S2/968 head gaskets
Discussion
What's the opinion here about the need to change the head gasket on these engines? I understand that issues with rotting gaskets allowing the coolant to 'short-circuit' and overheat the rear cylinders has been identified as a weakness and potential seriously expensive damage occurring if not sorted quickly!!
Looking at a 968 that is 21 years old with 114k miles and has never had a replacement but the compression test indicates all well and the opinion of a well known specialist is don't touch it until it shows signs of failure. Fair enough but does that mean constantly having to test the engine temperature, front to back, with an infrared thermometer??
Looking at a 968 that is 21 years old with 114k miles and has never had a replacement but the compression test indicates all well and the opinion of a well known specialist is don't touch it until it shows signs of failure. Fair enough but does that mean constantly having to test the engine temperature, front to back, with an infrared thermometer??
Lots of other things to worry about apart from head gaskets...cam chain / sprockets would be the first thing I'd worry about
Sure it's probably sensible to check it out at some point, along with lots of other good preventative maintenance jobs. My 230k S2 was on an original HG & it was looking a bit past its best, but still working fine, when we removed the engine (oil pickup failure).
Sure it's probably sensible to check it out at some point, along with lots of other good preventative maintenance jobs. My 230k S2 was on an original HG & it was looking a bit past its best, but still working fine, when we removed the engine (oil pickup failure).
If youre going to town then Id suggest removing the head and re-seating the valves, replacing the gasket and replacing the cam chain and tensioner. Hopefully you will be able to use both of the existing camshafts.
As Ed says though, it could be perfectly serviceable. Plenty aren't though and there are enough good reasons to remove the cylinder head.
As Ed says though, it could be perfectly serviceable. Plenty aren't though and there are enough good reasons to remove the cylinder head.
If your pockets are deep enough for piece of mind preventative maintenance is always better than sitting behind the armco on a motorway awaiting recovery far far away from home... But like many things how a HG will hold out will depend upon how well the car has been maintained (i.e. how old are the waterpump, thermostats, coolant etc.) and how hard the car is driven.
Having preventatively rebuilt the head on my 951 I found that the original gasket was pretty rotten, but all the important metal sealing rings were in good order so all in I'd say it was compromised but probably not at risk of failure. Particularly given I was renewing the rest of the cooling system at the same time. However I am of the opinion that due to the rotting of the fibre material the gasket is a long-term servicable item, but as stated above is probably less critical than the condition of the slipper pads and chain on a 16v car. Personally though if going to the trouble of removing the cams it's not a lot of additional time to remove the head whilst you're there. The main expense is time, so if you're doing it yourself it's very worth doing.
Having preventatively rebuilt the head on my 951 I found that the original gasket was pretty rotten, but all the important metal sealing rings were in good order so all in I'd say it was compromised but probably not at risk of failure. Particularly given I was renewing the rest of the cooling system at the same time. However I am of the opinion that due to the rotting of the fibre material the gasket is a long-term servicable item, but as stated above is probably less critical than the condition of the slipper pads and chain on a 16v car. Personally though if going to the trouble of removing the cams it's not a lot of additional time to remove the head whilst you're there. The main expense is time, so if you're doing it yourself it's very worth doing.
Thanks for all the opinions and advise.
Have researched further and found two well known specialists (Hartech and JMG Porsche) agreeing on the need to change head gaskets on a 10-12 year cycle to prevent potentially catastrophic failure.
This is what Barry Hart has said on the matter;
'In my experience - 10 to 12 years is the safe maximum for this head gasket - not so much to the point that it no longer seals the compression - but to an age at which it will start short circuiting the coolant and run the risk of local overheating. Age is the main cause as the coolant remains in contact with the gasket when you are not using the car.'
And Jon Mitchell's comment;
'The head gaskets on these tend to be in tip top condition when changed at 5 years, however at 10 years old they are beginning to become brittle, after 20 years they might be hanging on for dear life and still sealing, but when they finally fail, they fail in a big way. So my usual recommendation with head gaskets is usually to change them if they are over 10 years old.'
I realise there will be many folk who strongly subscribe to the view that it is unnecessary until it fails, but where do you stop with this philosophy? Wait 'til the tyres fall off the rims even though there is plenty of tread left, for instance??
As has been mentioned above if the head gasket is changed during a 'major' service then the additional cost of preventing a failure is considerably cheaper and gives an opportunity to check the condition of valves, guides, etc. for further peace of mind (or potentially more expense!).
As always, it depends on how you intend to use your car which ultimately decides on the course of action and if it is only a couple of thousand miles a year of local driving then the need to do this will be low down on the list.
