Gen 3 Timing Belt Failure Modes?

[Snowrydr01]

In my search for Gen 3s locally i seem to always be able to find some with "bad motor" in the craigslist add. From my research it looks like the #1 cause is failed TB #2 overheating #3 but rarely a spun bearing.

So what is the most likely cause of a timing failure on these engines? Toyotas seem to be able to push high hundreds on timing belt with no problem. Are the belts sized wrong and break or is it a failure of the hydraulic tensioner causing it to get lose and skip teeth?

If its not the belt, would it be worth the piece of mind to replace the tensioner at half the interval since you wouldn't have to disassemble anything?

 

[PA_JERO]

Do the proper PM intervals and use OEM parts and the Timing Belt isn't a problem. Most people have failed tensioners because they cheap out and buy aftermarket parts for timing belts. I'm guilty of doing this as well but after I had an aftermarket tensioner fail after 1 year with only 6k miles on it, I quickly learned my lesson. When a service interval is due, do it right with the right parts the first time or you Will regret it.

 

[Toasty]

X2 with PA_JERO

Mitsubishi and Toyota use the same supplier for bearings, tensioners and belts the only difference is that a Mitsubishi has much tighter tolerances when it comes to engines and owners typically don't take care of them like Toyota owners do. For example lets say your tensioner fails to 50% on both your Mitsu and Toyota era for era (lets say Mitsu 3.5 DOHC vs Toy 3.4 DOHC) Your Mitsu will be down on power and maybe close to valve interference, beyond that you get full interference and your motor now needs heads. The Toy however will just run like garbage, it ultimately will no longer run until the belt is replaced. Now some will say "Toyota just knows how to engineer an engine better than a Mitsubishi" or "This is why Toyotas are so much more reliable than Mitsubishi" The fact of the matter is that the Mitsu is better engineered than the Toyota but unfortunately it is less forgiving than the same era Toyota. So the reliability thing is a matter of care and perspective.

For comparison sake the 1994 Mitsu is 215 horsepower and 228 torque and 1996 Toy is 190/217, So there's what you get for your more precision engine. If you want a Mitsu that is as underpowered as a Toy that you can run into the ground repeatedly look for 1989-1994 Montero's with the 3.0 V6. Also i think it's worth noting that Mitsu is typically 5 years ahead of the other makes in technology so the later Toyota's have the same issues as far as breaking timing belts but they are newer trucks with licensed Mitsu technology anyways so Montero "problems" spread like the plague! No matter what you're always in the same boat, pick your poison.

 

[RyanY]

Both of the common issues that you've mentioned finding in your Montero search are directly due to poor or no maintenance on the part of the previous owner(s). It is not a Mitsubishi specific nor Montero specific problem. A Montero whose cooling system and timing belt maintenance has been done as recommended will not have those problems, much the same as any other vehicle on the road.

If a Montero with those problems is what you're attempting to purchase, you'd better plan to spend some extra cash bringing the rest of the maintenance up to date, along with the repairs necessary to get it running again.

 

[Offroadmuch]

Great thread so far.... So as far as the clicking sound on startup with a cold engine (3.8L, 6g75) I was thinking it was a stuck lifter, could it be a bad hydraulic tensioner? Any help with how I can figure that out?
Thank you-

 

[PA_JERO]

Yes, I had the exact thing, thought it was lifters and when I was hunting down a coolant leak I found my belt had a ton of slack. The hydraulic tensioner piston decided it didn't want to keep tension anymore (aftermarket tensioner).

Pull one side of the timing cover and see how loose your timing belt is after its sat for a few hours or over night.

 

[122andy]

For comparison sake the 1994 Mitsu is 215 horsepower and 228 torque and 1996 Toy is 190/217, So there's what you get for your more precision engine. If you want a Mitsu that is as underpowered as a Toy that you can run into the ground repeatedly look for 1989-1994 Montero's with the 3.0 V6. Also i think it's worth noting that Mitsu is typically 5 years ahead of the other makes in technology so the later Toyota's have the same issues as far as breaking timing belts but they are newer trucks with licensed Mitsu technology anyways so Montero "problems" spread like the plague! No matter what you're always in the same boat, pick your poison.

Yet in 2002 they have 200 HP. That's me biggest gripe, this thing is gutless. That and the glitchy Super-Select 4wd system.

 

[Toasty]

yeah in the US we got the shaft on motors for a few years and the ones we got are choked out by emmisions. I also have a couple of the late model 200hp trucks, we're working on some things for you...

 

[The Viper]

Are you guys talking about failures of the hydraulic tensioner or the belt tensioner? The Dayco timing belt kit for the Gen 3, is that a reputable tensioner?

 

[Toasty]

Only use OEM tensioners. One thing to not cheap out on

 

[PA_JERO]

Yes, only OEM on hydraulic tensioner.

 

[Offroadmuch]

Are you guys talking about failures of the hydraulic tensioner or the belt tensioner? The Dayco timing belt kit for the Gen 3, is that a reputable tensioner?

So as stated here can someone respond. I have the clicking sound that I thought was a stuck lifter but now I think it may be one of the above. Can someone say which is the one I should focus on? I also discovered this morning that I have a new timing belt and serpentine belt, both marked "Made in USA," funny because that would normally be a good thing but not necessarily with a Mitsu motor part. I have heard that Gates products are made here but I cannot confirm the brand. Is the tensioner a critical part I should replace quickly? The clicking gores away when warmed up. Does that mean it is working?

 

[ChargerX3]

Gates makes the oem timing belt for Mitsubishi.