951 Damaged 3rd set of valves.. I'm giving up
07-11-2001, 02:57 PM
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951 Damaged 3rd set of valves.. I'm giving up
Well.. the very much ill fated 951 rebuild opens another chapter. After about 3 miles of driving, my 3rd set of valves are bent beyond belief. I have no idea why this is happening, and frankly, am about ready to part it out and cut my $10,000 worth of losses. But.. then again, I love this car and might give it 1 more shot. Here is what is happening, to our knowledge, and any input would be helpful. Also, if there is any 951 experts in the Central Jersey area that would like to come and take a crack at it, I would be willing to pay since I will be back in Ohio for another 2 months.
Everything is new. Belts, rollers, tensioner, and water pump. For some reason, the timing belt seems to track toward the rear of the engine, coming very close to grinding on the head and block, but it does not touch it. Tension is good, even after the damn thing skips the teeth. This last time it shredded the teeth on the crank pully. I cannot see why it would track this way. I suspect the water pump is the problem. Could it be that it is not machiened square? It does not leak, but that is about the only thing that could change the pitch of the belt. (It did this with the old and new tensioner assemblies, so I can rule them out.)
I am simply at a loss here. There are no real indications of why it keeps skipping teeth and knocking out the valves. It times true every single time we put it back together. We spin it by hand 4 or 5 times and check it, then crank it and check, then start it and check, then break it in and check. But as soon as I hit the road with it for a few miles, bam, pop, crunch, another $400 for the vlaves and another wide fire ring head gasket set. (I am assuming that you cannot re-use stamped head gaskets.)
Again, any help would be appreciated. I might be selling off some of my goodies to cover the costs of this. Brand new Huntley MAF Kit (stage 1 maf with filter, arc-2, arm-1, and a billet fuel regulator.) I will ponder this for the next few days, but if you are interested in it, drop me a line.
Everything is new. Belts, rollers, tensioner, and water pump. For some reason, the timing belt seems to track toward the rear of the engine, coming very close to grinding on the head and block, but it does not touch it. Tension is good, even after the damn thing skips the teeth. This last time it shredded the teeth on the crank pully. I cannot see why it would track this way. I suspect the water pump is the problem. Could it be that it is not machiened square? It does not leak, but that is about the only thing that could change the pitch of the belt. (It did this with the old and new tensioner assemblies, so I can rule them out.)
I am simply at a loss here. There are no real indications of why it keeps skipping teeth and knocking out the valves. It times true every single time we put it back together. We spin it by hand 4 or 5 times and check it, then crank it and check, then start it and check, then break it in and check. But as soon as I hit the road with it for a few miles, bam, pop, crunch, another $400 for the vlaves and another wide fire ring head gasket set. (I am assuming that you cannot re-use stamped head gaskets.)
Again, any help would be appreciated. I might be selling off some of my goodies to cover the costs of this. Brand new Huntley MAF Kit (stage 1 maf with filter, arc-2, arm-1, and a billet fuel regulator.) I will ponder this for the next few days, but if you are interested in it, drop me a line.
07-11-2001, 03:53 PM
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Perry, I am very sorry to hear this as I was rooting for you on this ill fated debacle.
I don't think Garrity made the switch over to these new boards, but why don't you give him a call in St Louis, I recall, and talk it over with him and see if he could give you some leads on how to get out of this black hole?
From what I've been able to glean, he is one of the top porsche engine builders in North America and certainly was a nice and no bull**** guy by all reports.
Wishing you some good luck, for a change.
Dan
I don't think Garrity made the switch over to these new boards, but why don't you give him a call in St Louis, I recall, and talk it over with him and see if he could give you some leads on how to get out of this black hole?
From what I've been able to glean, he is one of the top porsche engine builders in North America and certainly was a nice and no bull**** guy by all reports.
Wishing you some good luck, for a change.
Dan
07-11-2001, 04:55 PM
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Perry,
I too am sorry to hear about your ongoing dilema. I know how frustrating it can be to do a repair once, let alone repeatedly
However, it is good to hear you are going to give it another go, and imagine the tremendous satisfaction you will get when you have it fixed and can sign out "87 951 Guards Red/Black All Opt. Gorgeous".
