Yesterday I bought a 1988 F250 XLT Lariat 4x4 7.3 Diesel King cab.



to get it to start you have to work the throttle and turn the key for 5 times as long as you should, has to turn over a bunch before it will start running. It has this problem even after it has fully warmed up so I dont think its the glow plugs. It has white smoke out the tail pipe even when its warmed up too. So I was thinking headgaskets might need replaced.

I have worked on more than 30-40 gas vehicles including major engine overhauls or replacements, but this is the first Diesel I have ever worked on or owned. (I am very excited, plan to keep this truck for a looooooong time)

So I am looking towards those that have been there done that, for a check list of everything I should check to get this vehicle running good again.

here is what the original craigslist ad said:
so to recap issues are:
1. very difficult to start, even once warmed up.
2. once running stalls easy, especially if you put it in gear
3. white smoke, even once warmed up and at an idle, suspect head gasket?
4. brakes work but no power, suspect brake booster or vacuum leak

I just bought this truck off craigslist last night for $425. I got it that cheap because he was ready to take it to the scrap yard and thats how much they said they could give him, but not until after the 4th of july, and he wanted to sell it that day. I didn't get home until around 2am.

So this morning I figured I would start off with a compression test, atleast thats what I usually do with my gas vehicles that I work on... What kind of compression numbers should I be seening on a healthy truck?

Also on gas vehicles I will put my lisle no spill funnel on the radiator and look for bubbles, thats usually a sign of head gasket failure if the bubbles never clear up, I assume its the same for a diesel?

 

White smoke on a diesel can be unburnt fuel. A compression check is a good idea, you will need a diesel specific tool. There was a thread recently about which kit actually worked on our engines. Don't assume the new injection pump and injectors are good.

 

it could also be something as stupid as an improperly installed injector pump that need the timing set.
for the lack of power brakes, 99.9% of the time it is a bad vacuum pump. .
hard to start is a sign of bad timing, and bad glow plugs. did they say what type of glow plugs were put in?
anything other than motorcraft ZD-9 plugs should be removed and thrown in the garbage where they belong.

 

Thanks for the response guys. I didn't realize I would need a diesel specific compression tester. I will have to look for that thread, and get that tool.

I will also have to read up on how to set the timing on these... on a gas vehicle you adjust the distributor or camshaft angle sensor using a timing light... im guessing it will be much different on these, since there arent spark plugs.

I just called the guy I bought it from he has no idea what parts, etc were installed. So it will be up to me to investigate what parts are in it, hopefully there are some marking on the plugs so I can see if they are motorcraft.

I found an OEM vacuum pump on ebay for $85 so I will probably go ahead and buy one.

Can these diesels put out white smoke from unburt fuel even after the motor has warmed up and the truck is just sitting there idleing?

I have not checked yet, but if I keep getting bubbles out of the radiator then its a good bet that the head gaskets need replaced right?

 

Not gonna believe what I just found, had it been daylight when I bought the truck I probably would have noticed it then.





That plug seems to be the MAIN PLUG that connects the trucks wiring harness to the engine, well.. I bumped the plug and could hear a short like CLICK and then something on the engine started running...

So that plug is problem number 1, gonna head to pick a part tomorrow and just get the entire wiring harness out of another truck, I could get just the plug and solder and shrink wrap it in but I don't like splicing wires if it can be avoided, plus who knows what other problems this harness might have... that plug looked partly melted on top of being broken and jerry rigged.

all of the battery connections are not very good either, so I will fix that up too.

rest of the engine bay:

 

i am not positive, but i am pretty sure that plug is for the glow plug circuit.

 

I think the black orange wires are for the charging circuit

 

These heads have a tendency to crack. Most machine shops will say "that is a running crack" meaning that you can run the engine with that sized crack. The real story is that ANY crack will never get any better. Last time I checked head castings were around $600- $700 ea.
It helps that you picked it up cheap!

 

What tests can I do to determine if my head(s) have cracks?

 

when I bought the truck he already had it running when I got there.

I have not been able to start it yet today. with the two brand new fully charged deep cycle batteries it is STRUGGLING to turn over the motor. I hooked up a third deep cycle with jumper cables give me even more cranking amps.

I have it turning over, but its acting like a car that has really bad blown headgaskets, and the cylinders are full of water, making it hard to turn the motor over. (because of the compression.)

sounds and seems like its kinda hydrolocking with how difficult a time its having to start, either that or the rings are seizing up... I am getting some resistance from somewhere, that much is for sure.


EDIT: Just learned of cavitation, hopefully its not that: https://www.ford-trucks.com/forums/1...owner-faq.html

 

Probably a bad starter, they can't handle being cranked on for eternity when the GP system isn't working.
Pull the GPs and crank on it a little, if there's coolant in the cylinder(s) it'll blow out the GP hole and confirm if that's a problem.

 

should I pull all the GPs or do one cylinder at a time? when checking for the coolant.

 

Either way, but if you do one at a time pull the wire from the fuel shutoff switch so the engine doesn't start on you while you're cranking.

 

I don't know how to check for cracks other than pulling them off.

Is this an auto trans or manual?? If a manual - pull start it.