Have researched further and found two well known specialists (Hartech and JMG Porsche) agreeing on the need to change head gaskets on a 10-12 year cycle to prevent potentially catastrophic failure.
This is what Barry Hart has said on the matter;
'In my experience - 10 to 12 years is the safe maximum for this head gasket - not so much to the point that it no longer seals the compression - but to an age at which it will start short circuiting the coolant and run the risk of local overheating. Age is the main cause as the coolant remains in contact with the gasket when you are not using the car.'
And Jon Mitchell's comment;
'The head gaskets on these tend to be in tip top condition when changed at 5 years, however at 10 years old they are beginning to become brittle, after 20 years they might be hanging on for dear life and still sealing, but when they finally fail, they fail in a big way. So my usual recommendation with head gaskets is usually to change them if they are over 10 years old.'
I realise there will be many folk who strongly subscribe to the view that it is unnecessary until it fails, but where do you stop with this philosophy? Wait 'til the tyres fall off the rims even though there is plenty of tread left, for instance??
As has been mentioned above if the head gasket is changed during a 'major' service then the additional cost of preventing a failure is considerably cheaper and gives an opportunity to check the condition of valves, guides, etc. for further peace of mind (or potentially more expense!).
As always, it depends on how you intend to use your car which ultimately decides on the course of action and if it is only a couple of thousand miles a year of local driving then the need to do this will be low down on the list.
Edited by yknot on Tuesday 23 September 14:30
Preventive maintenance on non critical parts is pretty much a thing of the past, if you were relying on the 968 to get to work or a trip around Europe it would make sense to spend a grand or whatever to do the head gasket. If it's a low mileage toy to have some fun in keep an eye on the water temp/level/colour and have AA/RAC recovery.
blade7 said:
Preventive maintenance on non critical parts is pretty much a thing of the past, if you were relying on the 968 to get to work or a trip around Europe it would make sense to spend a grand or whatever to do the head gasket. If it's a low mileage toy to have some fun in keep an eye on the water temp/level/colour and have AA/RAC recovery.
There have been at least a couple of people on 968UK who have had issues with bore damage due to very slight HG leaks which have gone unnoticed. Even on a weekend car it would be prudent to follow hartechs advice, IMHO. Saying preventative maintenance is a thing of the past is utter tosh. 
boy said: There have been at least a couple of people on 968UK who have had issues with bore damage due to very slight HG leaks which have gone unnoticed. Even on a weekend car it would be prudent to follow hartechs advice, IMHO. Saying preventative maintenance is a thing of the past is utter tosh.
Your HO is utter tosh IMHO. yknot said:
Thanks for all the opinions and advise.
I realise there will be many folk who strongly subscribe to the view that it is unnecessary until it fails, but where do you stop with this philosophy? Wait 'til the tyres fall off the rims even though there is plenty of tread left, for instance??
Of course not. Tyres will be cracking and all sorts before then I realise there will be many folk who strongly subscribe to the view that it is unnecessary until it fails, but where do you stop with this philosophy? Wait 'til the tyres fall off the rims even though there is plenty of tread left, for instance??
Edited by yknot on Tuesday 23 September 14:30
.I would be in the leave it and keep an eye on things camp as well in all honesty, or maybe in the past I have simply been OK with head gaskets (I tend to always have good fresh coolant in my cars etc, although I can appreciate other factors can bring on HG failure). On a 968 the cam chain would be my biggest worry and I would certainly change them.
I had a 900T16S years ago with its 16v head and original gasket that was about 14 years old at the time, well it failed in one place due to corrosion and lead to the cylinder head being cracked right through by the time it was noticed. The 968 I used to own had the top end fully rebuilt by the previous owner, its a well known issue on those cars causing them to be down on power due to valve guide wear, given how similar the S2 is I am surprised its not mentioned more often. Certainly on my race car it was one of the jobs done within a year of building the car and I think would have to be on the list for any of the front engined cars with 4v heads intended for the track. Barry Hart mentioned this issue a couple of years ago after he spotted a few cars which they did where the original head gasket had disintegrated so he started advising that for 968s the gasket should be changed as a precautionary measure if it hadn't already been in the cars lifetime. You pays yer money yer takes yer choice as they say.
>Cynical Mode On<
Specialist's points of view and owner's points of view are different. There will always be an inclination towards pessimism and hence more work from a specialist. How much inclination depends upon the specialist, and you only need to read the stories about unnecessary work being done by dealers to see the worst end of the spectrum, but it's there for anyone who is paid to do work on a car.
