1992 Mighty Max 3.0l 5spd Manual 4x4

[Geoff]

Hello,

I’m excited to enjoy my 1992 Mitsubishi Mighty Max. It’s a 3.0l V6 4x4 with 5 speed manual transmission. I bought it from the original owner (his brother actually, who put an additional 35 miles on it) so it’s basically a single owner truck. Well maintained. Seats and dashboard covered since ‘92. It’s a daily driver and, hopefully, an overlander in the near future. If I get ambitious, then maybe I’ll start a blog on the build. My first items will be basic tune-up and maintenance and then performance upgrades, if any.

I’m new to the site but there seems to be a lack of info related to the 3.0l V6 gen 2 Max’s. I’m also new to the Mitsubishi (Chrysler?) world so I’m sure info will become available as I learn to ask proper questions.

Thanks to to all for the info that’s already been archived here and thanks in advance for support in the future.

Sincerely,
Geoff

[geezer101]

Hi and welcome to mightyram. Mitsubishi knows how to build a 4x4 so if you ever get it out off road, you're not going to be disappointed. It'll climb stuff that would make a Jeep struggle without breaking a sweat or anything else. The usual run down for noobs - get a thread going, post pics and ask questions

[Chargerx3]

Welcome to the forum. That is a very nice and rare truck. I would love to see some pictures inside and out. There isnt a ton of info out there, but several of us on this forum have become well versed in these trucks. One nice aspect is that there is a TON of commonality across Mitsubishi and even Kia that will give you lots of build flexibility. I've owned 3 of the 4x4 V6 trucks and thoroughly enjoy them.

Like Geezer said, these trucks have arguably the strongest drive-trains of any Japanese vehicles of this era. Im already pushing 300hp in one of mine that I recently finished building and thats on stock trans and axles. Might have another build coming soon with a twin turbo 3.0L.

Feel free to fire away with the questions.

My two current V6's. 90 & 91

[xboxrox]

Happy Birthday Geoff Have you still got the MM on the road..?

[Geoff]

Sorry for the very long delay in responding. Major life changes in the last year. I’m still driving Mighty Maxine. Just did a run up the Grand Mesa today. Good times.

The truck’s running well after some major work, to me anyway. The truck was smoking badly and had severe valve lifter tick. I changed the valve stem seals and all the lifters. Smoke cleared, tick became intermittent. A new sound developed that was like a dry bearing sound at the front of the engine. Removed all belt driven accessories. No change. I changed timing belt and tensioner. No change. Water pump next. No change. Distributor. No change. That left the oil pump. The pickup tube was clogged with a 1/4” of burnt tar-like oil. Cleaned the pickup and changed the pump (pump was fine but I had the part). Mystery squeal is gone. Valve lifter tick is nearly gone. My theory is that the sound was caused by cavitation in the pump due to it being completely dead-headed at the pickup tube. I suspect the previous owner didn’t care for the truck as well he said. Probably ran the same oil for 30k miles. I’m afraid some of the oil passages are clogged with tar.

FYI, Autozone sells a 6G72 long block for a decent price. Four month lead time. Nutech 227A.

if the engine holds for a few weeks, then I’ll start a front end refresh. Bushings, ball joints, etc. Maybe a mild torsion bar crank to level it a bit.

I was hoping to document these repairs but just needed to get it running.

I tried to attach a pic. We’ll see how it goes.


-Geoff

[geezer101]

If you hadn't gone to the effort of changing out the lash adjusters and removing the pick up tube I would've recommended an engine oil flush. It's interesting to note that you had found the pick up to be restricted with crap. It's not something anyone would normally check (I know it's a PITA job to remove a sump to get to it) This might have to be added to the list of things to check. Thanks

[Geoff]

Gnarly.

[geezer101]

Oh man, this engine has suffered. Oil pressure would've been crap - you were wise to check this out this engine was destined for bearing damage. Good save!