Good Luck,
Eric
I too am sorry to hear about your ongoing dilema. I know how frustrating it can be to do a repair once, let alone repeatedly
However, it is good to hear you are going to give it another go, and imagine the tremendous satisfaction you will get when you have it fixed and can sign out "87 951 Guards Red/Black All Opt. Gorgeous".Good Luck,
Eric
07-11-2001, 06:05 PM
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In the _remote_ possibility that you haven't thought of & checked all of this (and no insult intended...I've done some really dumb stuff over the years):
Are the various sprockets & pulleys all fully & squarely seated on their shafts? No trash, gunk, etc. behind one, keeping it a tiny bit out?
Any sprockets that could possibly be installed backwards?
Is there any remote chance that you've got the cam timing wrong, or are changing it when you tension the belt?
Did you have the head shaved to flatten it, and could this cause both a minor change in cam-to-crank distance, and a loss of valve clearance?
Worse comes to worse, offer a good 944 tech $50-$100 to come over one evening after work just to check behind you while the covers are still off. ($50 to come over& look; $50 more if he finds it?)
I'm inclined to guess that you've got a bent roller or tensioner shaft, but that ought to show when spinning.
Jim, obviously grabbin' at straws here....
Are the various sprockets & pulleys all fully & squarely seated on their shafts? No trash, gunk, etc. behind one, keeping it a tiny bit out?
Any sprockets that could possibly be installed backwards?
Is there any remote chance that you've got the cam timing wrong, or are changing it when you tension the belt?
Did you have the head shaved to flatten it, and could this cause both a minor change in cam-to-crank distance, and a loss of valve clearance?
Worse comes to worse, offer a good 944 tech $50-$100 to come over one evening after work just to check behind you while the covers are still off. ($50 to come over& look; $50 more if he finds it?)
I'm inclined to guess that you've got a bent roller or tensioner shaft, but that ought to show when spinning.
Jim, obviously grabbin' at straws here....
07-11-2001, 08:21 PM
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Yikes, a sad story...
I am totally happy doing brake, tranny, clutch and suspension work, but engine work is something not to be taken lightly... for example:
I was annoyed when my "new" 85.5 944 needed a head gasket, and the mechanic said "better do the waterpump, belts and seals as well..." (50K+ since last replacement) This operation set me back $1,300 US but I figure it was worthwhile, "regular" maintenance...
If your are not a expert 944 mechanic, why on earth would someone attempt to do things as critical as "head" work when your friendly authorized Porsche mechanic does it with a 2-year, unlimited mileage warranty?
I realize that an unrelated component, not directly affected by the work done, may cause a failure, but most shops will bite the bullet in this situation, since it was an error in their judgment. (especially if the failure occurred 3 miles later!!)
I personally loathe giving money to mechanics, and do all my own maintenance where practical (new PS rack in last week) but I know when to defer to an expert and pay the price.
Not a flame, just hard reality...
I am totally happy doing brake, tranny, clutch and suspension work, but engine work is something not to be taken lightly... for example:
I was annoyed when my "new" 85.5 944 needed a head gasket, and the mechanic said "better do the waterpump, belts and seals as well..." (50K+ since last replacement) This operation set me back $1,300 US but I figure it was worthwhile, "regular" maintenance...
If your are not a expert 944 mechanic, why on earth would someone attempt to do things as critical as "head" work when your friendly authorized Porsche mechanic does it with a 2-year, unlimited mileage warranty?
I realize that an unrelated component, not directly affected by the work done, may cause a failure, but most shops will bite the bullet in this situation, since it was an error in their judgment. (especially if the failure occurred 3 miles later!!)
I personally loathe giving money to mechanics, and do all my own maintenance where practical (new PS rack in last week) but I know when to defer to an expert and pay the price.
Not a flame, just hard reality...
07-11-2001, 09:16 PM
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Don't give up, you can figure this out. You have two great replies already. Garrity would be a great guy to contact for a solid professional consult, and the other fellow offerred sound advice regarding something not being square or out of alignment. If you can find anyone else who has a 951 I would recommend getting a look at the front of their engine and start measuring relative distances between parts for a comparative analysis.
Also consider that this only happens after many thousands of RPM. I would posit one of two things: either something is very slighty out of plumb or your problem is related to forces only at play when the belt is turned at high speed.
