Hello! New to the group and to Hummers. Just bought a 2007 H3 3.7 with a blown engine. I have a chance to get a 2008 Colorado 3.7 but I'm a little concerned the engines may not be the same. I've looked at car-parts and ebay, it seems a 2007 is 2007 specific. When I look them up it lists a 2004, 5 and 6 as the same, 2007 only 2007, then 2008, 9, 10, 11, and 12 as being the same. Hopefully that made some sense. I believe I have a late 07 model. What is the difference between a 2007 engine and 2008? Can I put the 2008 engine in and be ok?

 

Not before you own a Hummer!

 

Three main things: 2007 uses the PCM to control all power controls and Transmission, has a different Throttle Body (TB), and less significantly uses a different intake.

The 2008s+ all use an updated PCM for power control, separate Transmission Control Module (TCM), and an updated Throttle Body.

The motor itself is basically identical in regard to your question.

So long as you have the 2007 PCM programmed to the replacement 2008 all should be good, you shouldn't even have to update the TB.

If you want to use a 2008+ PCM and TCM, gonna be a lot more wiring and programming.

 

Hey Shawnah, welcome!

The 2007 3.7L uses a different VVT timing sprocket than the 2008 3.7L. To make the swap function with your existing 2007 PCM and harness, the sprocket will need to be swapped (you can use the one from your old motor if it's still good).

The fuel injectors on the 2008 are different than the 2007 ones (different connectors & higher flow rate on the 08's).

Re-use these parts from your '07 engine:
-VVT timing sprocket (exhaust side cam sprocket actuator assembly)
-fuel injectors
-fuel rail
-crankshaft position sensor
-throttle body
-intake manifold

I have a 2008 3.7L I5 which has been "converted" to a 2007/2006. The swap definitely functions but requires timing work.

I look forward to hearing about your progress. 😎

 

Iirc you have to modify something to fit the crank sensor, i recall someone mentioning this in a post on this forum previously but cant tell who.

 

Dylan, how did you go about your timing work? I keep getting a P0017 code with mine. I used a 07 head and crankshaft with all other internals new 2008 internals. Cam sprockets, VVT solenoid, CKP and CMP sensors all new and relearned. Need all the help I can get here please, this thing is driving me NUTS!