Coolant tank - why so many baffles inside it? (refill rant)

[850forum]

Anyone know the purpose of the weird vertical baffles in the coolant tank? Got a diagram of how they flow?
I think I'm going to take some duct seal & stick a foot of PVC pipe over the hole, so I don't lose so much
overflow when refilling & getting the air out.

Or maybe replace the hose from the radiator with a much much longer piece of tygon, and let the steam & bubbles spurt into a bucket handing from the hood.

Or something.

How long should I let the car idle while it bubbles & I need to keep refilling the tank...

I wish I knew the thread size & diameter of the opening on the tank, I could fashion a connector & put a gallon bucket over the coolant tank so it would not suck itself dry so much. Every time that happens, I have to start over.

[scot850]

When I fill the coolant, I jack the front up on axle stands and then fill it slowly. Not 100% successful but usually reduces the issue. I still carry a 50/50 coolant mix in a gallon jug and a funnel and check it the first few times I use the car.

Neil.

[scot850]

Should have added, the baffles while annoying for cleaning are there to stop surging for the level sensor or it would be going on and off every corner.

Neil.

[scot850]

Should have added, the baffles while annoying for cleaning are there to stop surging for the level sensor or it would be going on and off every corner.

Neil.

[850forum]

So I will park my car on the hill when I do this !

Is it possible to over-fill this system? Last night after filling & refilling while it idled, I filled it when I shut the car off, and a few hours later the tank was empty so I filled it again. I have put at least 9 liters in; of course some has spilled but really not a huge amount. No puddles this morning.

Today I drove it around, and when I got home saw that the tank was steaming off. I think from the cap area & also the outlet hose connection on the bottom. So is the system way over-pressure? Also seeing the coolant light flickering, intermittantly.

The thermostat is steady about halfway up (fairly horizontal needle). I am not seeing a sudden drop that would indicate the thermostat opened - and they replaced it & the radiator 3 months ago. At least, they should have also replaced the thermostat.

Not long ago I had the heater core replaced, it was leaking coolant into the passenger compartment (real mess cleaning the carpets). Can it be leaking into the core again - and not spilling out?

Oh - I did not turn on the heater when refilling. I was monitoring the AC temperature (there's another problem going on there, with the temp out the vent sometimes being a nice 40 below ambient around 90 F, but then blowing at 70-80 deg. Where is the temperature sensor unit for this? They got an aftermarket relay for the one behind the glove box.

[scot850]

The internal temp sensors are built into the front seat roof grab handles. There is one for each side on an 850. You have to pull the trim above the door opening and remove the grab handle to get into the units. They have a little fan that pulls the cabin air into the sensor and then thermocouple reads it.

The fans get gummed up with air borne crap and probably need a clean.

While they may have an affect on the cabin temp, it is more likely the A/C compressor that may need to be shimmed. There are 2 typical methods folk use. One involves using a bread loaf packaging plastic clip, the other using zip-ties.

There are several threads on here on that subject.

How long does the temperature gauge take to get to the 3 o'clock position? If it takes a really long time then maybe the thermostat is bad. If the repair shop used an aftermarket one without a by-pass then it will overcook the heating system. If the top hose is hot when the gauge is at 3 o'clock position the thermostat is likely working.

The other possible issues are :

1) a bad overflow tank cap valve
2) the system really needs burped. I get told all the time that the coolant runs through the cabin heater core so whether you switch it on not makes no difference. The only difference is that the system directs air over the core to warm the car. Parking the car 'nose up' on a hill will work too.

If you are concerned about the heater core, you will have to lift the driver's side floor carpet to check for dampness under it. The carpet is rubber backed so you won't necessarily feel the carpet damp on the top side.

If the heater core is leaking you should smell a sweet smell and you may get fogging and a slimy haze on your front windshield, especially above the air vents.

Neil.

[850forum]

what is the box in front of the coolant tank? The connector in the rear is detached so its sucking or blowing atmospheric air somewhere.

I just parked it nose up on my hill & it took about another 2 liters. Iet it run for a while; the thermostat is bottomed out cold. First I ran the heat blowing 120 out the vent, then turned on the AC and it seems to get about 30 degrees below ambient (74F, just had a rain shower).

Me recollection is that the thermostat should be about 1/4 - 1/3 the way up in normal operation.

I'd like to see the AC drop 40 deg , esp when ambient is below 80, but I'll take what I can get out of this system.

[scot850]

The temp gauge should have it's needle horizontal at the 3 o'clock position. If it is lower than this even after a long run. there is either an air lock near the sensor in the block, or the coolant sensor which is right beside the thermostat, is bad. There is info on how to test it v's ambient temperature using an electrical tester. Also the connector is also a known trouble spot as the cars age. It is mounted on the back of the power steering pump and there is a connector there. It is fairly common of the wires to corrode either in the connector or either side of it, as well as the contacts inside the connector. If it is bad, it is one of the parts we recommend Volvo only. Sorry!

Neil.

[850forum]

Is the coolant tank bolted on anywhere, or just a friction fit to the fender? Looks like it ought to slide upwards.
Need to get to the back of that rectangular box to reconnect the "hose" fitting (its hard plastic with click-friction projections).

[scot850]

I can't recall on an 850 or 98 V/S/C70. I seem to recall it has a stupid tang on it you have to figure out how to move inward to the bottle body to remove it, and by sliding the bottle upward on the slider channels.

Neil.