Catastrophe. I'm out.....in the garage rebulding
08-28-2004, 10:54 PM
#91
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Three things I have been concerned about when doing TB jobs:
1) On some of the rebuilt water pumps I have seen the tensioner arm mounting hole is not in very good shape. I doubt rebuilders look at this closely at all, so its up to us to really inspect the treads and the surface. It is really critical.
2) When I did my last one Jim said the bolt was back ordered or NLA or something. A new bolt would be a really good idea. If the bolt is really NLA from porshce perhaps we can put our heads together and find a source.
3)New plastic bushings are a must. The last TB failure I had was because I did not put them in new the time before.
1) On some of the rebuilt water pumps I have seen the tensioner arm mounting hole is not in very good shape. I doubt rebuilders look at this closely at all, so its up to us to really inspect the treads and the surface. It is really critical.
2) When I did my last one Jim said the bolt was back ordered or NLA or something. A new bolt would be a really good idea. If the bolt is really NLA from porshce perhaps we can put our heads together and find a source.
3)New plastic bushings are a must. The last TB failure I had was because I did not put them in new the time before.
08-28-2004, 10:56 PM
#92
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Originally Posted by karl ruiter
Three things I have been concerned about when doing TB jobs:
1) On some of the rebuilt water pumps I have seen the tensioner arm mounting hole is not in very good shape. I doubt rebuilders look at this closely at all, so its up to us to really inspect the treads and the surface. It is really critical.
2) When I did my last one Jim said the bolt was back ordered or NLA or something. A new bolt would be a really good idea. If the bolt is really NLA from porshce perhaps we can put our heads together and find a source.
3)New plastic bushings are a must. The last TB failure I had was because I did not put them in new the time before.
1) On some of the rebuilt water pumps I have seen the tensioner arm mounting hole is not in very good shape. I doubt rebuilders look at this closely at all, so its up to us to really inspect the treads and the surface. It is really critical.
2) When I did my last one Jim said the bolt was back ordered or NLA or something. A new bolt would be a really good idea. If the bolt is really NLA from porshce perhaps we can put our heads together and find a source.
3)New plastic bushings are a must. The last TB failure I had was because I did not put them in new the time before.
08-28-2004, 11:00 PM
#93
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Originally Posted by karl ruiter
Does anybody know of any cases in which a 32V car had a belt failure and did not bend valves?
Someone I know quite well with an 87 5-speed snapped a timing belt at start-up. A new timing belt was all it took.
08-28-2004, 11:04 PM
#94
Three Wheelin'
Dave,
Yes it's important to get everything right. You'll be turning the engine over.
I suggest a leakdown. Actually, if you bent a valve, it'll be apparent either way.
I'm not optimistic. It's just the way I am. I expect damage. If the crank turns even a partial revolution, at least one cylinder is on the exhaust or intake stroke, and that means
Please, let me be wrong. I shouldn't have said any of that. But it's better to be aware of the possibility, and be happy when it comes out the opposite.
Yes it's important to get everything right. You'll be turning the engine over.
I suggest a leakdown. Actually, if you bent a valve, it'll be apparent either way.
I'm not optimistic. It's just the way I am. I expect damage. If the crank turns even a partial revolution, at least one cylinder is on the exhaust or intake stroke, and that means
Please, let me be wrong. I shouldn't have said any of that. But it's better to be aware of the possibility, and be happy when it comes out the opposite.
08-28-2004, 11:10 PM
#95
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When I built my '82 I swapped the unibody so I had is all apart for a LONG time. I pulled the motor with a rented hoist ($40?) and just set the motor on the ground to work on it. Kinda gave me the heebe-jeevies but there were no problems. I suppose a stand would have been nicer, but not at all mandatory. Even if yours was a 16 valve car pulling the motor would be the way to go if you have a garage. The motor goes in and out pretty easily and with the motor out you can pull the heads SOOO much more easily. Yes there is lots and lots of "while we're in there" things you can do, but this is really a choice. Its a great chance to replace motor mounts, clutch master, etc and clean the crap out of the whole compartment, detail everything, replace all hoses etc, but all this is totally optional. Don't let the cost of doing the things you would like to do intimadate you from doing the things you need to do. And not only will each of these extra tasks cost you time and money, but they each represent an opportunity to create new problems/break stuff even if you use factory new parts and are really careful. I would suggest just fixing the broken stuff this time and pulling the motor at a later date when you are not pissed off and don't need the car for a few months and don't mind spending $500 and a bunch of time making everything the the engine compartment perfect.
