ANOTHER 968 failure...
02-21-2002, 05:24 PM
#1
Race Car
Thread Starter
ANOTHER 968 failure...
[quote]Hi
Last weekend my '93 968 CS suffered some engine running issues. I got the car home (carefully) and later towed it to Kremer Racing in Cologne, Germany for a full diagnosis. I currently live in Cologne. I suspected it to be Variocam issues but didn't want to think about it too much! The camcover was removed to discover a Variocam chain tensioner failure which has resulted in the loss of nearly all of the cam teeth. Only five have been found (seventeen per cam I think)! Number four cylinder has had piston and valve contact.
This is obviously quite a shock. The vehicle was bought in Germany from a used Porsche specialist with FSH. Since buying the car ten months ago I have had to buy a new dual mass flywheel and clutch and now this, probably a complete engine rebuild! Porsche durability!?
I am currently awaiting the arrival of an insurance assessor who is due to visit Kremer and my car tomorrow. I took out a separate mechanical insurance policy when buying the car.
I have heard of cam teeth/Variocam issues before but I thought it was a very rare issue and couldn't possibly happen to me.
The cost to put right is very expensive.
Has this ever happened to anyone else?
Any comments?
James C<hr></blockquote>
This was posted on 968.net today. Frankly, I'm getting tired of hearing about all of the catastrophic issues with the 968 series cars. I'm strongly thinking that I'll compose another document to Porsche [as Martin did a while back] to convey our dissatisfaction with their lack support while being fully aware of the various failures these cars have come to experience [6 spd. pinion bearing, variocam tensioner, hydraulic timing belt tensioner]. Porsche has boasted about having the highest profit margin of any other car company the past few years, it's about time they use that money to give back to their loyal consumers rather than brag about what they're taking from us all the time!!
Last weekend my '93 968 CS suffered some engine running issues. I got the car home (carefully) and later towed it to Kremer Racing in Cologne, Germany for a full diagnosis. I currently live in Cologne. I suspected it to be Variocam issues but didn't want to think about it too much! The camcover was removed to discover a Variocam chain tensioner failure which has resulted in the loss of nearly all of the cam teeth. Only five have been found (seventeen per cam I think)! Number four cylinder has had piston and valve contact.
This is obviously quite a shock. The vehicle was bought in Germany from a used Porsche specialist with FSH. Since buying the car ten months ago I have had to buy a new dual mass flywheel and clutch and now this, probably a complete engine rebuild! Porsche durability!?
I am currently awaiting the arrival of an insurance assessor who is due to visit Kremer and my car tomorrow. I took out a separate mechanical insurance policy when buying the car.
I have heard of cam teeth/Variocam issues before but I thought it was a very rare issue and couldn't possibly happen to me.
The cost to put right is very expensive.
Has this ever happened to anyone else?
Any comments?
James C<hr></blockquote>
This was posted on 968.net today. Frankly, I'm getting tired of hearing about all of the catastrophic issues with the 968 series cars. I'm strongly thinking that I'll compose another document to Porsche [as Martin did a while back] to convey our dissatisfaction with their lack support while being fully aware of the various failures these cars have come to experience [6 spd. pinion bearing, variocam tensioner, hydraulic timing belt tensioner]. Porsche has boasted about having the highest profit margin of any other car company the past few years, it's about time they use that money to give back to their loyal consumers rather than brag about what they're taking from us all the time!!
02-21-2002, 05:38 PM
#3
Race Car
Thread Starter
That's another scary thing!!
[quote]Sorry, I should have included the mileage. It has now covered about 130k kms or roughly 81 k miles. As I mentioned before it has a full service history and has been looked after, especially by me.
An insurance assessor is due to visit the car today to decide who pays for the repairs. I am thinking of taking some digital pictures for my own records and could send you some if you like.
I will also let you know what the mechanics at Kremer say, although it's a little difficult for me as my German is not too good.
James C<hr></blockquote>
A failure at that mileage is ridiculous if you ask me. This guy is looking at a complete engine rebuild at ~80,000 miles!
[quote]Sorry, I should have included the mileage. It has now covered about 130k kms or roughly 81 k miles. As I mentioned before it has a full service history and has been looked after, especially by me.
An insurance assessor is due to visit the car today to decide who pays for the repairs. I am thinking of taking some digital pictures for my own records and could send you some if you like.
I will also let you know what the mechanics at Kremer say, although it's a little difficult for me as my German is not too good.
James C<hr></blockquote>
A failure at that mileage is ridiculous if you ask me. This guy is looking at a complete engine rebuild at ~80,000 miles!
02-21-2002, 07:40 PM
#4
Addict
Rennlist
Lifetime Member
Rennlist
Lifetime Member
[quote]Originally posted by PorscheG96:
<strong>That's another scary thing!!