I have a 25-year-old S2 on (as far as I am aware) the original HG. Compression is fine, tested power output (Weltmeister) is higher than spec, despite 190,000 miles on the clock. It goes every bit as well as you'd expect a healthy S2 to. I changed the belts and cam chain two weeks ago and debated whether to take the head off and decided not to; it would have cost nothing but time, but I didn't think that would have been time well spent. The gasket may fail spectacularly next time I start the car but I doubt it will, and pulling a head off and re-fitting it would have potentially caused more problems of other kinds.
"Rotten HG's on S2's" is something that has only been talked about in the last 3-4 years. If the recommendation from specialists is that they should be changed every 10 years, why haven't we been hearing about this for the last 15 years (i.e. when the first S2's were 10 years old)?
>Cynical mode off<
Oli.
Specialist's points of view and owner's points of view are different. There will always be an inclination towards pessimism and hence more work from a specialist. How much inclination depends upon the specialist, and you only need to read the stories about unnecessary work being done by dealers to see the worst end of the spectrum, but it's there for anyone who is paid to do work on a car.
I have a 25-year-old S2 on (as far as I am aware) the original HG. Compression is fine, tested power output (Weltmeister) is higher than spec, despite 190,000 miles on the clock. It goes every bit as well as you'd expect a healthy S2 to. I changed the belts and cam chain two weeks ago and debated whether to take the head off and decided not to; it would have cost nothing but time, but I didn't think that would have been time well spent. The gasket may fail spectacularly next time I start the car but I doubt it will, and pulling a head off and re-fitting it would have potentially caused more problems of other kinds.
"Rotten HG's on S2's" is something that has only been talked about in the last 3-4 years. If the recommendation from specialists is that they should be changed every 10 years, why haven't we been hearing about this for the last 15 years (i.e. when the first S2's were 10 years old)?
>Cynical mode off<
Oli.
The issue with rotting headgaskets may appear on cars that are not used regularly enough and/or have not had their coolant replaced regularly enough.
Aged coolant may cause corrosion on the mating surface of the head with the headgasket, and I would opine that a "higher quality" coolant might make a difference. I always use the pink stuff as recommended by VAG as a precaution. Not sure if it makes any actual difference with another type of coolant, but if it does it's cheap insurance.
A much more important issue with the 16V engines is that valve springs seem to let go around the 120k miles mark, and when this happens, well... you get the picture.
Aged coolant may cause corrosion on the mating surface of the head with the headgasket, and I would opine that a "higher quality" coolant might make a difference. I always use the pink stuff as recommended by VAG as a precaution. Not sure if it makes any actual difference with another type of coolant, but if it does it's cheap insurance.
A much more important issue with the 16V engines is that valve springs seem to let go around the 120k miles mark, and when this happens, well... you get the picture.
I had my 968 head gasket changed at 70k miles and 18 years old. I had no signs of any issues but partly after reading similar threads and partly as I had other work to do on the car I had it done.
Turned out it was in excellent condition, appeared original, and seemed like it really didn't need to be changed in the first place.
I assume various factors are involved, not least previous service history and maintenance on cooling system etc.
Maybe do a compression/leak test for starters, if there's any anomolies then probably worth getting the head re-done with obviously a new gasket fitted at the same time.
I would also recommend you talk to Kevin at EMC Motorsport in Birmingham, a wealth of experience with these engines, and his advice is very much zero BS and to the point so to speak.
PS - If you take the head off it's a good time to fit a new water pump, the seals on these are prone to failure with age.
Turned out it was in excellent condition, appeared original, and seemed like it really didn't need to be changed in the first place.
I assume various factors are involved, not least previous service history and maintenance on cooling system etc.
Maybe do a compression/leak test for starters, if there's any anomolies then probably worth getting the head re-done with obviously a new gasket fitted at the same time.
I would also recommend you talk to Kevin at EMC Motorsport in Birmingham, a wealth of experience with these engines, and his advice is very much zero BS and to the point so to speak.
PS - If you take the head off it's a good time to fit a new water pump, the seals on these are prone to failure with age.
The problem is I don't know how it can be checked without pulling the head and on the other hand one can't assume that you will notice it if/when it goes in time to avoid further damage. My old SAAB 900T16S as a case in point, I noticed it seemed down on power no real noticeable coolant loss so went to pull the plugs. The first one wouldn't come out and the second whilst it did come out the head had fallen off. On that car I was very lucky that the cars were not that old and parts from breakers were cheap so I got a complete head from Neo brothers for £300.
I take your points guys, its on that list of several things which are maybes where for anyone its a case of assessing the risks and deciding where one is going to spend money and how much. One big problem with these cars these days is that spending through all the things specialists advise can very easily add up to much more than a car is worth.
