Hi there, hope you guys can help me solve my leaky coolant problem, and thanks for any comments in advance.

I live in Dallas, where we normally don't experience subzero temperatures, but this year we did and my car hasn't been the same since.

The radiator had been leaking a bit before the hard freeze and I had just been adding water to the reservoir instead of mixing in the proper amount of anti-freeze. So needless to say, the liquid froze and opened up the radiator nicely. I bought and replaced it with a brand new one, making sure to change the thermostat while I was at it. The coolant stayed in the system without any leaks until I took it for a spin. Then I noticed that the water was gushing out of the radiator cap. I bought a new cap and that did not work, I then replaced the coolant reservoir and that did not help either. After reading some of the forums here I drained the system and purged it for any air. (I had used some of that stop leak on the old radiator to keep the leak to a minimum) This helped some because it no longer gushes out, but I can still hear vapors coming out or in from under the cap and I could see some water leaking when I took it on the freeway. On a cool engine I can properly fill the reservoir to max and driver for about fifteen minutes, after that the engine starts to over heat.

What could be causing the high pressure? There is no water in the oil and the hoses are fine.

 

Water pump issues, pressure leak from piston. Since the engine also froze you may have a bad head gasket but instead of it going into the oil it could be going into the combustion chamber and burning off, although then you would be burning coolant and you exhaust would smell a bit sweet and white smoke. Your seal could be strong enough to hold the coolant in but every time the piston fires it could leak a little bit of pressure into the coolant system. If there is air in the system the coolant will boil which will create steam. This will dramatically reduce the coolant ability to cool. It can also create hot spots in the engine that can burn up seals and piston rings.

To answer your question, I have no idea what it is for sure. I would make sure the Thermostat was installed right because that would cause over heating then excessive pressure which could do multiple things. Make sure the water pump is doing a good job of circulating the coolant & maybe a compression check. If the pistons are venting into the coolant system then you should see that leak if you do the compression test right.

 

Wow! Just doesn't pay to add water only.

It could be a number of things if water froze in the system, which it did. Who replaced the radiator? When it was done, was the system flushed and willed with 50/50 antifreeze mix. Why was the thermostat replaced? When the coolant system is drained and refilled it takes several days to get it topped off properly. Are you really filling the take ALL the way up? If it's over heating you likely have a problem with the thermostat or water pump.

I would suggest you take the thermostat out and run the car for 10 minutes, unless it tries to over heat again. If it does try to over heat again you likely broke your water pump when it froze.

 

My money is on the head gasket, but you'll have to pressure test the system to be sure.
Since the system froze, you could've lost an impeller like the pic above.
Just tee a gauge into the system and run it for a short time. The gauge will rise pretty quickly if it is the head gasket. A hand squeezing the upper hose will feel pressure from the pump.
Ed

 

I'm thinking the thermostat is in backwards or it's not opening. But like others have said it could be many different things. What thermostat did you put in?

 

Thank you for all of your suggestions.

In answer to JPN's post I did the radiator change myself and filled it with just water to test there if there were any leaks first. I haven't felt it worth while to add the proper mixture if it was just going to gush out.

I changed the thermostat because it took a long time for it to heat in cold weather, and it turned out to be a good thing because it was broken and left open. I have been thinking that maybe I could done something wrong in the replacement, but it's a straight forward process. I followed a write up and replaced it with one of the more expensive thermostats. I bought a new seal and placed the spring action facing down.

I do worry that it could be the water pump not providing sufficient circulation, but I would not put my money on the head gasket. The oil is clean there is no smoke nor sweet smell coming from the tail pipe. However, if I do need to test the pressure, where can I find a testing kit.

Going back to the just water mistake, I read that the proper antifreeze mixture can raise the boiling temperature to well over 250 degrees. The water itself could be turning to vapor and causing the excess pressure. And maybe there was some air trapped in the system the first time and caused the huge gushing as compare to the now slower leaking. I do have to add quite a bit of water after running it a while.

I will do another flush and fill it with the 50/50 mixture this weekend and see how it turns out. Thanks again for the comments

 

I would also like to add that if the car is in park and running idle it does not overheat or leak. It is only after it heats an is ran a few blocks. Going up a hill it went from normal heat to 3/4 heat, then the water slowly leaked from under the cap.

 

I think your previous reply was to JimKW's suggestion.

The thermostat has an installation orientation. There is a tiny bleed hole on the T-stat (at least on OEM stats) and I believe the hole has to face down (6 O'clock position as you view the engine compartment from the front of the car).

In actuality, pure water has more heat-transfer capability than coolant mixture, but as you know that pure water provides zero protection against freezing.

Once the cooling system is filled, keep the coolant level in the reservoir between "MIN " and "MAX". If filled to MAX, it would spill out the coolant. This is not addressed in maintenance manuals, but as long as the system is full and no trapped air, the reservoir should not be filled to MAX.

