1998 Volvo s70 GLT, coolant indicator light

dghost · Post by **dghost** » 14 Oct 2013, 13:30

I was recently driving when I noticed my coolant indicator light was coming on during accelerating then would go off when I let off the gas. I checked the reservoir and it was near the minimum line. The next day I went to add more coolant when the car was cold and the reservoir fill back up to the maximum when took off the cap. When the car is warmed up the level goes back down to the minimum line. Any Ideas what might be going on?

Post by **jblackburn** » 14 Oct 2013, 13:44

Let it warm up til the thermostat opens with the cap off. Then top it off and put the cap back on.

dghost · Post by **dghost** » 14 Oct 2013, 14:10

Just filled up the reservoir with the engine running and warmed up. I was under the impression that you needed to check/fill it cold. Thanks for the help.

Post by **rspi** » 14 Oct 2013, 20:44

Yes you should check and fill it COLD. Cold means that it has not been driven in 8 hours.

You are experiencing a strange situation. Make sure you have a good green cap and that it doesn't try to overflow now that you have added some coolant.

dghost · Post by **dghost** » 14 Oct 2013, 20:53

I have a green cap have been driving it around since I filled it while running. Isn't the purpose of the expansion tank to hold excess coolant when the engine heats up to its operating temperature? So It will be at its fullest point when the engine is at operating temp?

Post by **jblackburn** » 14 Oct 2013, 20:57

dghost wrote:I have a green cap have been driving it around since I filled it while running. Isn't the purpose of the expansion tank to hold excess coolant when the engine heats up to its operating temperature? So It will be at its fullest point when the engine is at operating temp?

Yeah. Opening the cap while running let the car burp the excess air out of the system. When pressurized, the level in the tank will change, and the cap holds that pressure up to a certain point (10 psi?). This forced your coolant level further down, and when you took off the cap, it all came rushing back into the tank to equalize.

You should be good to go now. Filling to the "max cold" mark when the rest is hot will still leave room for expansion, so you may see the level drop a bit more when cold. Keep a jug of antifreeze in the car for the next week or so in case it goes down any more and you're far from home.

dghost · Post by **dghost** » 14 Oct 2013, 21:00

Alright. Thank you for the help.

Post by **MoVolvos** » 15 Oct 2013, 03:26

dghost wrote:Alright. Thank you for the help.

Please let us know what you find as your situation is backwards in terms of the level when hot and cold. By the way, the Expansion Tank is not the same as an Overflow Reservoir. The Overflow is not pressurized nor part of the closed cooling system where as the Expansion Tank is part of the enclosed system and under pressure.

Perhaps there is air trapped in the system

which is only making its way into the tank when hot and air (lots of it in the tank) expands where as water not so much is pushing the fluid down. That does not explain however the higher level when cold as the air would need to go someplace other than the tank to push the fluid level up

Blessings,

BKM

**

Post by **cn90** » 15 Oct 2013, 07:34

You may have a slow coolant leak. If you have not replaced the 2 turbo coolant hoses, do them ASAP!

DIY: 1998 S70 GLT Turbo Coolant Hoses and 2 Radiator Hoses:
https://www.matthewsvolvosite.com/forums ... =1&t=55306

dghost · Post by **dghost** » 15 Oct 2013, 14:37

Just looked at the coolant level again after driving for a bit. It seems to be a a tad low from where I filled it the other day. Not sure if there is air working its way out of the system or what is going on. Will update later on.