[RossOtero]

what is going on in this pic? noob here

[tortron]

That round thing in the middle is the oil pick up for the engine (4wd truck, sump removed)
It's a mesh filter to stop stuff getting sucked through the oil pump and the through the engines bearings.

It's totally clogged with sludge, so engine has probably never had maintenance, oil pressure would be very low

[Geoff]

A year later, the engine is still running great but the sound is back. I’ll pull the pan on the next oil change. As geezer101 claimed - PITA.

Over the last year, I replaced the tie rod ends, front sway bar bushings, rear leaf spring bushings, steering box, and installed RS5000 shocks all around. It rides really nice now - for 90’s truck.

[xboxrox]

Try a quart of RISLONE to stop the noise ~ O'Reilly's got it

[geezer101]

I would now do an oil flush. If the pick up looked like that, then all of that crap would be stuck to oil galleries, oil drain return, crank case/block walls etc. The oil flush will help reduce (or even eliminate) any hydraulic valvetrain noise and also break up the gunk in the ring grooves to restore some compression. May also be time to think about a different engine oil? I know that some engines run small oil filters that can be swapped for larger capacity filters with the same diameter body and mounting thread. Bigger filter = more oil capacity and filtration surface. Always a bonus. Sometimes the bigger capacity filter is cheaper/easier to source too.

[Chargerx3]

2nd the oil flush. I have used Motorflush for over a decade with only good results.

[Geoff]

I started running Schaefer oil after the last batch of work I did. It has less than 2k on the oil but it’s overdue for a change time-wise. I think what got me here, in part, was doing a sea foam treatment and running marvel mystery oil. I suspect it knocked the gunk loose and clogged the pickup screen. The exhaust was smoking when I first got the truck and I tried an easy fix. YouTube told me to do it! Lesson learned. Just do the work. It needed new valve stem seals and new valve lifters, which I did. No smoke or valve tick after that. I started tearing into the oil pan tonight. Not sure how to do an oil flush. I’ll do some research. I’ll clean the oil pickup screen one more time, if it needs it. If it clogs again, I’ll plan an engine swap or, better yet, rebuild mine for fun. At first glance car-part.com looks like a good resource for salvage parts. I’ll research Rislone too. Thanks for the tips!

[xboxrox]

USNavy Seabee CM construction mechanics took care of the motor pool vehicles when I wuzza sailor ~ they most likely would drain out the 2190 TEP 30 wt non detergent OIL then fill crankcase with diesel fuel run the engine and repeat until the oil pan drained clear decent clean fluid ~ military crankcase flush

[Chargerx3]

Here you go.

https://motormedic.com/pages/motor-flush

And run it longer than 5 minutes. The bottle used to say 15 minutes years ago. I run it 15 minutes and gently increase the rpms towards the end. Stuff works great.

[geezer101]

Seafoam is ok for an intake treatment but it won't clean the backs of valves and adding it to a crank case isn't going to do much (or maybe anything...) My experience is off the shelf engine oil flush is just massively marked up diesel. Might have some other additive to it but it has the same consistency, similar smell and will dry your skin out exactly the same as diesel would. The bottles would all state it contains 'hydrocarbons' which is such an ambiguous description it could be anything. I have driven for a day with diesel/oil blend (and with it a litre lower in capacity) on high mileage engines without any ill effects. Had good results every time. Cleaner oil between regular changes, quieter hydraulics directly after full oil and filter change.

If you want to give it a shot - http://www.mightyram50.net/vbulletin...ll=1#post49592

*if the oil capacity on the V6 is greater than the approx 3.6L recommended on my post, simply fill to specs. Also go on the hunt for a bigger capacity oil filter..