Also consider that this only happens after many thousands of RPM. I would posit one of two things: either something is very slighty out of plumb or your problem is related to forces only at play when the belt is turned at high speed.
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07-11-2001, 11:26 PM
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Well.. here is the deal after getting it all back apart this afternoon.
It has 1 bent exhaust #3.. a broken spring, the lifter is wedged into the cam tower, and the tower itself is cracked. This all at about 2000 revs. I would assume that this time the keeper let the spring go, locking up the cam, and shredding the belt at the crank. (I'll be having words with the shop that I used for the head work) I have decided that the 2nd time the old tensioner did not fully open to take the tension all the way out. 1st time... all I know is that the belt was in decent shape, but it did grind a little on the head. Other than that, who knows.
Hey, at least I have somewhat of a lead why this happened this time. Ok.. to reply to all of the above.. and ask for more advice.. here goes.
1. I have yet to get in touch with Garrity. I will try on Monday, since the rest of this week will be spent in travel back to Ohio and much work to complete. He has impressed me in the past and I will give him a shout.
2. I do know what I am doing. 2.2 mopars, 3.0 911 SC's, 2.2 Hondas, 2.0 DSM's, and more recently worked side by side with my brother on the Rhonda Hartman-Smith NHRA Fram Top Fuel Dragsters (helped with heads). I know enough to do a timing belt and rebuild. Having said that, I have never in my life seen this happen, without some signs of why.
3. I thought of something on one of the rollers.. but there are none for the timing belt. All it touches is the cam sprocket, crank, up to the tensioner, then to the H20 Pump, and back to the cam. (the idler isnot a factor) All I can think is that new H20 pump is not seated properly, but then you would think that it would leak??? I dosen't know. I will say that the balance shaft belt tracks true!
4. Yup.. got the tensioner tightened down just fine. Set timing and tighten, rollit over a few times by hand, then re-check timing and "bounce" the tensioner a few times and repeat. I am 100% positive that it has been timed right every time. However, since it seems to be breaking when the motor is loaded.. as in pulling out of my hilly driveway (happened here 2 of the 3 times), something would be suspect in how that belt is becoming mis-aligned.
If it were my guess.. the H20 pump is the culpret of the bad belt alignment, and the goobered up spring the problem this time. I'd say if I can get the fine folks at PAP-Parts to swap me pumps and send this one out to the "not exactly right" pile, it would be a start. Then I need track down a cam tower and camshaft, along with a set of lifters, another (this is the 3rd) wide fire ring head gasket set. I might get this friggin thing back on the road at some point.
I will say this. Thank god the exterior and interior are in perfect shape. Keep in mind that I have 3 miles on the Konis at all 4, new rack, hell, new everything up front, clutch, mounts, bottom end, well... it is a new car for the most part. If it was a POS.. I would have gutted it already. 6 months and 3 trips to and from Jersey / Ohio, not to menton the hassle, time off... jeez. Now you know why I have about had it? I am about ready to loose my friggin cool!
Well.. thanks again to this board for the support and vast knowledge. Please, anyone who reads this, lay down a suggestion. Anything would help about now. Just make a guess, and by the time I find all the parts for it, we might come to a good conclusion. Thanks
It has 1 bent exhaust #3.. a broken spring, the lifter is wedged into the cam tower, and the tower itself is cracked. This all at about 2000 revs. I would assume that this time the keeper let the spring go, locking up the cam, and shredding the belt at the crank. (I'll be having words with the shop that I used for the head work) I have decided that the 2nd time the old tensioner did not fully open to take the tension all the way out. 1st time... all I know is that the belt was in decent shape, but it did grind a little on the head. Other than that, who knows.
Hey, at least I have somewhat of a lead why this happened this time. Ok.. to reply to all of the above.. and ask for more advice.. here goes.
1. I have yet to get in touch with Garrity. I will try on Monday, since the rest of this week will be spent in travel back to Ohio and much work to complete. He has impressed me in the past and I will give him a shout.