08-28-2004, 11:11 PM
#96
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Originally Posted by Gregg K
Dave,
Yes it's important to get everything right. You'll be turning the engine over.
I suggest a leakdown. Actually, if you bent a valve, it'll be apparent either way.
I'm not optimistic. It's just the way I am. I expect damage. If the crank turns even a partial revolution, at least one cylinder is on the exhaust or intake stroke, and that means
Please, let me be wrong. I shouldn't have said any of that. But it's better to be aware of the possibility, and be happy when it comes out the opposite.
Yes it's important to get everything right. You'll be turning the engine over.
I suggest a leakdown. Actually, if you bent a valve, it'll be apparent either way.
I'm not optimistic. It's just the way I am. I expect damage. If the crank turns even a partial revolution, at least one cylinder is on the exhaust or intake stroke, and that means
Please, let me be wrong. I shouldn't have said any of that. But it's better to be aware of the possibility, and be happy when it comes out the opposite.
08-28-2004, 11:15 PM
#97
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Big Dave,
I am at once sorry and PISSED! to learn of your recent engine failure (waterpump seizure followed by cam belt failure). I cannot tell you how apprehensive it makes me sometimes to realize that although I and the POs have taken care of my present S4 by-the-book, I am still exposed to potential $6-8k rebuild.
I love the 928 too but since I'm not a "wealthy" person...the original, intended customer...I cannot throw money at the problem come-what-may. Herein lies the problem for many current 928ers.
Like you and many others here, one can have a pristine Shark (mechanically and cosmetically) one moment and the next...POST cambelt failure / waterpump failure, it will be worth substantially less. So, what does one do in this situation? Sell the "rolling tub", renegade it (LT-1), rebuild it yourself, let a PCar shop rebuild it ($6-8k), or bail-out of 928dom altogether? In this situation, one must weigh their level of tolerance (emotional and financial resources) for such failures as the "big bang" could happen again without warning.
Thaddeus recently commented in this thread that a timing chain solution could be developed for the 32-v engines but that the development costs would run well into 6-figures ($$$,$$$!!!). Aren't there enough 928 enthusiasts (NA and ROW)who could contribute to this cause? I wonder if Sachs would be interested in the project? Not likely. I would contribute to the cause, if I could be given a reasonable amount of assurance that the project would be completed and that the resulting product would decrease the current failure rate and that the person (or corporate entity) developing said product would not: 1) declare bankruptcy in the process; 2) walk away with the investors' money.
Here's hoping that such a solution will come available before I'm too old to care about 928s anymore. Meanwhile, after I sell my current S4, I'm seriously considering the purchase of an early Shark...the Achilles heel is smaller, no?
Best of luck Big Dave...it has been a pleasure corresponding with you and reading your posts!
I am at once sorry and PISSED! to learn of your recent engine failure (waterpump seizure followed by cam belt failure). I cannot tell you how apprehensive it makes me sometimes to realize that although I and the POs have taken care of my present S4 by-the-book, I am still exposed to potential $6-8k rebuild.
I love the 928 too but since I'm not a "wealthy" person...the original, intended customer...I cannot throw money at the problem come-what-may. Herein lies the problem for many current 928ers.
Like you and many others here, one can have a pristine Shark (mechanically and cosmetically) one moment and the next...POST cambelt failure / waterpump failure, it will be worth substantially less. So, what does one do in this situation? Sell the "rolling tub", renegade it (LT-1), rebuild it yourself, let a PCar shop rebuild it ($6-8k), or bail-out of 928dom altogether? In this situation, one must weigh their level of tolerance (emotional and financial resources) for such failures as the "big bang" could happen again without warning.
Thaddeus recently commented in this thread that a timing chain solution could be developed for the 32-v engines but that the development costs would run well into 6-figures ($$$,$$$!!!). Aren't there enough 928 enthusiasts (NA and ROW)who could contribute to this cause? I wonder if Sachs would be interested in the project? Not likely. I would contribute to the cause, if I could be given a reasonable amount of assurance that the project would be completed and that the resulting product would decrease the current failure rate and that the person (or corporate entity) developing said product would not: 1) declare bankruptcy in the process; 2) walk away with the investors' money.
Here's hoping that such a solution will come available before I'm too old to care about 928s anymore. Meanwhile, after I sell my current S4, I'm seriously considering the purchase of an early Shark...the Achilles heel is smaller, no?
