Rebuilding a 7.3

[big van]

How come Mel? I'd like to know what the +/- for each one seein' how this 7.3 is my 1st diesel.

 

[Dieselguy123]

How come Mel? I'd like to know what the +/- for each one seein' how this 7.3 is my 1st diesel.

I'm interested too!

 

[oregon-mike]

If I ever end up needing to replace the engine in my '93 I'll look for a 6.9. Not sure what Mel's reasons are, but for me it's the thickness (or lack of really) of the cylinder walls on the 7.3. No cavitation problems with the 6.9 block.

Mike

 

[Agnem]

Mike nailed it. All things considered, if you don't know the SCA history of an engine, you'd be far better off buying a 150K on the clock 6.9, then a 7.3. I also think the 6.9, if equipped with all the upgrades given the 7.3, would have been a more stout engine. There is also the issue of the 7.3's valve seals. I'd rather have a 6.9 that burns oil, then a 7.3 that eats valves. Again, this is just taking an engine and running it. Naturally there are things that should be done to either to prevent these issues. The last issue is 6.9's are easier to cool because of the extra coolant passages. Granted, a cool 6.9 with a leaky headgasket is not as nice as a dry overheated 7.3, but the 6.9 will live to see that gasket get replaced.

 

[Darrin Tosh]

I agee with you Mel on less problems with the 6.9, I just don't want to drop 20HP right off the bat.

HOWEVER,..I have made my decision!

I have decided to leave the head gasket alone in the truck, Drive it only when needed, and rebuild the motor in my garage. When that is done then install it and be done with it once and for all!

I will take my time with it but woild like running in about 3 to 4 weeks. Well see how it goes.

At this point I am looking for any advice for rebuild kits, prices, machine work to be done, porting the heads, balancing the motor, things like that. Any links go other rebuilds that you know of?

Has anyone heard of running the performance cam by Melling for these motors that Summitt sells?

Here is a pic of the motor, and I will start the dissasemble process tomorrow morning!

 

[Dsl_Dog_Treat]

Here is a pic of the motor, and I will start the dissasemble process tomorrow morning!

AHHHHHH!!!
Hey that looks familiar.
Gee thanks for reminding me bout the HP drop.
Sorry ya set on the can a little too long last night.

 

[icanfixall]

Oh my goodness. What I would do to have a shop that size.... Thats a good idea, just do what you need to do. Give Promar a call on what a sleeved, decked and line bored block will cost. They seem to have a handle on these motors.

 

[Darrin Tosh]

I will call them tomorrow and see what they say.

Thanks for the Shop comments! Yes we are spoiled! Plus it is even Air Conditioned. You can see the wall behind the tool box, and bench, that is where Big Ed is parked for now. Then to the right there is another Lift.

Works very well for Bob and I.

I am looking at getting the motor balanced, and porting the heads. I should have the motor torn down tomorrow, I got it down to the heads tonight.

Should be a fun project.

 

[icanfixall]

Have the heads hot tanked and checked for cracks before you port them. I'll sent you a pic of the grinding burrs and sandpaper rolls that I found works best. Just take your time and watch the valve seats. They can be hurt.... I used the exhaust manifold gasket to show me what needed to be removed. Clean up the insides of the exhaust logs too especially where they feed into the "Y pipe". That area needs to be as smooth as possible. Lots of flow and heat in that area.

 

[Darrin Tosh]

Thanks!

I got the motor apart and found some cracks in 3 seats. Pictured is the worst one. There is a lifter that is totally gone as Rob found when he did the motor swap for me.

Can the cracks be repaird or am I looking for new heads?

Couple of scred pistons, the cylnder walls look good. My machine shop guy is stoping by today or tomorrw to take a look as well.

Here are some pics:

 

[Dsl_Dog_Treat]

Looks like ya got some good spare parts there.
Yup gonna need some different heads and a check on the crank for wear with it getting into the copper on the bearings.
Caught it in time so shouldn't be too bad.
Pistons don't look too bad considering how much time it had bee run hauling firewood on 7 cylinders.

I recognize that lifter too.

How'd the tops look?

Prolly a good thing That one didn't make it into the Colorado truck. Not much life left on it.

 

[icanfixall]

The heads can be repaired but would you trust them?? I just couldn't trust a weld repaired head. I have been a certified welder for some time. Stainless, inconel and several other exotic metals I have done in both stick and tig but.... Cast iron scares me. Its really difficult material to weld. Those that can do it are really an artist.... Give Diesel Cast Welding a call on new, complete or bare heads. They may be able to weld repair yours. Alabama Cylinder Heads is where I bought my new bare set from. They cost me $315.00 each. Not a bad price for new heads that have not been milled. They were both 4.800 tall too. The head spec is min to max demenision of 4.795 to 4.805 and they can be warped 0.003 in 6 inches and 0.006 inches overall. I have many other head and valve specs if needed. Just ask.

 

[Freight_Train]

Yea,Use the old heads as boat anchors now.Just buy new castings.Little more than rebuilds but only a few bucks more and you know what you actually have!

 

[Agnem]

So Darrin, did you find out what actually was leaking? That crank sure is impressive sitting there on the bench! You'll have to ask Joe how well his Chinese heads are holding up. I think that scares me more than welding American ones. Don't forget, that HP reduction is more due to IP calibration than anything.

 

[Dsl_Dog_Treat]

Mel, That's the infamous Colorado truck motor #2 that had a dead cylinder ie collapsed lifter.
I don't think Darrin has ripped into Big Ed yet.