1G 91 Talon TSi AWD Timing Belt?

[freebird_43]

Seeking some direction on this issue.

The Talon just died in the middle of the street! I was at idle waiting to turn. Got it trailered home and found the cam gears not turning while cranking it over, accessory belts turning.

Timing belt replaced less than 10k miles about 6 yrs ago. Belt seems to be intact and tight. Any ideas on this? Should I start at the Timing belt cover or?
Thanks for any and all suggestions.

 

[19Eclipse90]

If the cams don’t move with the crank and the belt is “intact”, it probably sheared the teeth off.

Pull the cover and start investigating. Do not turn the engine over more.

 

[freebird_43]

Thanks for your feedback, I was thinking the same, sheered teeth on the belt. Seems odd, wasn't hot rodding, car was running normal and at idle. Hopefully no major damage. I'll pull timing belt cover and check belt.

 

[Turbski91]

Do you know the brand belt? Iv seen after market belts do this. Also if a car sits for years without rotation the timing belt gets pinned at the same location and this can cause failure on restart.

 

[freebird_43]

Hello, not sure of the tbelt manufacturer, I will check that when I get the belt cover off. The car sits in a heated barn in the winter, I run it only in the summer. I've put about 2k on her this summer so far. If the belt did sheer its teeth under almost no load, I'm guessing the valve train has somehow locked up. I'm not real familiar with the tbelt drive pully off the crank, is it possible for it to loosen on the crank and freespin? This car is also mainly stock from the factory. Has 163k on the clock..

 

[19Eclipse90]

If it “loosens on the crank” and free spins, the pistons are taking some valves out as the crank turns.

Pull the cover and determine what the belt looks like. After that, you’ll almost certainly need to pull the camshafts to relieve pressure on the valve springs - theoretically, this should allow all valves to close. Then, pump compressed air into each cylinder to determine whether or not it holds air (valves are sealing / closed) or does not hold air (valves are likely bent).

If they hold air, rotate the crankshaft to align its timing mark, reinstall the camshafts with the dowel pins in the 12 o’clock position, and install a new belt. I’d recommend a compression test, just to be safe.

If they don’t hold air, you’ll need to plan for pulling the cylinder head.

 

[freebird_43]

Thanks for the info, I ll pull the belt cover to inspect belt, I'll post status shortly. Thanks again for the feedback.

 

[1990TSIAWDTALON]

The 4g63 is an "interference" motor. If the crank rotates out of time or doesn't turn the cams, you most definitely have valve damage. Not your fault, but it does fit the criteria mentioned above. I am all too aware of the issue unfortunately.

 

[freebird_43]

Thanks for the feedback, knowing that the 4G63 motor is an interference motor, I've been diligent about changing the tbelt. I should be able to get the belt cover off today and inspect it. Ultimately I better plan on yanking the head as well, going into unknown territory there! I will post as soon as I know about the belt. Going to need support from the DSM guys out there going forward with the repair.
Thanks for your input!

 

[freebird_43]

Tbelt sheared the belt teeth @ crank pulley. Pulled valve cover, no carnage to the untrained eye. By the looks of the cam lobes all valves are going closed. Something put the brakes on that belt in a hurry!
Thoughts?
Next step?
Thanks!!

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[19Eclipse90]

Pull the camshafts out and pump compressed air into each cylinder to get an idea as to the condition of the valves.

If the valves are okay, then the cylinders should hold air.

A leak down tester would be the best approach but just an air tank with a threaded adapter into each cylinder ought to give you some clue.

 

[freebird_43]

Thanks for the feedback, what psi should I put to the cylinders? I will do a leakdown on each cylinder. What I'm really interested in knowing is what caused the tbelt to lock up, Gotta be in the valve train somewhere but how do I diagnose?
Thanks for the assistance with this?

