*Almost* timing failure
 

I have been keeping a pretty good eye on my timing belt and the tension has been kept up and the like. I was driving and I noticed an odd sound, like a sqeak of a bearing going out in an alternator or something. I also noticed a knock, sounded like a rod knock, but irratic and would stop with increased rpm. So I pulled over and the sound was coming from the top end, I put my hand on the cam cover and felt a knocking! I inmediatly shut it down and had my buddy get the trailer and we trailered it home. Turns out the timing belt eccentric tensioner failed big time. I thought it was out of adjustment, but it wasn't tightening right so i took ahold of it and it came off in my hand with out removing the lock nut. So needles to say I'll be down till I get a new one. I am considering swiping the tensioner from my balance shaft belt until I can get a new one in, are they the same part? I haven't checked part numbers yet. Is there another bearing eccentric insert that will work? Anyone want to donate one? PM me!
Any input/sujestions/solutions are welcome.
Part # 944-105-127-03


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Glad to hear you saved it! Sorry to hear you'll be down for a little while. If I had one I would over night it to you!

Looks like the balance shaft and timing belts have different eccentrics. At least price isn't to bad, it's just the down time :/

the question is: how are you going to set it to TDC without that part?

Take the cam off, set the crank to TDC, LOCK IT, put the cam back on at TDC... Order a new cam housing gasket and the rear tower gasket while you have the cam off. :) Just did the job, it's not too bad. Just give yourself plenty of time. :) NO more oil leaks, and a couple new pieces for the timing belt. :)

ahh... GOOD answer!

Change the oil and fliter, do some degreasing... do you need a new water pump too? While you're in there... lol...

LOL, need or want a water pump? I want one while i'm in there, but I can't afford it. I replace parts on a failure basis at this point in life. When my water pump fails, I'll pull over and trailer it home. As for setting TDC, not a problem, been there done that. I think I may order one tonight and have it second day air shipped so I can fix it over the weekend.
Cheers!

the problem with that is that the waterpump has a high likelihood of taking your belt with it. ask me how i know...

How do you know?

Just being funny...or atleast trying. So when the water pump fails does it not do the ol' dribble dribble that they typically do? Are they usually a bearing seisure rather than a seal failure? Typically cars I've worked on in the past usually have tell tale signs the pump is exspiring, like chirping and weeping out the weep hole etc. I'm assuming yours just made a mess with out warning. Tell me more.

well, the shaft of the pump was worn and began to angle downward. this chewed the edge of the belt, eventually seizing the belt while the crank continued to turn. stripped belt, and 5 bent valves. i did all the work myself and was still into it about $1200.

Nice, very nice. Something to keep in mind for sure. At the moment I don't have 250-300 for a pump, hard to get parts w/o money LOL. But I'll certainly do my best to check the pump for wear like this. Thanks for describing it well so I know what to look for and I'll be sure to replace it when my wife or I one gets a job again. Sorry bout your luck though. Was this on the turbo that you had the bent valves? I bet prices were out landish for the valves! Thanks for the advice.

As for the TDC issue....
Pull #1 spark plug, insert dowel.
Turn until piston is at the mid-point of it's travel.
Rotate cam to TDC, then turn engine such that #1 piston is moving upwards, until it reaches TDC (~90* of rotation).
Now your engine is back in time.


As for the failure, where did all your roller bearings go? Bet you'll find them all in the bottom of the timing belt housing.

You are darn lucky, like when I pulled the belt covers for an inspection on the 951 2 weeks ago, and found a bolt sitting on the water pump pulley..... Had a nice groove worn in the pulley it had been there so long. Every now and then, between the catastrophic failures, we get lucky.

Does the cam need to come off to set TDC? Seeing as how it is no longer timed with the crank? Or is the mild collision and pushing on the valves by the pistons acceptable of under the minimal stess of hand cranking the crank? Or will any pushing of the piston cause minimal damage to the valves?

I like to be safe than sorry. I would take the cam off first, set the crank to TDC, lock it, then set the cam to TDC and put it back on. I would also get the cam housing gasket out of the way. I think it's $9. Mine was shot when I took it off. It came off in over 100 different crumbling pieces.

Zero, you had better believe I was lucky! I'm not sure where the bearings went off to. I'm bettin they are still in the cam housing as well. I need to inspect things good before reassembly.

As for timing, I don't think it will be out to much unless the cam has moved some on it's own since I pulled the gear off. But I'm bettin I can put the gear back on when I get the new one, rotate them cam to the timing mark, hold it there and then remove the tension and rotate the crank as it should be only a few degrees out as it. This would prevent valve to piston contact. It may not be as easy as I hope but we'll see. Should have the parts by this weekend. I only hope it's the only pully that HAS to be replaced as I just don't have money for any more right now. Once I get some sort of financial influx I'll do all the tensioners, rollers and water pump.

Cheers

There is a place (not Pelican) that sells remanufactured pumps for $86 with a two year warranty, $100 refundable core charge.

For anyone that doesn't know were there timing is, the idea stated above covers all. With all 4 pistons mid travel, i.e. half way up. There is no way anything will hit/bind. You can move the cam to any position without fear. Set your front end on all it's marks and move your #1 piston to TDC and done.
You had better check all your bearings! If that one was completely disintrigated, bet the others are about to go. Just spin them freely and listen for the dry/worn bearing wine. Same goes for the water pump. There is only a bearing and a seal like every other car.

I still don't have the money, LOL I now owe my grandpa $10 that I didn't have to pay shipping when I order the timing tensioner. However, what is the site that has the remanufactured pumps? Sounds pretty descent to me. Like I say, it's pretty high up on my to-do list. Thanks for the info.

