Rear heater cooling the engine coolant?

gezzza · Post by **gezzza** » Tue Jan 24, 2017 7:29 pm

I have removed the entire pipe system from both front and rear heater and my L300 runs great. The weather has been 35c-95f and my inline hose temp sensor has read up to 100c-212f on some long mild inclines then stabilises at around 80-85 when highway cruising. I put in a brand new 3 core rad from ebay and re lubed my visc fan. I did lose a litre of water from a recent trip and could straight away notice the slightly higher temps but I continued to drive the extra 150km. Topped up, all is good again (touch wood).

204explorer · Post by **204explorer** » Wed Jan 25, 2017 5:35 am

Did you ever check how much coolant is actually flowing (from the outlet of the rear heater core). If your heater valve is closed or the core is partially plugged, you get a big difference between the inlet and outlet hose but since there is next to no flow, there would be no impact on engine temperature.
I don't have any L300 experience, just talking in general.

Sent from my SM-G920W8 using Tapatalk

Furi · Post by **Furi** » Wed Jan 25, 2017 12:21 pm

Thanks both for the feedback.

So the long story is that I removed the controls in anticipation of removing the heater/AC. And I didn't check/remember what the setting was before removal. I tried to find out if the valve is open by default or does the heater setting in the cabin opens the valve ; but haven't been able to verify that. But what you said makes sense though. I'm in process of connecting back the controls and testing again with different settings. Also taking a look at the manual to see how the rear heater coolant flow functions overall. To verify if the valve that is controlled by the cabin control in the back heater? Or is that valve more part of the front assembly that allows the coolant to flow to the back heater and back.

sealica · Post by **sealica** » Tue Jan 31, 2017 12:02 pm

Hey I'm just wondering if you can access the rear heater / blower from anywhere besides the bottom of the van? I saw reference to a floorpan removal "group 52" in the shop manual for the heater systems, but can't find group 52 manual.

Is there such a thing as access from the inside of the van floor?

Post by **Growlerbearnz** » Tue Jan 31, 2017 5:10 pm

From memory: not really. Removing the side panel will get you to the ducts, but the bulk of the heater is under the floor, and has to be removed from below.