A failure at that mileage is ridiculous if you ask me. This guy is looking at a complete engine rebuild at ~80,000 miles!</strong><hr></blockquote>It may be ridiculous, but it's not that uncommon. I know a local 944 S2 owner that had his tensioner fail at around 70K miles and it cost $3500 to fix the engine.
These types of failures drive me nuts with Porsche and their lack of responsibility. At the very least they could issue a Technical Service Bulletin to check the tensioner periodically and replace it under a set schedule. But no... they are content to just let us fend for ourselves. Most owners don't even know the tensioner should be checked.
The 911 guys haven't faired much better. I mean, how many years did it take Porsche to design a semi-reliable chain tensioner for the 911... about 25? And don't even get me started on their clutch designs <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
<strong>That's another scary thing!!
A failure at that mileage is ridiculous if you ask me. This guy is looking at a complete engine rebuild at ~80,000 miles!</strong><hr></blockquote>It may be ridiculous, but it's not that uncommon. I know a local 944 S2 owner that had his tensioner fail at around 70K miles and it cost $3500 to fix the engine.
These types of failures drive me nuts with Porsche and their lack of responsibility. At the very least they could issue a Technical Service Bulletin to check the tensioner periodically and replace it under a set schedule. But no... they are content to just let us fend for ourselves. Most owners don't even know the tensioner should be checked.
The 911 guys haven't faired much better. I mean, how many years did it take Porsche to design a semi-reliable chain tensioner for the 911... about 25? And don't even get me started on their clutch designs <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
02-21-2002, 07:55 PM
#5
I hope you can post the specifics of the tensioner failure,what I am interested in is the failure the nylon guide or did the tensioner itself fail?If it was the tensioner that failed I would recommend installing a stop collar,I posted this question on the forum a couple of weeks ago.I have a 944S and am concerned about tensioner failures,if you replace the nylon guide every 40,000 miles or so and install a stop collar then the only other thing that could break would be the chain and I have not heard that this is a problem.Good luck. <img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
02-21-2002, 08:40 PM
#6
Rennlist Member
Join Date: May 2001
Location: North Of Chicago
Posts: 1,992
Likes: 0
Received 0 Likes
on
0 Posts
Agreed, I would like to know how if this was a tensioner failure as opposed to the guide failure?? Was the pad intact but the tensioner fully collapsed??? Please clarify if you can....
It is pretty much a crime that there is no TSB to check the tensioner.
Best,
It is pretty much a crime that there is no TSB to check the tensioner.
Best,
02-22-2002, 02:16 AM
#7
Race Director
I don't know if there's enough data out there to determine this... but would there be more failures, percentage wise amongst the 968s with VarioCam as opposed to the 944S/S2? It would appear that the VarioCam mechanism would place more stress on the chain and therefore the tensioner than cars without VarioCam. The 968 is probably one of my favorite Porsches and it's too bad that it has had so many growing pains. First the rash of pinion-bearing failures and now the cam-chain tensioner appears to be making the news with more frequency.
It looks like converting the cam drive over to dual pulleys (like all DOHC BMWs & Japanese cars) and getting rid of that troublesome chain-tensioner may be the ultimate solution to this problem.
Where did I see a picture of that conversion, was it on Milledge's website?
It looks like converting the cam drive over to dual pulleys (like all DOHC BMWs & Japanese cars) and getting rid of that troublesome chain-tensioner may be the ultimate solution to this problem.
Where did I see a picture of that conversion, was it on Milledge's website?
Trending Topics
02-22-2002, 03:30 AM
#8
Race Car
Thread Starter
This is the second time you've mentioned the independent cam drive, I'm very intrigued. I'll look into it more and hopefully I can do away with this aweful chain and tensioner deal.
02-22-2002, 08:09 AM
#9
Rennlist Member
Join Date: May 2001
Location: North Of Chicago
Posts: 1,992
Likes: 0
Received 0 Likes
on
0 Posts
Only place I have seen an image of the dual pulley drive is in a Windward Perf. advert. in Pano or Excellence; I believe it was a picture of their 968 to 968 turbo conversion. If anyone can find a pic and post it, that would be great. Can't imagine it is cheap or very easy modification.
Cheers,
Cheers,
02-22-2002, 09:17 AM
#10
Three Wheelin'
Join Date: May 2001
Location: Asheville,NC (Don't move here!!!)
Posts: 1,744
Likes: 0
Received 2 Likes
on
2 Posts
Looks like I'll be inspecting the cam chain & Variocam tensioner every 15K or so henceforth (just did it a few thousand miles ago). I may change my procedure to include letting the car sit for a couple of days in advance, just to see if the unit shows any signs of leak-down or collapse.
At least it's easy to get to.
And since I'm now at 70K miles, I guess I'll be replacing it around 85K or so...
Jim... "Paranoia strikes deep, into your soul it will creep..."
At least it's easy to get to.
