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If there is an ID tag on the engine, either on the lower left side of the block or on the aft left corner of the camshaft cover it will have the build info. Look for a 10 digit number starting with a T. The second and third digits will be the build year i.e. "T 07 xxx xxxx".
 

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Lucky...still not sure how you found that. Nothing like that around from car-part. all 1,200 or more.
I am a 2006 Hummer H3 owner. The 3.5 threw a rod one week after purchase. I saw a reference to this site re: 3.7 swap on a Hummer forum. It appears that most everything would be the same as in this swap but..Does anyone here have any insights? Thanks
 

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I put a 3.7 in my 2005. Been working good for over a year.

I used my computer, wires and sensors from my original engine. Need to swap the fuel rail. Return system vs no return.

I used the 3.7 valve cover and coils. The coil has different shape, so need to stick w 3.5 valve cover and coil, or use the 3.7 cover and coils.

The exhaust ports are different sizes, I did a poor port match job w grinder to help get the 3.5 manifold holes to match the 3.7 better.

Only issue I remember was my 3.7 came from a 2WD and my truck is 4WD. I did not realize the oil pan was different shape until I tried to raise the front axel in place. I had to pull engine back out and then swap the oil pans.
 

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I put a 3.7 in my 2005. Been working good for over a year.

I used my computer, wires and sensors from my original engine. Need to swap the fuel rail. Return system vs no return.

I used the 3.7 valve cover and coils. The coil has different shape, so need to stick w 3.5 valve cover and coil, or use the 3.7 cover and coils.

The exhaust ports are different sizes, I did a poor port match job w grinder to help get the 3.5 manifold holes to match the 3.7 better.

Only issue I remember was my 3.7 came from a 2WD and my truck is 4WD. I did not realize the oil pan was different shape until I tried to raise the front axel in place. I had to pull engine back out and then swap the oil pans.
Did you use a 2007 3.7?
 

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Yes.

I forget the difference, but 2008 and up use different sensors that don't work w older PCM.

There is talk of that on this site about that somewhere.
 

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Well, got her done! YEAH!!! She is now able to be driven! Man am I happy! I have some bugs to work out...and MAY have to even pull the trans back down :ugh: BUT she is drivable for now. That's what is important! For those of you who have not been keeping up, I hydrolocked a 3.5 in my 04 truck. So i swapped in a 07 3.7!!


First question everyone wants to know...what is the difference..? It's AWESOME! I had my 3.5 tuned, had the cat gutted, and was running mobil 1 fluid. There is NO comparison! The 3.7 is just awesome! From the bottom end she pulls harder, from teh top end she pulls harder, and you had better hold on when she shifts! LOL I KNOW I am gonna get even more from her when I do eventually do the exhaust. And of course get PCM's for less to retune her...But for now, I am LOVING the extra power.

Now, as for the tips YOU should know and the whole reason I made this new thread...

3.5 to 3.7 swap...

1) MUST use 3.7 from 07 model truck NO OTHER WILL WORK.
2) MUST swap fuel rails from the 3.5 TO the 3.7. Why? Because the 3.5 use's a return style fuel rail, the 3.7 use's a returnless fuel rail. I also swapped out the fuel injectors sense they were newer.
3) MUST swap over the EGR block off plate. The newer engine use's a egr, our older engine's did NOT.
4) MUST use your older 3.5 harness! The newer one has wire's ran for the egr valve, as well as some connector's I DID NOT see on there for my engine. MAYBE you could get away with useing it, But I highly doubt it.
5) IF you have a factory Block heater....YOU WILL NOT have it anymore..lol. The new 07 engine does NOT have a hook up for it. So be prepared for that.
6) There Are TWO O2 sensor's on the 3.7 mani...the 3.5 only has 1!!! SO, what do you do? lol I hooked up teh rear o2 sensor from the back of teh truck like it was stock. then i hooked up the FIRST o2 sensor closer to the engine...it works great. Then i just left the last o2 sensor just in case, and tied up the wire. But this is just another of those things I could not find anywhere on here..
7) The 3.5 ECM will run the 3.7 just fine. No need to swap it for the 3.7 ecm. Well, at least for me that is.
Now, some install tips...

IF the engine you buy has been setting for any lenght of time..it WILL knock upon start up unless you prime the oil pump. My engine had a ticking from the valve's for a good 30 minutes that would start and stop..now it run's baby butt smooth. Well, except for my issues that is.

IF you decide to do this, You may as well pull the trans with it!!! The trans is a WHOLE lot easier to get to when its out of teh truck. And you CAN pull them bth at the same time WITHOUT fear. It will come up and out of teh engine bay in one piece. You DO have to remove the rad...but sure you would anyway.


Once you get the trans back together and you need to reinstall the 3 bolts that mount the fly wheel to the Torque Converter, you will need to remove the little round disk by the dust guard. It is a view access point for you to line everything up! You simply look up in there, use a screw driver to turn it till one of teh 3 mounts are straight down, then turn the engine over till the hole in the flywheel lines up with the hole in the torque coverter, and install yoru first bolt! Then of course when you turn the engine over using the front mounted crank bolt, the flywheel and TQ will already be aligned for the other 2 bolts!

And last DO NOT remove the nuts that hold the trans cooler lines!!!!! IF you do you will be in for a long long day! If you look hard, you will see a retaining pin. Pull that out with a screwdriver and the line's pop right out! IF you are just now reading this AFTER you already undid them and now thinking oh shit...Well, here's how to can save face and get them bolted back in. Since of course you know that when you try to screw them in it simply pushe's back in right? LOL Well, get one of yoru wife's bobby pins. Bend it as to have a small hook on one end. Cut off the little bund on the end so it will "BITE" into the side of the cooler. Now, insert the bobby pin hook threw the nut you took out. Push it into the hole and try to hook it into the cooler. When you do get it to bite then slide the nut over it and slowly and barely screw it into the cooler. If you do it right, you will be rewarded with the nut getting a bit tighter until finally she stops. Then thank god your done with that one and start on the last one!

USE a leveler...it will make moving the engine and tilting it so much easier...

Have a buttload of kitty litter on hand to soak up all the oil, and trans fluid you lose.

The fan comes off the the LEFT! If you turn the screw right...you will be there ALL day. Turn LEFT! WHILE the damn belt is on! IT WILL make it so much easier!



IF you want to know, or need to ask a question you can always PM me. I am almost always on here...and of course get emails of PM's too...if i CAN help, I will. Good luck.

What do you know about a 2.8 to 3.7 swap? Or could you direct me to a thread about that?
 
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