2. I do know what I am doing. 2.2 mopars, 3.0 911 SC's, 2.2 Hondas, 2.0 DSM's, and more recently worked side by side with my brother on the Rhonda Hartman-Smith NHRA Fram Top Fuel Dragsters (helped with heads). I know enough to do a timing belt and rebuild. Having said that, I have never in my life seen this happen, without some signs of why.
3. I thought of something on one of the rollers.. but there are none for the timing belt. All it touches is the cam sprocket, crank, up to the tensioner, then to the H20 Pump, and back to the cam. (the idler isnot a factor) All I can think is that new H20 pump is not seated properly, but then you would think that it would leak??? I dosen't know. I will say that the balance shaft belt tracks true!
4. Yup.. got the tensioner tightened down just fine. Set timing and tighten, rollit over a few times by hand, then re-check timing and "bounce" the tensioner a few times and repeat. I am 100% positive that it has been timed right every time. However, since it seems to be breaking when the motor is loaded.. as in pulling out of my hilly driveway (happened here 2 of the 3 times), something would be suspect in how that belt is becoming mis-aligned.
If it were my guess.. the H20 pump is the culpret of the bad belt alignment, and the goobered up spring the problem this time. I'd say if I can get the fine folks at PAP-Parts to swap me pumps and send this one out to the "not exactly right" pile, it would be a start. Then I need track down a cam tower and camshaft, along with a set of lifters, another (this is the 3rd) wide fire ring head gasket set. I might get this friggin thing back on the road at some point.
I will say this. Thank god the exterior and interior are in perfect shape. Keep in mind that I have 3 miles on the Konis at all 4, new rack, hell, new everything up front, clutch, mounts, bottom end, well... it is a new car for the most part. If it was a POS.. I would have gutted it already. 6 months and 3 trips to and from Jersey / Ohio, not to menton the hassle, time off... jeez. Now you know why I have about had it? I am about ready to loose my friggin cool!
Well.. thanks again to this board for the support and vast knowledge. Please, anyone who reads this, lay down a suggestion. Anything would help about now. Just make a guess, and by the time I find all the parts for it, we might come to a good conclusion. Thanks
07-13-2001, 06:29 AM
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Someone on the email list mentioned that their rollers had varying numbers of washers behind them to space it out from the block. Don't know what the correct distance is, but that may be factor. Good luck -danno
07-13-2001, 01:35 PM
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WOw, I had the same problem on my 931, except of course the timing belt on the 931 is much simpler.
My belt, was tracking the other way, it was tracking off center, like yours...but mine was tracking toward the front of the car..
In my case, what I found that helped the tracking of the timing belt was the torque on the head bolts. After I retorqued the head bolts, the belt tracked signficantly more in the center....it was as if I could control its tracking. (don't go and tighten one bolt to 50 pounds more torque than the other! I am talking about very slight adjustments! 2 foot pounds more on a few of them on one side of the head)
SO, that solved my tracking problem....
THEN, i went out driving for about the forth time in the car, and there i was on the street scared to **** when I got out of my car and saw the timign belt on the ground.
It had wobbled off, NOT because of the tracking, because the belt overstretched under normal driving. The ***** who sold me the timing belt gave me a bad belt. I didn't know this for quite a long while... I was under the impression that it was my engine, some stupid think like a bent pulley or crankshaft or camshaft! But, it was just the place I was getting belts from! The belt required constant attention, I kept having to tighten it each day! I should have stopped and said, "this is not right, the belt is stretching too much"
But, I assumed, well, its rubber, stretching is normal for the first few days. But not when the belt stretches each time you turn the car on, and you have to retension it after a 20 mile drive.
So the belt was working marginal as long as I kept tensioning it every 10 miles (I thought it was just getting worn in...i thought maybe it took a few days for it to finally settle out..!)
But the one day that the belt broke, the belt finally stretched more than it did the other days, and wobbled right off the engine and got splied by the tensioner. No teeth were broken, it just wobbled right off.
(931 engine is interference like the 944/951)
My belt, was tracking the other way, it was tracking off center, like yours...but mine was tracking toward the front of the car..
In my case, what I found that helped the tracking of the timing belt was the torque on the head bolts. After I retorqued the head bolts, the belt tracked signficantly more in the center....it was as if I could control its tracking. (don't go and tighten one bolt to 50 pounds more torque than the other! I am talking about very slight adjustments! 2 foot pounds more on a few of them on one side of the head)
SO, that solved my tracking problem....