[Chargerx3]

Contents of Motor Flush:

Hazardous components
Chemical name CAS-No. Concentration (% w/w)
Diesel fuel no. 2 68476-34-6 89.8547
Kerosene 8008-20-6 44.9274
Distillates (petroleum) 64742-53-6 9.9437
Distillates (petroleum) 64742-52-5 9.9437
Alkanes, C10-C20 928771-01-1 4.4927
Naphthalene 91-20-3 2.3362

[geezer101]

LOL diesel is on top of the list. Naphthalene was an interesting ingredient - didn't expect that. Alkanes are similar to paraffin/methane (not sure why it needs that) Kerosene and other petroleum distillates would be just more solvents. So there you have it sports fans

[Chargerx3]

Hence why they are NOT the same. Each of its chemical ingredients plays a part in breaking down sludge, carbon, and other items in your oiling system.

[geezer101]

I'm thinking the naphthalene is doing something sneaky like acting as an anti-knock agent if there is significant loss of compression due to frozen rings. Adding something that will dissolve carbon and laminated oil could blow pass the rings and possibly affect air/fuel burn while the process is taking place. In all honesty, 5-15 minutes of low rpm run time is nowhere near enough to allow for rings and hydraulics to regain full actuation. I've done my oil flush on a few older/higher mileage engines with good results.

I also did it for an elderly couple that had a 2014 model Corolla that they were killing with kindness. 2 or 3 weekly short trips and sitting at idle and waaay lower mileage than a car of it's age should have accumulated. When I pulled the filter it was coked up badly so I did the flush blend and took it for a solid hour run uphill and back along the coast. It ran like a pig. No power, felt like the VVT wasn't actuating properly, a little valvetrain noise. Just over half an hour into the run it found it's mojo. When I got onto the oil change I was surprised at how much cleaner the old filter was after removing it. Used a full synthetic oil, ran like a champ. And then the old guy totalled it 2 weeks later lol.

[Geoff]

Wow! Thanks for the feedback everyone. I appreciate it. I should have the oil pan off tomorrow to see what I’m working with. I’ll consider all of your suggestions. Thanks again!

[Chargerx3]

I'm thinking the naphthalene is doing something sneaky like acting as an anti-knock agent if there is significant loss of compression due to frozen rings. Adding something that will dissolve carbon and laminated oil could blow pass the rings and possibly affect air/fuel burn while the process is taking place. In all honesty, 5-15 minutes of low rpm run time is nowhere near enough to allow for rings and hydraulics to regain full actuation. I've done my oil flush on a few older/higher mileage engines with good results.

I also did it for an elderly couple that had a 2014 model Corolla that they were killing with kindness. 2 or 3 weekly short trips and sitting at idle and waaay lower mileage than a car of it's age should have accumulated. When I pulled the filter it was coked up badly so I did the flush blend and took it for a solid hour run uphill and back along the coast. It ran like a pig. No power, felt like the VVT wasn't actuating properly, a little valvetrain noise. Just over half an hour into the run it found it's mojo. When I got onto the oil change I was surprised at how much cleaner the old filter was after removing it. Used a full synthetic oil, ran like a champ. And then the old guy totalled it 2 weeks later lol.

Naphthalene is a byproduct of the oil refining process. Being that is it is in such a low concentration of the overall mixture it has little to do with the overall efficacy.

I wont pretend to know how your Diesel flushing goes, but ive been using this product for over 15 years on many of my cars and 15 minutes is sufficient for a good, strong cleaning. You can run longer if you like, but there comes a point where the risk starts to outweigh the reward.

Wow! Thanks for the feedback everyone. I appreciate it. I should have the oil pan off tomorrow to see what I’m working with. I’ll consider all of your suggestions. Thanks again!

Why not leave the pan on and run some flush through the oil?

[geezer101]

Wow! Thanks for the feedback everyone. I appreciate it. I should have the oil pan off tomorrow to see what I’m working with. I’ll consider all of your suggestions. Thanks again!

I'm thinking he's dropping the pan for an inspection to see what is lurking in there now considering how much gunk was clogging the pick up. I'm amazed this engine is still going despite how bad it was before Geoff started working on it...