Has anyone ever tried to repack the bearings on these things or is that a bad idea as heated grease could contaminate the belts? What about a moly lube? Just curiouse, I haven't checked mine yet, but I too am betting they are all on the blink.

No problem, check out the remanufactured ones, (http://www.***********/acatalog/Water_Pump.html).

Thanks for the link. Helps alot.

I checked the pulleys on my engine and I seem to have some wear on my idler pulley for the cam, it has some end play. If I'm not mistaken, on the timing belt loop there is a crank pulley, cam pulley (neither of which have bearings) the tensioner and the idler. The tensioner will be replaced. So that leaves the idler on the "important" loop. Balance shaft failure is not as scary as timing failure, that is unless it causes the timing to fail! I think the idler will be ok. It doesn't experience the same stress the tensioner does (at least I don't think it does).

^^^^ Correct for rotating the crank and cam separate. You do not have to take the cam off. Also ditto for the rest of the rotating belt tensioner pulleys.

Also checked the waterpump and it feels real good I think. No end play, no "dry" feel, just smooth and free of play.

Got my new tensioner today, not to impressed with it. It cost $30 from thepartsbin.com. Can't recall the brand and I'm to lazy to go out and see. But the cog is made of plastic/composite something or another. The bearings felt nice, it's just obviously not the same as the original. Did Porsche change the part or is it an aftermarket part? I am assuming aftermarket. I'd like to start on fixing it tonight, but I have to get up in four hours to help my brother move, so no such luck tonight. I'll keep ya'll posted.

All of the new type tensioners are less metal, more compsite types and have been for several years. The new tensioner uses a 27mm hex, the old ones 22 or 21 mm (so long ago since I've seen one, forgot the size) We always replace all of the tensioners and rollers unless there is history of being changed recently (as in the last belt change). Water pump change every second belt change.

These cars, as with all cars, need proper maintenance, which costs money.

if one of the rollers is bad, they are all bad. using worn out rollers will cause failure and can cause the belt to cut into the balance shaft pulleys, etc., and will cause the belts to wear out prematurely.

Thanks Brian! Your post now has me paranoid! I tired to take the car out last night for a nice drive, and watch the girls in the short skirts... and I didn't get to enjoy it very much. I always notice any new noises on my cars. Now I am hearing every noise every car in the world near me makes! Squeeky brakes and bad wheel bearings on other peoples' cars are haunting me! Not to mention the fact that I have muted the crazy stereo system I put in the car!

Hahaha! Sorry to be a kill-joy John!

It happens... I feel better when I personally use this tension tool on the belts. Then I will know that I have no problems for sure. :)

Finished the job tonight. Nice to have the machine up and running!

imagine how comfy you'll feel with all the rollers, belts and seals done in the front end.

Off course you will notice a new sound after. When you do all this you'll have the customary roller whine that sounds like a turbo. They all do this for awhile.

LOL, yeah, I took my buddy for a cruise last night and told him it sounded hotter with the temporary whine. I punched the gas and found out it only sounded that way, dang it!

Hi, my car had the exact same symptons as yours, but i am confused on why does it knock from the cam tower if the bearing was a bad timing beraing? sry im new to working on these types of engines.
joe

Put your hand on the cam tower and see if you can FEEL the knocking. In my instance I could. The knocking was actually the timing belt slapping the cam tower housing because the bearings went out on my tensioner rendering it useless. Also mine tended to stop making noise after the motor picked up a few rpm, I supose because the load or maybe frequency the belt was exposed to changed. In any instance, if you suspect this is your problem do not drive it or start it! It could result in alot of damage and work. Pull the front cover off and inspect the timing belt, it is the belt closer to the engine block. Check it for cracks and see if it has adequet tension. The tension should be checked with the engine on top dead center. There is also a tool that you should use to check the tension, however if you're familiar with how tight a timing belt should be you can tell if that's your problem. If the belt seems OK start the motor with your cover off and look for the timing belt to vibrate excessively. Also check your tensioners and idlers, especially on your timing belt, but also your balance shaft belt. Your balance shaft belt is not as important, but important none the less. Good luck. Let me know how things turn out.

Engine doesn't have to be on TDC for belt tension.

If you're not setting TDC, just don't take the belt off. :) Setting TDC is always safe yet time consuming.

I would tend to disagree with the engine not having to be at TDC for a tension check - if the cam is in some other postion with valves part way open/closed, and the tension of the valves closing is 'pulling' the cam over one way or the other on the cam lobe, then that may put a false tension on one side of the belt. With the accuracy required to get these belts tensioned right, that would probably be enough for you to be off.
For the sake of moving the crank round to TDC I wouldn't take the chance.
DK

Also, if the balance belt breaks it can take out the timing belt leaving you in the same bad spot. The balance belt is not required to be in place for the engine to run properly, but if it is bad and does break it can, and in many cases does, take out the timing belt. There's not a lot of room in there for things to be flying around at a high rate of speed and the timing belt needs to be protected.

If the balance belt is bad AND for some reason you cannot replace it right away AND you need to drive the car then you are better off to take the balance belt right off. The engine will not be "balanced" but you will not cause damage to the timing belt. There are some people that have taken off the balance belt for different reasons. The car is 100% driveable, but there would be a little extra "shaking" with the engine being "unbalanced."

Check out Clark's for more info and the history of the balance shafts. The timing belt is a very important part of the engine and will cause major damage if it is broken or if TDC is not properly matched on the cam and the crank.