 

[19Eclipse90]

I would try to go to normal static cylinder pressure (150-165 psi), if possible. I don’t think my compressor would get me there so anywhere close would be my aim. Depending on the condition of things, it may not be necessary to go that high. You ought to hear leaks pretty quickly if they are there.

Further investigation really depends on the results of this or a leak down test.

 

[pauleyman]

Thanks for the feedback, what psi should I put to the cylinders? I will do a leakdown on each cylinder. What I'm really interested in knowing is what caused the tbelt to lock up, Gotta be in the valve train somewhere but how do I diagnose?
Thanks for the assistance with this?

I saw alot of oil. Contamination? Balance shafts are also suspect. Just make sure everything turns freely. It may not be possible if you have bent valves. One step at a time.
Its low miles but 6 years? Guessing it sat first long periods of time in the same spot? Unless you drove it like 5 miles a week for 10 years?

 

[1990TSIAWDTALON]

If the pistons came up without the cams turning, you have bent valves. Plan to replace valves, seals and possibly valve guides, as they tend to crack, being cast iron. Its possible they are OK, but the valves that were "open" when the belt went will all be bent. Just preparing you. In my case, the crank pulley worked forward and off of the keyway. That put me in the same situation, crank turned, cams didn't but made a partial rotation, bending all 16.
Pops

 

[freebird_43]

Gents, thanks for the feedback!
Oil contamination is from the valve cover.
The belt is much much older than I thought! I will get accurate details on when the belt was replaced and post information later. I don't think the belt is the problem, I believe what the belt was driving (valve train) was/is the problem. Next step is to determine if balance shafts are moving freely. Then onto a cylinder leak down @ 130 psi, (max psi out of my comp). Should I attempt to manually move / rotate the cams before removing the cams?
Thanks again for everyone's input!!!

 

[1990TSIAWDTALON]

DO NOT turn the cams. Remove the cam caps and remove the cams. After that, you are safe to not make anymore damage if you turn the crank as all valves are closed or supposed to be. At this point, you can use a straight edge across the valve stem tips to visually see if any are not the same hight. If any are coming up "short" when doing that, those are bent valves.

 

[freebird_43]

Thanks for the response! Won't get to the talon tonight. I found info on last belt change, 147K in 2020, so 5 yrs old with 15K on the belt, around (162K now)
I'm guessing there's a special tool needed to thread into the spark plug ports to do a compression or leakdown test? I'm going to have to get one before I can proceed.
I drive it about 6 months out of the year, in winter it's up on blocks for something or other! (DSM)

Thanks again for all the horsepower here! It's really appreciated!

 

[19Eclipse90]

Simple hose with the correct threaded fitting for the spark plug hole and an adapter to connect to the air compressor.

Something like this:

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[freebird_43]

Thanks for the info, should be easy to find. I'll be back soon with leakdown status,

 

[1990TSIAWDTALON]

You can Rent those at most major Auto Parts stores and then get your money back after use. Just ask your locals.

 

[freebird_43]

Thanks for the tip! I'll look into it.

 

[freebird_43]

Finally got some time on the Talon. Camshafts out. Still waiting on leak down tester unfortunately. Took some images of the piston tops and found 3 Undamaged, but #3 piston took some lite hits. Found nothing locked up anywhere. If cylinders pass leak down test, what would be the next step? The 1st set of images are pistons showing hit mark on #3 piston.

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[1990TSIAWDTALON]

There are "witness marks". Plan on replacing those valves in that cylinder. They aren't super expensive if it didn't hurt the guides or seats. It would take a good lapping in of new valves to know they are sealing. Good job of scoping the cylinders.

 

[pauleyman]

Finally got some time on the Talon. Camshafts out. Still waiting on leak down tester unfortunately. Took some images of the piston tops and found 3 Undamaged, but #3 piston took some lite hits. Found nothing locked up anywhere. If cylinders pass leak down test, what would be the next step? The 1st set of images are pistons showing hit mark on #3 piston.

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You dont even need a leakdown now. You found the problem.