Precautionary head gasket changing?

[robwright]

I have worked in engineering for the last 22 years both in the Army and now in the rail industry so when you talk about planned maintenance then I think I know my onions. Funny how planned, timely maintenance can keep a Bedford MJ running for 40 years or an 08 shunt engine (08934) in my particular case running for over 50 years (and that has white metal bearings in the axle box!!!). We do it in our work but rarely pay any regard to it with our cars!!!

 

[Copperman05]

Not wanting to play devils advocate but I'll always take a garages opinion that my HG must be changed ASAP with a pinch a salt no matter what anyone says. All respect to baz for sharing his findings but I've not seen a recent increase in blown HG in this or any other 944 forum over recent months/years.

Having said that a precautionary look into how your HG is holding up after 20+ yrs years does seem advisory...

Edd

 

[Lowtimer]

ORIGINAL: Copperman05
Having said that a precautionary look into how your HG is holding up after 20+ yrs years does seem advisory...

Which means changing it, surely?

You wouldn't seriously go to all the labour of stripping the head off to inspect a 25 year old gasket, and then leave it there, would you??

Edited to say, ok, in your case only 22 years old... []

 

[zcacogp]

I don't want to fan the flames of disagreement here, but have to say that head gasket failure of the type described by Baz was something I had never heard of before Baz's thread. Baz most certainly knows more about 944's than most, and I don't doubt that what he says is true, but the incidence of failure must be pretty small if it hasn't been heared of on here before.

Given such a small incidence of failure, I am surprised at the fact that we now have people worrying about the state of their own gaskets, and worrying whether their gasket will 'make it through to another belt change'.

Famous last words, and I am quite happy to be ridiculed on here for saying so, but I drive my S2 everyday, about 15000 miles a year, and don't intend to totally strip the engine on the precaution that the head gasket may be going rotten, purely based on an internet thread. I apprecate that the fact that it is running fine is no indication that the gasket is OK, and I also understand the risk of bore scoring should the engine overheat as a result of gasket failure.

I'd say this is different to the belt changing issue; cam and balance belts do age and there are well-documented failures of engine damage due to failure. People on here have experience that failure, and the incidence is much higher when maintenance schedules are stretched. The cost of replacement is (comparatively) low and the job much easier than a head-off gasket change.


Oli.

 

[Copperman05]

ORIGINAL: Lowtimer

ORIGINAL: Copperman05
Having said that a precautionary look into how your HG is holding up after 20+ yrs years does seem advisory...

Which means changing it, surely?

You wouldn't seriously go to all the labour of stripping the head off to inspect a 25 year old gasket, and then leave it there, would you??

I meant a check through testing oil or coolant as discussed earlier, not a physical head off inspection.

HG changes cost a lot, usually £1000+ IIR, If the 10-12 year life of the HG as put forward by Baz were true then you would think we would all have experienced a failure by now, however most of us have not...

Edd

 

[Suffolk944]

ORIGINAL: homesea

Jon what head gasket did you go for?  (ie standard or after market, wildfire etc)

I believe a Wildfire is going on - needs a strong one for the extra POWER that will soon be surging through the engine...[8D]

 

[Suffolk944]

ORIGINAL: zcacogp

I don't want to fan the flames of disagreement here...
Oli.

Yeah right [][]

 

[pauljmcnulty]

If the 10-12 year life of the HG as put forward by Baz were true then you would think we would all have experienced a failure by now, however most of us have not

I read Baz's post differently, I might go back and start again as I've obviously misunderstood it.

I got the impression he was suggesting that a HG might be causing internal damage long before it showed signs of major failure? As such, it's cheaper to change it after 20 years than rebuild the engine.

Total failure in NA cars isn't common, but those that are having it changed for whatever reason are showing signs of being very rotten. I guess it's down to whether you feel that an aged HG is doing any harm or not.

 

[zcacogp]

ORIGINAL: Suffolk944

ORIGINAL: zcacogp
I don't want to fan the flames of disagreement here...

Yeah right [][]

Erm, well, point taken! []

(But it doesn't involve the superiority of the S2 over the turbo, so it's not a usual point of disagreement for me ... )


Oli.

 

[Copperman05]

ORIGINAL: pauljmcnulty


I read Baz's post differently, I might go back and start again as I've obviously misunderstood it.

