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Discussion Starter · #1 ·
Hi,

I have a Saab 9-5 2.3t with 125000kms

I had the check engine light come on afew weeks ago and the temp needle dropped to 0 so as suspected when the code was read it indicated i needed to change the sensor. i haven't gotten around to doing it yet as ive been away with work etc but it was intermittent and the gauge was indicating normal when working.

I also recently tightened the bolts on the head due to the fact i could see a oil leak from the gasket at the front of the gasket. and also oil seemed to be coming out of the filler cap- it does not have the updated PVC ( was going to be done in about a weeks time) tightening the bolts stopped the leak from the gasket but not the oil around the filler cap.

I was going to do a radiator flush at the same time and refill, because there doesn't seem to be much coolant in the bottle - mostly water ( its never used much water at all or oil)

anyway today after about an hrs driving the Temp gauge was slight above the center and not rising. at the light while waiting for a red steam started from under the bonnet. it got worse quite rapidly so it turned her off. at that point i heard a bang and steam was everywhere. we pushed the car to a parking spot and i checked the damage.

turned out the bang was the plastic cover on the left side of the radiator blowing off - exposing the honeycomb on the side.

can't see a leak from anywhere else and once it cooled i started it and drove around the corner to my place- no steam.

the water that is left in the bottle is now a rusty colour.

hose seem intact

i'm guessing ill need a new radiator, but i'm wondering if sludge or poor breathing will cause it to heat up to that point or am i looking for a block somewhere in the cooling system.

would anything else like - a blown head gasket, heater bypass valve, thermostat?

thanks in advance
Sam
 

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I suspect you are in for a head gasket replacement, the rad probably exploded because the system over pressured caused by the bad head gasket.

I recommend pressure testing the system but that's going to be impossible until you replace the radiator.
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A compression test might tell us if the headgasket has failed.


It would be possible to plug the ends of the two rad hoses, but the overflow tank is connected to the rad, so there's no way to pressurize the cooling system.
 

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Discussion Starter · #4 ·
I'm up for a new radiator anyway so that'll be the first thing i do, can you just buy the end caps and replace them?

i thought it was a bad sensor for the temp gauge but after abit more reading i'm thinking it might be a bad thermostat. there has been the occasional time where after a drive its idled quite high. possible its been abit sticky and on this occasion was stuck closed? was driving for about 30mins on the motorway before she blew. I'll replace both the thermostat and the sensor because one of them is defiantly not working properly.

I tightening the bolts awhile ago to stop a leak which worked, the leaks hasn't come back but last night took the ignition coil out and there was abit of oil inside, also no sign of leaking coolant around the heater bypass valve - all from the radiator.

the pressure bottle, now empty, has a brown residue in it but its more rust like than oil like. also no sign of water or coolant in the oil cap.

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The end caps are not designed to be replaceable. You want to buy a good radiator, new or used.


If the head gasket is bad, either because of overheating, or causing overheating, would you fix the car?



Also a bad head gasket can damage your new radiator, or blow out some hoses. That is why I would do a compression test before going any further.
 

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Get the coolant that remains tested for combustion by products. There are kits do to it, that'll tell you if the engine is putting pressure from combustion into the cooling system. This will pressurize the cooling system and cause one thing after another to fail.

A compression test may help determine if you have a head gasket failure but may not. I had an engine with a leak between the combustion chamber and the water jacket and it had good/consistent compression. It would idle and run great with no issues. But as soon as it boosted there was excess pressure in the cooling system. blew a hose, coolant bypass valve and then the radiator. Fix one thing and then the next weak item in the system will fail.

The best thing to do is to fix the radiator and then pressurize the system (~8PSI or so) and see if you find leaks. take the plugs out and listen to hear if any air is going into the cylinders. Then crank the engine to see if coolant comes out of the spark plug holes. (and then start it to see if there is a lot of steam from burning the coolant in the cylinders)

But as was mentioned by bob3000 I suspect you have a head gasket replacement in your future. To get it done in the US you're looking at $1500 or so. Parts are probably $200-$400 depending if you have to get the head planed if you do the job yourself.
 

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Radiators with plastic end caps blow. Or they leak.....they are short term items.

I have replaced over 8 in 9-5s. Sometiemes they just blow like yours, oter times they leak.

Long term fix is an all- aluminum raidator. I love mine.

I see a lot of over thinking here. Replace it with a Nissens and keep driving with nice new fluid.

99% chancee no more problems.
 
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