Volvo 850 reservoir tank boiling

MrsJones1988 · Post by **MrsJones1988** » 19 Dec 2017, 13:56

Hey everyone! I have had it to here with this Volvo!

I’m losing coolant like crazy! As soon as the engine is hot I get bubbling coming up through the cap. To the point where I just started using water. The car has not overheated. I just ordered a new reservoir and cap from partsgeek.com but before I keep throwing money at the cooling system, does anyone had insight on what this could be? The only thing I’ve replaced is the alternator about 3 weeks ago... so that’s not connected...

Hayley

CEBirnley · Post by **CEBirnley** » 19 Dec 2017, 14:02

Just spitballing here...it could be an issue w a cracked cap, reservoir or hoses. It’s my understanding the system needs to be pressurized and of a leak is present, then it cannot be properly pressurized.

I’m looking forward to seeing what the more learned folks have to say.

MrsJones1988 · Post by **MrsJones1988** » 19 Dec 2017, 14:13

So should I hold off on replacing the radiator and t-stat?

Teddy1975 · Post by **Teddy1975** » 19 Dec 2017, 14:32

If it isn't overheating and there are no leaks from radiator it isn't due for replacement. T-stat normally only if the water temperature drops when driving long straights.

Replace the reservoir cap for starters before throwing more money at parts you likely don't need to swap out yet. Keep in mind that water alone actually lowers the temperature at which it'll start boiling, where the 50/50 recommended mix of HOAT coolant/distilled water will raise the boiling temp. (Not to mention if it's tap water you've put in, you may face problems with calcium and other deposits in the cooling system and engine.)

Post by **RickHaleParker** » 19 Dec 2017, 14:35

So should I hold off on replacing the radiator and t-stat?

Hold off radiator and t-stat.

Any white smoke coming from the tail pipe?
Does the bubbling from the reservoir smell like exhaust fumes?

Pull the plugs: Water droplets, brown spotting, and rust around the threads are all signs of head gasket failure.
A compression test might be telling.

Post by **scot850** » 19 Dec 2017, 15:38

Some places like Autozone also loan tools. See if they have a cylinder head gas leak tester. Basically you attach the tool to the header bottle and it has a fluid that changes color if there are exhaust gases getting into the coolant. If gases are getting into the coolant system you have a head gasket leak. You may not get white smoke from the tailpipe if the gas leak is only into the coolant.

Neil.

Post by **E Showell** » 19 Dec 2017, 15:44

Very likely poor seal on reservoir cap. Could be a very simple fix. I've been lucky like that once before.

MrsJones1988 · Post by **MrsJones1988** » 19 Dec 2017, 15:52

Thanks! I will start with the simple things and work my way up. Hopefully it’s a simple fix. There’s always a puddle directly under my reservoir so maybe I’m just overthinking. I don’t have white smoke out tailpipe but I am getting white smoke out of the oil dipstick but from the looks of it, that’s the PCV system correct?

Post by **scot850** » 19 Dec 2017, 16:22

Yes that is typically the PCV system needing cleaned.

Testing the coolant for gases is a simple thing to do before you go throwing money at it. If there is a junkyard around where you live you might be able to get a black cap from a 240 which allows a higher pressure before letting fluid out.

Neil.

MrsJones1988 · Post by **MrsJones1988** » 19 Dec 2017, 16:53

Neil, how do I test the coolant for gases? And can you explain the purpose of doing this? Is it to figure out if it’s the head gasket or what?