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The mkiv Supra Owners Club

Timing belt keeps jumping teeth...?????


Florin

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Replaced the tensioner with brand new one and 9 miles later it jumped again.... The belt has 50 miles on it and does not look damaged at all..Also I'm having a hard time figuring out what this little spacer star looking thing thats behind the dapner is called???? Is that what sends the signal to the spark plugs??? if so does it do it via a sensor reading the teeth?? does that sensor go bad, Is there a way to check if its doing what its supposed to do before I start just replacing parts for the hell of it

 

Been working on this car for 10 months and have drivin it a total of 2 hours. I just cant figure it out and the only ppl around that can help me want 70$ an hour. I just cant give a guy 3 or 4 hundered eveytime theres a slight problem or a new noise I havent heard before. Spent 1000$ for him to put a man boost controller on, cut out defender, and weld some pipes on the intake. The car ran great for a cpl of days and now I have a new problem with this timing,engine dying, not startinf right thing and I just cant afford to turn around and give him another 1000$ just coz he knows his shit and can fix it in 30 mins .....Meanwhile he can tell me he did this and that and I wouldnt know the diffrence.

 

Please help....

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Where is it jumping the teeth? Is it down at the pulley it's jumping or is it the cams? One or both?

 

The first time both cam gears were clock wise off by 5 teeth each from the sign on the back plate...... Took the belt off got everything tdc and put new tensinor on drove it 9 miles it back fired once then died got out to look and now it looks like the intake cam gear is off by 2 teeth clock wise and the other is right on the money. The car will start pretty easy and sound norm (as your turnig it over) but once it starts the rpm just goes up and down 700 to 1300 or so , try to take off and it jolts some if the makes any sense when that happend i just parked it....

 

To the first reply....What would lock the cams to begin with???? In order for "someone t5urned the crank with the cams locked"

what is the "bel"

what is "binned"

 

Thank you very very much guys

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If that***

 

If feels like you would be running out of gas when you try to take off i should say. Thats why other then the timing belt issue. I'm wondering if the spark, spark plugs, coils, coil plugs, and whatever sends the plugs there signal might be the problem, I think the peace is called the "trigger"

?? ...also it might ( just guessing here) have something to do or be the mass air flow sensor??

I know Ive rambeld a bit and that I might be stating facts about diff problems but I thought it would help get a better idea of the car

94 tt 6 spd

a cpl of bpus and a bypassed vsv under the front turbo

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Is it a tt ? if so you may have bent a valve or 2 causing it to stick and make the belt jump

With it a tdc take belt off and try turning each cam feeling for any tightness

but isnt the car a non-interference engine??? if so then the valve cant get bent ????

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The TT is a non interference engine. Did you use a genuine Toyota tensioner and pulley? Was the timing set up correctly? Are the cam gears aftermarket or stock?

I call that star thing a trigger wheel or timing star, its teeth are counted by the crank position sensor. Generally if the cps is shot the engine wont start at all.

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Thats what I thought also. The trnsioner I got from the dealer. The belt from auto parts store. The cams are stock. Did not replace any pullys. not sure if the first time it was done right but am sure the second time it was. tdc etc....

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Not really sure what you mean. I dont have a manual.....

 

The tensioner puts a silly strain on the timing belt if it isn't fitted correctly. The correct way to do it is to put the tensioner in a press and align up the holes so that you an fit a 1mm or 1.5mm allen key through them. You then take the pressure off and fit the tensioner in place. Once it's in and secured you pull the allen key out and the correct pressure will be put on the belt. It takes a lot more force to compress the tensioner than it does to hold it in place, if you screw the tensioner in without pre-loading it you will over strain the timing belt.

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Ill bet you are winding the tensioner in on the 2 12mm bolts that hold it to the timing cover, if so thats your problem.

 

All this tensioner talk could VERY well be my problem!!! But the NEW tensioner came with a pin in it. So I just bolted it on put the belt on the pulled the pin,,,,Correct or no???

 

Will try to post some pics, but i think last time i tried to put some of the car it didnt work to well I might dont be doing it right the (uploading)....

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All this tensioner talk could VERY well be my problem!!! But the NEW tensioner came with a pin in it. So I just bolted it on put the belt on the pulled the pin,,,,Correct or no???

 

Will try to post some pics, but i think last time i tried to put some of the car it didnt work to well I might dont be doing it right the (uploading)....

 

Thats the correct way to do it dude, so thats not the problem, are you definatly getting the tight side of the belt on the short run down from the cam pulley on the inlet side arent you

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Right, the tension needs to be from the inlet pulley to the crank pulley, it should be tight and all slack is between crank and ex pulley, this is where the tensioner does its job, tensions and removes slack, if you have slack between in pulley and crank as the engine cranks the the crank can pull the belt round without it pulling on the inlet pulley and moving the cam pulleys at the same time.

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Is the belt definitely the correct one? It might just have been me but even with the tensioner off I had a hell of a time getting my belt on due to just how tight a fit it was when "loose". Or is there something wrong at my end?

 

All I did was put the belt on, give the pulley a small turn to put as much tension on the inlet side as I saw fit and then mated up the tensioner before pulling the allen key.

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Personally I would probably strip down the turbo pipes, intercooler pipes etc. Give them all a good clean and quick inspection then put it all back together. A few of the stock rubbers between the turbo outlets are known to collapse. No harm in giving everything in that area a good going over to be sure that everything is as it should be.

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It wants to stall in 3d- 4th -5th when its between 1500 and 2200 rpm I know thats when right around where the turbos kick in. so you take off in first with any issues (not stepping on it ) just like you were driving a corolla :) the go to second and third now you step on it and it wants to stall but after you pass 2500 its fine... same thing with 4th 5th

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