This began with a low coolant light on my 96 850 GLT. When I checked the overflow tank, I noticed a ring of crud around the opening after removing the cap. The level was just barely triggering the warning lamp on turns. I topped the fluid, but am now experiencing low heat from the climate control system. The engine temp pretty quickly gets to the normal position and stays there. So it doesn't sound like a thermostat problem. I have never had an indication of overheating. But when I topped off, I screwed up and used undiluted antifreeze. Could it be something as simple as too little water in the cooling system? Or is something else going on?

Yeah you should have a GREEN reservoir cap not the old grey one. Only use Distilled water in the coolant mix, otherwise you'll end up with a bunch of lime, calcium, mineral buidup in the radiator and cause blockage. You can buy a coolant tester at PepBoys or just about any autoparts store for less than $10. The GREEN cap is available from Stant and sold at PepBoys, AutoZone, just about everywhere for $10. Oily black residue is not good in the reservoir. If you are getting a frequent pressure relief noise from the reservoir it could indicate a blown head gasket. Get the GREEN cap and keep an eye on it. Good luck......


Mike
'95 850T

Common problem with leaking if you have the older grey cap. The newer green caps are an improvement, but have had them go bad too. I carry a spare cap in my glove box. You can't repair these caps and there isn't an after market replacemnt that I know of.
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Current owner of a '04 V70 2.5T. Previous owner of a '94 850 Turbo Wagon

What color is your cap. I was losing a slight amount of coolant until I bought a new green cap.

Have you checked the fluid level since then? If it is down again, perhaps you have some air in the system. If it is low, add an amount of water equal to the coolant you added, although I wouldn't worry about a little extra antifreeze.

Another way you could improve the situation is to have your antifreeze tested, then you will know what the mix is, and how to correct it.
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96 855R, 95 855,854, 90 744 Ti - 340,000 Volvo miles put on 7 bricks

Thank you folks! Fluid looks clean and it's been holding the level since I refilled. Have my shop testing the coolant as we speak.

1996 850 GLT 149,000
1990 240 DL Wagon 238,000