It ripped the whole Tensioner right off the motor

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Hello folks,

Well the Jeeps have been doing very well for us, and we both love them but I ran into what I believe might be a major problem. What do you folks think?

I will try and keep this short and sweet. The Jeep in question is the mine from my signature.

So I am headed into work in the morning going down the highway at 76 mph. Then it happens, the Jeep motor dies I grab neutral and head for the shoulder, get stopped and tried to restart it but it was obvious it was not. It sounded like the timing was not correct. So I called the wife and the Tow truck. I assumed it was the timing belt which is odd considering I should only have about 50,000 miles since the last replacement. The Jeep has 180000 miles on it. So I Get home, look under the hood and the accessory drive belt is loose and broken. I look a little closer and there is no tensioner. Just the bolt and a broken piece of aluminium. Now I am concerned and I am afraid something major has occurred. I get it in the garage and put it on battery charge because it sounds like it is having a hard time turning over. With that I am leaning towards the timing belt is gone to lunch. I Pulled the oil fill cap and watch the camshaft go round and round. Now what, I am pretty sure the timing is off because while it is turning over it would cycle thru normal cranking and then it would get really hard to rotate like the compression is really high and difficult to continue turning over. I have yet to dive into tearing it down mostly because I am afraid that is it not going to just a timing belt, pump and rockers, like maybe pistons, crank or something really serious.

What do you folks think, just a timing belt, or greater? I can do the work, I guess I am looking for a heads up as to what it might be and for things that I might miss.

Thank you for your time and considerations.
Clint

Sir Sam · **Posted:** Sat Nov 10, 2018 11:09 am

It's really hard for me to see a correlation between a serpentine belt failure and a timing belt failure.

Even on engines that have trashed rockers, dropped valves, and straight up thrown rods out the block they don't take out serpentine belts.

You can spend a lot of time guessing, or 3-4 hours taking it apart to find out whats gone on. Get the timing belt cover off and you will start to have a better idea, and be prepared to pull the intake off to check the rockers. Be prepared to do a leakdown check after you get the intake off.

I have a set of videos that you may find useful for checking your engine, ill skip forward to the compression check but you may find some of the earlier videos useful as well.

https://www.youtube.com/watch?v=398gUBr ... Zfl81yBIIV

WWDiesel · **Posted:** Sat Nov 10, 2018 12:00 pm

There have been cases where, when the accessory/serp belt breaks it can wrap around things and jolt the engine sufficiently enough to either break the timing belt or cause it to shuck a few teeth. It is very rare indeed when this happens! :shock:

You can check the timing using the engine cover access plugs and the flywheel alignment pin, to see if they line up when the engine is at 90ATDC - if you don't have the proper pins, temporally in a tight you can use a couple of drill bits (shank end) 1/4" or 17/64" for the cam pins, and a 6mm allen in the flywheel just to confirm proper alignment.

If the cam pins don't align with the crankshaft at 90ATDC (3:00), then I'd highly suspect a timing belt slip.

Just as Sam suggested,
If things don't align, time to pull the timing belt cover and see just what the problem is.

Note: if indeed you find the timing belt slipped or jumped a few teeth, it's highly probable you have damaged rockers as well? :juggle:

PANHEAD · **Joined:** Thu Feb 26, 2015 7:26 pm **Posts:** 63

I just lost serpentine belt due to mount arm on water pump snapped and air pump angled down few degrees and belt wouldn't stay put.
But that shouldn't effect Timing belt as Sir Sam said.
Sounds very similar to mine when it dropped an exhaust valve.....

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Thanks folks, yep I full intend to replace the rockers, when hers went it too was a surprise, so I do know the trials and tribulations associated with rockers but hers was straight forward and I could see that the camshaft was not rotating. Although I did not do ours the first time, I am doing them from now on. Also thanks for the great ideas and videos on where to look.

I am still listening if others have had a similar event I would like to hear about it.

Thank you
Clint

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

FOUND IT! Well I am pretty sure I did anyway. I tore it down enough to check the timing pins and sure enough the intake cam was off compared to the exhaust and fly wheel which were in time with each other. Soooo to me it looks like either the accessory drive belt or the tensioner for such failed and the belt ended up wrapping around and behind the crank pulley, pushed in the cover and got between timing belt and the crank timing belt pulley and either stretched or pulled it out of time enough to trash the whole timing idea and smoked the exhaust valve rockers at least if not all ( the exhaust camshaft pulley turns round and round with very little resistance).

As for the condition of the timing belt and associated parts, it is too bad because they all look and appear to be in great condition, but I am sure that they need to be replaced. I may not do the water pump, I haven't decided yet on all the parts but I know I will at least do the timing belt and idler pulleys.

