Plugged heater core. BMW F32 435i

BMWTurboDzl

Thread starter
Joined
Apr 15, 2010
Messages
8,749
Location
Atlanta,GA
My vehicle developed a no heat condition and I think I've narrowed it down to a plugged heater core. There's a heater control valve on the inlet hose which controls the amount of heated coolant making its way to the heater core. My diagnosis is based upon the fact that the inlet hose between the control valve and the heater core is warm which leads me to believe that the control valve is functioning. The outlet hose is cold.

I'm wondering what sort of experience people have flushing the core only OR whether you guys think it's easier to just use a cleaner flush on the entire system?

Recommended products? Liqui Moly, Motul, and others have a 500 ml "pour-n-idle" product.

My engine (N55) has an electric water pump and I don't have a block drain so I don't know how I would flush out any cleaner.

UPDATE: 63k miles on the odo. 2015 MY
 
Last edited:
Joined
Oct 5, 2005
Messages
5,281
Location
Kansas
I’ve backflushed several vehicles with plugged cores with a garden hose. Just don’t overdue it. I’ve told the people that owed the vehicle what could possibly happen, such as a leaking heater core afterwards. I consider it a last resort, as the core should be replaced and the cooling system maintained better.
 
Joined
Jul 30, 2003
Messages
2,347
Location
GA
It's not uncommon to be able to disconnect the hoses going in and out of the core through the firewall at some point in the routing. Then it's just a matter of holding a garden hose up to each end and alternating direction until it runs clean. I'm able to do this on my car with hoses on top of each side of the engine without messing with the firewall connections which can be troublesome.
 
Joined
Feb 25, 2019
Messages
2,295
Location
Texas
I've backflushed with a water hose as well but only on old American vehicles. I don't know how the system is in a bmw. But how old or how many miles are on the vehicle. I find it very odd it could be the coolant already. Has to be something else. How does the coolant look.
 

BMWTurboDzl

Thread starter
Joined
Apr 15, 2010
Messages
8,749
Location
Atlanta,GA
A 435i? That can't be old enough for a plugged heater core unless it has 300,000 miles on it and the coolant was never changed.
Original coolant (2015/63k miles). The system does develop some deposits. I was planning on changing the coolant at year 6 (Recommended interval from BMW), but Covid and I haven't been driving it (<5k miles in 2 years). I may just take it to my shop and see what they think.

Instead of snake oil, try a tool like this:

No air.
I've backflushed with a water hose as well but only on old American vehicles. I don't know how the system is in a bmw. But how old or how many miles are on the vehicle. I find it very odd it could be the coolant already. Has to be something else. How does the coolant look.
2015/63k miles. It's not entirely unheard of with this model. The BMW system is the same as everyone else. 2-hoses lead off from radiator to the firewall where they attach the the heater core.
I'm amazed there's a valve in there at all, thought they were all removed 2 decades or longer ago
Ya. It's electronically controlled valve.
 
Last edited:
Top