doing heads on 7.3 idi

[Fordfan90]

Hey guys I think I found my coolant right at the passenger side head. I was wondering how hard it is to replace the head gaskets on these motors?

 

[IDIoit]

get heads machined.
buy studs.
that's the hardest part.

 

[OLDBULL8]

Those heads weigh 85 lbs. They go in and out at an angle. The bolts close to the fire wall come out with the head.

It's doable with the engine in the bay, but way better with it out.

If you do it without pulling, when you reinstall the head, get 4 bolts to use as guides.

Whatcha got, a 6.9 or a 7.3. Put you truck in your signature, including engine and trans.

 

[Fordfan90]

Those heads weigh 85 lbs. They go in and out at an angle. The bolts close to the fire wall come out with the head.

It's doable with the engine in the bay, but way better with it out.

If you do it without pulling, when you reinstall the head, get 4 bolts to use as guides.

Whatcha got, a 6.9 or a 7.3. Put you truck in your signature, including engine and trans.

1990 f250 4x4 7.3 idi N/A with 5speed manual.

 

[IDIBRONCO]

I would definatly pull the engine to install studs.

 

[Fordfan90]

I would definatly pull the engine to install studs.

Can you explain on the studs vs regular head bolts?

 

[shawn deere]

I had pics. But my gal dern phone reset and deleted!!!
Studs hold head gaskets. - they have threads on both ends and have more clamping pressure. Idiperformance.com has em for about $450 i believe.

Non turbo. I would pry just re use the head bolts. Maybe torque them a freckle more than stock. But not much. - my uneducated opinion, mind you.

 

[crash-harris]

I figured whenever I have to do mine, I'll leave the block in-frame, line the heads up with some all thread or something and install the studs with the head hanging on the all thread.

By using all thread to locate the heads, I mean cutting sections short (or factory head bolts) and putting a good slot in them so they can be removed with a flathead and a magnet. Clean and chase the threads in the block first, of course.

 

[shawn deere]

I figured whenever I have to do mine, I'll leave the block in-frame, line the heads up with some all thread or something and install the studs with the head hanging on the all thread.

By using all thread to locate the heads, I mean cutting sections short (or factory head bolts) and putting a good slot in them so they can be removed with a flathead and a magnet. Clean and chase the threads in the block first, of course.

Like cut the heads off the factory bolts and run em in a few threads to line stuff up?

If you do studs GET A THREAD CHASER! I did not.. studs screw in farther than the head bolts do. Had a few issues getting the studs screwed down far enough to clear the rocker arm pedistals... but got er done

 

[Macrobb]

Also, when having the heads machined - Have them cut as little as possible.
The tolerances are /tight/, and you have to be careful of piston to valve clearances.

There are specific tolerances for "valve recession", which is how far the head of the valve sits below the surface of the head. After everything is said and done, make sure to check these numbers before installing the head.

If your valves aren't recessed enough, your piston will hit and destroy the valve guide in short order... and you may not notice it for a while.

 

[crash-harris]

Like cut the heads off the factory bolts and run em in a few threads to line stuff up?

If you do studs GET A THREAD CHASER! I did not.. studs screw in farther than the head bolts do. Had a few issues getting the studs screwed down far enough to clear the rocker arm pedistals... but got er done

Yup. I got lucky when I did head studs on my 300. Was cold as crap and had limited time so I didn't walk the 50 yards to even look for a chaser tap. Instead I cleaned the old bolt threads and used those and compressed air to clean the threads in the block. I'll be doing it properly on the IDI.

Also insure that you lube the threads in the new head studs. ARP usually includes assembly lube and the studs can usually be installed with an allen key.

 

[plywood]

Studs aren't as important for a 7.3 as a 6.9. Also whether you plan to or have turbo is a factor.
If you just want to do gaskets it can be done with engine in the truck of course and that is a pain for sure but removing the engine I don't think could be easier for a simple gasket job. For studs yeah. Although I would use a cherry picker to set the heads on. Clearances for rear bolts are tight. If you put the pass head on you won't be able to put the rear head bolts in the holes. Of course different years and options matter but as I recall I put the rear bolts in with a zip tie to hold them up so the bottoms were flush with the bottom of the head. It's been some years since I was in that deep but it seems like there is a proper order or trick for pass side exhaust manifold but that may be for a turbo job.

 

[Macrobb]

Studs aren't as important for a 7.3 as a 6.9. Also whether you plan to or have turbo is a factor.

You can get away with 15 PSI without studs on a 7.3; if you intend to go bigger than a 90CC pump, you want them.

There are also a number of people out there with 6.9s and head /bolts/ running turbos(even 14+ psi), but I'd be careful of more than 5-6 without studs. With studs on a 6.9 it's about 15-20 before they won't hold.

If you just want to do gaskets it can be done with engine in the truck of course and that is a pain for sure but removing the engine I don't think could be easier for a simple gasket job.

I've done it both ways. Still not sure which is easier; it took me a couple of days of wrenching either way.

For one head, in the truck is easier. For both(especially if you want to do some added maintenance), just pull the motor.
Then, you can do a few other things you probably need to do, like front and rear seals, oil pan etc.
It's also a good time to possibly look at the oil cooler and re-seal it, etc.



If you pull half the air box off the AC cabin air piece(it's the plastic box that the ac cooler goes inside), it will make life a /lot/ easier to do the passenger side in the truck.
A few screws and a bolt from the inside hold it together.