Coolant pressure to high

Bramdeman · Post by **Bramdeman** » 05 Jun 2006, 07:26

Hi all i've got a pretty big problem with my '98 v70 turbo, its got too much pressure on the cooling system, the hoses get rock hard after it heats up and when its hot or after shutting it off coolant squirts out the filler cap. There is no oil in coolant or visa versa, its starts and runs perfectly without smoke, the heater works fine and (according to the gauge anyway) it doesn't overheat. The radiator fan kicks in just before the boiling point and the radiator doesn't seem to be getting too hot.

I removed the thermostat for testing sake but it doesn't make any difference apart from that the engine takes longer to heat up.

three options as i see it.
1Headgasket but it runs and starts so well...
2radiator but the coolant looks fine and the ingoing hose is hotter than the outgoing
3waterpump not pumping enough water due to worn blades, i just doubt that all together

anybody got any better ideas or explanations?

gtg737m · Post by **gtg737m** » 05 Jun 2006, 13:22

I would change the cap from the antifreeze container. That cap has a valve that opens when it reaches a certain pressure. I had a similar problem with my car and I bought that cap like for $24 at a Volvo dealer.

Bramdeman · Post by **Bramdeman** » 05 Jun 2006, 14:57

Thanks for the reply, that is what i thought at first but the hoses aren't supposed to get this hard, i'm suprised the cap will hold that much pressure. Also i'm worried about the heater core and the radiator bursting

Post by **MadeInJapan** » 05 Jun 2006, 22:27

Test your coolant. For it to get that hot to build up pressure that much I would suspect it's not doing its job properly. You can get the little testers at any autoparts store that you suck up the coolant into and it reads how well it's cooling. Also, you mentioned taking your thermostat out but it didn't do any good except take the coolant longer to heat up?? Maybe I'm missing something here but what exactly did you do with your thermostat? Could be part of your issue.

Bramdeman · Post by **Bramdeman** » 06 Jun 2006, 14:28

I took out the thermostat to see if it was faulty, perhaps not opening enough but it made no difference in max temperature.

i'm pretty sure its the headgasket, i had a look at the sparks and #2 is burning a lot hotter than the rest... damn...

Anyway i ordered a block tester to see if there is CO in the coolant and i suspect there is. If so the head is coming off. If it was anybody elses car i would have had the head off already but i treat this car so well, a burnt valve i could understand but a headgasket... go figure...

I''ll let you know and thanks for the help

Post by **robert213** » 06 Jun 2006, 15:26

Bramdeman wrote:i'm pretty sure its the headgasket

You could do a cooling system leakdown test, too.

Bramdeman · Post by **Bramdeman** » 07 Jun 2006, 13:40

Well i did the co test with a tool from Midlock, pretty sturdy thing bytheway and works like a charm, i can recommend it. Anyway it came out negative, no CO in the coolant

I flushed out the coolant and replaced it but still no go. I geuss its waterpump time tommorow and if that doesn't help i'm taking the head off regardless, i still don't like the way that #2 spark looks.

unless anybody has any other ideas...

Post by **MadeInJapan** » 07 Jun 2006, 21:57

You can try AutoRx treatment and see if it makes a difference before you go tearing apart your engine....just a thought and it could help.

Post by **pfeener** » 08 Jun 2006, 05:03

Why not run a compression test. If that cylinder is low it will cause the plug to burn differently (and it's quick and easy to do).

Bramdeman · Post by **Bramdeman** » 17 Jun 2006, 05:35

I dont like additives even though they might work in this case, but it wil just pospone the problem.

A compression test wont really tell me much apart from a slight variation in the cilinders wich i'm sure it will have, the engine has about 300000km's under its belt so a little wear and tear will be normal. It still runs fine on all 5 cilinders so it wont have a major loss of compression.

Anyway i took out the waterpump and it looks like it was hardly even used but replaced it anyway. No difference as expected.

After a few people recommended that i do a leaktest on the coolingsystem i went ahead and did one even though i hate to do it becouse other things like the heater matrix might burst in the proces. The reservoir cap has an overpressure valve that open at 1,5bar and it has opened a few times so i figured testing it at 1,3bar would be safe. I left it like that and 2 hours later the pistons were still dry but my radiator was leaking from the side. *sigh* So i ordered a new radiator and replaced the damn thing (PITA job bytheway) I had faint hopes that maybe my radiator wasn't cooling enough and a new one might solve the problem but alas no difference.

So a lot of money and time later it hasn't gotten any better and i'm going to replace the headgasket after all.

Bram