I take your points guys, its on that list of several things which are maybes where for anyone its a case of assessing the risks and deciding where one is going to spend money and how much. One big problem with these cars these days is that spending through all the things specialists advise can very easily add up to much more than a car is worth.
Thom said:
A much more important issue with the 16V engines is that valve springs seem to let go around the 120k miles mark, and when this happens, well... you get the picture.
I'm not sure whether it's the way you have worded it, but that statement suggests that it's common for valve springs to go on S2's at around 120,000 miles or soon thereafter. I strongly disagree; there have been a few stories of S2's breaking inner valve springs (inlet, usually) at higher miles but I'm not aware of any going as soon as 120,000 miles, and also know of a lot more S2's going strong at 180,000 miles than ever had problems.
As with the rotting head gasket issue, I think we're looking at a very small number of cases being over-extrapolated to apply to all cars, creating needless concern amongst the many.
NJH said:
I take your points guys, its on that list of several things which are maybes where for anyone its a case of assessing the risks and deciding where one is going to spend money and how much. One big problem with these cars these days is that spending through all the things specialists advise can very easily add up to much more than a car is worth.
.... and that's precisely the point; when it's something like a DME relay, it's worth an owner spending twenty quid to keep a spare in the glovebox and sleeping soundly at night. When it's biggies like head gaskets and valve springs, the notion of spending a grand (possibly more) to change it 'just in case' is neither good economics nor good news for the model as a whole. If your S2 is a fast-response vehicle in a critical situation, where it has to run perfectly, on the button, every single time it is started up, and you have a limitless budget to keep it in this state, changing the head gasket preventively will be a good idea. If your S2 is a £6000 piece of pork that you enjoy driving on high days an holidays (as most 944's now are), and your budget to keep it on the road just about gets to four figures a year, you spend £50 on RAC/AA/ADAC cover and enjoy the car for what it's worth. Let's avoid scaremongering. It doesn't help anyone.
Oli.
zcacogp said:
I strongly disagree; there have been a few stories of S2's breaking inner valve springs (inlet, usually) at higher miles but I'm not aware of any going as soon as 120,000 miles, and also know of a lot more S2's going strong at 180,000 miles than ever had problems.
It may probably remain an anecdotical issue but when it happens to you it would not make sense not to mention it. If you are lucky you are not going to bend any valve, but I maintain that replacing valve springs preventively at 120k miles is safer/cheaper than waiting for one to break and cause damage potentially expensive enough to justify moving the car into the scrapyard.If I were now to maximise safety in the context of purchasing an S2 with more than 120k proven miles with an unclear service history I would probably budget for a full top end refresh including replacing the headgasket, valve guides, tensioner pads and valve springs. That is of course if camshaft sprockets are still in good condition. Some lifters off the VAG parts list will work just fine and cost a lot less than OEM lifters, too.
By the way that did happen to me with the S2 on track, its what lead to the head off and rebuild. Two valve springs broke when coming onto the pit straight at Silverstone at 6500 rpm resulting in a couple of clipped valves and very lucky not to have much more extensive damage. ISTR the head rebuild was about 1600 quid or so, so not a huge bill disaster in the great scheme of things as its at 170K+ miles now and still on the original bottom end.
Thom said:
It may probably remain an anecdotical issue but when it happens to you it would not make sense not to mention it. If you are lucky you are not going to bend any valve, but I maintain that replacing valve springs preventively at 120k miles is safer/cheaper than waiting for one to break and cause damage potentially expensive enough to justify moving the car into the scrapyard.
If I were now to maximise safety in the context of purchasing an S2 with more than 120k proven miles with an unclear service history I would probably budget for a full top end refresh including replacing the headgasket, valve guides, tensioner pads and valve springs.
Indeed, and in an ideal world we'll have a bare metal respray once the shell has been dipped, new shocks, springs and dampers and new bushes and bearings everywhere. And, while we're at it, let's re-trim the interior and invest in some new carpets. If I were now to maximise safety in the context of purchasing an S2 with more than 120k proven miles with an unclear service history I would probably budget for a full top end refresh including replacing the headgasket, valve guides, tensioner pads and valve springs.
You are, of course, right. But pragmatically, I don't believe the risk outweighs the cost of the repair if it all goes bang - certainly not if you are paying for labour. I do my spannering myself, and even then I'm not sure it's worth it. (I'm aware that I may live to regret these words.)
Out of curiosity, what is the significance of "an unclear service history" in terms of valve spring breakage? I'd have thought that the likelihood that a valve spring will break isn't related to service history, it's a matter of time and cycles.
Neil - thanks, yours was one of the (three) examples I was thinking about.
OLi.
Gassing Station | Front Engined Porsches | Top of Page | What's New | My Stuff