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Discussion Starter · #1 ·
Should the radiator expansion tank have a rubber seal under the pressure cap.

The reason I ask is that my 2.3T gets through a bit of coolant - from about max to "check radiator" in about 2 weeks of driving (1200 miles). I've checked all the obvious things - no excessive steam, no obvious smell on the exhuast, no water in the oil, no obvious oil in the water, no red/orange coloured coolant, no damp smell in the car, no water under the car. Also if I dont use it then the water level doesn't seem to drop.

Steve
 

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If it does not seep out from the expansion tank cap (when engine hot), then I am afraid your car is showing signs of head gasket failure. Just to be sure, swap your cap with another known good one or a new one and then monitor the situation. If problem persists, head gasket has called it a day!
 

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Discussion Starter · #3 ·
hmm was hoping not to hear that... but should it have a seal under it (its a K reg). My H reg did but my P reg seems not to which is what is confusing me.

Having seen engines with coolant systems without a direct leak but basically running unpressurised loose about a pint a day due to evaporation I was just hoping it was not going to be somethign expensive.

Steve
 

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Steve,

Here's a pic from the underside of my expansion cap, circa 1993. The 1992 one I had was the same. Apart from the seal, you can also see the overpressure relief valve assembly. The seal itself is an integral part of the cap, and it's difficult to see how you could be missing it and not the pressure relief valve, as you will see from the pic...

 

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Discussion Starter · #5 ·
On my H reg there was a separate rubber gasket that went between the bottom platic flange of the cap and the top of the tank. On the K reg the cap does not tighten down to the top of the tank leaving a gap..

I shall swap the cap with my P reg this morning - once I can brave the cold

[Updated] Couldn't swap the cap as the bonnet on my P reg is frozen shut.

However got to work and opened the bonnet to look for any leaks and steam was coming from the back of the engine (under the injectors/inlet manifold) so it may just be a shot pipe

Steve
 

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Originally posted by mutungi:
[qb]If it does not seep out from the expansion tank cap (when engine hot), then I am afraid your car is showing signs of head gasket failure.[/qb][/b]
Are you saying that water leaking out of the expansion tank via the cap when the engine is hot isn't a symptom of H/gasket failure?
 

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I think what was meant was that if coolant is disappearing and it isn't leaking out anywhere, then by elimination it must be leaking either into the oil system or the cylinders, via a faulty headgasket.

It is also true that failing head gaskets can cause the coolant system to become over-pressurized and can force the caps to vent or cause other leaks.
 

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Originally posted by John Carlyle-Clarke:
[qb]I think what was meant was that if coolant is disappearing and it isn't leaking out anywhere, then by elimination it must be leaking either into the oil system or the cylinders, via a faulty headgasket.[/qb][/b]
Thanks for the explanation, currently have problems with a leaking expansion tank cap, as listed in Arrgh Help!! thread, hence the interest!

Didn't mean to question mutungi, just read the post wrong
 

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Discussion Starter · #9 ·
Changed the caps this morning - put the yellow cap from the P reg on. Topped up the coolant.. got into work and checked it all - no coolant on tank, level stil just under MAX, no steam coming from rear of engine. Am starting to wonder if the valve on the black cap is stuck and its over pressurising. Guess I'll have to wait a couple of days and see if the level drops again.

Steve
 

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Discussion Starter · #10 ·
Ok its still getting through an expansion tank full every couple of days so I guess its time to visit the garage and get them to check it out.

As the engine has done 100K and has had no major work done on it is there anything else worth doing at the same time if the head has to come off?

Steve
 

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If you plan to keep it for some time, then I'd also take a good look at the condition of the timing chain.

[edit] Forgot to say you could take a look at the spark plugs to see if there's any variation between their condition which would indicate signs of gasket failure. Also is there any oil floating on top of the coolant in the expansion tank. Else it could be your heater matrix. Do you suffer from excessive misting?
 

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Discussion Starter · #12 ·
Nope - no misting, in fact with the a/c in auto the car gets very dry.

No oil in header tank - have dipped my finger in and it cam out clean.

Spark plugs look OK and the engine is totally smooth and steady (since I gave it an extreme dose of injector cleaner!).

Car starts fine - no steam for about a minute then it steams for a couple then stops steaming.. in fact sitting in traffic jams on the way out of town I seem to be the only car NOT steaming like the Flying Scotsman.

Have dropped it off at the garage for them to do an investigation. If it is the head then I'll get them to check the chains at the same time (although there is not a hint of rattle from them). The garage says that they have had no problems doing 9000 head gaskets - apart from getting the parts: so if anyone can recommend a good supplier of decent saab parts then I would be grateful.

Steve
 

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Discussion Starter · #13 ·
Fixed!!!

The local garage pressurised it and found there was a leak under the inlet manifold (where I had seen the steam coming from). They put it up on the ramp and found that the clips holding the rear hoses on were not actually tightened up.

A quick check in all my paper work shows that Oxford Saab changed this hose... so a pox on them

Total cost for the pressure check, tighten up, antifreeze top up, check for back pressure etc was just under £50 inc vat.

Steve
 

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Discussion Starter · #15 ·
Yes it certainly is and its money thats going to be spent on the service next week (would much rather spend it on a new sony head unit - the existing one does not have RDS)

I have asked them to check the autobox and from experience they find things like worn suspension bushes on their services (which feel like they may be a bit spongy)
 
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