Replacement Engine Question

[boathead]

If the computers aren't the same then you could be in for a very big headache.

 

[normal_dave]

While I can't answer for the '97 Sport 3.5L, I can tell you there is a fair amount of difference between my '03 Montero Sport 3.5L 6G74 and my '02 Montero Limited 3.5L 6G74.
-Oil filter/pump on the other side of the engine
-Timing belt tensioner and setup is different, and sets in a different "direction"
-Accessory cradle is different on the front. (Montero for example doesn't require removal of power steering or A/C compressor to service timing belt, Sport does.
-Coolant crossover piping is different. (of course this is an accessory).
-Water pump different
That's all I can think of on short notice.

As far as computer controls go, if you use the Gen 3 electronics, harness, fuel injectors, intake, (everything), and just the long block, no electronics, from the donor engine, I imagine all should be well? (I've done this on different year/electronics in other vehicles successfully).

I bought a parts car twin to my wife's '03 Sport Limited, bragging about having a spare engine for either of our trucks, only to discover all is not equal. I've not researched enough to see if the oil pump setup can be moved to the other side, (Sport/vs Montero), but the prospect of having to fool with it was enough for me to scratch the idea, and be happy with a spare motor and transmission in "stock" for just my wife's Sport.

Here's a brief discussion:
Surprise surprise...

Alternatively, you could just jump on a plane, plan a road trip: funny, this one doesn't have a power moonroof?
'05 Montero Limited

 

[nwoods]

LOL, you guys.
Well, there are some significant differences in the engine accessories, that's for sure. I've started the diagnostic tear down. The front plate of the engine is totally different on the 2002 3.5L SOHC verses the one on my old 1998 3.5L SOHC. The belt is one belt instead of several, automatic tensioners, the timing belt covers are different, and you can change the water pump without having to remove the crank bolt/pully assembly OR the dreaded AC compressor (I hate accessing those bolts). The timing belt assembly itself is a bit different, with a totally different tensioner system and location. I far prefer this improved front plate design over that of the older 3.5L SOHC engines!

So far, timing belt assembly and positioning looks fine. Darn it.
Now I need to tear into the top end and examine the heads

 

[nwoods]

Here is the front plate of the 2002 3.5L SOHV Montero motor

Here is the Timing Belt Assembly with the front plate off:

 

[normal_dave]

FWIW, maybe it's the lighting, but that '02 sure looks clean in the timing belt area, wrench marks on the cam gears make me wonder, has somebody recently done the front cam seals? Looks like a new water pump, maybe even tensioner and idler pulley? Without documentation, hard to prove, but it sure looks like possible good news.

 

[tyty13]

Hey folks, thinking of dipping my toes back into the Montero world again. This time the hard way, by swapping motors from a donor into a nice clean 3rd gen platform for eventual use by my daughter as her first rig.

Do you know if a 1997 Montero sport 3.5L SOHC engine will fit in a 2002 Montero Limited? Same engine specs, but I don’t know of the mounts line up, tranny connects, exhaust manifolds will work, etc.... I have my eye on 2002 with a seized motor and am thinking of doing this motor swap. Never done anything like that before. Bit scary!

Anyway, this 1997 engine is very affordable and would make this hole deal a lot more attractive.

Do you have any idea how much LKQ “PickYourPart” wants for an engine? $2,350 for one with 80,000 miles on it, not including anything that bolts on, like compressors, pumps, manifolds, etc.... Yikes!

I don't think 1997 Montero sport came with 3.5 SOHC

 

[coffeegoat]

I agree with Normal Dave - that looks way too clean to be original (and wrong color - mine were black and cruddy). In particular the cam seals look fresh, as does the idler pulley (the color is wrong - original was red/orange). However - the crank bolt looks original, the new ones are shorties and that still has the long version (which you absolutely need to change.)

It also looks like a bolt ear on the AC compressor is broken off, I verified it against the pictures in my rebuild (see my sig) and the auxilary belt idler pulley (upper left) looks new, as does the water pump pulley.

Soo... all that to say, it's not clear what's wrong yet. In my rebuild I tore it all the way down to the heads, so it may be helpful to peruse those pictures, I'm pretty confident mine was entirely original. I'm curious if someone did the water pump/timing belt project and bollocks'd up something that caused this. I don't have any theories, but I suppose it's possible.

 

[mezmochill]

Compression test will help tell you if there was significant *hit that happened.

 

[mudraider]

There is a kind of write up over on the Mitsubishi Monteros USA page under the files section. It's been done a couple times now. Seeming like the power of the 3.8 is what's needed for the expectations of the American driver. Pushing the 3.5 to have the Montero keep up with the rest of traffic is eating up a lot of 3.5's

Sent from my SM-G950U using Tapatalk

 

[Superduty]

Are you in a state with strict emissions laws? In CA you can't install an older engine into a newer vehicle.....unless of course there is nothing that will tip off the smog guy (including when they hook up the OBD2).

 

[mudraider]

There is a kind of write up over on the Mitsubishi Monteros USA page on Facebook under the files section. It's been done a couple times now. Seeming like the power of the 3.8 is what's needed for the expectations of the American driver. Pushing the 3.5 to have the Montero keep up with the rest of traffic is eating up a lot of 3.5's

Sent from my SM-G950U using Tapatalk

Sent from my SM-G950U using Tapatalk

 

[nwoods]

Normal_Dave, you have a good eye. Yes, the previous owner just had a huge heap of work done to this thing:
- New Radiator (aftermarket)
- New spark plugs
- New timing belt kit with water pump
- New grooved idler pulley
- New smooth idler pulley
- Machined heads with reseated valves, seals, etc...
- New head gasket
- New head bolts
- New coolant

Plus labor, to the tune of $2,500.
4 days later, the engine seized up. The Owner gave up and sold it for scrap on CraigsList. That's when I entered the picture.

It seems logical to assume that the issues are related to the timing belt, but it sure doesn't seem like it after pulling the front plate off.

 

[nwoods]

Compression test will help tell you if there was significant *hit that happened.

Mezmochill, I can't do a compression test, because I can't turn the engine over. It seems siezed up. I can turn it about 20 degrees, back and forth within that small range, but that's it. Can't go beyond that.

 

[nwoods]

Okay, I've taken things down to the valve cover stage. Not entire sure what to do next. I am seeking advice. I think i'm going to start a new thread on this:
https://www.expeditionportal.com/fo...-3-5l-v6-sohc-that-might-be-seized-up.194567/

 

[nwoods]

I agree with Normal Dave - that looks way too clean to be original (and wrong color - mine were black and cruddy). In particular the cam seals look fresh, as does the idler pulley (the color is wrong - original was red/orange). However - the crank bolt looks original, the new ones are shorties and that still has the long version (which you absolutely need to change.)

It also looks like a bolt ear on the AC compressor is broken off, I verified it against the pictures in my rebuild (see my sig) and the auxilary belt idler pulley (upper left) looks new, as does the water pump pulley.

Soo... all that to say, it's not clear what's wrong yet. In my rebuild I tore it all the way down to the heads, so it may be helpful to peruse those pictures, I'm pretty confident mine was entirely original. I'm curious if someone did the water pump/timing belt project and bollocks'd up something that caused this. I don't have any theories, but I suppose it's possible.

CoffeeGoat, thanks for your comments. You are right on the money in your observations. I will be checking out your photos for sure. Since you've gone down this path before, I would value your continued participation in my other thread I just started. Cheers, NW