THEN, i went out driving for about the forth time in the car, and there i was on the street scared to **** when I got out of my car and saw the timign belt on the ground.
It had wobbled off, NOT because of the tracking, because the belt overstretched under normal driving. The ***** who sold me the timing belt gave me a bad belt. I didn't know this for quite a long while... I was under the impression that it was my engine, some stupid think like a bent pulley or crankshaft or camshaft! But, it was just the place I was getting belts from! The belt required constant attention, I kept having to tighten it each day! I should have stopped and said, "this is not right, the belt is stretching too much"
But, I assumed, well, its rubber, stretching is normal for the first few days. But not when the belt stretches each time you turn the car on, and you have to retension it after a 20 mile drive.
So the belt was working marginal as long as I kept tensioning it every 10 miles (I thought it was just getting worn in...i thought maybe it took a few days for it to finally settle out..!)
But the one day that the belt broke, the belt finally stretched more than it did the other days, and wobbled right off the engine and got splied by the tensioner. No teeth were broken, it just wobbled right off.
(931 engine is interference like the 944/951)
07-13-2001, 02:26 PM
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Lars' comment reminded me of the problem I had 3 years ago with my 90 RX-7 convertible.
In 97 I replaced the alternator because the car ate 2 belts. In 98 I tuned the car and changed all the other belts (the car had 25K)using what the local parts store had. The alternator belt which of course was closest to the block snapped. Fortunately I was near a Midas, and left the car there to have the belt replaced.
About a week later splat, and the Midas belt broke. Fortunately again it was near another Midas. Neither manager was too thrilled to find a mint/shiny convertible blocking their bay.
Guess what happened a week later? This time I replaced the Midas belt with a "genuine" belt from a Mazda dealer.
Three years and 10K later I'm still on the Mazda belt. BTW visually they were all pretty damn close to one another. Go Figya!
In 97 I replaced the alternator because the car ate 2 belts. In 98 I tuned the car and changed all the other belts (the car had 25K)using what the local parts store had. The alternator belt which of course was closest to the block snapped. Fortunately I was near a Midas, and left the car there to have the belt replaced.
About a week later splat, and the Midas belt broke. Fortunately again it was near another Midas. Neither manager was too thrilled to find a mint/shiny convertible blocking their bay.
Guess what happened a week later? This time I replaced the Midas belt with a "genuine" belt from a Mazda dealer.
Three years and 10K later I'm still on the Mazda belt. BTW visually they were all pretty damn close to one another. Go Figya!
07-13-2001, 08:29 PM
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This is a long shot thought.. a sticking valve? it does happen.. one gets stuck down bangs off of the top of a piston...A loose guide might do this.. it would be OK while moving slowly or at a start up...Just a thought... My only other thought on this is a poorly made cam..A lobe to high... good luck on this..it is a weird problem..but I do think it points to a part somewhere not made correctly...
07-14-2001, 12:57 AM
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Has the car ever been in a fender bender?? I heard that even the mild benders can just wreak havoc on the mecanics of a vehicle, and I do believe it. So if it has been damaged at some time, I would sell it immediately and invest in one that hasn't. Just the littlest thing can drive you to insanity, and it could just be that. I may be wrong, but I may be right.
07-14-2001, 12:27 PM
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Nope.. no wrecks, no nada. All I can figure is that I got a bad set of belts, and when the valve whent this last time, it may have been it all along.
When the cam tower came off of it this last time, it was cracked. I honestly never checked it during this whole process before new. Valves, springs, guides, and keepers are new, so the head is just fine. Only shaved it a little. I will try a new cam and tower and see what happens. I am also going to toss on another water pump and see if that takes care of the tracking problem.
For now.. it sits until I find the parts. Thanks to all. I'll keep you updated.
When the cam tower came off of it this last time, it was cracked. I honestly never checked it during this whole process before new. Valves, springs, guides, and keepers are new, so the head is just fine. Only shaved it a little. I will try a new cam and tower and see what happens. I am also going to toss on another water pump and see if that takes care of the tracking problem.
For now.. it sits until I find the parts. Thanks to all. I'll keep you updated.