How bad is the HG job on a 7.3 IDI?

[Nero]

The main seals are the round ones that seal the crankshaft.

To do the timing cover you do have to pull it apart quite a bit to do... But having both covers off makes it easier to press the main seals in... Otherwise you need the special seal installer.

 

[steelholder]

The main seals are the round ones that seal the crankshaft.

To do the timing cover you do have to pull it apart quite a bit to do... But having both covers off makes it easier to press the main seals in... Otherwise you need the special seal installer.

I thought there were only 2 seals that needed replacing while the engine was out. The front and main seal, so there's a rear seal as well? How many more am I missing? I have no idea how to access any of these seals.

 

[jrnice]

I did mine in 2014, so some of my knowledge is dated.....but...I did basically the same thing Rock did. I did my research and decided to leave the engine in the truck. My engine was a reman replacement with lower miles, so I wasn't too concerned about warpage or cracks. But i did check with a straight edge. I ABSOLUTELY agree with using a cherry picker and leveler to pull and replace heads. I used the removal to plan replacement. The heads are heavy, especially for an older guy, and bent over.
I used the ARP stud kit, which I understand are no longer available. I'd seek a comp. I used Victor Reinz gaskets. I replaced (IIRC) the last few firewall end studs by fitting them in the head and securing them so they stayed out of the way until head was down. Also, whether you pull the engine, or do in place, make sure not to skid the head across the gsket surface. One head didn't land right and damaged the gasket. Luckily the gaskets were sold individually.. ......I was very careful but it happens. The rest was pretty easy except for one injector leak. I had a Banks Turbo so it needed to be right. The rest was pretty "easy". Good luck! And yes, I miss my rollback.

 

[Nero]

Every engine has a front main, and a rear main seal. The paper gaskets are for the seal carriers. You can do the seal without pulling the carrier, I do them if I'm that deep in.

 

[steelholder]

Every engine has a front main, and a rear main seal. The paper gaskets are for the seal carriers. You can do the seal without pulling the carrier, I do them if I'm that deep in.

So to sum it down I need the front and rear cracnkshaft seal, plus the gaskets that go between the cooler and the engine right? Plus the HG itself, what else should I be getting? Thanks.

 

[steelholder]

Did an AI search and the info actually seems pretty good, anything to add or omit? I'm probably not touching anything related to the IP, even rec brands, I know ARP is dried up, whats the next best thing? Wont be doing turbo ever.

1. Essential Seals & Gaskets​

Aside from the ones you mentioned, these are critical for a leak-free build:

front and rear crankshaft seal, the gasket that goes between the oil cooler and the engine and the HG itself

• Valve Cover Gaskets: Use the high-quality rubberized ones, not cork.
• Intake Manifold Gasket (Valley Pan): This is a large metal tray. It is technically the intake gasket and should always be replaced during an HG job.
• Oil Cooler O-Rings: You mentioned the gasket to the block, but the oil cooler itself has internal O-rings (two headers, one bundle). These are notorious for leaking oil into the coolant.
• Water Pump Gasket: Even if the pump is new, the gasket is a one-time use.
• Injection Pump (IP) Gear Housing Gasket: The gasket between the gear housing and the block.

2. The "Must-Do" Preventative Maintenance​

• Head Bolts or Studs: The 7.3 IDI is known for stretching head bolts. Most enthusiasts strongly recommend upgrading to ARP Head Studs ($$$) to prevent future HG failures, especially if you ever plan to add a turbo. If using bolts, ensure they are new.
• Return Line Kit: The plastic caps and O-rings on the injectors (the "fuel return rails") almost always leak after being disturbed. Buy a complete kit with Viton O-rings.
• Oil Pressure Sender: Located at the back of the block; it’s a cheap part that is impossible to reach later.
• Glow Plugs: Replace these now with Motorcraft/Beru ZD-9s only. Avoid Autolite or Bosch, as they are known to swell and break off in the head.

3. Critical Checks​

• The Oil Cooler Headers: Inspect the cast aluminum ends of the oil cooler for cracks.
• Valve Stem Seals: Since the heads are off, pop them over to a machine shop to have the heads decked (checked for flatness) and the valve stem seals replaced.
• Cylinder Wall Inspection: Check for "cavitation" (pitting) on the cylinder walls.

---

Brand Recommendations & Resources​

Component	Preferred Brand	Why?
Head Gaskets	Fel-Pro or Victor Reinz	Industry standards for IDI sealing.
Head Studs	ARP	Superior clamping force over factory bolts.
Glow Plugs	Motorcraft (ZD-9)	Only brand that won't swell and ruin your heads.
Oil Cooler O-Rings	DieselOrings.com or Ford	High-quality Viton prevents oil/coolant mixing.

 

[steelholder]

What do you guys think about this set?

CDD 6.9/7.3 IDI Master Reseal Kit

Complete engine reseal kits with our upgraded head gasket set, valve stem seals, and motorcraft thermostat. Included: Viton front and rear main seals with install sleeve Front and rear engine plate gaskets Oil pickup tube gasket Oil drain gasket Oil dipstick tube o ring Genuine Motorcraft oil...

classicdieseldesigns.com

How about these? Seem very pricey

ARP 250-4204 ARP Pro Series Cylinder Head Studs | Summit Racing

Free Shipping - ARP Pro Series Cylinder Head Studs with qualifying orders of $109. Shop Cylinder Head Fasteners at Summit Racing.

www.summitracing.com

 

[IDIBRONCO]

Intake Manifold Gasket (Valley Pan): This is a large metal tray. It is technically the intake gasket and should always be replaced during an HG job.

