Cooling issue

[m3f_MOTRSPRT]

My 1998 M3 has Mishimoto silicone cooling hoses, a Mishimoto replica aluminum radiator, a new 176*F thermostat. This car will not cool itself down. The upper radiator hose gets hot, but the lower radiator hose will not. I'm getting steam blowing from somewhere on the right side radiator towards the top. When I open the bleeder screw I only get steam. Never fluid. And then the temp's keep rising to the point I have to shut the car off.



Every symptom pointed towards the thermostat: engine hot, radiator cool, and hoses somewhat cool. So I changed it out. No change to the cooling system whatsoever.



Does anyone have some suggestions? Could my radiator be plugged somewhere?

[m3f_cscat87]

Have you verified the water pump is working? No plastic blades sheared off? I'm no expert, but it sound like coolant isn't being moved through the system.

[m3f_MOTRSPRT]

I replaced the wp with a metal impeller about 100K miles ago. Totally possible the wp could be the culprit. There does not seem to be any fluid moving at all, and on the outside really looked like the thermostat was failing shut. I'll give that a shot. Other than not seeing any fluid cycle in and out of the overflow tank, I don't know how else to check it.

[m3f_fiveightandten]

Have you verified the water pump is working? No plastic blades sheared off? I'm no expert, but it sound like coolant isn't being moved through the system.

This.



And if your water pump has 100K on it, you're on borrowed time even if it is ok.

[m3f_badgtho]

Bad water pump, thermostat in backwards or other severe blockage.

I'd start with the pump. With 100k on it it's shot anyway.

[m3f_englishtom1596q]

+1 for water pump.


stuck closed thermostat = top radiator hose not hot when engine is obviously hot


Stuck open thermostat = top radiation gets warm right away and engine takes an extended period to warm up.


Also verify that the belt is still on, has tension and is turning the pump pulley. Seems obvious but…just incase

[m3f_MOTRSPRT]

Thanks guys. I'm gonna change my water pump today, and maybe post some pix of the old pump for grins and giggles.


The belt is definitely still on as I was just in there yesterday and didn't notice anything strange.


Sent from my superior iPhone 5 using Tapatalk

[m3f_MOTRSPRT]

Changing the water pump actually went faster than changing my thermostat. I had it changed in about 30 minutes even with the supercharger belt in the way. I could have sworn the pump I replaced many years back had a metal impeller, but this one I pulled out was plastic. Hmmh! Whatever. After inspecting the old one I didn't see anything wrong with it. So this has me worried.



I got the new one installed and decided I needed to check out my radiator as well. I managed to get everything plugged up and began pressurizing the radiator with a gauge so I can monitor the pressure. Well, low and behold my radiator has about 16 leaks at the top. What the hell?? This isn't the factory radiator as that busted about 3 years ago, and this aluminum unit is the one I replaced it with. How could the radiator leak like this? This really sucks because it's a big ticket item to replace. Can aluminum radiators be repaired?

[m3f_pbonsalb]

I think Mishimoto has a lifetime warranty. Take pictures of the broken one and they should send you a new one. The pressures at which the BMW cooling system operates is pretty high and it is hard on radiators. Also, quality control on the inexpensive Chinese aluminum radiators is probably minimal.

[m3f_englishtom1596q]

wow i was not expecting that result. At least now you have a good metal water pump installed for the future.


Most aluminum radiator companies have lifetime. If its a mishimoto one then contact them and they should replace it. Kindof pathetic that it would fail like that though

[m3f_MOTRSPRT]

Well, the radiator I put in there in 9/2011 was a Mishimoto clone so no lifetime warranty. I should've taken pix of what was happening when I pressurized the radiator while squirting Windex on it. The upper 10 rows had leaks at either end of the tubes.



But I'm updating for 2 reasons. First, the professional shop I took my radiator to for testing found basically the same thing that I found. Due to the nature of the leaks, though, they were asking me questions about how I drove the car. According to them, it looked like the radiator had suffered some torsional stress causing it to leak in the specific areas. They said it looked like the chassis was flexing in the front enough to stress the radiator causing leaks. Huh?? Anybody ever hear of this or experience it? I've driven my car hard, once maybe twice, but it was long before the factory radiator gave up. Could the water pump failure cause the radiator to pressurize abnormally high in some way? Doesn't make sense to me.



