7.3 idi to 6.9 idi

Dieselpowerking

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Hey guys I have a 1990 f250 4x4 zf5 speed it's a 7.3 idi N/A. I replaced my head gaskets last year well I over heated the truck this last October pulling my travel trailer. I was replacing my positive battery cable and saw coolant that's been leaking from the head gasket. I found a 6.9 idi the guy only wants 250 for says it needs a valve job. Questions are what parts can I swap from my 7.3 to the 6.9 injectors? Water pump?a/c compressor all that kind of stuff. Will a zf5 bolt up to a 6.9 and will my Luk clutch kit work on the 6.9? I just bought it last year. Thanks for your input.
 

icanfixall

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Yes. The 7.3 glow plug system fits the 6.9. Just a note about any idi engine.Every drilled hoole is the same from 6.9 to 7.3 but...You need plenty of machine work to fit a 6.9 head on a 7.3 engine. But 7.3 heads fit the 6.9 without issues. Only the head bolt diameter is different between the 6.9 and 7.3.Of course the piston size is different between the 6.9, 7.3 and 7.3 turbo engines.So outside the engine every bolt on part easily swaps from 6.9 to 7.3. Now be careful with the van application engines to the truck engines. They have different drivers side exhaust manifolds and the oil cooler headers are different.Just ask before you buy a part for these engines. Someone is here 24 7 365 wanting to help with advice.
 

Dieselpowerking

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Yes. The 7.3 glow plug system fits the 6.9. Just a note about any idi engine.Every drilled hoole is the same from 6.9 to 7.3 but...You need plenty of machine work to fit a 6.9 head on a 7.3 engine. But 7.3 heads fit the 6.9 without issues. Only the head bolt diameter is different between the 6.9 and 7.3.Of course the piston size is different between the 6.9, 7.3 and 7.3 turbo engines.So outside the engine every bolt on part easily swaps from 6.9 to 7.3. Now be careful with the van application engines to the truck engines. They have different drivers side exhaust manifolds and the oil cooler headers are different.Just ask before you buy a part for these engines. Someone is here 24 7 365 wanting to help with advice.

Thanks icanfixall time to go get the 6.9 and start taking it apart.
 

IDIBRONCO

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That would be the easy way. That's one of those little things that a lot of people overlook. If you have the pump and injectors already off, then it's easy to do.
 

Justin B

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I just did this swap, 1990 7.3 had bad valve guides, needed rebuilt heads.. I found an '87 6.9 and threw it in. Just like these veterans are saying, everything swapped over easily, easy fit. The 6.9 already had the updated glowpug system that was actually in better shape than the 7.3's, all the plugs connect with no issues. I found the Felpro gasket kits from Summit to be a good deal; came in two sets, top an bottom end, included the nice rubber valve cover gaskets. The valley pan wasn't included, but the guy I bought the 6.9 threw one in on the deal.

I'd suggest picking up some measuring tools and measuring everything while you're in the engine, might identify a potential issue before doing all the work on the swap.

Was the 6.9 bolted to a manual or automatic? When I swapped mine, I put the "flexplate" an balancer from the 7.3 on the 6.9. This one was fuzzy to me about what SHOULD be done, but everything seems to work just fine the way I did it
 

IDIBRONCO

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When I swapped mine, I put the "flexplate" an balancer from the 7.3 on the 6.9. This one was fuzzy to me about what SHOULD be done, but everything seems to work just fine the way I did it
The balancers wouldn't have to have been changed. They are the same as long as neither one is from a Factory Turbo engine. You should run whichever flexplate/flywheel goes with your transmission. I'm not sure if you can interchange a flexplate from a C6 and a E4OD. The same goes for the flywheeels for the manual transmissions. I know that the input shaft from a ZF5 is bigger in diameter than one from a 4 speed so the clutch plates can't interchange. None of the flywheels/flexplates care whether they're bolted to a 6.9 or a 7.3 though. The bolt patterns on the back of the cranks are the same.
 

Dieselpowerking

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I just did this swap, 1990 7.3 had bad valve guides, needed rebuilt heads.. I found an '87 6.9 and threw it in. Just like these veterans are saying, everything swapped over easily, easy fit. The 6.9 already had the updated glowpug system that was actually in better shape than the 7.3's, all the plugs connect with no issues. I found the Felpro gasket kits from Summit to be a good deal; came in two sets, top an bottom end, included the nice rubber valve cover gaskets. The valley pan wasn't included, but the guy I bought the 6.9 threw one in on the deal.

I'd suggest picking up some measuring tools and measuring everything while you're in the engine, might identify a potential issue before doing all the work on the swap.

Was the 6.9 bolted to a manual or automatic? When I swapped mine, I put the "flexplate" an balancer from the 7.3 on the 6.9. This one was fuzzy to me about what SHOULD be done, but everything seems to work just fine the way I did it

Trans was a c6 that they had bolted to it
 

Dieselpowerking

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Anything out there performance wise for the 6.9? I plan on rebuilding it but just want to know if anyone knows about a good rebuild kit also.
 

bbjordan

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The balancers wouldn't have to have been changed. They are the same as long as neither one is from a Factory Turbo engine.

The 6.9 and 7.3 have different balancers. I have pics here somewhere. Just have to find them. :)

I have a ZF-5 bolted up to my 6.9. The Dual Mass flywheel from the host 7.3 was used. The balance isn't great, but usually I don't take it over 2500 rpm. I drive like a grampa...most of the time. :)

Ideally, I'd balance the whole assembly and put a Fluid Damper on it, but that's not likely to happen soon.
 

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