Oil Pump Sprocket broke

[PrimerPLus]

So I am confused as how my oil pump sprocket broke into 2 pieces today.

I went out this morning started my car good oil pressure at 70psi (cold in Alaska)
Went to walk back inside and I hear this weird noise like if you dropped a socket onto concrete. Then my motor shut off. I went to check things out looked all around the engine bay checked all fluids etc and the belts that I could reach. Everything looked fine. I went to start it again and as soon as it went to crank I heard a weird noise so I immediately just stopped and I didn't let it start.

So I got the belts off timing covers off and I was looking around to see if I could notice anything and that's when I seen my Oil Pump Sprocket gear was in 2 pieces.

With the timing belt on I can turn the engine over both backwards and forwards but it is very difficult to turn it forwards. So I cut the belt as I wont reuse it now.
The sprocket gear bolt that you tighten down is not coming off. I used red loctite on it when I did my rebuild. So I can turn the bolt and the oil pump gears feel good, but the sprocket just sits there. The little key on the sprocket on the inside somehow shattered. So I have no clue as to how that could of happened.

I have STM BSE kit so it came with all bearings and the oem short stubby shaft.
The only reason I can think that it cracked is that I used a 3/8 impact to tighten it and maybe over tighten it? Also it has never been replaced and has about 116k miles on it. The crank spins just fine, cams spin fine, oil pump gears spin good. (Correction, spins good in reverse not forward-in reference to engine running)

Is it possible the oil sprocket gear caused the motor to die when it broken into 2 pieces and its guide pin stuck between gear and belt?

Well I got the nut amd gear off had to use a dremel. The brand new oem front case/oil pump gears seized/broke. I have stm bse kit along with 1990 straight cut gears for the oem stubby shaft. I have no idea why this happened. I packed those gears full of red line assembly lube torqued everything to spec used red loctite. Any insight would be helpful.
The scarring on the surface is from my dremel.

 

[Purple_Demon]

Does your stubby shaft have the oil hole in it? Some shafts are advertised as "OEM" but do not have the oil hole in it, sometimes causing the internals to seize.





Never mind, I see that you say the oil pump gears spin fine.

 

[PrimerPLus]

This is the kit.

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[crimsondragon]

Time to pull your engine out. Your engine died because the gear broke and lost all tension in the belt. At best, your valves kissed the pistons. At worst, you bent the valves. That fracture looks like it was indeed cause by overtightening. There is a torque on that nut for a reason and it's not something you just machine gun on. Suck it up as a learning experience.

 

[PrimerPLus]

Actually the gear didn't come apart until I removed the nut. But the belt was still very tight. But I will check and see if valves are bad once I get it out.

 

[Purple_Demon]

From the looks of it, the stubby balance shaft does not have an oil hole like the OEM factory shafts. That can cause seizing of the oil pump and gears. It is possible that the sprocket, gears, pump seized(while the sprocket still trying to spin) resulting in it being shattered. Just a thought

 

[crash89]

From the looks of it, the stubby balance shaft does not have an oil hole like the OEM factory shafts. That can cause seizing of the oil pump and gears. It is possible that the sprocket, gears, pump seized(while the sprocket still trying to spin) resulting in it being shattered. Just a thought

Thats what happened to a buddy's engine. Had less than 5 miles on the engine. He used an Ebay BSE and the oil pump seized. I didnt know this until we tore it down.

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[Roberti 2G]

Your valve are prob fine. I had this happen when I had to use a bolt for the inspection hole since the previous owner had the knock sensor in its place. I used a bolt that was too long and it touched the Balance shaft and my sprocket broke in two the same way. Belt was good and the sprocket came apart when I took the nut off. Luckly I just cranked the engine and knew something was wrong so no other damage All in all everything was fine my engine is running better then ever and all I did was replace the sprocket and redo the timing.

 

[white92talontsi]

You over torqued the sprocket nut.

 

[RamenPride]

From the looks of it, the stubby balance shaft does not have an oil hole like the OEM factory shafts. That can cause seizing of the oil pump and gears. It is possible that the sprocket, gears, pump seized(while the sprocket still trying to spin) resulting in it being shattered. Just a thought

From their website:

Our own STM kit includes Clevite block off bearings, an OEM mitsubishi stubby shaft, and an OEM mitsubishi block off plate for your front cover.

This one is the one you don't want:

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