It should be spelled "should". Nero was right. It's best that you replace it, but you can reuse it and seal it with a thin coating of RTV. I've done it and I'm still doing it every time that I start my truck. This the only option other than spending a not-so-small fortune during the shortage during Covid.

 

[IDIBRONCO]

Injection Pump (IP) Gear Housing Gasket: The gasket between the gear housing and the block.

There's no gasket here. It's sealed with RTV from the factory.

Oil Cooler O-Rings: You mentioned the gasket to the block, but the oil cooler itself has internal O-rings (two headers, one bundle). These are notorious for leaking oil into the coolant.

You can get all of these as a kit. In the early oil coolers, there's actually three o rings per end of the bundle. There wasn't a lot of those that I saw even 25 years ago.

Oil Pressure Sender: Located at the back of the block; it’s a cheap part that is impossible to reach later.

If you're happy with how the gauge is working, I see no reason the replace this. It's not impossible to reach with the engine fully assembled. It's difficult with a turbo, but still not impossible.

What do you guys think about this set?

CDD 6.9/7.3 IDI Master Reseal Kit

Complete engine reseal kits with our upgraded head gasket set, valve stem seals, and motorcraft thermostat. Included: Viton front and rear main seals with install sleeve Front and rear engine plate gaskets Oil pickup tube gasket Oil drain gasket Oil dipstick tube o ring Genuine Motorcraft oil...

classicdieseldesigns.com

How about these? Seem very pricey

ARP 250-4204 ARP Pro Series Cylinder Head Studs | Summit Racing

Free Shipping - ARP Pro Series Cylinder Head Studs with qualifying orders of $109. Shop Cylinder Head Fasteners at Summit Racing.

www.summitracing.com

The reseal kit is complete. It's funny that the description says that a thermostat isn't included yet there's one in the picture. It must just have been overlooked.
Yes the studs are expensive. CDD lists some that aren't ARP, but they're still over $500. About 10 years back, I went with studs from R&D because they were a lot cheaper than ARP. His studs are more expensive than CDD's these days. You just can't find head studs that aren't pretty expensive.

Head Bolts or Studs: The 7.3 IDI is known for stretching head bolts. Most enthusiasts strongly recommend upgrading to ARP Head Studs ($$$) to prevent future HG failures, especially if you ever plan to add a turbo. If using bolts, ensure they are new.

I don't know that 7.3s are really known for stretching head bolts, but it is a good idea to replace them. A retorque isn't a bad idea if you're not removing the heads. In that case, you're not replacing the bolts. A retorque is more important on a 6.9 since they have smaller diameter bolts than a 7.3 does. Also don't believe anyone who says that 7.3s have torque to yield bolts. They aren't.

 

[steelholder]

There's no gasket here. It's sealed with RTV from the factory.

You can get all of these as a kit. In the early oil coolers, there's actually three o rings per end of the bundle. There wasn't a lot of those that I saw even 25 years ago.

If you're happy with how the gauge is working, I see no reason the replace this. It's not impossible to reach with the engine fully assembled. It's difficult with a turbo, but still not impossible.

The reseal kit is complete. It's funny that the description says that a thermostat isn't included yet there's one in the picture. It must just have been overlooked.
Yes the studs are expensive. CDD lists some that aren't ARP, but they're still over $500. About 10 years back, I went with studs from R&D because they were a lot cheaper than ARP. His studs are more expensive than CDD's these days. You just can't find head studs that aren't pretty expensive.

I don't know that 7.3s are really known for stretching head bolts, but it is a good idea to replace them. A retorque isn't a bad idea if you're not removing the heads. In that case, you're not replacing the bolts. A retorque is more important on a 6.9 since they have smaller diameter bolts than a 7.3 does. Also don't believe anyone who says that 7.3s have torque to yield bolts. They aren't.

The fel pro studs are $100 is it really worth spending 5 times more on the ARPs I linked above? Especially if no turbo?

 

[Nero]

I didn't see felpro studs listed here... You sure they aren't just regular head bolts?

I've had 4 idi's apart. All of them had at least a few damaged head bolts. That's why I say go head studs. Or put new bolts in.

 

[steelholder]

I didn't see felpro studs listed here... You sure they aren't just regular head bolts?

I've had 4 idi's apart. All of them had at least a few damaged head bolts. That's why I say go head studs. Or put new bolts in.

These here, look like head bolts

https://www.oreillyauto.com/detail/c/fel-pro/fel-pro-m12-1-75-thread-hex-cylinder-head-bolt-set/fel0/es72161?srsltid=AfmBOooCZVF4ZFs4_-dnky1GlkTThgqQpG7dueJ7S9C-dMyLZYW73DDK

 

[Reggie f250]

Those are metric bolts. They don't fit an idi

 

[Reggie f250]

Mahle gs33348 will fit. You will need 2 sets. I work at oreillys so I have researched almost everything we sell for idi engines

 

[steelholder]

Mahle gs33348 will fit. You will need 2 sets. I work at oreillys so I have researched almost everything we sell for idi engines

Thanks how do these compare to the ARPs?