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DISCUSSION => Engine + Driveline => Topic started by: bmwman91 on February 07, 2014, 12:19:22 AM
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More strange things going on. More adventures. Yay.
I noticed that the cold coolant level has risen a bit in the last few days. It went from being at the cold line to being 2 or 3 ribs above it. The top rad hose was under a reasonable amount of pressure too. Tonight, I opened the radiator cap when I got home (engine still hot) and the coolant rose up to maybe 4 ribs from the top of the tank. Strange. So I got a screwdriver and bled the system for a minute or two, if for no other reason than to get the coolant level down to a reasonable level. It did not seem like much air came out really.
Then I drove around for 15 minutes or so, and gave it a few good pulls up to 6k. When I got home, the level was maybe a tiny bit higher, but none of the hoses felt like they had any pressure in them. The heater blows hot and when I was bleeding it coolant was coming out (maybe a little weak compared to what I remember, but it is hard to say). No overheating or anything. The radiator is warm, as are the heater core hoses.
So...my initial (and least pleasant) thought was a head gasket leak or cracked head blowing combustion gases into the system. I'd think that I would have gotten a ton of air out if that was the case though. Granted, I need to let it cool fully and then repeat the bleed so that any air in there has a chance to settle. The most obvious thing would seem to be the pump since the hoses do not seem to get pressurized after driving for 15 minutes, but the heater works and I don't overheat (it is ~45F outside). Can the pump partially fail...like work enough to circulate some water for bleeding and the heater and even to cool the engine when it is not hot out, but be dead enough to not pressurize the hoses? Or does it take a lot longer than 15 minutes to get things up to pressure? Also, I didn't really see the coolant level in the engine dropping as I revved the engine, and that normally occurs right?
In the case of HG leaks and head cracks, I would expect to be losing coolant little by little every time I turn the engine off as it drains into the combustion chamber, and I'd see some white smoke when I started the car. The oil is clean, no goop there either. It was hard to see in the dark, but I didn't notice any bubbling in the expansion tank when I revved the engine and the exhaust does not smell sweet.
My thought is that IF the water pump is crapping out, the rubber hoses have been slowly contracting and pushing coolant back into the system. When I opened it, they fully contracted and pushed a lot of coolant into the tank (and they do expand enough to require a fair amount of topping off for 2-3 weeks after putting new ones in). The pump was replaced in 2011 and has ~15k miles on it now, which seems premature for failure, but it did also sit for about 14 months in an empty system as I dealt with an engine rebuild. A lot of things seemed to get messed up by sitting dry for 14 months.
Any thoughts?
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One more thought. Last time I really paid any attention to the coolant system was months ago when it was a good 30 degrees warmer outside. Could it be that the thermostat is simply not opening up much? Or, maybe the thermostat is pooping out? It is also fairly fresh since I replaced it with the pump in 2011.
If it was the HG or head, I assume that the top hose would have felt like it built up at least a LITTLE pressure, no?
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To be safe you can do a coolant pressure to make sure there is no leaks. It looks to be the opposite which seems to be a flow issue. I am thinking it could be tstat related and its restricting coolant to move to the other side of the engine/radiator.
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That seems normal to me. I'd also run a pressure test to put my mind at rest and see what's going on. Coolant should expand when it's hot, and the expansion tank level should rise when you remove the pressure cap. I've never looked to see how much expansion is OK though. You could have a bad cap.
I'm curious, do you still have the original thermo bypass between the heater core hoses?
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My level was up and down for a bit as well. Also my temp gauge would flicker as if it had an electrical glitch. Turns out it was an air pocket in the cooling system. I re-bled it when the car was cold and now the level is consistent and my temp gauge is steady.
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My level was up and down for a bit as well. Also my temp gauge would flicker as if it had an electrical glitch. Turns out it was an air pocket in the cooling system. I re-bled it when the car was cold and now the level is consistent and my temp gauge is steady.
I had the very same experience recently. I also gutted my heater "safety" valve in order to get my heating system back up and running.
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Thanks for the responses guys. Must just be my paranoia. I suspect that fluctuating outside temperatures will definitely affect how much the thermostat opens, and how much the rubber hoses expand/contract. The afternoon temperature has been steady lately and the coolant level seems to be also. It was just super alarming to go from what I thought was a super slow leak somewhere to seeing the cold level go 3 or 4 ribs above the cold line in a few days. Anyway, with warmer outside temps, the hoses build pressure again. It would seem that a well maintained cooling system will not build pressure when the outside temp is 43F or less (tstat doesn't open much or at all). I'll take an overkill cooling system over an inadequate one any day though!
Dave, as far as I am aware the heater bypass valve thingy is original still. I remember replacing all of the hoses and considering replacing the valve thing until I saw the price. "Hmm, wellllll, I'll just let that be until I have some sort of reason to buy another one."
I'll just focus on the heater core for now lol. I catch a whiff of coolant from time to time with the heater running. Must be the valve thingy on the inlet line.
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If this is with the new engine then your cooling system may not be keeping up depending on climate.
About 30% of heat from fuel goes to exhaust and radiator the remainder is in the acceleration.
But it sounds like an air blockage somewhere, but if this is the new engine change thermostat, pump you don't want to damage it.