Lower rad hose not getting hot...
 

I've been having intermittent heat (as in above 100 temps) and intermittent heat (as in cold air in the cabin). Today I decided to run it and see what's up.

Well for one, the lower rad hose never seemed to get hot! Not even warm. Even as the car reached operating temperature. Hot air was in the cabin though.

Another thing...I seem to be losing coolant. Having a need to top up every little while gets tiring after awhile.


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Lower hose will rarely get hot in the winter... Upper hose gets the hot water.

Buy, borrow or rent a cooling system pressure tester to find where the coolant's going. Don't forget to test the cap. If the cap and system hold to spec (1.2 bar?) when the engine's cold, you might have a tired head gasket.

Sixto
MB-less

Well guys, things just came to a head this morning. On. The way into work, the temps climbs close to the critical level. I pulled over and right away, the heater (which was blowing cold as usual) got hot and the temps dropped rapidly.

Limped home the whole way like that. Get hot, pull over, let temps stabilize and finally got home. I opened the reservoir, was still at the almost full mark. There was some wet at the bottom of the overflow and the overflow hose was wet. So I guess it must've boiled over some.

Another odd thing to note...there was a squirting sound INSIDE the cabin when the heat came on. Fearing the worst, I sniffed but could not discern any odd smells. The carpets seem dry too.

What could my problem be? Bad thermostat? I thought they all failed in the open position? Bad reservoir cap? Does it need pressure to keep cool? Why does heat only come out when the car is stopped? Once moving it picks up heat quickly. But as heat comes into cabin, the engine temps drop correspondingly.


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time to pull the radiator, and verify flow.

pull thermostat and test it will open at temp.

pull water pump and inspect the impeller for damage.

you have a serious problem, you need to verify the cause.

One way I have found leaks is to let it run till up to opeating temperature. Have the heater on full blast in the process. The car needs to be parked on a dry patch of concrete, and then turn the car off. While it is cooling down start searching for leaks inside & outside of the car. On the inside you need to be able to see the area where the heater system is exposed. You can't always go by the wet carpet syndrome. If you can do it the pressure test previously mentioned is a very good way to pinpoint problems. You could possibly cause yourself more problems trying to drive it, and it getting hot like that. Over heating an engine just isn't a good practice.

Guys thanks a lot for the suggestions. Don't worry. I have no intention of driving the car. You're right, time to tear it apart to find out what's wrong. I could very well be the water pump.

There IS water in the rad. Although I wonder if it's just frozen solid. You see, over time, I've put in quite a bit of distilled water to top off the coolant level when it falls. I've just come to the realization that perhaps my coolant / antifreeze level might not be optimum, and it's been below 0 degrees Celsius here for quite awhile now.

Make me wonder if the squirting sound is that of hot coolant squirting through frozen heater core!


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Topping off with straight water is never a good idea. This prevents the antifreeze from doing its job when it gets cold.

One thing you can check is if there is antifreeze in the block. Intermitent heat would lead me to believe that coolant isn't in the block. I was messing with the heater lines on my 300D and drained coolant from the block in the process. I stupidly assumed that the coolant in the radiator would automatically go into the block. Nope. It overheated until I poured more coolant in.

Another thing you might try is completely removing the thermostat. If it still overheats with the thermostat removed, you know the problem is with the radiator or water pump.

You mentioned a leak. Have you seen coolant or just noticed the radiator being low?

Here's the odd thing. I have a really small leak in the reservoir. It's just slightly below the full mark. I figured if the coolant level gets below that mark, there should be no more coolant leak. But there is. I don't know where it's going. I've checked engine oil and there's no mayonnaise there, and the level doesn't increase, so I don't think it's going there.

I've been thinking about no coolant in the block. Just now before my ride came in, I had a look at my reservoir. It was full when I drove back this morning. It we empty when I looked at it and no water on the driveway anywhere!


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If you believe your coolant was diluted enough to freeze inside the radiator, heater or even the block then id try to address that first.
Hauling the car to a heated garage or shop would be a start. Myself, i wouldn't want to play with the possibility that there's ice in the engine block and try to run it.

First... if you have ANY leaks you are not running a pressurized system... thus water boils at approx 212 F.... not good...
Second... less than approx 50-50 mix of recommended coolant water ratio allows the possibility of your coolant eating a hole in your heater core....
Third... You could freeze and crack your block.....

Geez. It sounds like I may have seriously buggered my car :-(


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Not necessarily.. Live and learn:)

Don' t assume the worst.... just do a logical and thorough testing.....

I was guilty of the same thing, my wife's cooper started leaking from the rad a month or so ago. I plugged the hole with some epoxy but it still leaked a bit. I ordered a new radiator, i just didn't feel like going into all this plastic fantastic, so i kept on topping it off with water.

Yesterday it was the last warmish day around here according to what the weather people say so i got it done and i did it on time but just barely.