E30 goofy cooling system problem - United Bimmer Community

**BigEvil** · 06-14-2008, 12:26 PM

So I have an '86 325e. The car has 268,000+ original miles on it. I have retrofitted the AC to 134 and it works, the brakes, tires, suspension is all still in great shape (I personally fix it as it needs it). Last year I did another timing belt, tensioner pulley and water pump, these parts have about 8000 or less miles on them and not quite a year in service. Several days ago I had an overheat and immediately pulled off the road and shut it down. I popped the hood to find no visible damage (no bulging or ruptured hoses, no hot spraying coolant or steam) but the coolant was boiling and dumping out the overflow line. So I figured the most likely culprit would be the thermostat, I got a new one with an o ring and when I removed the housing the old one looked a bit baked and was kind of sticky, replaced it filled the system turned it over, same problem. NO fluid is getting up the lower radiator hose to the thermostat housing so nothing ever comes out the bleed screw. I figured must be a badly clogged radiator, I removed it ran a hose through it cranked on the water full flow no restriction......ok bad water pump - stuck a feeler in the bypass passage and I can feel the individual impeller blades and the fact that they rotate just fine with the pulley not a bad water pump. So that leaves blockage in the engine water jacket - damm - ran a hose to the upper and lower intakes to the engine, full flow no restriction. Ok, maybe it just couldn't overcome the air bubble in the lower hose. I put everything back on and reversed filled the entire system from the lower radiator hose. Yes forced water from the lowest point of the system until it flowed out the highest point of the system and I could hear the air escaping as I did it. Fired it up SAME PROBLEM. In fact all the water got sucked out of the bottom of the system and boiled out the top of the system. NO the thermostat is not in backwards, you can't even put it in backwards the heater is off and has been off the entire time, all of the fluid loss has been accounted for, not a head gasket blow or anything like that, no water in the oil or coming out the tail pipe none of the usual suspects seem to apply here. I'm guessing if I'm having this problem someone else must have had it also so if you know or even think you know please help

Thank you,

Big

**elsabor67** · 06-15-2008, 04:12 PM

Big,

WHen you bleed the air out of the system YOU HAVE TO have the heater system on full blast and on with the car running idle. That alows the water that goes thru the heater core and any air that might be trapped in there can come out. If not you can wind up like i did a couple of months ago with a warped and busted radiator. Also pull your radiator and check for any separation of the core. If you have any separation, ditch it and get a new one.

**BigEvil** · 06-16-2008, 09:03 PM

Yup, that had occurred to me, in fact the heater core on my car has been bypassed suspecting a clog (I'm in Phoenix, heaters aren't really a necessity here) but alas it still just heats up. I removed the new thermostat entirely same problem, I can feel all of the individual blades in the water pump with a probe theres no restrictions and it sucks water just spinning it by hand. The only thing I could come up with after several hours online was an obscure reference to some kind of T fitting on a hose somewhere under the hoses around the brake booster area coming off the heater core that was involved in some kind of recall back in '86 that apparently could cause the very type of crazy overheating problem I'm currently having. The real kick in the scroat however is the only way I can see to access anything down there is by removing the intake manifold. I'm spending the time on BMW number 2 right now (87 325is) as I need a car and not the big gas hog truck I'm stuck in now. Have you heard of or do you know anything about the previously mentioned recall? Also I need an elbow fitting for the brake booster check valve on car 2 and no parts warehouse seems to know that the cars even have them, the valve that is. Any ideas?

Thanks in advance,

Big