2G Timing component failure

[Blinkyblinx9]

So recently I had a timing component failure and am still kinda iffy on what happened.

With the head in the shop and finally having the time to look things over I found that the belt was not the weakest link. None of the rubber in the belt looked softened, squishy, or dry rotted as I unwrapped the wire core from the crank pulley. The teeth were cleanly sheered off and it was obvious that something had bound up and caused this. I ended up with 16/16 bent valves, cracked guides, marred up cams, and a wiped out CRPS.

I determined everything else in the engine was perfect. No glitter, factory machine marks all around, and everything spins freely. Intake cam has acceptable bind considering what happened but I wouldn't run it. SO what happened? The tensioner rebounds freely which is not normal but it is only 2 years old. I had the water pump pee all over things about a year ago because I didn't replace it with the timing components. I dried things up and replaced the pump but didn't consider that the tensioner sat there with water sitting on it for days while the pump shipped. That's the only thing I can think of besides a premature failure of the tensioner. Any thoughts on the cause?

Is it cool to just touch up the crowns and throw it all back together with good innards once the head comes back and I reassemble it? If so any ideas on how I can protect the cylinder walls and keep crap from falling between the walls and pistons while I touch up the crowns? Painters tape maybe? The short block is still in car with no means of removing it within reason.

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[97egl]

Does the oil pump spin freely? Sometimes if the stub shaft used for a balance shaft delete doesn't have the groove in it the oil pump gear can lock up. Just a thought.

Best way to keep the pistons clean when cleaning the block deck is to go around them with painters tape or masking tape and go from the cylinder wall onto the top of the piston and then when you are done you can just vacuum it out and remove the tape. I clean the cylinder wall with alcohol or ATF to get any goo off left by the tape.

Also If you have any real bad gouges in the pistons from the valves you can use a demel and knock them down so they don't create hotspots. Do this before you remove the tape and get a roll of aluminum flashing which you can stick in the bore to act as a sleeve and protect the cylinder walls in case the dremel gets away from you

 

[Blinkyblinx9]

Yeah, pump spun freely with no wear marks. Still has the factory machine swirlies and everything and gear to housing clearance is tight. No debris found anywhere but there was 2 tiny marks on the rear balance shaft inner bearing (not the pump bearing). Gouges on the pistons aren't that bad but I wanted to clean them up a little anyway. Would you recommend BS delete for the sake of beat on reliability. NVH isn't an issue, with solid poly mounts the car vibrates quite a bit already and I really don't care. If so should I worry about reducing oil pressure by diverting it elsewhere?

 

[danl]

If the oil pump is ok, if cams are spinning freely, if tensioner is "ok", and if crank (assuming) is not seized, I'm unsure how it can be anything but the belt. I just went through this and my advise is if it looks like a duck and it quacks like a duck, its a duck. Put another way if you hear hooves look for horses, not zebras.

A loose tensioner allows a couple teeth to skip and you kill some valves. A siezed cam, oil pump, or crank could cause the timing belt to find its inertial limit, resulting in failure. I'm looking at your belt and your description and trying to figure out why you are trying to find another boogyeman?

Lets start with what brand belt is it, how many miles, how many years.

 

[Blinkyblinx9]

2 years and less than 25k on all the timing components. Was probably the tensioner. It came out of a gates kit. I should have known better than to trust anything but OE with a pre-sealed part. Expensive lesson learned I suppose.

 

[danl]

Is it cool to just touch up the crowns and throw it all back together with good innards once the head comes back and I reassemble it? If so any ideas on how I can protect the cylinder walls and keep crap from falling between the walls and pistons while I touch up the crowns? Painters tape maybe? The short block is still in car with no means of removing it within reason.

It will be fine to put together as is. If you had a sharp edge sticking up, I would knock that down, but I don't see one. Use the old HG and bolt it down to protect the deck surface if you get after it with tools. Just vacuum while you are working and it should be fine.

Here is what mine looked like before/after cleaning with CRC direct injection carbon cleaner. Let it soak in, wipe off with rag. Took me 3 applications. Since no hard tools were used, I did not need to protect any precision surfaces.

I then coated the cylinders/pistons with fluid film to keep surface rust from forming while the head was out at the machine shop.

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I've since run the car and it is perfect.

 

[Blinkyblinx9]

It will be fine to put together as is. If you had a sharp edge sticking up, I would knock that down, but I don't see one. Use the old HG and bolt it down to protect the deck surface if you get after it with tools. Just vacuum while you are working and it should be fine.

Here is what mine looked like before/after cleaning with CRC direct injection carbon cleaner. Let it soak in, wipe off with rag. Took me 3 applications. Since no hard tools were used, I did not need to protect any precision surfaces.

I then coated the cylinders/pistons with fluid film to keep surface rust from forming while the head was out at the machine shop.

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I've since run the car and it is perfect.

Thanks man, This is the farthest I have ever been into an automotive engine. Funny thing is that I rebuilt the automatic trans in my BMW and did valve body and clutch modifications to my talon but this is what intimidates me.

 

[danl]

Thanks man, This is the farthest I have ever been into an automotive engine. Funny thing is that I rebuilt the automatic trans in my BMW and did valve body and clutch modifications to my talon but this is what intimidates me.

In my opinion, valve body and automatic trans work is more difficult. Cylinder head work is annoying. You need to measure a lot of things and make sure things are flat. There are also a couple gotchas.

I really like jafromobile videos on YouTube. Watch his cylinder head videos where he covers all the gotchas and more.

 

[Dericsh]

In my opinion, valve body and automatic trans work is more difficult. Cylinder head work is annoying. You need to measure a lot of things and make sure things are flat. There are also a couple gotchas.

I really like jafromobile videos on YouTube. Watch his cylinder head videos where he covers all the gotchas and more.

Agreed with both statements, but I guess it’s all what you’re used to. I’ve never broken into an auto trans, it was always just swapping out a reman if it was bad.

I think his tuning series is pretty good too, I’ll definitely be re-referencing it when it’s time for me.

 

[Blinkyblinx9]

Ahh, I have watched those. I actually pulled a mostly good cylinder head off a 4g63 yesterday and stripped it down for parts. He makes some good stuff