Not am easy swap. I will let Edward handle this one. I think he has some experience in this issue.;D ;D
Oh, yea, THANKS!
pinstryper:
Been there, done that.
Transplant 6G74 engine into a 6G72 Montero Sport?linkThe 3.5L donor was a '02 Montero Sport. THIS is important! There are MANY 3.5L Mitsu engines in a lot of vehicles but the bosses change amount other things. I got an ENTIRE engine short the alternator, PS and A/C. Its impossible or nearly so to get individual external parts - so if you're missing something you could have major issues.
In brief:
The actual mechanical swap is easy. You need to chop a pair of 3.0L engine mounts and a pair of 3.5L engine mounts and make one pair out of the two pair. Takes about an hour if you have a welder.
Not a big deal.
Mitsu doesn't make the DR down pipe for the '99 3.5L - w/o CAT - anymore. They DO make the PS side, which is what counts. Slight modification to the DR side pipe and you're good to go. Took the exhaust shop about an hour to put in the entire exhaust, muffler, CAT, and down pipes and modify the DR down pipe.
The bell housing backing plate is different than the M/T. We used the backing plate off the '02 A/T and filled the two little gaps with RTV. Getto but it worked.
I changed the height of the engine mounts to move the engine up just a tad. That gave me just a slightly better drive line angle. Not necessary unless you're doing a SAS with a NP231 and doubler.
Since I didn't have a mechanical fan when we did the swap, I can't say one way or the other whether the stock fan moves forward or what impacting clearance between the fan, radiator and shroud. I run a HUGE radiator and I do know that a mechanical fan will not clear now - simple fix is the Ford Contour dual electric fans.
The stock 3.0L throttle body assembly from the existing 3.0L must be used. We swapped my original 3.0L TB onto the 3.5L. The 3.0L throttle cable bracket needs to be modified slightly. They cut the tab, made the mod and welded it back together.
I seem to remember that some of the plumbing for the hot water had to be changed. The 3.5L engine is wider than the 3.0L on the top end so most of the 3.0L stuff doesn't fit - it has to come on the donor 3.5L. Some of that may or may not be available from Mitsu by now. There wasn't anything earth shattering here and I may be remembering wrong. They originally tried to swap the entire top assembly to get around the TB swap, but that doesn't work do to the width difference.
I can't remember if it was the ECT, the gauge, but one of those needs to be extended a couple inches. This is delicate work. The joints need to be properly jointed and soldered otherwise it throws off the resistance of the wire which throws off the reading from the sender.
There are recommendations from the DMS guys, Eclipse, EVO, Galant, etc. bunch that the 3.5L fuel injectors be swapped out for the 3.0L injectors. I didn't do this so I don't know if this is a good idea or not. The rational is that the 3.5L injectors supply too much fuel because they're not matched to the ECM. I see the ECM supplying too much fuel, so this makes sense. Maybe some day I'll try this.
Otherwise, the wiring, senders, etc. are all the same. The entire swap could be completed in a few days to a week if you had all the tools and parts handy.
Now the bad stuff:
The 3.5L and 3.0L engines are a completely different mathematical model. Interestingly, the 3.5L - mathematically speaking - is almost identical to a v8 Pontiac 326/350/400 cid. The 3.0L is for all practical purposes a Chevy 327/350 cid missing two cylinders.
The issue is that the 3.0L - like a Chevy - can handle and needs more timing than a 3.5L - or a Pontiac.
A lot more. And, just like the Pontiac, too much timing causes detonation which generates a ton of heat which results in cooling problems.
The Montero and Montero Sport have no way to adjust timing. Like idle, timing has a base setting and then the ECM/PCM takes over. Changing the base mechanical setting only confuses the ECM/PCM which then sets it to whatever it wants anyway. The ECM is not programmable in the '97-99 3.0L.
NO Sport ever came with a 3.5L on a M/T so there are no ECM options. The early Montero came with a 3.5L on a M/T but that ECM is ancient. The last year was '96. While in theory it should be possible to retrofit a '96 Montero ECM onto a '97 Montero Sport, I've been unable to do so after spending close to 3 years on the project.
That said, I've managed to get it to work. More or less. Mostly more, but there are a caveats.
I run mine between 4,000 and 14,000 ft. The lower I go, the worse the over-heating problem gets. The higher I go the better it runs. And, yes, that is a symptom of too much timing.
My big Sport weighs in at almost 6,000 lbs now + another 7-800 lbs when I'm in Moab. Timing is decreased under load by the ECM.
I run a huge Griffin radiator - WAY bigger than would normally be necessary if everything were normal. I also run the Contour electric fans with a pair of genuine Ford motors. I figured out a couple months ago that those motors draw a lot more air than the Chinese knock-offs. They pull between 25-30 amps each at start up and around 25 amps each at 100%. One fan has to be on all the time at at least 70% (except in subfreezing temps) and frequently I run both at 100% on the passes even when its cold. On the plus side, I have NO issues with overheating EXCEPT on the highway.
Wheeling requires both fans at 100% most of the time even if its zero degrees outside and definitely if its anything over 50 degrees.
Decreasing load increases the timing - which means the lower I go in t-case gear ratio, the worse the problem gets. Higher gearing = less engine load = more timing. I have no confidence this swap would even be drivable in a stock weight Sport.
I live in CO so 8 months out of the year its cool. So pretty much between October and June I have no real cooling issues. That helps a lot because the other four months is kinda sucky.
I HAVE gotten it down to the point that the temps remain under 210-215 and for the most part even when its 100 degrees will mirror temps in a stock 3.5L Sport.
Lastly, everything has to be PERFECT. I mean EXACTLY PERFECT! If anything goes haywire, like the EGR, evap, etc., everything goes straight to hell real fast. Any issues are magnified way out of proportion.
What sucks out of all of this is when it runs it is
AWESOME!!!! I like the 3.5L with the A/T, but the Gen 2 A/T programming is a POS. That engine has SOOOOOOOO much more potential than any of you realize. That engine really wakes up with an M/T. I can't imagine what a stock Sport with a 3.5L and M/T and the proper ECM would be like.
So, basically, with enough band-aids and under the right conditions, this swap works. How long? I have no idea. Detonation is very, very bad for an engine so I'm guessing I may get 100-150K miles on the engine if I'm lucky.
Something that could make this swap actually work. I have emission testing and they test for OBD and CEL - anything missing or not right fails so I can't do this.
Replace engine management with a MegaSquirt FI/timing system. You don't even have to replace the FI, but you might as well. The MS system has been installed on numerous 3.0L engines and since there's no difference in electronics this would be an easy install.
The AEM FIC worked if you fiddled with it enough. KIM you will get NO support from AEM since this would be used to do exactly the opposite of what its designed for really.
Triggered CEL so I gave up on this solution.
Others have suggested fiddling with BARO and other things to fake the ECM out and get it to reduce timing. Not worth the effort. There are other things in the ECM besides timing that are not right for the 3.5L so this would just been yet another band-aid.
At the top of my list would be the MegaSquirt.
BTW, Sports do not have knock sensors. Neither Gen 1 or Gen 2. That would be something the MS could add and that would be a HUGE help by itself.
Edward
Not a big deal.
Wheeling requires both fans at 100% most of the time even if its zero degrees outside and definitely if its anything over 50 degrees.