My G35x with 350k+ finally let go and i'm in search of a donor motor. I found a guy selling his 2003 coupe with only 100k on the motor, its also an automatic.

My question is, can I swap his motor (I believe I will need to swap my upper oil pan as the cv axel passes through it on my car). Will anything else need to be changed to make it fit?

Second thing is, can I also use the transmission? Will the transaxel on my car bolt up to the coups tranny?

Any help is much appreciated.

 

Are those miles on your original engine and transmission? If so, you might have the high mileage record for as-built durability....

https://g35driver.com/forums/g35-sedan-v35-2003-06/114242-highest-mileage-g35-here-do-not-post-less-than-389-076-miles-31.html#post7204195

 

No I wish, sorry that's kilometers.

 

Yes you can use the engine and transmission.

Engine you already covered it, replace the upper oil pan, everything else is the same. I would recommend throwing on a new water pump since you'll have the timing chain cover off. Keep ALL your existing sensors, fuel injectors, coils, etc from your existing motor, you know they all work. No guarantees on the donor. Not a bad idea to get your injectors cleaned while they're off. Usually there's someone local that can do that for cheap.

Transmission you can use the gearbox yes, pull the donor valve body and wiring harness out. Use your existing valve body and TCM (the donor won't have a TCM inside the transmission) and the wiring harness. You can keep the existing front and rear turbine revolution sensors in the donor transmission just be careful with the wiring, remove the tailshaft housing from the donor and bolt your AWD transfer case in it's place. Definitely take some pics of your existing valve body when you take the pan off so you can get the wiring back correctly. Keep track of the various bolts, some are different length, if you do get them mixed up the FSM has good pics for what goes where.

 

Thanks very much for this info, hopefully this donor is decent and hasn't been abused. I will most definitely be doing a compression test before handing over the cash. Speaking of which, considering this engine has about 95k miles on it, what would be a reasonable number to expect from that compression test?

 

With 100k miles I'd say probably cold engine, 140-165 or so.

Hot engine 175-200+

That can vary a LOT on a cold engine though, especially if it's sat for a long time and the oil has completely gone out of the rings. I've seen used JDM engines that were only like 100psi when we received them and test while they're still on the pallet but once they fired up and oil the rings properly were 180psi.

Also depends on if anyone sprayed WD40 in the cylinder to protect it if it has sat for a long time, you'll be down below 100psi if that's the case because it removed ALL the oil from the rings and they seal terribly with WD40 in them.

Biggest thing is to just make sure the cylinders are all close to the same reading, high or low, it just needs to be the same.

If it's lower than 140 cold I'd be asking some questions though to find out WHY, especially if it was a local non-JDM engine. The JDM engines though typically are good about actually testing compression prior to sale.

 

He sent me a couple videos of it running and revving so I'm not that concerned about the rings being starved of oil. It fired right up and sounded good to me. I think he's selling it because the subframe and body need work to get it to safety at least that's what he's said to me. Obviously I'll be doing the compression test and looking at the dipstick to see if there is any evidence of mistreatment, but if that's all good I'd say getting that mileage motor and transmission for $2k CAD is a decent price. I'll probably part out the rest of it as well.

The only problem is that he's a 4 hour drive from me so I'd hate to drive out there to buy a clapped motor and transmission.

 

Another question about removing the engine and transmission as one piece from my X. Should I just try to jack the car up on jackstands as high as possible and drop everything out the bottom? I have to remove the front CV axels anyways, or should I try to shoehorn it out the front like most people try to do? I just see that might be more problematic on the X with the front diff and the transaxle to deal with.

 

Personally I'd do them separately rather than trying to pull the whole thing as a single unit. It can be done but it's a REALLY tight fit. Separately though it's pretty straightforward. I'd start with just the engine though, make sure everything is functioning properly, then do the transmission at a later date.

Especially since there's probably life left in your transmission, no sense replacing what's not broken, bag up that tranny and store it away for a year or two.

 

Have another question. There is a wrecked 2006 M35x in my local boneyard. Could I possibly use this engine and transmission in my 2006 G35x? Is there anything different between the two?

 

Should be compatible yeah, might need to keep your existing valve body/TCM but I'd try it with the donor ones first.

It's the same powertrain used in the M35, just check the engine to make sure it's a DE and not the dual intake HR. Not sure when they changed from the DE to the HR but it was probably 2007 just like the G35.