I've got a 03 Camry with the 3.0 VVT-I. She has 347k and I'm fairly positive I have a head gasket leaking. It actually calls less for R&R then it does to replace the gaskets so I figured if I can put a bigger/better engine in, now would be the time. Will a 3MZ or more preferred, a 2GR swap in? Has anyone tried or done this?

 

The 3MZ may have been an option. The 2AR may have been for later years.

It can be done but it requires a LOT of parts!

If you want to swap engine models find a donor car of the same year or at least the same general having the engine model you want then start swapping parts.

A different engine model requires a different trans, axles, computer, wiring, perhaps radiator and who knows what else. It's a parts swap job but requires a lot of parts beyond the engine.

Your are far better off and will spend less money fixing the current engine or installing a used one of the same model.

 

I was looking at the 3MZ or 2GR since they were both installed in the Camry's, with the 3MZ also being in my body style. I was just wanting to get a power upgrade since I need to replace the engine, I just didn't know how much different they would be. I think the 3MZ would have the same drive train because I'm pretty sure the 2GR was mated to the 8spd auto

 

You have some good points.

If serious about this do some research as follows.

There is a sticker on the side of the drivers door listing the transmission model. The model would be 1 letter, 3 numbers and perhaps another letter, a configuration something like U240E, etc. Once you have the model find out what years of Camry and engines it was used on. You can find this by doing internet search, checking online sites that sell used trans, etc.

You can also go to a Toyota dealer parts website, input you cars VIN to find the Toyota part number of the trans in your car, With this info use the site to find out what other car models used this part number. Then check other items such as half shafts, engine mounts, wiring harness, radiator, etc. The more parts numbers the match, the less work.

You will still need a different computer as they are engine, trans, year, etc specific. Here you could find out the specifics of your car then find a replacement computer for these specifics but having the replacement engine.

If the proposed replacement engine was an option for your year/model car then the job would be a parts swap job. If the engine was not an option then your on your own.

People have put non-option engine into Camry but its more work.