... why a clogged or corroded heater core would stop heating on the drivers side first as it ages, starting with the defrosters and working it's way down to the foot heaters? This seems to be a very consistent problem with X-350's including my 05 SV8. How can it blow ice cold on the defrosters and face vents and still be warm(ish) at my feet (the passenger side is very warm at the feet). The heater core has one inlet and one outlet so if one part is clogged wouldn't that block the hot water flow in the entire unit?.

It also doesn't make sense to me that air for different parts of the cabin flow over different parts of the heater core. Doesn't all the air flow over the entire core and then get blended to the different vents? If the problem is scale and corrosion building up on the inside of the tubing why would it always build up in the same areas of the heater core from car to car?

The Aux heat pump has been replaced so should I just replace the heater core and stop overthinking it?

Thanks
Jeff

P.S How do I set up my profile so my car model shows beneath my name??

 

Did you test/replace your auxiliary water pump located on the passenger side of the radiator yet?

I have the same problem and my pump is not working. It's a 100 dollar part. The brushes go back inside the dc motor.

Coolant cant get around like it should behind your dash and you loose that hot heat.

 

The Aux heat pump was replaced 11 months ago.

 

 

The Aux heat pump was replaced by the previous owner. I've only had the car for 2 months. If I turn off the auto climate and just run the floor outlets at 80 degrees setting I can survive NY winter down to about 20 F. If I were to let it run on auto mode I might as well open the windows.

 

I now resolving same thing. I changed aux pump a year or two ago.. now problem is back. Flushing system is useless - system is absulutely clean like it came from the factory Btw always thought it is a nonsense as the there is no way to get any dirt into but just flashed it to firmly beleive. Now i think it is a wiring problem in my case as i got some other electrical issues with this. Will report back as soon as fix it.

PS as temp fix you can drive in manual on 2 or 3 gears limiter as i do. Aux pump is just needed on low rpms and idling. When you rev it heat is going back.

 

The only answer is to replace the matrix and saw the old one in half (or more).

Post the results please I have wondered about the same thing. lol

 

The plain fact is that the matrixes clog up. There was once a photo of one sawed in half on this forum but some years ago. The clogging still allows coolant through but there is no longer enough surface area available for enough heat to be transferred. Radiators can be similar, in that coolant still circulates, but doesn't transfer enough heat to cool the engine.

 

Sure seems there should be a product of some sort, to dissolve the build up.
Disconnect both ends, fill, let set a few hrs.
Then back flush things till clear with distilled water.

 

Here's my old one cut open:



As I understand it the airflow is split between drivers side and passenger side, hence why the blocked part causes no heat to just the drivers side. In RHD vehicles the matrix is mounted with inlet/outlet pipes to the left side, and reversed on LHD vehicles, so it's always the drivers side that suffers irrespective of whether the car is LHD or RHD.


Ben

 

I have used trhe CLR (Calcium Lime Rust) product for this purpose.with success, but have not yet tried it on an X350. On other vehicles I've disconnected the heater hoses at their ends furthest away from the heater core and blown out as much old coolant and sludge as possible with moderate compressed air pressure. Then I've tied the hose ends up to the hood, stuck funnels in each hose and slowly poured CLR into both funnels until it pooled in both funnels. Let it soak for 30 minutes, untie the inlet hose and stick the end in a catch jug, then flush with multiple fills of distilled water poured into the funnel at the outlet hose followed by compressed air. I don't know if this method could unclog a core as badly plugged as Ben's, but it might be worth a try given the alternative of having to replace the core. You just have to pray you aren't going to open any pinhole leaks in the core.... CLR is not recommended for use on aluminum or brass, so that's why I limit soak times to 30 minutes. Use at your own risk.

Cheers,

Don

 

Don B wrote
I have used trhe CLR (Calcium Lime Rust) product for this purpose.with success, but have not yet tried it on an X350. On other vehicles I've disconnected the heater hoses at their ends furthest away from the heater core and blown out as much old coolant and sludge as possible with moderate compressed air pressure. Then I've tied thei hose ends up to the hood, stuck a funnel in the outlet hose and slowly poured CLR in until it began to pool in the funnel. Let it soak for one to two hours, untie the inlet hose and stick the end in a catch jug, then flush with multiple fills of distilled water poured into the funnel at the outlet hose. I don't know if this method could unclog a core as badly plugged as Ben's, but it might be worth a try given the alternative of having to replace the core. You just have to pray you aren't going to open any pinhole leaks in the core....

What kind of vehicle did you use CLR in?
Want to make sure it won't harm the aluminum, if that is what the core is made of.
So many things are not agreeable with each other.
Have wondered about this as a cure since i bought the 04.
Bought it in warm weather, heat seemed fine, air blew cold on the way home.

 

A wide variety including a Jaguar XJ40. I'm sure some or all of them had aluminum heater cores, but you're right to be cautious of unwelcome interactions. CLR is not recommended for use on aluminum or brass, but by limiting soak times to 30 minutes I've never had a problem. Use at your own risk.

 

Honda has a repair bulletin to flush the heater core for this reason too. You run clr from a container with a pump hooked up to the heater core. Just replaced mine last year and mine was clogged wa worse that pic above. It eventually quits heating on both sides when fully clogged. The drivers side is on the end of the core that gets clogged first because it is like being on a dead end street and the sediment collects at the end of the city water line and never gets flushed out. What i delt with at my last house till they looped it around to another street. My feeling is the core is not that much and if you're going through the trouble to access why not just replace it and be done being sure its totally clean.