And since I'm now at 70K miles, I guess I'll be replacing it around 85K or so...
Jim... "Paranoia strikes deep, into your soul it will creep..."
02-22-2002, 01:14 PM
#11
Pro
Join Date: May 2001
Location: Tucson AZ
Posts: 678
Likes: 0
Received 0 Likes
on
0 Posts
I have an old fashoned 8V N/A. No dual cams.
Love my car (most of the time), but I will restate what I have said any number of times: Even a Yugo would last almost forever if it was lavished with the amount of attention we give our German "Wunder" cars.
If the 944 had a Mitsubishi or Nissan emblem on it rather than what it has, given the recurring problems, would any of us still consider owning one?
Just curious, bored, and trying to get a little discussion going..
Cheers!
Bob S.
Love my car (most of the time), but I will restate what I have said any number of times: Even a Yugo would last almost forever if it was lavished with the amount of attention we give our German "Wunder" cars.
If the 944 had a Mitsubishi or Nissan emblem on it rather than what it has, given the recurring problems, would any of us still consider owning one?
Just curious, bored, and trying to get a little discussion going..
Cheers!
Bob S.
02-22-2002, 01:18 PM
#12
Race Director
Ah hah! Here's the Powerhaus turbo conversion with the dual-cam drive:
I guess this will also take care of the problem of the worn-out non-replacable sprockets on the cams as well (if you've survived the tensioner-pad problem, this will probably hit you next).
I guess this will also take care of the problem of the worn-out non-replacable sprockets on the cams as well (if you've survived the tensioner-pad problem, this will probably hit you next).
02-22-2002, 03:01 PM
#13
Rennlist Member
Join Date: May 2001
Location: North Of Chicago
Posts: 1,992
Likes: 0
Received 0 Likes
on
0 Posts
Nice pic!!! <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
[quote]Originally posted by Danno:
<strong>I guess this will also take care of the problem of the worn-out non-replacable sprockets on the cams as well (if you've survived the tensioner-pad problem, this will probably hit you next).</strong><hr></blockquote>
This is a new one to me, the cam sprocket wears out???? Are you talking about the front sproket driven with the cam belt?? As for not being replaceable, the sprocket is not a one piece unit with the cam. Is the sprocket not available seperately???
Cheers
[quote]Originally posted by Danno:
<strong>I guess this will also take care of the problem of the worn-out non-replacable sprockets on the cams as well (if you've survived the tensioner-pad problem, this will probably hit you next).</strong><hr></blockquote>
This is a new one to me, the cam sprocket wears out???? Are you talking about the front sproket driven with the cam belt?? As for not being replaceable, the sprocket is not a one piece unit with the cam. Is the sprocket not available seperately???
Cheers
02-22-2002, 03:08 PM
#14
Race Car
Thread Starter
[quote]Originally posted by Riff:
<strong>Nice pic!!! <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
This is a new one to me, the cam sprocket wears out???? Are you talking about the front sproket driven with the cam belt?? As for not being replaceable, the sprocket is not a one piece unit with the cam. Is the sprocket not available seperately???
Cheers</strong><hr></blockquote>
No, there are sprockets cast into the middle of the camshafts themselves. Only the intake camshaft runs off of the cam timing belt, the exhaust camshaft runs dependently off of the intake camshaft. There's a metal chain that turns the exhaust cam as the intake camshaft turns, and the mechanism that tensions this chain is what failed in James' 968. As the tensioner begins to get tired it allows slack in the cam chain, this is what rounded off [actually broke off] both camshaft gear sprockets.
<strong>Nice pic!!! <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" />
This is a new one to me, the cam sprocket wears out???? Are you talking about the front sproket driven with the cam belt?? As for not being replaceable, the sprocket is not a one piece unit with the cam. Is the sprocket not available seperately???
Cheers</strong><hr></blockquote>
No, there are sprockets cast into the middle of the camshafts themselves. Only the intake camshaft runs off of the cam timing belt, the exhaust camshaft runs dependently off of the intake camshaft. There's a metal chain that turns the exhaust cam as the intake camshaft turns, and the mechanism that tensions this chain is what failed in James' 968. As the tensioner begins to get tired it allows slack in the cam chain, this is what rounded off [actually broke off] both camshaft gear sprockets.
02-22-2002, 05:57 PM
#15
Rennlist Member
Join Date: May 2001
Location: North Of Chicago
Posts: 1,992
Likes: 0
Received 0 Likes
on
0 Posts
I was aware of the drive mechanism for the intake cam being driven by the exhaust cam. I was startled to hear that this sprocket is a wear issue. The links on a chain should give out long before the sprocket teeth get worn down. How do you know that the tensioner gave out??? Was the nylon pad still intact??? The sheared teeth on the cams could have been due to the chain stopping movement. Without the rest of the details, we won't really know if the tensioner gave out or not.
Cheers
Cheers