I got the impression he was suggesting that a HG might be causing internal damage long before it showed signs of major failure? As such, it's cheaper to change it after 20 years than rebuild the engine.

[/quote]
Referring to the HG for 944 2.7, S2 and 968 Baz said.

In my experience - 10 to 12 years is the safe maximum for this head gasket

Seems pretty clear to me.

Edd

 

[zcacogp]

ORIGINAL: pauljmcnulty

If the 10-12 year life of the HG as put forward by Baz were true then you would think we would all have experienced a failure by now, however most of us have not

I read Baz's post differently, I might go back and start again as I've obviously misunderstood it.

I got the impression he was suggesting that a HG might be causing internal damage long before it showed signs of major failure? As such, it's cheaper to change it after 20 years than rebuild the engine.

Total failure in NA cars isn't common, but those that are having it changed for whatever reason are showing signs of being very rotten. I guess it's down to whether you feel that an aged HG is doing any harm or not.

I think the point is that an aged HG is not doing any harm in day to day use. The issue is that the rotten HG causes the cooling of the rear cylinder to deterioraite. This isn't a problem; there remains enough cooling, but under constant heavy load (hot track day in the middle of summer, for instance), things can get hot and cause a stuck piston.

This clearly is only a problem if two circumstances happen:

1. HG is rotten in the critical area. (And this is one particular area, not simply that the HG is generally 'rotten')
2. The car is driven hard, for a long time, on a hot day.

If these two don't occur at the same time, there will be no problem and no damage.

How many S2 owners on here have had this problem? Or even seen a car with this problem? To the best of my knowledge, none. I'm not saying that these things don't happen - they clearly do, as Baz has described. But I suspect the incidence of the problem is not high. And, as such, £1000+ (and probably a chunk more) to change the HG as a precaution is quite a high premium to pay to insure against an unlikely problem.


Oli.

 

[Lowtimer]

Doesn't cost anything like that if you have it done as the same time as a belt change, though, which is the smart time to do it.

 

[chrisg]

Boys a lot heated arguments for and against.

Statement of fact, the 'youngest' 944 out there is 19yrs old, mine is 22yrs old. I therefore take the approach, if it will rot/ corrode, bend or break = gasket, steel pipe, rubber hose, seal or bush it needs replacing.

As hinted at, if you look after these Porsches they will go on for years - if in doubt replace it, if only for peace of mind....

I've been meaning to do the rear fuel and brake lines under the axle for years having simply slapped cura rust on to keep it at bay.

Tell you what, having removed the 2 x rear fuel lines, I was gob smacked at how thin and rusty they both were, in particular the return line - so for the sake of a few hundred quid and my time, I've now ensured that the rear of the car won't barbeque itself when a rusty steel fuel line let's go.....

Similar argument for a HG, cam or balance belt and the chain and slipper on the 16v heads...

If you want a cheap performance car go buy a 10yr old beemer or jap mobile !

 

[sawood12]

No-one can argue against the common sense approach of preventative and pro-active maintenance, however in the real world people need to be pragmatic. A cylinder head gasket job is expensive and you might find something else while you're in there e.g. the need for head skimming or even scored bores, which ramps up the cost of the job even more. Sometimes ignorance is bliss and an "If it aint broke, don't fix it" attitude pays off. In the vast majority of cases HG failures are benign and you get plenty of notice that it has given way (coolant loss, oil contamination in the coolant or vica versa) so you may as well drive them till they show signs of failure, unless you're in there doing another job.

I don't think HG rotting is a new issue (it is most likely to be pretty common i'd bet), I've read about it before, and clearly if there is debris floating about in the coolant then a blockage is a risk - however how much of a risk? It feels like it is quite a rare thing on the basis there are many thousands of 944's out there that are used and abused. There has been a few reports of people's turbo's releasing material down the intake leading to scored bores but people don't really consider rebuilding or replacing turbo's until they start showing signs of being tired. I guess in an ideal world you'd completely strip down every part of the engine and refurbish and rebuild, but that is not an option for the majority of people. It is a case of you make a choice and take a risk and if you're unlucky you might come unstuck, the the chances are you will be lucky.

