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420A Timing Belt Slipping

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Skyline-Tweak

Proven Member
64
2
Nov 11, 2012
Kunkletown, Pennsylvania
My timing belt is sliding off the cam gears towards the valve cover. This happened before and it shredded the belt and made it come off and get stuck. Does anyone know how to solve this problem?
 
Quick check: See if there is any grooving on the timing belt. Grooving would indicate some debris or misplaced hardware that is interfering with the belt. If this occurs it will cause the belt to drag and stretch in a minimal amount of time. A stretched belt can jump time. Another possibility is a worn tensioner/ pulley.
 
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Here is what is happening. You can see it runs off on the intake side first. Then on the exhaust side. This happens when the motor is being turned over and it does it even when the timing covr is on. I need a permanent fix for this.
 
Quick check: See if there is any grooving on the timing belt. Grooving would indicate some debris or misplaced hardware that is interfering with the belt. If this occurs it will cause the belt to drag and stretch in a minimal amount of time. A stretched belt can jump time. Another possibility is a worn tensioner/ pulley.

Worn tensioner/pulley, this happened to me last summer.
 
Now when you say tensioner you mean the h-tensioner? And what do you mean by pulley? When I look at the picture it's set up exactly the same, only that I see the words tensioner and pulley twice.
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[DOUBLEPOST=1412181293][/DOUBLEPOST]Also how would I be able to test which one is the worn one? Or are they both worn? And thank you guys so much for any help. My brother and I spent alot of time on this rebuild and we don't wanna see it go to waste.
 
If you have rebuilt this engine why are you using what looks like a used/pretty worn belt?

What i did when I rebuilt was ditched that crappy hydrolic set up and went with the mechanical tensioner.

You can find the kits from rock auto. Comes with a belt both pullies and the mechanical tensioner for around $100.

I love the mechanical tensioner. It makes life so much easier and I have had zero issues with it.
 
Replace both the idler pulley and tensioner pulley with OEM ones [not aftermarket or you will regret it down the road - they don't last and are always a tiny bit different - example: the pulley offset on it's bearing which causes a slide like you're describing. Aftermarket will also start wobbling (wearing out) 3 times sooner than oem].
 
The belt was brand new from Autozone a few weeks ago. iput it on and ran it and it began to fray a very small amount on the outter edge where it was slipping. The rest is just oil from our hands on the belt. Also, where would I get the stock OEM pulleys from? I doubt Advance Auto or Autozone would have them. And should I go with the mechanical tensioner too? What would be the benefits of it? I wouldn't want to go spend around $100 for something that might just mess this up more.
 
oem parts: https://www.jnztuning.com/oempartscat.html

You can go mechanical if you want (cheaper) but you may have to re-adjust it every year should the belt loosen (they are not supposed to with all the strong tensile strength wires in them but you know the real world...age, endless heat/cool cycles, rubber thickness wearing, quality, pulley bearings wearing out, etc). I'd stay with the oem hydraulic tensioner which will always provide proper tension with belt condition. Just install it properly (this is for the 4g63 turbo but gives you the idea: http://www.dsmtuners.com/threads/timing-belt-tensioning-tips-for-4g63-turbo.214625/). And prior to install compress it VERY VERY slowly (to put grenade pin in) or you will blow its seals and it will leak later.
 
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So while I was at work my brother noticed that the Tensioner Pulley was bent. When the belt originally fell off and was stuck, it was because of a backed out bolt. I guess as it got more loose it bent it from the tension. Thank you guys so much for all your help.
 
Ah yes the famous hydraulic tensioner and idler pulleys. I always go w. OEM parts(Last Longer). If you get a quality aftermarket timing Belt and did you remove the balance shafts setup, if not ID suggest changing that small belt as well while your in that area. But if you did a rebuild ost try to delete the balance shafts. Ive had a 1G that I took em out of and all that was diff was a lil more vibration at idle or high revs, but I think high RPMS and any lack of oil or cheap dinosaur oil will turn to water w/ hot as turbos run. The balance shaft delete kits you can remove the small belt for front balance shaft and leave it in the engine. You just have to remove the rear balance shaft and put the new oil pump straight cut gears on a stubby shaft. This way you dont have to pull the engine out and I think more reliable w. out these taking a crap or throwing a bearing since in a rebuild some people ignore this area. Good Luck
 
Ah yes the famous hydraulic tensioner and idler pulleys. I always go w. OEM parts(Last Longer). If you get a quality aftermarket timing Belt and did you remove the balance shafts setup, if not ID suggest changing that small belt as well while your in that area. But if you did a rebuild ost try to delete the balance shafts. Ive had a 1G that I took em out of and all that was diff was a lil more vibration at idle or high revs, but I think high RPMS and any lack of oil or cheap dinosaur oil will turn to water w/ hot as turbos run. The balance shaft delete kits you can remove the small belt for front balance shaft and leave it in the engine. You just have to remove the rear balance shaft and put the new oil pump straight cut gears on a stubby shaft. This way you dont have to pull the engine out and I think more reliable w. out these taking a crap or throwing a bearing since in a rebuild some people ignore this area. Good Luck

the o.p. has a 420a engine, which has no balance shaft in it at all.
 
Oh I assumed it was turbo engine since cams were on the right side like a 4G63T, I see the picture is Showing him on the passenger side of motor so yes it is a N/A sorry didn't see that Title. All but the balance shaft/turbo wear I mentioned can be thrown out. N/A can be more reliable w/ out all the extra heat/stress a turbo and extra Torque can do on drivetrain etc. Maint. is Key on all cars. Good car/mootor for a more reliable DD.
 
We got a new tensioner pulley and bracket. OEM too. It still runs on that side of the cams but it doesn't slip off anymore. When it gains more speed it actually evens itself out.
 
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