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Cant Figure out why the timing belt snapped

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GeoTalon91

10+ Year Contributor
79
1
Feb 8, 2012
Laredo, Texas
So I've been trying to figure out why the timing belt tore on my 92 Talons TSI.

The engine has rust all over so that's one of the first issues I'm going to have to fix up with the engine.

This is what the timing components look like on the car.:notgood:

<img src="http://www.dsmtuners.com/gallery/files/1/3/5/5/0/8/timing_comp_one.jpg" alt="Rusted Timing Components" />

<img src="http://www.dsmtuners.com/gallery/files/1/3/5/5/0/8/crank_pulley_two.jpg" alt="Rusted Pulley And Engine " />

I first thought that perhaps the oil pump had seized and caused timing belt failure but it spun freely, I did however feel a small amount of play on the sprocket that goes connected to the timing belt. Is this normal?

Then I though maybe the balance shaft belt went bad and took out my timing belt, but it was intact so that wasn't the culprit.

The hydraulic tensioner is rusted on the outside but there is no sign of oil leaks and on it and it feel sturdy but i have not tired compressing it. (I'm going to change it either way)

The tensioner arm that goes to the pulley did move freely about a half inch to an inch but keep in mind there is no timing belt on the pulley. Is it normal for it to move that much with not timing belt on?

And last but not least when I got to the lower timing belt cover I did notice that it only had the lower two bolts(marked with red arrows) on the rest of them were missing. So only the two bottom bolts were holding the timing cover onto the engine.

This is the reason the cover was rubbing with my accessory pulleys because it would wobble back and forth so much

<img src="http://www.dsmtuners.com/gallery/files/1/3/5/5/0/8/timing_cover_bolts.jpg" alt="Timing Cover Bolts" />


I'm assuming the previous owner did a belt job and just lost them or did not think to put them back. :nono:

Also when I was taking the cover off I did notice that the cover was pinched up against the oil pump gear, where the timing belt would be. I had to use a wrench to get the bolt off when really a socket should fit just fine.

Is it likely that the timing belt cover pinched the belt so bad that it caused it to break? I don't see any sign of the timing belt wearing or eating into the timing cover..

I just want to make sure I figure out the problem before I start putting it back together..

Thanks
 
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damn, that is rusty. clean that up or throw some new/used stuff on there to start with. past that, i wouldnt want any play in the oil pump gear, thats just a disaster waiting to happen. the rear BS could have seized, and when the belt broke from it, snapped the shaft (unlikely but possible). i would look in that area. then ###### do a balance shaft delete or make sure u put a good belt on it before you toss a new T-belt on there.

i dont think the cover caused the problem, especially if you dont see any wear from either on the cover or belt.

also, make sure you set tension properly on your new belt. good luck! :thumb:

Here is a picture of the broken belt

<img src="http://www.dsmtuners.com/gallery/files/1/3/5/5/0/8/torn_timing_belt.jpg" alt="Broke Down 1g" />

is it just me, or does that belt look a lil oil soaked and/or old and worn?
 
I think if the oil pump or BS had seized, it would have stripped the teeth from the insude of the belt.

Are you sure it is not just an old belt? past due to be changed out? When was the last Tbelt job?
 
Being that the belt is torn and not shredded you can rule out the timing cover. It looks like it is oil contaminated from the pic, but i don't see any oil on the engine. Have you tried turning the cams to make sure that neither one is seized? It is possible that the hydraulic tensioner got stuck also and applies too much force to the belt. What brand is that belt?
 
I have no clue as to when the previous owner changed the timing belt on this car. I bought it from him and two days later the timing belt snapped.

But for some reason most of the bolts from the timing belt cover were missing so I know he took the cover off at one point..Perhaps it was when he JB welded it at the top..

<img src="http://www.dsmtuners.com/gallery/files/1/3/5/5/0/8/cover.jpg" alt="Timing Belt Cover" />

The cam gears were rubbing on the cover and made a nice gash on it, he then Jb welded that part..

All the teeth from the belt are intact and the timing cover was loose on the top so it was prone to water contamination and anything else that could get through there.

