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catmastertech, Technician
Category: Heavy Equipment
Satisfied Customers: 2345
Experience:  19 years Cat, 3 years Case
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1997 GMC: the difference between Cat 3126 and 3126 B engines..kick

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What is the difference between Cat 3126 and 3126 B engines.
Where is the best palce to get one and at what cost?
We have a 1997 GMC Model T 7500 top kick with a Cat 3116.
Will either either the 3126 or the 3126 B bolt in or what must be modified?

The 3116 in your truck is most likely the MUI (mechanical unit injector) fuel system. The 3126 was offered in a MUI version but, mostly as equipment and marine engines. The 3126B was the HUEI (hydraulic electric unit injector) and uses and ECM (computer) the operate the fuel system. The B series also has three valves per cylinder and later became the 3126E. It now is call the C7 because it is 7.2 liter displacement.

It would take a lot of wire to install the HUEI version. If you have a MUI engine, it should bolt in. The only difference in the 3116 and 3126 is the 1mm larger bore in the cylinders.

I don't think the HUEI engines swap any parts except the crank and rods. Always ask you local CAT dealer for any surplus engines. You might get lucky and find a crate engine for a good deal.

Customer: replied 7 years ago.
Our 3116 is a HEUI, not a MUI
The swap should be easy, check for obvious differences. Air inlets being different, exhaust and turbo mountings. Match the sensors on the harness to each engine. If you don't see many changes the swap can work without having to rewire the engines. The ECM may need to be swapped if the engine is from a different truck. You might need to check the differences by comparing the arrangement numbers and the performance specification numbers. These numbers are printed on the data tag on the valve cover or the side of the block. I can get some of this information but, the detailed truck crossover may need to be confirmed with a CAT truck service technical support. Some dealers will do this free.
Customer: replied 7 years ago.
Donnie, Did you receive payment for your assistance?

No payment has been made to me. I don't have any record of it being accepted by you.

I would normally see an accepted mark here but, I do not see either reply marked as accepted.

Did you request or receive a refund?

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Customer: replied 7 years ago.
I don't remember either, but I do appreciate your reply so I accepted it again. If I paid twice, it was worth it. Thanks!

Thanks for the accept. It is showing as accepted now.

Please use JustAnswer again, I will be glad to help.