Other S80 Problem: S80 2001 Pressure in coolant when stuck in traffic

[maven05]

I've read this forum and many others but could not find a solution to my problem.

If any Volvo mechanics who might of seen or came across this problem could help that would be awesome.

Problem: Pressure builds up in the coolant system when I drive in hot weather mainly when driving from traffic light to traffic light (or in traffic).

How I know it: I get message that Coolant is low on the dashboard. I let some air out by slightly opening the cap.

What I did: Changed thermostat and engine coolant sensor, changed fan also (it was used fan but in working condition).

I drove about 400km on the straight road (drove to another city) and had no problems at all with pressure.

I think i get pressure in the coolant because the fan doesn't turn on when it should. Even in hot weather when i turn off the engine and it is HOT the fan does not turn on. The interesting part is when I unplug the engine temperature sensor the fan starts to rotate and the temperature gauge drops on the dashboard. When I see the board computer to reset itself and the temperature gauge goes to the middle the fan stops working and few minutes later I get a message that the coolant low because of the pressure.
Almost every mechanic I talked to in Tallinn (Estonia) told me that I have blown head gasket but would not my hoses explode when I drove 400km because there would be constant pressure?

I really want to figure out what is the problem here.
Any help would be greatly appreciated.

Max

[SonyVaio]

On initial read through I had in my head the causes could be either:

Head Gasket
Air lock in coolant system
Thermostat
Temp Sensor

If it was head gasket I'm sure ANY garage would be able to conduct the sniff test to tell you straight away, tests for exhaust fumes in the coolant. So perhaps we can put this to the side just now but for complete piece of mind you might want to have this test done. Over here most garages don't even charge as it is such a quick simple test.

Air lock, you could have an airlock in the cooling system. This would cause some of your symptoms but not the fan not running on problem.

Thermostat, if this is not working correctly then it will not allow coolant to flow round the engine correctly and can cause the head gasket to split. Did you replace with a new item??

Temp Sensor, again was this a new item or 2nd hand?

Can you put up the specs of your vehicle, I've got it is a 2001 S8 but what engine (engine code if possible).

A complete guess just now (if your head gasket has not gone) would be your temperature sensor itself.

[mikealder]

Get a dye kit that you can put in the coolant bottle then run the engine, if there is exhaust gas getting in to the coolant the dye will change colour which would indicate a head gasket/ cracked head/ block issue - If it stays the same then you know the engine is healthy.

Coolant needs the pressure to prevent the coolant from boiling, the normal temperature for the coolant in these engines is above the boiling point for water. The fan should kick in when it reaches around 106 DegC at slow speed, if the temperature gets up to 115 DegC the fan goes to high speed, at 117 DegC the temp gauge will move above the three o'clock position.

Are you sure the new thermostat is installed the right way around and sat in the rubber seal ring rather than just resting on top of it? - Mike

[maven05]

Hey! Thanks for your input.

Originally Posted by SonyVaio

Air lock, you could have an airlock in the cooling system. This would cause some of your symptoms but not the fan not running on problem.

I do not think it's an air lock because I can the car in idle with reservoir cap off for a while to let any air out. (read it somewhere that it helped one guy)

Originally Posted by SonyVaio

Thermostat, if this is not working correctly then it will not allow coolant to flow round the engine correctly and can cause the head gasket to split. Did you replace with a new item??

Yes, just today put in a brand new piece.

Originally Posted by SonyVaio

Temp Sensor, again was this a new item or 2nd hand?

Yes, it is a brand new (Wager I belive.. starts on W)

Originally Posted by SonyVaio

Can you put up the specs of your vehicle, I've got it is a 2001 S8 but what engine (engine code if possible).

I don't have the paper with me but more specific: Volvo S80, 2001, 2.4 Turbo 147kWt, benzine engine.

Originally Posted by SonyVaio

A complete guess just now (if your head gasket has not gone) would be your temperature sensor itself.

Nope, just a brand new, I ran the test with multimeter and it read .20 OMH (ran test on 20K mark) when the engine was warm. When can the display stated 1

I'm guessing for a second week now what might be wrong. Everything seems to work well when I test individually but all together just doesn't make sense.

[maven05]

Hey Mike!

Originally Posted by mikealder

Get a dye kit that you can put in the coolant bottle then run the engine, if there is exhaust gas getting in to the coolant the dye will change colour which would indicate a head gasket/ cracked head/ block issue - If it stays the same then you know the engine is healthy.

I will stop by TOYOTA tomorrow because my friend works there and he asked guys around and the will do the test.

Originally Posted by mikealder

Coolant needs the pressure to prevent the coolant from boiling, the normal temperature for the coolant in these engines is above the boiling point for water. The fan should kick in when it reaches around 106 DegC at slow speed, if the temperature gets up to 115 DegC the fan goes to high speed, at 117 DegC the temp gauge will move above the three o'clock position.

I noticed on the right side on the radiator wet spot (if you face the front bumper). I used to have a leak somewhere but when I put in Radiator Stop Leak it stopped. Drove around 10K km and there were no trouble. When it got hot @ about 30*C i noticed a puddle of antifreeze on the ground right under the reservoir and the reservoir was wet from coolant.

Originally Posted by mikealder

Are you sure the new thermostat is installed the right way around and sat in the rubber seal ring rather than just resting on top of it? - Mike

Correct me if I'm wrong please, I placed the thermostat in the seal ring (came with the thermostat) and placed it in the housing so the little valve was to the front of the car. Also, I checked the old one and it was perfectly fine. I just changed it because I took it apart.

Also could it be the antifreeze itself? I noticed that many people post images of their antifreeze in radiator and it was candy/greenish color but mine is just blue. My mechanic changed it in November and I had no trouble the entire winter. And when the summer started we had some pretty hot days and the cooling system worked just fine. Only few weeks ago I've been battling with this problem.

[SonyVaio]

When exactly did you put in the stop leak additive?

[Thanatos]

If it was before the antifreeze change the new antifreeze will be eating through the old stuff

If you think it's the head put a bottle of steel seal in and follow the instructions to the letter and you won't have any leaks it lasted 60k miles and 4 coolent changes in a vectra before I scrapped it.

Kseal lasted about 4-5 months as its only a quick fix not a perminant one

[maven05]

I put in the Stop Leak substance after the antifreeze change.
And i put it in (cannot tell exactly) but I think it was February or March.

I would rather change the gasket... The problem is that here in Estonia there is no Liquid Gasket to repair head gasket. At least not a reliable one.

[alre]

I had same problem.Changed head gasket.Now everything is O.K.

[stuartggray]

Could it just be the cap on the expansion tank needs replaced? I've heard that it can go and not vent properly when heat builds up.