Tomorrow brings me to tearing into the intake and everything to get to the rockers so I can see the damage.

I would like to post some pictures, but apparently I don't know how

Sir Sam · **Posted:** Sun Nov 11, 2018 10:25 pm

Is your front cover damaged? Was the serpentine belt wedged behind it somehow?

You should pull the intake off next, you need to check the rockers for damage. Then if possible, do a leak down check on the cylinders to make sure the valves are sealing correctly.

Plan to replace all 16 rockers. All 4 copper crush washers, all 4 injector sealing O rings. I reuse the valve cover gasket.

Plan for a full timing belt kit, including water pump. Recommend considering new fan clutch. Alternator can always be replaced later without much trouble, fan clutch not so easy.

At 50k your water pump is already halfway of lifespan. Do you want to do all this work over again in 50k miles just for the water pump?

At 100k I did my belt and not water pump. at 155k my water pump failed and trashed my perfect rockers. I rolled the dice and lost.

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Yes the cover was damaged and the Accessory drive belt (serpentine belt) was wedged into and past the cover and was eventually wrapped around the Crank pulley for the timing belt and then wedged under timing belt and which I believe resulted in the screwing up the timing and then taking out the exhaust valves.

Yes I do plan on taking off the intake today, and I am thinking about pulling the head. Why pull the head, well I am not sure but apparently it is done a great deal on "lost' and I think it would be a good route, but I will evaluate that when I see the damage to the rockers.

Thanks for the heads up on the water pump. I will in fact do the water pump with those details.

I don't think I will do the fan clutch just yet, it was not too bad to get due to the fact I didn't follow your videos videos to a "T". I didn't pull the front of the jeep apart and I got it all apart without having to pull the radiator or intercooler.

WWDiesel · **Posted:** Mon Nov 12, 2018 12:51 pm

Well that explains it! Not common but I have read of it happening before although very rare.

:idea:

A Tip: Many including myself have cut the fan shroud in half to facilitate removal in the future much quicker and easier. (while you got it out)
Some opt to cut and discard the lower half while others like myself opted to modify the shroud to allow keeping the lower have in place while still making it two piece for easy removal of just the top half.
See this thread:> viewtopic.php?p=916154#p916154

Another friendly suggestion; if you end up pulling the head for any reason, replace all the exhaust valves. :wink:

There have been quite a few incidences reported of an exhaust valve breaking and if this occurs very major expensive catastrophic damage can occur and possible destroy the engine. :grim:

You can do a search on LOST to read some of the reports on these types of events.
See this:> viewtopic.php?f=5&t=84902&start=100&hilit=exhaust+valve+broke

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Awesome help, I will check out the links. I think I am going to pull head and do the while top end.

Thanks

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Here are some pics of the the assesory drive belt in the crank pulley

How bad are the valve lash adjuster bore holes if the lashes look like this? It looks like just the top of the hole is oblong, I haven't pulled them yet because they did not come out easily. I am not sure I understand how the oil gets in, from the bottom or not. But how important is the lash to hole clearance tolerance?

The exhaust side, every one of the rockers were smoked but none of the lashes were damaged like the intake side. Some of the rockers on the intake side were damaged. I also tapped on the valve stems lightly and all the exhaust sounded solid, but four of the intakes sound hollow and don't sound like they should. So I am sure those valves are smoked as well.

So the next step I am going to pull the head when I have time.

Question for Sir Sam, where did you get the tools like intake locating pins and injector seat tool and others I may not know about. I was going to order the leak down tester but no use now seeing hows I am going to pull the head.

At this point I am up for suggestion....

Thanks
Clint

Tree Catcher · **Posted:** Mon Nov 12, 2018 10:03 pm

mine did that, I lost the serpentine belt, it went right into and under the cover and screwed up my timing, stretched the belt. Fear not though only a bunch of new parts later and shes still purring right along. I never took off my head nor did a compression test since all of the valves were at the same height. I would expect that if a valve was bent that the valve stem would not line up with the others. Good luck, its only a few days of rebuilding and she will be purring again... Does scare me though, Mine was about the same mileage after I replaced the timing belt along with the rest of the parts, water pump, serpentine belt, tensioner. Did we get a bad batch?

Sean

WWDiesel · **Posted:** Mon Nov 12, 2018 10:20 pm

Tree Catcher wrote:

mine did that, I lost the serpentine belt, it went right into and under the cover and screwed up my timing, stretched the belt. Fear not though only a bunch of new parts later and shes still purring right along. I never took off my head nor did a compression test since all of the valves were at the same height. I would expect that if a valve was bent that the valve stem would not line up with the others. Good luck, its only a few days of rebuilding and she will be purring again... Does scare me though, Mine was about the same mileage after I replaced the timing belt along with the rest of the parts, water pump, serpentine belt, tensioner. Did we get a bad batch?
Sean

Don't believe this was mentioned,
but it has been established that a bad or improper alternator override pulley can cause excessive bouncing of the serpentine belt and it's tensioner pulley.
Which in turn could lead to early failure of the tensioner pulley and / or the belt.

