things. low fuel level in tank being #1. the fuel pickup in the tank tends t crack around the 1/4 tank mark which will cause it to suck air and make like it has run out of fuel even though the gauge says it still has fuel in it.
or it could be a cracked line. or bad tank selector valve. or bad lift pump.
what i do is connect a portable fuel tank directly to the fuel pump and see if it will run. if yes, move the portable tank connection back to the switch. if still runs move back to the fuel tank connection itself. if still runs, the problem is in the tank.

load test the batteries too, new does not mean good anymore.
top of the pre powerstroke page in the read first box is how to tell a good starter from a bad one.
those two videos are quick reference for starter health. i did not know how bad my starter was until i put the new one in.

 

^^^THIS^^^

The shop needs to give you compression results on ALL the cylinders. They should do the compression test with all the glow plugs removed. If they didn't do that, then...

 

so i can say with 100% confidence that my starter is good,

 

If it was low compression the motor would spin easily..

If it's not cranking fast, go over the batteries, esp the connections, grounds, starter, and put the batteries on a charger.

Compression shouldn't have anything to do with cranking..

Sounds like bad connections to the batteries and or starter.

and then it's probably also something plugging up the fsv fuel selector valve, junk in the tank plugging the pickup, or a collapsed fuel hose or debris.

This is very common, unfortunately, the fuel system was intended to run, built and designed around regular diesel fuel.

They switched over to a new lower quality, standard, ultra low sulfer diesel in the fuel pumps today, this new fuel is corrosive to natural plastic and rubber.

Our fuel system had plastic 'shower head' strainers in the tank, that exploded into 1000 little pieces and plugged up the tanks and fuel lines, also hoses degraded from the inside out.

It would be more unexpected if you didn't have a fuel delivery problem.

After tiring with plugged lines and crap aftermarket fuel pumps, I recently resolved to totally fix the problem, and I rebuilt the entire fueling system front to back.

now I have no issues, I used 1/2 plumbing PEX, stainless strainers, cleaned and repaired both tanks, FSV delete, manual fuel selector valves, new rated rubber fuel hoses, everywhere, everything new or repaired.

For you, I would suggest getting a Jerry can and a good electrical fuel pump and pipe the delivery and return directly to the IP, and then replace and repair as much of the old fuel system as you can or want to.

TLDR
batts, starter, cables, for cranking.

repair fuel system to and fuel lift pump to keep it running.

I wouldn't go with any shop advice until I could crank and start it, and give it straight dope fuel from a Jerry can, and then go from there.

 

so i finally got the exact compression numbers
1. 420
2. 400
3. 400
4. 405
5. 400
6. 355
7. 200
8. 300

 

The head gasket could be blown between cylinders 6 & 8.

 

I second that opine, probably the head gasket, mine burned through like that, I think maybe in those same cylinders, rear two cylinders on mine. They accumulate oil from the cdr and seep oil and pressure and blow after some, several hundred thousand miles, not a problem, it just happens like that with high milage and use all head gaskets will probably go eventually if you put alot of miles on it.

For me, it had made a light chuffing noise out the intake like an errant exhause note, it was indeed blowing the exhaust forward though the intake manifold, it could otherwise blow exhaust into the coolant, but mine was a break in the land between those two cylinders.

It had a bazillion miles, when the head gasket let go, so I wasn't mad at her.

If you're really ded set on rebuilding the engine, and have the money to do it, go for it, it can only be to the good.

But beware, when you get your fresh engine back from the shop, you'll still have to fix the problems of starting, and keeping it running, and tuned up properly.

I'd suggest that you purchase all yhe engine parts, after asking the machine shop to mic the tolerances, head gasket brand, rear main seal brand, use oe bimetal or whatever origanal style bearings, I wouldn't use the new cheap aluminum composite equivalents for like mains or however, don't let anyone tell you, that "we use these new parts all the time without a problem" for gaskets bearings and rings and pistons. Research every single part, they want to install and get the original or best available.

Oe stuff might cost 200 for a set of one or another bearings or pistons or something, and new equivalent might cost like 30.

There is a huge problem with the new garbage, will run for a wile fine, but not to last hundreds of thousands of miles, and soak up abuse like this one, it likes to get beat on, thats what makes these motors good in the first place, toughness and loyalty.

Yes, rebuild it if you can, and use good quality parts, then fix it all up, you'll have a very nice truck.