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teeb

M2 cooling challenge

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Sometimes when you're too deep into a system, you can't find your way so I need a doctor or a team of doctors!

I have a S14 with all new cooling parts: pump, hoses, custom all aluminum radiator, pusher fan, S14 thermostat, fresh synthetic oil, a remote oil cooler and I have not been able to determine why it over heats! It recently got 3/4 gallon Prestone to avoid freezing, but have been working with water in the past. I lifted the car's nose and ran it with the cap open to see if I could get a bleed. Laser thermometer and the sense of touch indicate the top of the radiator gets hot but the bottom is cool. It runs at idle for about 8 minutes and then it reads 230 at the water gauge. The head gets hot and I shut it down. I had a 2002 thermo in it prior, and it did the same thing so I bought a new OEM S14 thermo. It doesn't have the heater box lines hooked up, and I kept the head line into the radiator.

Marshal...have you had similar issues?

Much appreciated!!

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I can see you have big problems there. Best course of action is to stick it in a shipping container and send it to me for...disposal

:-D

On a serious point you mention running it with water that will give better cooling initially but you risk funking up the cooling passages in that expensive head with corrosion. Maybe take it to a good radiator shop for a pro flush? With every thing else new the only thing it could be is block circulation and heat transfer. 100% certain there is no air in the system?

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Send me a 3 party - out of country check and I will be sure to ship it down under!

Not sure about air? Only info I got was that after several "warm up" attempts the coolant dropped slightly. Assuming it's not escaping into the exhaust (no smoke or smell), I thought I got the bubble out. Obviously not. Or if I did, the issue is still there.

Somebody suggested to open the coolant temp sensor along the aluminum return hose to allow trapped air out. I haven't yet tried that, but it makes some sense.

Mor einfo. I measured the temps at the top and bottom of the thermo and I was well above 100 f, so it should be operational with those temps.

Thanks for your idea on a flush.

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ya gotta burp it...a lot. repeatedly squeeze the lower hoses while it is warming up. don't get the nose too high. just a few inches. make sure heater is on high temp.

i am assuming the car is not moving yet and this is just an idle issue? how is your pusher fan set up? is is coming on? where is sensor for it?

is this the first start up of the car with the engine in it?

where is your sensor for the water temp?

where in VA are you?

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Marshall,

I'm in Virginia Beach via Shanghai, China. My car was at my friend Martin's garage in Richmond and he corresponded with you on the S14 build last year. It is now with me in Virginia Beach, but I am currently in Shanghai, China doing the research and planning the work.

The car IS moving. I drive it with and without the pusher fan on and it does the same thing. The pusher is currently on a manual switch. Water temps are pulled off the aluminum return.

Burping by squeezing the lower hose....why? Does it push air through the thermostat?

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ahhh, now i remember it!

yes, can get an air pocket in there.

does the temp run fine on the road? only overheats at idle?

mine runs warm at idle on warm days. i blame it on a poorly mounted elec fan which is not as close to rad as it should be. fixing this winter.

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Connect a Vacuum cleaner to the filler-neck for a second or two. The partial vacuum will expand the air bubble (if there is one) and hopefully move it to the radiator.

Do this with a wet or dry vacuum, and make sure the radiator not filled all the way to the top, so you won't suck out the coolant.

I think this works best with the engine running; but try it with the engine stopped also. Let us know the result.

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Double check and make sure the t-stat is not upside down.........don't ask how I know!

Phil

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It runs hot all around Marshall, but your fan proximity idea just triggered something in my mind...see pic. I mounted the oil cooler in front of the fan (as per the suggestion of a "knowledgable" BMW tech). To me, this would seem to draw higher temperature air across the radiator than usual. It may also interfere with the flow rate. This must be a big piece to the puzzle. I wouldn't bet my life that it is the only piece as we experienced dramatic temp differences from the top of the radiator = 230F compared to the bottom and 65F. I wonder if the position of the oil cooler and air flow from the fan might somehow relate? See the pic? The cooler is positioned at the top of the radiator....hmmmm??

OK, so relocating the remote oil cooler will be the first test! I feel good about this one....

Thanks all!!!!


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Don't forget the oil cooler is thermostatically controlled too, so it shouldn't have any hot oil circulating until the car is up to temperature. I don't think this is your issue - are you 100 percent sure your T stat is working and your water pump is good?

N

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Remote oil cooling schooling....

OK, so being new to this class of technology...how does that work? I included a picture of the remote oil cooling bracket off the filter mount. I see the oil temp? sensor not yet hooked up. And the sensor is NOT hooked up and could that be part of the problem as you suggest? Hmmm....

I know what to do next.

If it were hooked up, how does the system open up?

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seem to recall there's a sprung valve that only flows oil to the cooler when it's hot enough.

This won't be causing the problem you have described. Sounds like a simple T stat issue to me - so have you taken it out and checked operation in a pan of water on the stove? If your rad is cold at the bottom and hot at the top what else could it be?

The bottom hose isn't kinked is it? You never know with custom set-ups.

N

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yes, oil cooler tstat is mechanical. not the issue.

your oil cooler is in a common location (mine is there too). not the issue.

the large temp gradient accross the radiator is because no/not enough coolant is flowing through it. still think you have an air lock in the lower hoses or t-stat issue. I might say it is a radiator issue except it looks new.

post pics of what your lower cooling plumbing looks like. it does not appear you have a normal setup.

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Im guessing that the problem is in the fan, everyone that did somewhere mount a fan before radiator knows that, if radiator pushes air through the radator is much, much less effective than fan that pulls air through the radiator. So if you dont have the space behind the radiator you must pull much more powerful fan with side walls to block the air from turbulances back.

One option is to mount radiator more to front and lean it so fan can be mounted on the back side.

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