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Quote:

Don't believe this was mentioned,
but it has been established that a bad or improper alternator override pulley can cause excessive bouncing of the serpentine belt and it's tensioner pulley.
Which in turn could lead to early failure of the tensioner pulley and / or the belt.

Thanks for the heads up, and yes that was one of the first things I checked along with all the other pulleys, when I first opened the hood and saw the belt and tensioner missing, and everything was as they should. Also the tensioner and belt were less than two months old.

My guess is one of them failed, which one first hard to say, but I am going to have a talk with my Napa dealer and see what they saw about any kind of warranty, which I am sure they will tell me to go pound sand, but its worth a shot.

As for the valve heights I think this is the best shot I could get, but it looks like they are all the same.

Tree Catcher · **Posted:** Mon Nov 12, 2018 11:36 pm

grr and I just noticed that the belt was squeeking a bit more when the AC kicked on.... Will check that out this weekend..

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Quote:

grr and I just noticed that the belt was squeeking a bit more when the AC kicked on.... Will check that out this weekend..

Sorry man, didn't mean to make you spoked again about it, or bring back bad memories...

Sir Sam · **Posted:** Tue Nov 13, 2018 10:28 pm

rescue.tech wrote:

Here are some pics of the the assesory drive belt in the crank pulley

How bad are the valve lash adjuster bore holes if the lashes look like this? It looks like just the top of the hole is oblong, I haven't pulled them yet because they did not come out easily. I am not sure I understand how the oil gets in, from the bottom or not. But how important is the lash to hole clearance tolerance?

The exhaust side, every one of the rockers were smoked but none of the lashes were damaged like the intake side. Some of the rockers on the intake side were damaged. I also tapped on the valve stems lightly and all the exhaust sounded solid, but four of the intakes sound hollow and don't sound like they should. So I am sure those valves are smoked as well.

So the next step I am going to pull the head when I have time.

Question for Sir Sam, where did you get the tools like intake locating pins and injector seat tool and others I may not know about. I was going to order the leak down tester but no use now seeing hows I am going to pull the head.

At this point I am up for suggestion....

Thanks
Clint

We cant see any of the photos, I'd recommend using imgur.com if you need free easy image hosting.

I would be interested in see what you mean about bore holes.

I would recommend you do the leakdown check before/instead of pulling the head, I think it pretty unlikely you need to do any head work. Look across the tops of the valves and see if they are all in line, if something is not then maybe you have a valve issue. I wouldn't say anything about the condition of the valves based on sound alone. Its really about what pressure they will hold.

I also don't think replacing used valves is necessary enough to pull the head, and here is why; Infant Mortality.

I have a used head that was a brand new from VM head, it made it less than 5k before dropping a valve and trashing an engine.

I have the first head that engine came with as well - which is warped beyond use.

The first head was replaced because it was warped, the second head, brand new from VM, had a NEW valve fail soon.

You have proven working valves that have passed the infant mortality phase. I don't see the need to replace good valves with new valves that "might" be good long term.

Granted its not often that a new valve fails so quick, but I am not of the opinion that replacing the old ones gets you anything better than you have now.

My tool set is the Jeep OEM set, however ID parts sells a very nice set of timing belt tools. If I needed to buy tools now I would likely buy their set.

If leakdown check is good go with ARP studs while its off and following my recommendations above for other parts. Some of your thoughts seem odd to me, willing to pull the head without checking if its needed first, but hesitant to buy a water pump. Granted you haven't made any decisions about how exactly to proceed yet, but those thoughts just seem at odds to me.

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

I tried to repost the pics using the sight you suggested but apparently I am not "IT" enough to understand how to do it. I copied the pic and placed in within the ImgImg. I will look around see what I can find out.

rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Ok I finally figured out I think.

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rescue.tech · **Joined:** Sat Dec 31, 2011 10:55 am **Posts:** 43

Quote:

Some of your thoughts seem odd to me, willing to pull the head without checking if its needed first, but hesitant to buy a water pump. Granted you haven't made any decisions about how exactly to proceed yet, but those thoughts just seem at odds to me.

Mostly just thinking out loud, mostly so others can set me straight... :oops:

I am with you on Mortality and the sound doesnt mean much, I am waiting for tools to show up to do the leak down test, then I will be better informed to have a better idea on what to do.

It ripped the whole Tensioner right off the motor

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