Best of luck Big Dave...it has been a pleasure corresponding with you and reading your posts!
08-28-2004, 11:36 PM
#98
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Originally Posted by tuk_928
I am at once sorry and PISSED! to learn of your recent engine failure (waterpump seizure followed by cam belt failure). I cannot tell you how apprehensive it makes me...
One more thing to check carefully when a waterpump is replaced.
Can I be the voice of reason? (I mean, I *have* to be the voice of reason because I have several of these "time bombs" and if I'm not the voice of reason my head will explode...)
So far I've not heard of a belt catastrophe that once diagnosed was not the result of something that was wrong and had given signs prior. My friend that snapped his belt had sporadic low tension light syndrome. He had the belt tension checked and set but the light was still sporadic. So, he had his timing light circuit grounded because he didn't want to spend $1500 on the R&R and have the car off the road during the process because he needed the car during that particular time window. This-instant need for the car soon turned into complacency and several months later... snap or slip or whatever the failure mode was.
I've heard of another belt catastrophe where a sporadic low tension light was ignored for over a year. And another where a belt was retensioned (tighter of course) several times in the space of a few months.
Has anyone heard of a t-belt catastrophe that was diagnosed as "the belt just gave up for no good reason?"
We should all probably - each of us - chip in for a valve or spring or something for Big Dave. Because we have all learned something new from his experience. Everyone will be checking that bolt when they do a waterpump from now on. And thus, it may be possible, that no other shark will die due to this failure mode!
Big Dave: persevere!
08-29-2004, 12:04 AM
#99
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(*snip*)
Observations:
1. The passenger side cam gear appeared to be in line with the crank.
2. The driver's side cam gear was off about 45 degrees.
3. With the crank put at the 45 degree mark (belt removed), I can turn each of the cams with a wrench. I don't heard anything grinding, but both of them seem spring-loaded. It's impossible to line up their timing marks exactly since they move to a certain point and then leap forward past the mark.
Opinion:
1. This would seem normal, as the pass side is on the 'pull' side of the circuit.
2. Also normal, this is the 'push' side of the circuit, where slack would build up from the crank drive.
3. You are pushing against the valve open and close. Normal, you won't hear any diff with bent valves.
Questions:
1. With the plugs removed, should the cam gears be spring-loaded? Should I be able to turn them by hand?
2. If valves are bent, would I hear clanging or other noise inside the heads when I turn them?
3. Will my timing be correct again if the crank is at the 45 degree mark, and the notches on the cam gears match the notches behind the gears? I assume that I don't have to worry whether I'm 180 degrees off if all of the notches match up and the crank is at 45 degrees.
Opinion:
1. You should be able to turn the cams with a wrench. If you encounter solid resistance, stop.
2. No noise if valves are bent.
3. Correct. Only becomes important when you line up the dist for elect timing.
Now, there was a question about your compr check. I suspect you have a simple tester that has a hose with an o-ring and a gauge at the end. This is not a compound or leak down type tester. Do NOT crank the engine without all the correct parts on the belt, including new the tensioner bolt. However, if you get a compound (leak down) at one of the car parts or tool houses, you can check the compression with a small air compressor, by turning the engine CAREFULLY by wrench hand at the crank bolt. Watch the cams to insure they don't slip a tooth.
Follow the directions on the tester for setup at the plug hole.
Start on #1 TDC, and work your way around using the firing order.
When you test a drivers side hole, it is important to determine if the piston is holed. To do this, follow the directions as before and listen for lots of air coming out of the oil fill cap! You may have to plug the intake and the exhaust with plastic to get an accurate test. Most likely, one or both of the valves on the drivers side will be bent. The pressure will be very low on the gauge, but if the piston is not holed, you will be back in business with a drivers side head rebuild. I think, and hope, that your pass side is okay.
All the noise you heard when it let go was the belt chattering around the pulley. I've heard it before. A trained ear can hear the valves hitting, but since it's inside the engine surrounded by aluminum and water and steel, it's not as noisy as you might think, BTDT too.
Best of luck.
Observations:
1. The passenger side cam gear appeared to be in line with the crank.
2. The driver's side cam gear was off about 45 degrees.
3. With the crank put at the 45 degree mark (belt removed), I can turn each of the cams with a wrench. I don't heard anything grinding, but both of them seem spring-loaded. It's impossible to line up their timing marks exactly since they move to a certain point and then leap forward past the mark.
