Request a cross check on heater plumbing

Guys

Before I tear into the heater plumbing, take a look at my schematic. I can measure 140 degree heat on the engine side of the 4 way valve but on 60 on the heater side. I see the motor on the diverter valve move when I turn the switch, but it still stays cold on the heater side of the lines. So before I open the lines up, does anyone see a plumbing issue with the hoses from the water pump in/out, through the 4 way to the heater core and back? I was told it makes no difference which direction the water enters/exits the heater core, but the in out lines from the engine to the 4 way are important.

I think the 4 way valve may be stuck closed.


LS3 Heater Hookup v2.jpg
 

Joel K

Supporter
Dan,

Base on this diagram I found, do you have the heater inlet/outlet on your water pump reversed?

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Joel

I hope not. Based on the LS engine forum, they have a schemtic that shows the smaller 5/8 tube is the pump outlet and the 3/4 is the inlet. That is opposite the picture you have. So now I have a mystery. Where did your picture come from?
 

Joel K

Supporter
Sorry Dan, that info may not be reliable and I don’t really know. I was just trying to help and did a search. I found another diagram of an ls3 water pump flow and it shows the opposite. I think that diagram before may not be an LS3 water pump. So, I’ll defer to someone else on this topic.

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Not an issue Joel. I found that same article on Pirate 4x4 and found it Interesting and see the picture above is in this article. Note that their very next picture describes the front view of a pump labeled with the small 5/8 line as the out side of the pump. I think they labeled the backside picture incorrectly, that being said, I presume my plumbing is correct and that will require me to investigate the four way. Unfortunately for me it’s located in a very tough spot to reach with the body on. Just my luck......worked one minute and at the worst possible time, may have failed. I’m going to have use a bore scope to see if the internal flapper is opening at all. And I thought I was nearly finished........
 

Ken Roberts

Supporter
Looks like you have it hooked up correctly Dan. Here is a quick sketch of the internal flow path. The picture in post #2 is incorrect. The 3/4" barb is the return.

IMG_2262.JPG
 

Ken Roberts

Supporter
I had a car back in the early 80s that had the heater hoses to the core hooked backwards and had poor flow/little heat. A garage changed out the engine and hooked them up backwards. I reversed the hoses and got full heat. Your picture in post #1 shows the hoses from the 4 way valve to the core as being backwards compared to my sketch (heater out/heater in). I can't explain why it made a difference which way it flowed through the core in my case.

The mini slimline instructions specifically state the lower pipe is the inlet and the upper pipe is the outlet (at the heater core).
 
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Ken. Thanks for that internal sketch. Yes my heater in out labeling is incorrect. I need to trace the upper lower core hoses, I don’t see why that matters, but it’s their system.

Thanks
 
Gents

Thanks to Ken, I did my due diligence on the four way valve and discovered that the set screws between the motor solenoid and the flapper door was never tightened sufficiently at the factory. The motor and valve had gotten out of synchronization. If you ever have an issue with your heater this is something to check. Also Ken discovered that my top drawing had an error in labeling of the in out tubes of the four way valve, so I corrected it and added IAW Vintage air on page 9 (Heater Hose Installation), the upper hose on the Slimline is the inbound connection and the lower tube is the outbound. Not sure why it makes a difference, but it must, so I labeled the drawing as such. Honestly, I got lucky with the plumbing as it was installed correctly, and finding the valve motor/valve not working as advertised should solve my problem.



LS3 Heater Hookup v2.jpg
 
Sorry, I got the inbound/outbound words wrong in the text #10. Bottom slimline to the intake, top slimline back to pump. Drawing is OK, and I now have heat. Must of gotten up too early to post that morning. My error. But do re-read Slimline instructions page 9 so your sure.
 
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