GEN1 LWB 6G72 12V Engine Refresh

[chadzeilenga]

After life taking up the last two weeks I was finally able to get some work done on the Montero.

Pulled the rear main seal off the Donor motor. Despite being peak free, there was some wear on the seal lip

Here is new one installed. I had a real faint groove in the crank from old seal. I cleaned real well and tried my best to put the new seal evenly in the bracket. I made sure to apply plenty of assembly lube to the crank and seal for startup.

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[chadzeilenga]

Spent some more time getting the JY motor refreshed.
Crank Seal
Valve seals - rope method worked well!
Cam seals
Water pump
Timing belt

I have most of the front of the motor buttoned up and now will be getting the upper intake on so I can drop back in. It has been nice to work on outside vehicle.

I do have a new crank bolt and washer to install. Wasn’t sure which side the chamfer on the washer went, but figured under bolt head.

Is hood removal required for putting engine back in?

One thought I had to torque crank bolt was to use zip ties to hold flywheel, anyone else use this method?


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[PacS14]

You could always put a big sticker on the radiator that reads "don't forget to thighten the crank shaft bolt!" And just do it after you drop the engine in...

 

[PacS14]

Good progress by the way! Keep it up!

 

[chadzeilenga]

With the great progress over the weekend getting the motor buttoned up, I feel that I’m gaining some momentum.

Was able to install my new OEM motor mounts.
Pulled the old ones from cross member and found a cross threaded bolt that I retapped to clean up, so it’s likely the old motor had been out at some point in the past 200k.

Removed the old exhaust manifolds from the pipes since I’m planning to lower motor with manifolds and motor mounts installed, unless anyone has any better guidance.

I decided to just check the torque of exhaust manifold bolts before installing and #6 lower bolt just spun...I removed the loose part and found it had sheared at the start of threads

Is it common for these engines to fail exhaust studs? It didn’t even give me any resistance when checking torque, so I think it was already broke. I’m hoping I can ez-out and install a new one.


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['round n' back again]

may i suggest pulling the block, (easy to do) and sealing it up and reusing what you have?

unless there is a very pressing need; piston holes, broken ring (s) , lands etc, the mitsu assembly will be superior to a rebuild unless you plan of a turbo or something viscous.
Further the finished product of a rebuilt 3.0 will not warrant the money invested.
they are still a dog tired engine, even freshened.
you will wish you had saved the dough that you spent on the bottom end for such a poor return on investment.
heads are altogether different. they can stand some expert asian specialist head builder to clean them up.

The Chrysler version of this engine is more powerful than the pajero version because of the cams and the intake /exhaust design.. both are dogs.

lastly, the a340 series of transmission is a power hog. it will consume any power improvements you might squeeze into the engine and waste those improvements in the form of still gutless performance and poor fuel mileage.
Further there are no known improvements that can be made to the transmission to remedy this problem.
In its defense, the transmission, properly cared for, will give you 500K in service, they are tough.

 

[chadzeilenga]

may i suggest pulling the block, (easy to do) and sealing it up and reusing what you have?

unless there is a very pressing need; piston holes, broken ring (s) , lands etc, the mitsu assembly will be superior to a rebuild unless you plan of a turbo or something viscous.
Further the finished product of a rebuilt 3.0 will not warrant the money invested.
they are still a dog tired engine, even freshened.
you will wish you had saved the dough that you spent on the bottom end for such a poor return on investment.
heads are altogether different. they can stand some expert asian specialist head builder to clean them up.

The Chrysler version of this engine is more powerful than the pajero version because of the cams and the intake /exhaust design.. both are dogs.

lastly, the a340 series of transmission is a power hog. it will consume any power improvements you might squeeze into the engine and waste those improvements in the form of still gutless performance and poor fuel mileage.
Further there are no known improvements that can be made to the transmission to remedy this problem.
In its defense, the transmission, properly cared for, will give you 500K in service, they are tough.

I'm not following you...My 205k mi block is already out with unusable heads and a crank that is heavily scored. The block only had 120PSI compression when it was running. While I was contemplating the rebuild, I found a complete used 6G72 engine with only 90k mi on it. All of my initial inspections indicated that this was well maintained, very complete and doesn't show any evidence of being disassembled except for the typical maintenance. I'm confident that with refreshing the items that age (rubber seals, etc.) and upgrading known weak points (VLA's) I will have a reliable engine for many years to come. The prior engine at 120PSI satisified any power needs I had, so I'm sure this one will as well.

 

[GrantC]

I decided to just check the torque of exhaust manifold bolts before installing and #6 lower bolt just spun...I removed the loose part and found it had sheared at the start of threads.
Is it common for these engines to fail exhaust studs? It didn’t even give me any resistance when checking torque, so I think it was already broke. I’m hoping I can ez-out and install a new one.

I've encountered more than one exhaust stud sheared like that. In fact, the most recent one was on my 2.6l Montero engine. The remainder came out with no issues when I put the remover on it.

 

[chadzeilenga]

I've encountered more than one exhaust stud sheared like that. In fact, the most recent one was on my 2.6l Montero engine. The remainder came out with no issues when I put the remover on it.

Good to know. Luckily the rest of the bolts on the engine are rust free, so these exhaust studs should come out without issue. I'm glad I decided to pull the heat shield and just double check torque before installing, that one would have been a nightmare to extract in the vehicle.

 

[chadzeilenga]

I got the failed stud out pretty easily and reinstalled the manifold. Also checked torque on the passenger side and the same stud, lower rear was loose. In tightening it up to 20ft-lbs it snapped. I removed stud and installed a spare. Used an even torque sequence and all went to 20ft-lbs without issue.

Also, I noticed a bit of carbon buildup on my #3 & #4 cyl. Came off pretty easily with a stone grinder. Any thoughts on cause? Others looked fine

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['round n' back again]

earlier i posted a reply about your engine project that was out of place. im new to this new format and did not realize i had read only the first page b4 offering my advice .
so of course by the 3rd page my advice was senseless, like it most of the time is.

that mess in cylinder 3 and 4 is oil. you have either blow by or a cracked head, allowing oil into the combusiton chamber. look at your plugs in those cylinders.
jsut run a hotter plug to more thouroughly burn the mixture if its not too much blowby. get those manifolds hot tanked. also do not reinstall the tin covers.over the manifolds.

 

[chadzeilenga]

It’s no problem R&B, I was just confused by the advice.

The carbon was very dry, so I was thinking the engine might have been over fueling or had a bad spray pattern for those injectors? The plugs all had an equal amount of coloration

The oil on plug is from when I had motor upside down to pull oil pan.

Why not reinstall the heat shields around the exhaust?


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[chadzeilenga]

Motor is back together and ready to go in, except for that oil filter haha!

I’m assuming that this is a hood off process?


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[chadzeilenga]

Getting there, all bolted in on the bottom. I’m saving the top 4 bolts from trans to block for tomorrow!

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[chadzeilenga]

Got it running today. Runs well except for some chatter out of Pass valvetrain.

I re-pulled the VLA’s to make sure I didn’t put in any upside down. All were installed correctly. I reprimed them to be sure. Good and firm prior to installing.

I’m wondering if some of the oil drained out of the VLA’s when I turned motor upside down to install the oil pan. Didn’t think about this until now. Also, if there is any air in the oil passages of the rocker arms, will this just get pushed into the VLA at first startup?

Oil pressure was ~45psi at idle which is double that of last motor. No leaks “yet” haha. I’m waiting for the sealant I put into the corners of valve cover gasket to dry before I fire back up and take for a drive.


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