Second, while sitting around work talking about my issue someone related a story his parents went thru with a car of theirs. Apparently, they went thru 2 radiators before finding out that the exhaust was pressurizing the cooling system blowing up the radiators... IS THIS EVEN POSSIBLE??? At the moment, I'm open for any and all assumptions so this possibility has me worried. Once I get the car buttoned back up I would still have to take it to a shop to get the entire cooling system professionally pressurized. That drive in itself could lead to another failed radiator if the exhaust is pressurizing the cooling system. And, because the engine did get pretty hot during all this fiasco I stand the chance that the head gasket is bad. Even the head could be warped at this point. I wasn't about to order a Zionsville radiator (which would be the last radiator this car would ever need) if I'm gonna be cracking radiators right and left, and need some major engine work. So, I ordered a new Mishimoto thru Bavarian Autosport.



Anybody have any ideas or opinions?

[m3f_englishtom1596q]

I don't see any way for the frame to twist and pop the radiator. It's suspended by plastic clips on the top and rubber nipples on the bottom allowing it to move or break those before a metal radiator ever would.


As for the exhaust pressurizing the cooling system. The only way for this to happen is a significantly blown head gasket but the car wouldn't run long enough to Pop the radiator.


I think those guys were pulling this out of their asses.

[m3f_drosato]

my roomate actually had something similar happen to his mustang at the track.. 200 shot of nitrous lifted the head gasket and sprayed coolant everywhere. With that catastrophic of an engine failure happening it still didnt pop his radiator but pushed the cap off. thats why those things are spring loaded and you have an overflow. they pop open and the system bleeds pressure

[m3f_fiveightandten]

Well, the radiator I put in there in 9/2011 was a Mishimoto clone so no lifetime warranty. I should've taken pix of what was happening when I pressurized the radiator while squirting Windex on it. The upper 10 rows had leaks at either end of the tubes.


But I'm updating for 2 reasons. First, the professional shop I took my radiator to for testing found basically the same thing that I found. Due to the nature of the leaks, though, they were asking me questions about how I drove the car. According to them, it looked like the radiator had suffered some torsional stress causing it to leak in the specific areas. They said it looked like the chassis was flexing in the front enough to stress the radiator causing leaks. Huh?? Anybody ever hear of this or experience it? I've driven my car hard, once maybe twice, but it was long before the factory radiator gave up. Could the water pump failure cause the radiator to pressurize abnormally high in some way? Doesn't make sense to me.


Second, while sitting around work talking about my issue someone related a story his parents went thru with a car of theirs. Apparently, they went thru 2 radiators before finding out that the exhaust was pressurizing the cooling system blowing up the radiators... IS THIS EVEN POSSIBLE??? At the moment, I'm open for any and all assumptions so this possibility has me worried. Once I get the car buttoned back up I would still have to take it to a shop to get the entire cooling system professionally pressurized. That drive in itself could lead to another failed radiator if the exhaust is pressurizing the cooling system. And, because the engine did get pretty hot during all this fiasco I stand the chance that the head gasket is bad. Even the head could be warped at this point. I wasn't about to order a Zionsville radiator (which would be the last radiator this car would ever need) if I'm gonna be cracking radiators right and left, and need some major engine work. So, I ordered a new Mishimoto thru Bavarian Autosport.


Anybody have any ideas or opinions?

-We can't answer your radiator question without knowing how your radiator is mounted. It's aftermarket, so fitment and mounting are unknown to us. That being said, there's no way that a properly installed OE radiator can be twisted to the point of failure by driving the car hard. This is assuming the car does not have any structural damages or deformations.


It's more likely that you bought a cheap radiator which has failed due to defects manifesting themselves after some use. If there are any deformations in the car that cause mechanical stress on the radiator in its mounting position, the heat cycling will eventually cause it to fail. If the mounting or fitment of the radiator subjects it to mechanical stress while installed, the same will be true.


-It is 100% possible for exhaust gasses to enter the cooling system. This happens either due to a failed head gasket, or a crack in the cylinder head. Hot exhaust gasses leak into the cooling system and over-pressurize it.


That being said, unless the radiator is on its way out (or a very poor quality part), the radiator cap should vent the extra pressure long before the radiator sees enough pressure to fail. Additionally, even if the cap was faulty and did not vent, I would think you would see a hose failure before a radiator failure due to over-pressurization. But, truth be told, we don't know for sure without knowing what car that happened in, what mechanical condition it was in, and what kinds of parts were installed on it.

[m3f_cscat87]

Get a real Mishimoto radiator. The quality and fitment of the current design is awesome. Mine went in perfect and still looks great a year later. There's just a bad rep about them because the old design fit like doo-doo.