crank pulley problems

[riverdude]

the saga of my crank pulley

crank pulley bolt comes loose, pulley spins and takes small chip out of one end of key way, pulley and key replaced all seems to be good hear noise, start to doubt my mechanics ability. Take to new mechanic, bolt has come loose again, replace crank pulley and the crank sprocket JBweld the key into the keyway on the crankshaft, lock tight bold and torque on with impact, all seems to be good. think i hear the noise again and the bolt is possibly coming loose. Why would this bolt keep backing out, i assumed that the key was just to hold the pulleys position and the bolt did the holding. Mechanic was at a loss, said we could grind out the keyway with a diegrinder and use a bigger key or tack the pulley on to the shaft in the recess between the bolt and pulley or........


any ideas guys i would love the input don't want to loose my van

[jessef]

new bolt

the existing bolt is stretching

and JB welding the key may not be enough for the torque applied there. A new crank or machined shaft with new key looks like it's the solution down the road.

[thedjjack]

I would change the bolt for sure. Sounds like the key way is damaged. Look on post for Mazda Miata's this is a very common problem on that motor (advantage that the motor is non-interferace meaning the valves always clear the pistons if the belt fails).

They do make a lock tight for shafts (used it on printing presses). I looked at a car once that had the pully welded on. Might be an option if you need a new crankshaft to fix! I think the pull and tension on the accessories may play a role too. If you do not use the airconditioner I would take off the belts to reduce load.

Good luck with it.

[nxski]

I just got a call from my mechanic about 5 minutes ago saying my crank pulley is loose. Hopefully it doesn't become a recurring problem!

[jessef]

I posted it before about loose crank pulley's.

Get a new one with bolt and key.

They aren't cheap but it's worth it in the long run.

[nxski]

So buying the bolt and key separately just isn't a good option? That's the next step depending on what the mechanic says. Batteries, glow plugs and a lift are the other big purchases for this month!

[CVI]

Hi... Check the crankshaft key way housing for wear and ovality. Lots of times, when the bolt comes loose, the pulley starts wobbling on the shaft wearing that shaft quite a bit. If the shaft has worn down, there's no way you can put a new pulley and bolt without repairing or rebuiliding that crankshaft keyway and housing first. The only remedy is to pull the crankshaft out and get it rebuild professionally or get a used crank.

Sorry...

Butch

[nxski]

I'm having a similar problem with my Mighty Max now...

The bolt has completely broken off. It's at the mechanics now but he has no idea where to source a new bolt or even what the original size was since it's so mangled. Any ideas on what I can do? I'm hopping nothing is too badly damaged. The engine is a 6G72 if that helps!?

I'm assuming some Pajero of L400 owners may have had this problem. Apparently there was a recall of the 6G72 engines from 1992-1996 and it was problematic in the 1989-1991 years as well.

Thanks

[strada-caster]

I'm having a similar problem with my Mighty Max now...

The bolt has completely broken off. It's at the mechanics now but he has no idea where to source a new bolt or even what the original size was since it's so mangled. Any ideas on what I can do? I'm hopping nothing is too badly damaged. The engine is a 6G72 if that helps!?

I'm assuming some Pajero of L400 owners may have had this problem. Apparently there was a recall of the 6G72 engines from 1992-1996 and it was problematic in the 1989-1991 years as well.

Thanks

a bolt for this engine will be much easier to find, check out rock-auto online.
a lot of montero's and mighty max's have these engines. still very popular in the US (rock auto operates out of the US).

as for the diesels, if the crankshaft and keyway are decent but the pulley has teh mangled keyway, find a machine shop to put a new keyway into it. really simple process (don't know what the cost would be though)

[nxski]

a bolt for this engine will be much easier to find, check out rock-auto online.
a lot of montero's and mighty max's have these engines. still very popular in the US (rock auto operates out of the US).

There are tons of vehicles that have this engine but as it's a work vehicle and I've already taken 7 days off work this month to source a radiator I'm hoping to source a bolt locally rather than have to wait days to have one shipped from the states. I've found a few ads for bolts but none list the exact dimensions. Maybe the mechanic will have more luck figuring this out. He was saying that if the crank shaft is damaged (which is a highly likely) that I will have to replace the engine!

http://en.wikipedia.org/wiki/Mitsubishi_6G7_engine

[thedjjack]

Might be time to replace the mighty max with a Ford or a Toyota...

With work trucks you do not have time to search for parts. I would just swap the engine (usually 6 hour job)....I have an engine hoist if you need to borrow it (Arnold has it right now).

Good luck

[nxski]

I'm only the principal driver of the truck, I don't own it, so unfortunately that's not my decision. I would rather be driving a Ford Ranger for work, cheap, easy to find parts. I'm having to make-do though since the truck is only being used until May so scrapping it for a new one wouldn't make sense for the owner.

[thedjjack]

If you are only keeping it to May. You could try welding the pulley. I knew of a guy that was getting about 40,000km on his welds holding the bottom pulley on a turbo mazda.

[nxski]

That's a possibility as well, I'll have to see if the mechanic would be up for doing that. It won't drive so I'm at his mercy right now.

Although I would probably put on more than 40,000km before May.

[nxski]

The crankshaft is destroyed so the engine is dead. Looks like the truck will be scrapped...