90 gsx timing belt slippage

[90rslaser]

Well, here's an explanation of whats going on with my 1990 gsx (90k original miles.) last year i bought the car from an older gentleman for $700. hes the first owner of the car has used it since 1990 to commute back and forth from home to his job (about 70 miles a day,) about a year and a half ago the timing belt broke and caused bent valves. he had the head replaced by a local shop. brand new head, new timing pullies and tensioner, new oem cam gears, etc etc.
about a week after that the clutch went out on him so he had that replaced. about 2 months after that, the turbo went out on him, so he had a shop install a new oem turbo. As soon as they started the car right after the turbo install(im assuming after about 30 minutes of driving time) the car started smoking real bad and making funny noises. The gentlemen decided he had enough with the car due to a shop telling him the brand new head was bad again. After purchasing the cra i got it home and found that both the coolant feed and oil feed lines had been completely kinked off from removal/installation of old and new turbo causing it not to get any oil or coolant. I then replaced the turbo with a 16g, and had some good hard lines laying around from previous builds. car started up and ran fine without any kind of smoke. I then continued to drive the car for about 6 months or so when one day when i was on my home the car would shut itself off. Got it home, checked out everything and found that one of the cam caps had not been properly torqued down from last install causing it to melt and destroy the head. So i purchased a new head, new cams, new timing pullies and tensioner and timing belt(this was for my own satisfaction of knowing everything is done properly.) and reused some old cam gears i had. i have just within the past day installed everything new on the car(forgot to mention cometic headgasket and arp headstuds.) got the timing set right, started the car, and it shut itself off. found the oil pump pulley had been off by a couple of teeth somehow. redid all the timing, making absolutely sure everything was aligned, and re-started the car. i noticed while the car was running, that the timing belt was pushing towards the outside of the engine(driver side of car). turned carr of and checked timing and made sure everything was nice and tight. pushed timing belt back on, started car again, and it did the same exact thing(about 1/16 of an inch off the cam pullies.) so i started the car and revved it up to about 2000rpm, and the belt would come off the pullies about a quarter of an inch, until settled back down to idle, then it would go back to being about 1/16 of an inch off te pullies. So, i guess my question would be if anyone else has ever had this problem, what caused it, or what else to look for? I have tried absolutely everything i can think of, and STILL cant find the culprit causing the belt to come off. Any/all help would be much appreciated.

 

[Black-Out]

Well, here's an explanation of whats going on with my 1990 gsx (90k original miles.) last year i bought the car from an older gentleman for $700. hes the first owner of the car has used it since 1990 to commute back and forth from home to his job (about 70 miles a day,) about a year and a half ago the timing belt broke and caused bent valves. he had the head replaced by a local shop. brand new head, new timing pullies and tensioner, new oem cam gears, etc etc.
about a week after that the clutch went out on him so he had that replaced. about 2 months after that, the turbo went out on him, so he had a shop install a new oem turbo. As soon as they started the car right after the turbo install(im assuming after about 30 minutes of driving time) the car started smoking real bad and making funny noises. The gentlemen decided he had enough with the car due to a shop telling him the brand new head was bad again. After purchasing the cra i got it home and found that both the coolant feed and oil feed lines had been completely kinked off from removal/installation of old and new turbo causing it not to get any oil or coolant. I then replaced the turbo with a 16g, and had some good hard lines laying around from previous builds. car started up and ran fine without any kind of smoke. I then continued to drive the car for about 6 months or so when one day when i was on my home the car would shut itself off. Got it home, checked out everything and found that one of the cam caps had not been properly torqued down from last install causing it to melt and destroy the head. So i purchased a new head, new cams, new timing pullies and tensioner and timing belt(this was for my own satisfaction of knowing everything is done properly.) and reused some old cam gears i had. i have just within the past day installed everything new on the car(forgot to mention cometic headgasket and arp headstuds.) got the timing set right, started the car, and it shut itself off. found the oil pump pulley had been off by a couple of teeth somehow. redid all the timing, making absolutely sure everything was aligned, and re-started the car. i noticed while the car was running, that the timing belt was pushing towards the outside of the engine(driver side of car). turned carr of and checked timing and made sure everything was nice and tight. pushed timing belt back on, started car again, and it did the same exact thing(about 1/16 of an inch off the cam pullies.) so i started the car and revved it up to about 2000rpm, and the belt would come off the pullies about a quarter of an inch, until settled back down to idle, then it would go back to being about 1/16 of an inch off te pullies. So, i guess my question would be if anyone else has ever had this problem, what caused it, or what else to look for? I have tried absolutely everything i can think of, and STILL cant find the culprit causing the belt to come off. Any/all help would be much appreciated.

On most cars when I have seen this sort of thing it's because someone neglected to replace the large "washer" that goes on between the crank sprocket and the harmonic balancer which helps maintain belt tracking while the car is running. I'm not positive that there is one there but I'm betting there is and that it is no longer where it should be, or the crankshaft sprocket could have a lip on one side and it's been installed backwards allowing the belt to track off the cam and tensioner pulleys and then back again at lower engine speeds.....Do you have a repair manual which may show a picture of the parts prior to disassembly?

William-

 

[91boostedgst]

Sounds like something is wrong with the tensioner its self. Try hand cranking it by hand see if u can see whats going on.also try another belt.

 

[muddfisher85]

I just fixed mine it kept doing that too. Turns out mine was the crank sproket. Mine had lost the ring that is on the one side cause it to wobble and push the belt off. It actually wallowed out the guide pin hole on it out so bad my timing was a tooth off. Ruined that and the little metal plate behind it with the crank timing mark on it. Fought that problem for 5 months and 3 heads. x2 On the change the T belt. I also changed mine at the same time.

 

[90rslaser]

checked the haynes, and chiltons manual, also looked on the internet as much as possible. the only thing i could find for a tracking plate is as follows on the crank: balance shaft crank pulley with plate(towards block), plate by itself over that, TIMING belt pulley, and then harmonica balancer. i have found absolutely nothing about a plate going inbetween the timing belt crank pulley and the harmonic balancer. went and bought two more new timing belts(now have 3 brand new timing belts) tried both belts earlier and they both do the same thing still. also on my 2nd tensioner. the only thing i have noticed, is the tensioner doesnt sit very far back on arm when its pushing it up.

 

[muddfisher85]

The plate goes inbetween the between the balance shaft sprocket and the timing belt sprocket. Make sure the sprockets themselves are good.

 

[90rslaser]

Issue fixed. Found that the exhaust cam gear was out of round/bent, how that happened I have no damn clue. But replaced it with a new one again and timing belt is working flawlessly. Thanks for all the help though!