You're lucky that your engine did not crack from freezing. If not done yet, I would also change oil, as the engine gets cooled via convection heat transfer from the internals of the engines to engine oil, then cooled by coolant. If the engine has overheated once, changing oil is not a bad idea.


JPN

 

Hello guys,

I would like to know which coolant is the best to use on a 1994 Volvo 850? I'm losing some water coolant in the reservoir and I'm just putting water as a replacement for now. Also I don't find a leak anywhere but, I'm suspecting that my radiator fan is not working because I can't hear her rotating when after I turned the car off to somehow cool the radiator? Could that be the case that when I'm driving I watch the water temp and it's normal but when I'm done driving at least I should expect to hear the Radiator fan do some action to cool the radiator right?

 

Need a little more info on the car... turbo, n/a, mileage, where do you live?

If your loosing coolant you have a leak somewhere or your burning it.
Have you had the system pressure tested?
Have you done a compression test?
What coolant are you putting in it now?
Keep in mind if you going just water the water will evaporate from the heat.
A far as the fan goes it will only come on when the temp sensor gets a high reading and it needs it to pull the air thru the radiator.


Keep in mind This is a 8 month old thread, you might be better off creating a new thread if you dont get many more responses.

 

Pentosin "Pentofrost" Engine Coolant / Antifreeze is the Volvo recommended brand. It is available at OReillys and probably most other auto parts stores if you ask for it by name. Most will likely need to order it in for you.

Antifreeze in a mixture with water does four main things. It lowers the freezing point of the coolant below that of straight water. It raises the boiling point in a pressurized system above that of straight water. It retards waters natural desire to oxidize the metals in the cooling system and it also aids in heat transfer. It does a lot more than just keep the system from freezing.

Most people I've seen buy a name brand like Prestone, Zerex, Pennzoil ... or if you change it fairly regularly the house brand on sale is a good choice too. It all depends on how much $$$ you want to spend and if you feel better with a name brand.

 

What did you ever figure out was the cause of the overheating?

 

Hello KissaFrog, thanks for the response. I drove my car this weekend and I couldn't believed that it didn't over heat. I just change the oil and I put regular water on the reservoir. I plan to change the coolant out of the radiator soon as it needed to have a coolant replacements. The car didn't overheat. I was amazed but thanks for the response.

 

Pat: You need to drain the water out of that motor ASAP. Plain water doesn't give your motor and coolant system the protection it needs as listed above. If you don't have a certain percent of antifreeze you risk freezing if you're in a cooler climate. If the water in the system freezes it can expand and break things. Plain tap water has a lot of chemical things in it that causes rust, and stuff like that. Premature failure of the radiator, water pump and other things will cost you money.

 

Hello RSPI,

Thanks for your concern. I don't live up north where it does snow or go below 30 degrees. Im in Southern Cal. I will be flushing the radiator system soon. I just bought the Pentosin, Pentofrost NF and I will make sure that I will do 50/50 so that it will create the proper mixture. I will be using distilled water for the mixtures. I have to pressure test the cooling system first, so that I can see if the hoses needs to be replaced and I'm just putting things together now, so that I can use this Volvo 850 that I got as a blessing for a long period of time. It has over 200k miles and still runs like a champ. God bless this car....

 

Its a possibility the Bars Stop Leak clogged your heater core. If the problem arises again, I would pull core out and check the flow through with hose.

 

He meant your motor, not the radiator. He is worried that you have water in your motor oil...check it. Pull your dip stick and look to see if you have a muddy brown sludge on it, check the oil filler cap too.

I live in Cal too and approve this message.

 

You can plug the heater core lines (or core itself) and you shouldn't be able to overload the cooling system or cause any problem.
The radiator, fan, hoses and pump are designed to dissipate any heat the engine would normally produce plus a margin for deterioration over the years.

 

Thanks guys for your response. I just change the motor oil a month ago. The oil oil didn't look muddy or watery. It was black like coffee, heheheheh. Don't worry I didn't taste it to see if it's taste like coffee.. Anyway, I discovered that the plastic coolant reservoir was cracked and I bought a new one from car stuff and it only cost me $18.16 cents for a new one, which arrived yesterday after I had ordered it in 6 days before... I bought a Prestone Flush to get all of the green anti freeze. I bought the Pentofrost recommended by KissaFrog.. I still need to buy 2 more Pentofrost because the whole cooling system calls for a 7.4 qts of liquid if I were to do the 50/50 with distilled water will be used to be the diluted parts. Here's my question? Have you heard of Hyper Lube Coolant that is suppose to cool your engine some more to 6-8 degrees cooler? I went to their site, I check the pro's and con's the only thing that I saw negatively was that one guy said that Hyper Lube is not good with a Lexan Coolant Reservoir as it will crack the plastic..Thanks always in advanced for your response and have a great Thanks Giving.. Hopefully when you eat your Turkey this Thanks Giving it will not be taxed...... Heheheheh

 

Boxpin, thanks for the Youtube Volvo Drag racing.. This is so cool...