Valve spring failure S2

[robsangster]

Full story to follow - but for all of you busy doing summer tinkering, LED upgrades, TLC etc etc...... before you do anything else, check your valve springs! Only 5,000miles before the outer spring failed on this car it was treated to a FULL service inc, all belts, water pump, tensioners and rollers, cam chain, slipper pad (both pads) and new hardwear and rubber/gaskets were appropriate.
Several - coughs and splutters were the first indication of anything wrong when cold .... but these soon past - and just as a precaution the distributor, rotor and leads were changed (while we are here the car only ever had genuine OPC supplied parts).... all seemed ok...... until BANG

I will put more up on this thread soon - but broken cam belt is not the only way to loose the heart of your beast - trust me - the attached pic is from my car. It has created a real mess and on removing the head I have discovered that ANOTHER outer spring was also broken - but had not yet manifested further.

Car (was) a 1991 S2 Cab with 90,000 genuine miles, full history from AFN and the best Indies in later life, no fewer than 4 cam belt services, all MOTs and servicing above and beyond Porsche's recommended schedule...... and still this!

If your S2 ever so much as misses a beat - get that cam cover off and run your finger over those springs!!!!!!
I now have the task of sourcing a replacement motor (have been for a while now) - that is already proving to be an utter mine field - amazing how every second hand unit has less than 100,000 miles - but sadly no history to back that up.

Like I said more pics to follow later some time - but yes the piston was PUNCTURED too!!

 

[xenon]

[] Unlucky. It's a good point about the springs.

 

[zcacogp]

Not pretty. Sorry to hear your story.

How do you check the springs without taking them out? Run your finger over them ... ?


Oli.

 

[robsangster]

Yep - normal will have ZERO movement and be effectively rock solid - if it moves/rattles/jangles etc - its fractured/broken.
On mine both the outer springs were broken - inners were fine. Its not symptom free to my knowledge - you will have noticed a running issue - but believe me it was subtle to begin with. Possibly just one of those things but both were inlet valve springs.

 

[sawood12]

Bad luck matey, first time i've heard of this. However, I doubt the time between the spring failing and catastrophic damage being done is very long so it is probably pointless to check, however i'd never tell anyone not if it gives them a bit of piece of mind. You'd have to be extremely lucky to happen to find a spring that had failed before any internal damage has been done. Unfortunately it is probably one of those things where you have to ride your luck. I don't think this is a particularly common thing on any 944 model, i've certainly never heard of it before so looks like this is one of those unlucky one-offs.

I think the only thing anyone can do is if their engines suddenly starts to make any unusual sounds, don't continue to run while you try to figure out what the problem might be, shut off the engine and get the car towed somewhere where a proper diagnosis can be made. I've read a few stories of people driving for many miles listening to some strange sound trying to suss out what the problem is only to have their engine chew itself apart from the inside out and they end up by the side of the road leaving a trail of chunks of engine behind them.

 

[tref]

I guess it is the kind of thing it does no harm to look out for when the cam cover is off anyway for cam-chain/slipper inspection for example.

With regards how long it could run without causing damage... I wonder if that might be rev-related in this case. The inner spring may-well be strong enough to close the valve before the piston comes up to meet it at low revs, so only after a given time at higher revs might valve/piston impact do damage. Of course, if the broken ends were to interlace, then I would expect follower/camshaft/head damage before piston/valve damage.

 

[garthcatkinson]

Very interesting. I was considering posting about this myself not that long ago. I've now had 2 Valve springs go on my S2 (91). The first happened on the way home from an OPC after a full service in Apr 2000 with 54k on the clock. Car suddenly started to sound like a tractor/diesel - at first I thought the Cam belt had gone but turned out to be a valve spring on No 4 cylinder (not sure if in/out). Engine stripped thankfully no major damage, head skimmed and put back together. Then in March this year the car started sounding a bit rough/hesitant, but did not sound serious as I had just driven from north of Glasgow to Portsmouth for work. Checked the plugs and found a lot of oil around the plug recesses (mild panic). Changed plugs and cleaned up checking Oil/water for any cross contamination etc. Car started but still idled/ran rough. Subsequently replaced the Rotor/dist Cap and plug leads (Thanks to Bert) but no joy, all the time continuing to drive her quite cautiously (no comment on my stupidity please). The car then did another long distance dash back home to Scotland as it was due a service and MOT, some 4 weeks after problem occurred. My local/trusted mechanic found a faulty injector which he replaced (at big expense as it turned out my S2 was one of the very last and had different injectors from earlier S2s!!!). However, problem persisted and it turned out that another spring had gone, although about 9/10ths of spring intact so still functioned to an extent. Again on inspection no major engine damage despite over 1000 miles, including the Helensburgh - Portsmouth - Helensburgh round trip. Car has been running fine although not driven for the last couple of months as I have been away with work and SORN'd her.

