Diagnostic after serpentine failure

[LOWTYD]

Following a diagnosis from VW that quoted $6k for a new engine, I'm trying to help out my sister and her daughter by repairing her TDI. I owned the car for the last 4 years, bought with full history from the original owner. Full Amsoil from break-in on. Timing belt was replaced with a Gates unit @ 89k. Vehicle now has 125k and has had zero issues. Two weeks to the day after giving my niece the car, it shuts off while in a Taco Bell drive thru. They rolled it out of the lane and I helped diagnose the issue over the phone and after checking oil, coolant and electrical, the culprit was a shredded serpentine belt. Here is where things could have gone south. I instructed them that it may have jumped time, and not to attempt to start it until the had the timing verified. They didn't follow my advice. Threw on a new serpentine and tried to fire it. They said it sounded like it tried to turn over but would not start. Fast forward to today, and I've pulled valve cover, oil pan, pass motor mount and have access to the timing belt. It looks to be intact and not missing any teeth. So, with all tension off of the valvetrain, and turning the engine by hand, it will turn almost 180 degrees clockwise and almost 180 counter clockwise but will not go further. Next step is the pull the head, but does anyone have a guess as to why the engine will not make a full revolution? Thanks in advance for any help.

 

[narongc73]

Obviously valves may be stuck preventing the engine from turning over all the way? No idea but you'll find out soon enough. I keep seeing posts like yours. Did you not change the serpentine belt during timing belt change? Checked pulleys and tensioner?

 

[Andrewh]

did you pull the serpentine belt?
something made it shred. perhaps an accessory locked up partially?

 

[N.CaTDI]

Sorry no idea lost my alternator pulley and serpentine dropped off but did not shred and had no trouble. If engine turns over when you used the starter I would think you would be able to turn by hand. Try turning it over without the Serpentine on? again really no help but will be following.

 

[Ol'Rattler]

Most likely early failure mode is a sub standard and/or incomplete timing belt kit and/or improper installation.

http://www.oreillyauto.com/site/c/s...swagen&model=Jetta&vi=1432708&mn=Gates&mc=GAT

If this was the kit used, 30 to 40 K miles till failure is about right.

 

[LOWTYD]

I'm not sure what gates kit was used but the belt change was done in conjunction with the serpentine. I can get the numbers and post them. I checked all accessory pulleys and tensioners and they all seem to turn freely without resistance or play in the bearings. One thing I did notice, completely unrelated to the failure was how clean the internals of the engine are. I've been working on engines of some sort for a lot of years and this one amazed me how clean it was inside. Is that a result of the Amsoil or not? This is the first one I've torn down that's used amsoil from day one. Probably not the best brag since I'm repairing it but it was so clean I couldn't help but mention it. So, another question, do I need to get the specific tools to remove the cam pulley and keep the crank stationary or can I bother with that when I'm putting it back together?

 

[narongc73]

It wasn't the timing belt that failed. It was the serpentine belt which caused the timing to skip.

 

[Ol'Rattler]

It wasn't the timing belt that failed. It was the serpentine belt which caused the timing to skip.

I have heard of that happening on the CR's, so ya completely plausible if the cover etc. are similar on the BRM.

 

[Ol'Rattler]

I'm not sure what gates kit was used but the belt change was done in conjunction with the serpentine. I can get the numbers and post them. I checked all accessory pulleys and tensioners and they all seem to turn freely without resistance or play in the bearings. One thing I did notice, completely unrelated to the failure was how clean the internals of the engine are. I've been working on engines of some sort for a lot of years and this one amazed me how clean it was inside. Is that a result of the Amsoil or not? This is the first one I've torn down that's used amsoil from day one. Probably not the best brag since I'm repairing it but it was so clean I couldn't help but mention it. So, another question, do I need to get the specific tools to remove the cam pulley and keep the crank stationary or can I bother with that when I'm putting it back together?

So in this case the timing didn't fail necessarily because of substandard parts, but possible because of what norongo mentioned.

Clean internals were not necessarily because of the brand of oil, it's just how these engines are. Is Amsoil a good oil? IDK. Probably. On the BRM make sure you use 5W 40. The deal with Amsoil is they were one of the first if not the first to sell full synthetic and compared to the dino oils of the day, they were superior. Compared to another full synthetic today they probably don't have an edge anymore.

The downside is that Amsoil doesn't feel a need to have their oils approved to the car manufacturers specs. There "recommended" or "meets or exceeds" claim amount to them saying our oils are better because we say so.

Turn the crank 90 degrees before TDC. The pistons all will be In the middle of the stroke with no possibility of valve contact. When you go back together, you would pin the cam and turn the crank that 90 degrees CW and then pin that.

You don't really need any special tools to take things apart. I used a couple of long bolt and tire iron as a holding tool to loosen the cam hub bolt. Once the cam hub bolt is loose, leave the bolt threaded on by a few threads and smack the cam hub from the rear with a brass drift and it will pop off. Leaving the bolt in will keep the hub from flying across the room when it breaks free.

 

[LOWTYD]

Excellent. Thanks rattler for the insight. Are there any marks on the pulleys that let you know when you're at TDC?

 

[oilhammer]

You need a crank lock tool and a cam lock pin.

 

[Rig]

Check out the other concurrent thread about a serpentine shredding and knocking the timing belt off a tooth or two. I'm checking my serpentine in the morning!

 

[N.CaTDI]

Check out the other concurrent thread about a serpentine shredding and knocking the timing belt off a tooth or two. I'm checking my serpentine in the morning!

That is a scary thought

 

[narongc73]

Check out the other concurrent thread about a serpentine shredding and knocking the timing belt off a tooth or two. I'm checking my serpentine in the morning!

Something else might have caused it to go. It's normally replaced with the timing belt. At least the smart ones do.