I'm hoping it was just an old worn belt, it would give me peace of mind when installing all the new parts.

I'm not sure what brand the belt is, the car is currently at a friends house so I will go later and check up on that.

Also on the head I was able to rotate both cams before I took it off from the engine block. But all the valves were bent.

I will be using a new head that I bought from a member on this site.

Is the arm that goes to the tensioner and is connected to the tensioner pulley supposed to be loose when there is no belt on it?

Before the belt snapped it had a high idle like 1000-1200 RPM and it would get what I would describe as fuel-cut, anytime the throttle was mashed and boost went up.

But it never boosted above 10psi, first thing I did was install an aftermarket boost gauge because the factory one was reading 14psi so i'm sure the readings from the aftermarket gauge were correct.

The car was rolling at 60mph when the belt snapped, actually the engine oil light came on so the clutch was quickly engaged and I i turned off the ignition.
 
yes the arm should move freely if the belt is removed.

sounds like it may have been out of time. belt may have been over tensioned and due to age or element contamination, broke. (or it could be a crappy belt).

i would say over tightening over anything. good call on teeth being stripped if the oil pump had seized. i still dont like alot of play in the pulley, but depends on how much it is :hmm:
 
Wear and tear, a bad tensioner replace that belt, and do a full timing kit oem, and you should be good to go, replaced the water pump while your there, and anything else you know you havent replaced or feel unsure of.
 
Wear and tear, a bad tensioner replace that belt, and do a full timing kit oem, and you should be good to go, replaced the water pump while your there, and anything else you know you havent replaced or feel unsure of.

+1 :thumb:
 
My 90 that I recently retired had much more rust than that with 365K. ( it still runs just rusted beyond the point of repair)
Never lost the belt either.
I'd agree looks like a worn belt.
I would replace the belts with some quality parts along with the tensioner at the least.
 
What I see here is

1 : You have rust everywhere. You might have a pulley that is binding up or causing a ton of resistance on the belt.

2 : Bryan called it. That belt doesn't look like it's wet, it looks like it's saturated and oil has just destroyed it's integrity.

3 : That timing component setup looks very neglected. If anything, it looks like it was time for it to give.

You need to strip this side of the engine down completely. Make sure neither balance shafts are bound. Replace ALL pulleys. Replace the auto tensioner. Do your timing job Correctly and not half assed. Replace that crank pulley - it looks like it's about ready to go.
 
Right, I plan on changing all the timing components and the water pump. I may even change the oil pump if its not too hard doing it with the engine in the car.

Would a Dayco hydraulic tensioner; Gates Pulleys, Timing belts and water pump be good for this application?

Also on the crank pulley which brand should I go with? I've heard the doorman's are prone to failure very easily.

And does anyone know where I can get the bolts for the lower timing cover? Or better yet what size would they be, I only have the lower two bolts and I know that some of the bolts from the timing cover are different depending on where they go.

Thanks, everyone has been of great help and it is very much appreciated.
 
I recommend going oem on all the timing components and water pump/oil pump. Gates timing belt is ok.

for the timing cover bolts, DSM Graveyard - Your #1 Source for DSM Parts!. That gives the oem part numbers for the bolts, maybe you can also find them elsewhere. I know I've seen a post here where someone gives you the exact measurements for the bolts and you can get them at Ace or whatever, but I cant find it. I would just go oem for those bolts also.

Also, make sure you put the timing cover bolts in the proper places, they are different lengths. If your lower timing cover is warped, maybe get a new/used one.

The crank pulley I would also recommend oem, or the expensive fluidampr one.

Check out JNZ or Extremepsi for oem parts.

Good luck
 
Also man I have been seeing alot lately on here with people not aligning the oil pump sprocket correctly. That sprocket is weighted so when u go to put it on it's timing mark make sure the weighted part is at the bottom to do this When it's on it's mark slightly move it it sould remain mainly stationary, but if I slightly move it and it turns a good bit clockwise u need to fix it

Also if you line it up wrong when u put it all together and start the car u will have severe engine vibrations then you will have to tear it all back down
 
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