 

[bertelli_1]

Certainly popping to the shops is unlikely to cause a problem. The gasket does not have to rot 'in a critical area', it is the general deteriation of the material, which as it fails, allows coolant to flow freely between the head and block before it reaches cylinder 4. I have seen a lot of rotten gaskets & suspect the problem appears worse on the s2 due to the piston clearance & lack of taper. I have on doubt there are a lot of cars out there with a very rotten gasket (certainly more than the quantity of owners who use this forum, who's problems we never hear about) but they may never fail to the point of the owner noticing - in fact when they fail they are more likely to leak some oil than cause the issues we normally associate with a HG failure.

 

[zcacogp]

Chris,

I think the debate isn't whether this is a good idea or not; it is. It's whether it is worth spending the money on given the likelihood of failure.

If you are 95% of the way to getting the head off already, it's probably worth changing the gasket.

If (as I do) you have a car which is working fine, showing no signs of problems, a bill into four figures to eliminate a possible future problem, that has a low likelihood of occurring and which would (at worst case scenario) produce a bill of £2000*, it's not worth doing.

Putting it another way, the cost of insurance is based on the size of the possible damages multiplied by the likelihood of the damages occurring. In this case, the premium is too high for the damages being insured against (if that made sense).


Oli.

* - How much is a good second-hand S2 engine? £1500? Plus the cost of fitting - another £500, perhaps?

ETA: How do head gaskets go rotten anyway? I've never seen one made of a material that I would think would rot. Are we talking about rust, or cardboard going soggy? And Ant, I slightly disagree. My understanding of the situation is that the problem is caused by the HG giving up, allowing coolant passage between two areas which should be sealed from each other. Therefore, it does have to be a HG which has gone rotten in a particular area ...

 

[jasonp]

have to agree with oli.edd and scotty, my specialist when i mentioned the to do or not to do the head gasket also said he as never come across this sort of failure but with the benefit of hindsight, i would have changed the head gasket when i had my belts changed and the large amount of work on the engine completed just over 13months ago,if i still own her in 3 years or 38,000miles, i will get the head gasket done then, i hope we have not tempted fate by our talk of non-failures[] cheers jason p

 

[zcacogp]

This is a specialist failure; we aren't talking about general HG failure here. So experiences with other cars won't apply.

I am, from Baz's post, convinced that this is a problem with 944's (esp. S2's) and 968's. Baz is a genius with all things Porsche, and what he says is ALWAYS worth listening to.

What I am not so convinced about is that it is enough of a problem to warrant precautionary changes. Experience will probably prove me wrong, and you can all expect there to be a four-person thread on here within the next month, called something like "Overheating S2's?", started by me with Edd, Sc0tty and jasonp all coming along to recount identical symptoms.

(If anyone wants to stockpile 4 S2 engines, it wouldn't be a bad idea. There will be a sudden spike in demand soon, no doubt .... )


Oli.

 

[bertelli_1]

here is a pic of a typical (from my s2 infact) HG, this had not 'failed' but shows the holes where there used to be gasket material. The coolant should flow from right to left below the gasket (in the block), then travel up through the gasket next to cylinder 4, then left to right above the gasket (in the head). With these large holes the coolant can flow from head to block completely bypassing the rear cylinders.

 

[scam75]

Well after mulling this over for a few weeks I called my specialist in Glasgow today (no, not Alasdair, he's in Bonnybridge!). He is very knowledgeable about 944 engines and told me that as much as he would love to take my money I shouldn't bother. He says the gasket WILL go at some point as they can and do rot (he also mentioned incorrect anti freeze can accelerate said rot) and at the point the gasket goes he says I should park it up and call the AA and arrange for the head to come off then.

He says as long as I notice the temp rising, stop and don't cook it all should be fine. If it's not I can get a block for a couple of hundred quid and probably be no worse off than with the "precautionary" HG change. In fact I will buy the spare block Alasdair has just now and that will be my insurance!

He mentioned the possible can of worms getting opened, head pitted slightly, needing skimmed, altering compression which is not advisable for a turbo, not to mention many other things that may need attended to once in there.

Use it regularly and if it ain't broke don't fix it. Be aware of the standard tell tale HG failure signs and keep an eye on irregular temp readings. It might go tomorrow, it might go in ten years.

I am not in the habit of caning my car although it does get reminders when road conditions permit, I don't do track days, and therefore I will not be changing my HG as a precaution.

The specialist in question has 30 years experience with all things Porsche.

Now I ain't discounting a thing Baz says, in fact I believe it 100%. It's simply the risk/reward equation and I favour Oli's train of thought after weighing up my options.

Stuart