Must be the luck of the Irish as I did not suffer the same fate as Robs car.

 

[tref]

Garth, I have to ask... do you, or did you with the problem, chase it up to the red-line, or do you change up earlier than that?

Some-one will have gotten away with it and blow my theory out of the water... but interested to hear experiences in that respect. I have heard of S2 valve spring problems, and now I cannot remember which, but I thought it was the inner causing a problem generally from a well respected independant.

 

[garthcatkinson]

Tref - Intially I thought it might be dirty injectors so red lined her a few times with fuel cleaner to see if that helped. She seemed to run alright but coarse and with a little hesitancy. She still gave 31 MPG on the motorway dash sitting at 80ish so I did not initially suspect anything too serious as the symptoms were very different from the first spring failure when the car was undrivable.

 

[evoboy69]

Great... another potential thing to worry about!!

These cars are great but the more I learn, the more I find them a little fragile...[]

 

[sawood12]

Don't fall into that trap. It's like the modern Porsche RMS thing where everyone think its common but in actual fact it affects a small % of cars - you just get to hear about almost every case where it does go wrong. There are plenty of S2's out there with over 200k miles on the clock with no such issues so though this may be an issue, it is probably very rare and is probably caused by a freak coming together of a number of contributory aspects that just happen to coincide on a small % of cars. Like I said earlier- in about 6 yrs on this forum and keeping an eye on others i've never got a feeling that there is a fundamental issue with the springs. If it was a big problem you'd have heard about it long before now. Having said that the original posters car is a low milage car, and Garths sounds like it is a low mileage car. Maybe this is one of those things where cars that are used regularly avoid such issues?

 

[zcacogp]

It's an interesting one, for sure. I have heard of this before, on the S2, but thought it was an isolated case. Now we have two more examples ... Garth, a Q. When you had the first spring break, did you have ALL of the springs replaced or just the broken one? i.e. What was the age of the second one that broke - had it been in since the car was new, or since the first one broke?

(My state of mine is similar to that of evoboy's. And not helped by the fact that I'm not sure my S2 was quite as smooth as it usually is when I drove it into work this morning. And it is due to go up to North Wales next week, on hols. [] )


Oli.

 

[garthcatkinson]

Scott - Tend to agree with your thoughts. My car now has about 106k miles on the clock, but these miles have been racked up in fits and starts during my tenure. The car was first reg in Jun 92 and I bought her in Apr 96 with 19k on the clock. I am in the Royal Navy so have spent quite a bit of time away with the car garaged/idle long for periods, although the last few years saw her used on a daily commute of only about 14 miles round trip and when she did get a leg stretch it was normally quite spirited. or a long motorway run from Scotland to Portsmouth. I guess my bad luck with the springs stems from this infrequent use over the years, just fortunate none were catastrophic.

 

[garthcatkinson]

Oli - Only the individual broken springs replaced each time. The first in 2000 at 54k miles and the second this year at 106k, so the first at 9 yrs and second at 18 yrs.

 

[robsangster]

Sorry been slow on updating this one - been manic - I will do in due course - but thought you might like to see the piston - note 'its punctured'!! Right old mess, only a camera phone pic so bore damage not too visible - but its there!

For those of you who think this problem is super rare.... both Northway and Hartec assured me that valve spring failure can be quite common between 90-140,000 miles... as ive never had cars with this mileage before it was a first - and clearly I was unlucky given the comparative lower end mileage I had. Everyone is always going to have different opinions on this - and lets face it most 3.2 owners budget for top end rebuilds - generally before the 100k mark, but when I finally manage to locate an engine im happy with - I will be doing the springs and associated other bits - just to be on the safe side!!

Clearly it wasnt a nice place in here when that valve dropped in!

 

[Diver944]

Yikes! []

I never realised the crown of the piston was that thin.

 

[ChasR]

EDIT: Just read your block is scored, nevermind.

Either way, good luck finding another engine. If you happen to in the unlikely event come across two decentish S2 engines let me know .