I’m all out of ideas. I’ve bled and bled and bled, on uphill slopes and level ground. Some days this week the water fall noise was gone, other days like today it comes back. Temps are between 188 and 196. The only cooling system component I haven’t replaced in the last couple weeks is the water pump. Is there any way this could be a cause? It’s very audibly confirmed to be at least pushing coolant around.

 

I had one like that. Turned out to be a blown hg on the outside rear of no. 7. Ran great otherwise. Occasional misfire 307 and temps were good.

 

How is the heater? Both hoses feel nearly the same temp? My 02 heater core gurgled on me once then stopped, then when I needed the heater I had nothing. Ended up being clogged up entirely. Back flushed it & blew out a lot of snot looking goo. Problem went away after that.

When you remove the bleeder on the T can you still add coolant? Keep doing so until you can't. It can sometimes take a few warm up/cool down cycles to get the air out completely.

 

The heater blows hot. I haven't checked for a temp difference between the two hoses, mainly because if it's blowing hot, I figured its circulating properly. I back flushed it before installing new hoses and didn't blow out snot, but more just crusty crystallized crust nuggets. I ran about two gallons of water through it before running clear and then finishing off by flushing with distilled.

When I remove the bleeder on the T I can still add a wee bit of coolant. I keep doing it through the expansion tank though until it runs out steadily from the T. I put the bleed screw back in while it's running steadily, so there's no instance where I can fill through the bleed port.

The water pump has never been replaced. The truck is at 156,000 miles. With BMWs I've had in the past, the water pump is very clear when it needs replacing. Either the impeller explodes and send plastic all over the water galleries, or it starts bleeding out the weep hole. Neither seems to be happening with this water pump yet. Well, the impeller isn't plastic on the D2, so not a risk there. The pump probably has nothing to do with this, right?

 

Waterfall noise is simply just air.

A

 

And what coolant are you running?

 

BMW. 50/50 distilled.

 

Your water pump is working fine hence you got heat
your temps are good
just drive it and eventually it will go away
just make sure your not losing coolant

 

Either burning it, coolant, or heater matrix is leaking. If the windows have a film on them then it’s got a heater core gone. Lift the carpets and smell the liquid. Shouldn’t smell at all.

 

Heater core isn't leaking as far as I can tell. No moisture on the windows or carpet. And here's the kicker... the coolant level isn't changing.