1999 BMW 323 5SPEED COOLING ISSUE - THOUGHTS?

[bmwjohn]

Hi: Never thought I would ask this here but hey....co-worker has 175k BMW 323I 4 door 5 speed E-46? cool on road, very hot when stopped or slow and, as I understand it, intermittent heat/no heat from heater. Unknown history, he replaced w/pump recently, then new radiator 2 days ago, still problem. 1 suggestion was to vacuum bleed system, using pressure (Cal.BMW shop). Could a radiator pressure tester w/cap adapter work, as can borrow at Autozone, pump up and then release bleed screw? Of course, I suggested the new rad, and also to get t/stat, hoses, rad. cap, (not happened yet). 5 speeds have electric fan only, which spins at unknown speed, a/t cars have fan+fan clutch + elec. fan. Anyway, he got rad at my suggestion, I think I lost my Guru merit badge.Thanks!Lots of BMW background but all on older cars.

 

[cool_breeze]

t-stat sticking but that would throw a code.
with this many miles an entire cooling system overhaul is necessary on these cars. It has lots of plastic parts with are some of the worst quality i have seen. buy parts offline and save your **** from the dealer.
pelicanparts.com
oembimmerparts.com
are just a couple...best wishes

 

[scurvy]

Does that generation BMW have a plastic impeller waterpump? Very common for the impeller to become separated from the shaft, in which case you get no coolant flow and overheating in city traffic.

If the water pump was recently replaced, he should know what kind of pump went in and what the impeller was made from.

 

[Kuato]

Sorry cool_breeze, but it's not the thermostat. If it stays cool on the highway and overheats in traffic or when stopped, it's the electric cooling fan.

I'm not familiar with BMW, but many vehicles have a relay that activates the fan, or some other electrical connection/switch. The fan itself could also be bad, or there could be some chafed wiring.

Either way, some diagnosis will be involved.

 

[FowVay]

Two recalls on this model come up in search:
- recall of the thermostat housing due to cracking. Applicable to the Behr brand housing only.
- recall of the crankcase ventilation hose due also to cracking and leakage.

The thermostat is electrically operated so it's possible that it's faulty.

Symptons do point toward a faulty water pump or cooling fan. Since the pump is new then it can likely be disregarded. There's also a electrical control valve that controls the flow of coolant to the heater core (search E46 heater control valve) which often go bad so this may be related to the erratic heat in the cabin.

Just some thoughts to ponder.