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Rebuilding top end of motor.

2K views 28 replies 6 participants last post by  Bill1013 
#1 · (Edited)
So due to a series of Unfortunate Events, I'm going to be rebuilding entire top end of my motor over the next few weeks. Does anyone have any suggestions? This will be my first time going this far into a diesel motor. I will post pictures of progress. Just wondering if anyone out there has done this that could give me some pointers. I am going to need all the help i can get with this....thanks in advance!
 
#2 · (Edited)
If by top end you mean just the heads? If so, there's not much you can do other than R&R them and inspect for rocker arm/pushrod wear. All the head work has to be done in a truck shop or auto machine shop. They'll check for excessive valve guide wear, head cracks, check for head warpage 4 different ways with a straight edge (.006 max is allowed IIRC), grind valves and seats and replace valves as needed. Check valve spring tension and replace or shim as needed.
 
#3 ·
What makes you think the top end needs rebuilding?
 
#4 ·
If you ran it HOT EGT's (around 1400*F) you can bet the precups are cracked. Maybe piston damage if held at that temp for 10 - 15 minutes.

What Chuckster57 said. ^^^^^. Why?
 
#5 ·
What makes you think the top end needs rebuilding?
If by top end you mean just the heads? If so, there's not much you can do other than R&R them and inspect for rocker arm/pushrod wear. All the head work has to be done in a truck shop or auto machine shop. They'll check for excessive valve guide wear, head cracks, check for head warpage 4 different ways with a straight edge (.006 max is allowed IIRC), grind valves and seats and replace valves as needed. Check valve spring tension and replace or shim as needed.

I own a custom motorcycle shop with a functional machine shop. Most of the time I have people just bring me their diesel heads and I do the work there with just the static head. I guess I figure I better do this right something is going on inside, it's the second time that the that a fuel injector has gotten stuck(bottom half) inside the head on the passenger side. The first time i made a tool and popped it out after a few tries. This time it didn't work so I know I have to pull that head. The first time it got stuck I understood because they were original injectors 250k mi. This time I am at a loss for words because the new injectors have only 8k miles on them before one of them 2 of them failed. I am going to place a call BWD and ask them if they have had faulty callins. I have always been taught that it is good practice that if you're already there to go ahead and change the base gasket. Not sure if that goes for diesel also. Would like some feed back on that. Also since I am doing one side I am going to go ahead and do both. Any special instructions or pointers would be greatly appreciated. Chuck, glad to see ya in here on this!
 
#6 ·
That makes doing the machine work a lot easier. Gotta figure out WHY a new injector got stuck.

FWIW, I would fix the issue, check for flatness and if good put things back together.
 
#9 ·
I did mine and it was pretty straight forward. 1990 7.3 IDI and I'm a shade tree mechanic. I got a lot of help from here. The most difficult part was getting the heads in place without screwing up the head gasket. On mine, some of the bolts have to be in the head before you lower it on especially on the passenger side. The head is very heavy and I didn't have a cherry picker. I used a game hoist bolted to the rafter in the garage. That was 235,000 miles ago. If the motors out you wont have this problem.
 
#11 · (Edited)
IDI isn't Wet cylinder. Block is one piece and bored/honed. If your going to pull it out and put it on a stand, I would probably do bearings/rings because "your there". My training for 40+ yrs is with lot of miles, if your going to take it apart might as well replace service items.
 
#12 ·
I see, this truck is my daily driver. I have a harley that i am going to be riding in the meantime. I just had ACL surgery about a month and a half ago. So its hard for me to do a lot of the things i normally would be able to. I have to get it done though before i go back to work at the beginning of june. So i guess ill be getting busy here on monday.
 
#13 ·
Sounds like it. Be careful not to tear anything, making your recovery that much longer. Any questions, feel free to post as there is almost always someone on the forum with answers.
 
#16 ·
Yeah. There are lifting Eyes, but you could make your own.
I'm thinking a couple of rocker pedestals and a chain between them to lessen the load on any single side.
 
#17 ·
Like eric40901 said the heads are super heavy and its super hard to keep from botching the gaskets during installation. If you pull the motor make sure your hoist is rated for the task, it weighs about 1,000lbs. While your heads are off I would recommend changing the plugs in the back of the oil rails. They are impossible to get to with them on the truck. I've heard of leaks there and it would suck to do all that work and find leaks there later. Are you planning to use regular head bolts? If not good luck trying to get those heads on in the truck with studs in place.....it won't happen. In my opinion pull the motor throw it on a stand and check it out. That will make the head work that much easier. Plus when you reinstall the injector cups it will be a sinch. Good luck....
 
#18 ·
Since its an IDI, there are no oil rails, or injector cups.


After thinking a bit more, there will be machined, threaded holes on the ends of the heads for mounting accessory stuff. A plate with an Eye at each end will lift the head with ease.
 
#19 ·
I did it with the motor in the truck. I meant to say drivers side was the difficult side to lower the head on. I messed up the gasket on the first try and had to get another. Some one on here had tip to use the old bolts with the heads cut off as a guide. It did help on the second try. This will make more sense after you get into it.
 
#23 ·
Those heads weigh 85-90 lbs each. The bolts next to the firewall won't come all the way out until the head is removed, lift them up and fasten them somehow, I use a wire tie around them. Hook however your going to use, so the heads come up at an angle, the positioning dowels in the block on each upper corner will tend to make the head stick.

You mentioned that a couple of injectors came apart leaving the nozzle in the block. To remove them the next time, take an old injector and grind the large threads off, then you can screw it back into the nozzle, keep screwing in and lifting, the nozzle will come right out then with the top end of the injector.
 
#26 ·
SWEEEEETTTTTT!!!!!
 
#29 ·
Always good to hear these old bastards are up and running again. Always lots of fun working on them. I'm 88 so it's a little difficult to get around them anymore.
 
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