Opinion:
1. This would seem normal, as the pass side is on the 'pull' side of the circuit.
2. Also normal, this is the 'push' side of the circuit, where slack would build up from the crank drive.
3. You are pushing against the valve open and close. Normal, you won't hear any diff with bent valves.
Questions:
1. With the plugs removed, should the cam gears be spring-loaded? Should I be able to turn them by hand?
2. If valves are bent, would I hear clanging or other noise inside the heads when I turn them?
3. Will my timing be correct again if the crank is at the 45 degree mark, and the notches on the cam gears match the notches behind the gears? I assume that I don't have to worry whether I'm 180 degrees off if all of the notches match up and the crank is at 45 degrees.
Opinion:
1. You should be able to turn the cams with a wrench. If you encounter solid resistance, stop.
2. No noise if valves are bent.
3. Correct. Only becomes important when you line up the dist for elect timing.
Now, there was a question about your compr check. I suspect you have a simple tester that has a hose with an o-ring and a gauge at the end. This is not a compound or leak down type tester. Do NOT crank the engine without all the correct parts on the belt, including new the tensioner bolt. However, if you get a compound (leak down) at one of the car parts or tool houses, you can check the compression with a small air compressor, by turning the engine CAREFULLY by wrench hand at the crank bolt. Watch the cams to insure they don't slip a tooth.
Follow the directions on the tester for setup at the plug hole.
Start on #1 TDC, and work your way around using the firing order.
When you test a drivers side hole, it is important to determine if the piston is holed. To do this, follow the directions as before and listen for lots of air coming out of the oil fill cap! You may have to plug the intake and the exhaust with plastic to get an accurate test. Most likely, one or both of the valves on the drivers side will be bent. The pressure will be very low on the gauge, but if the piston is not holed, you will be back in business with a drivers side head rebuild. I think, and hope, that your pass side is okay.
All the noise you heard when it let go was the belt chattering around the pulley. I've heard it before. A trained ear can hear the valves hitting, but since it's inside the engine surrounded by aluminum and water and steel, it's not as noisy as you might think, BTDT too.
Best of luck.
08-29-2004, 12:05 AM
#100
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Big Dave-
If you find out the bolt is still NLA, (it was a few months ago when I ordered one for my car) and can't find a replacement locally, let me know. My dad is a machinist, and made a spacer sleeve for a grade 12 bolt to replace my broken part. He could no doubt easily build another one. Good luck with the compression testing.
If you find out the bolt is still NLA, (it was a few months ago when I ordered one for my car) and can't find a replacement locally, let me know. My dad is a machinist, and made a spacer sleeve for a grade 12 bolt to replace my broken part. He could no doubt easily build another one. Good luck with the compression testing.
08-29-2004, 01:15 AM
#101
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Dave: I just returned from a two-week vacation to read about your unfortunate circumstance. My best wishes for a happy outcome. If you are attached to your 928, as I am to mine, I can only imagine the despair you must have felt. However as you continue to work to discover and repair the damage I am confident that your enthusiasm and passion for your car will quickly be rekindled.
08-29-2004, 01:22 AM
#102
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Dave
If you need the bolt, I have my original bolt which was replaced last summer with the TB job.
It loooks fine and is not bent .
It's yours if you want it, let me know.
If you need the bolt, I have my original bolt which was replaced last summer with the TB job.
It loooks fine and is not bent .
It's yours if you want it, let me know.
08-29-2004, 02:38 AM
#103
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Dave, I didn't see an answer to your question about doing the compression check by turning the key to crank and runnng around to check.
I suggest that instead, you wire up a remote starter switch. You can buy one ready-made at most any auto parts store, or make one with about 12 feet of regular two-wire extension cord, two beefy alligator clips, and a momentary pushbutton switch. Hook the switch to one end of the cord, the alligator switch to the other, then clip the two leads to the two terminals on the starter solenoid that have wires from the harness attached.(one larg, one small). pressing this switch will engage the starter.
You really need a device like this for what you are doing, as in your particular situation you need to be able to watch the compression gauge as well as the belt, and be close enough to listen. Also, observe how much compression is produced on the first, second, third stroke. If one cylinder pumps up to nearly the same pressure as the others but takes twice as many compression strokes to get there, that may indicate a problem.
I suggest that instead, you wire up a remote starter switch. You can buy one ready-made at most any auto parts store, or make one with about 12 feet of regular two-wire extension cord, two beefy alligator clips, and a momentary pushbutton switch. Hook the switch to one end of the cord, the alligator switch to the other, then clip the two leads to the two terminals on the starter solenoid that have wires from the harness attached.(one larg, one small). pressing this switch will engage the starter.
You really need a device like this for what you are doing, as in your particular situation you need to be able to watch the compression gauge as well as the belt, and be close enough to listen. Also, observe how much compression is produced on the first, second, third stroke. If one cylinder pumps up to nearly the same pressure as the others but takes twice as many compression strokes to get there, that may indicate a problem.
08-29-2004, 02:58 AM
#104
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Originally Posted by Big Dave
I've got a compression tester and I'm ready to check tomorrow. As I understand it, I'm going to put the tensior back on, thread the belt back on with the crank at the 45 degree BTDC, both cams gears having their notches lined up with the notches on the backing plates. With that done, I plug the compression tester into each spark plug hole, reconnect the battery and turn the starter on for a few seconds (the caps and rotors are not installed). Then I turn off the starter, get out and check the gauge for the reading. It should be 150-180 right? Or....do I have someone else turn the key so I can watch the guage while the starter is spinning? Can I turn the crank by hand instead?
I've never done compression testing, so I need confirmation that I'm doing it right before plowing ahead here. I don't want to cause more damage.
I've never done compression testing, so I need confirmation that I'm doing it right before plowing ahead here. I don't want to cause more damage.
08-29-2004, 08:13 AM
#105
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Dave,
A big double YES to what Bill says! Do NOT set the crank at 45 deg - and then set the cam drives at their OEM index marks to install the belt : to do so will potentially bend all the valves!
If the cam gears were marked previously @ the 45 deg crank setting (not the machined dimple in the gear, but a file mark or paint spot 22.5 degrees offset from the 'dimple) - then set the cams on those marks, and carefully rotate the crank to 45 deg BTDC: verify #1 piston rising to TDC.
If these hand applied marks are not there, I'd drag out a protractor, and measure off 22.5 deg spots on the cam gears clockwise from the OEM marks. Set these spots on the block index marks - then set the crank at 45deg BTDC
Use this to install the belt, and then carefully hand turn the engine. You need all plugs out to minimize effort and improve sensitivity of turning the crank. Turn to verify that TDC and the cam gear marks line up - if off a tooth, correct and proceed to tension, compression test, ...
When the water pump cratered on my S4, the shaft tilted sideways causing enough loss of tension to bring in the alarm (was checked only 500 Km earlier). The plastic impeller broke free when it touched the block, causing a pretty rapid boil over: even this brief incident chewed the top edge of the belt off and filled the covers with crap - I felt a whole lot better about working on the engine after a thorough clean up: lined the floor with papers and pans, took a gallon of paint thinner and a paint brush, and washed it down. This was good for both of us
.
Have someone check out the 'math' above - but that is what came to mind if all timing reference points were lost: Make it run again!!
A big double YES to what Bill says! Do NOT set the crank at 45 deg - and then set the cam drives at their OEM index marks to install the belt : to do so will potentially bend all the valves!
If the cam gears were marked previously @ the 45 deg crank setting (not the machined dimple in the gear, but a file mark or paint spot 22.5 degrees offset from the 'dimple) - then set the cams on those marks, and carefully rotate the crank to 45 deg BTDC: verify #1 piston rising to TDC.
If these hand applied marks are not there, I'd drag out a protractor, and measure off 22.5 deg spots on the cam gears clockwise from the OEM marks. Set these spots on the block index marks - then set the crank at 45deg BTDC
Use this to install the belt, and then carefully hand turn the engine. You need all plugs out to minimize effort and improve sensitivity of turning the crank. Turn to verify that TDC and the cam gear marks line up - if off a tooth, correct and proceed to tension, compression test, ...
When the water pump cratered on my S4, the shaft tilted sideways causing enough loss of tension to bring in the alarm (was checked only 500 Km earlier). The plastic impeller broke free when it touched the block, causing a pretty rapid boil over: even this brief incident chewed the top edge of the belt off and filled the covers with crap - I felt a whole lot better about working on the engine after a thorough clean up: lined the floor with papers and pans, took a gallon of paint thinner and a paint brush, and washed it down. This was good for both of us
.Have someone check out the 'math' above - but that is what came to mind if all timing reference points were lost: Make it run again!!