Preparing to Remove Dash to Replace Heater Core
in the house
Joined: Jul 2010
Posts: 5,139
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From: Kansas
Post mortem it made sense to you...you should have simply employed that line of thinking earlier, e.g. "heat was working fine prior to repair, ergo problem is DUE to repair...so what changed". I have found that using logic paths like this ultimately shortens up the diagnostics. But then sometimes in your head you 'add 2 and 2 and get 5', and are going down the wrong path from the get-go.
Personally that mechanic that put it in would be wearing it as a butt plug, especially considering the attitude he copped with you!
Personally that mechanic that put it in would be wearing it as a butt plug, especially considering the attitude he copped with you!
Captain of Industry
Joined: Nov 2011
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From: Arklahoma
Post mortem it made sense to you...you should have simply employed that line of thinking earlier, e.g. "heat was working fine prior to repair, ergo problem is DUE to repair...so what changed". I have found that using logic paths like this ultimately shortens up the diagnostics. But then sometimes in your head you 'add 2 and 2 and get 5', and are going down the wrong path from the get-go.
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Joined: Feb 2012
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From: SE Michigan
Senior Member
Joined: Feb 2012
Posts: 3,770
Likes: 2,178
From: SE Michigan
Didn't need to take apart dash to change heater core after all. The mechanic who installed VVT Solenoids had to take off the manifold covers. To make it easier he took off at least one heater hose that was in his way. I believe it was the output of the heater core. I am a little confused as to where the outlet of the heater core goes to, but I believe it is over by the thermostat housing. In any event, when he took off the hose (opposite side of where it connects to the heater core) he used a plug (see attached images) to make sure nothing falls into the port, a thoughtful gesture. However, after reinstalling the manifold cover he reinstalled the heater house but forgot to take the plug out. The day after he worked on it I took my truck back to his shop and told him that I lost all heat after he did the work. The heat was working fine before he worked on it. He told me it was nothing he did, then suggested I get a new thermostat. I thought it was quite a coincidence that the thermostat would go bad right after he worked on it. He admitted to taking the hoses off to do the work. After changing the thermostat and still having no heat I was sure he introduced air into the system, which was now blocking the flow of coolant through the heater core. Diagnostically I would always go back to that fact that the heater core outlet hose was cold to the touch telling me it was not the blend door and definitely some sort of clog, like an air bubble lodged in the system. To make sure the issue was not a clogged heater core i flowed house water (50 PSI) through the heater core in both directions, eliminating the chance it was a clogged heater core. No way would I have thought he clogged the line. I was sure it was a pocket of air. I tried a few different ways to purge any air in the system (including draining and vacuuming in coolant) but failed each time. I was completely baffled as to why I couldn't purge the air out. The mechanic who found the plug (not the mechanic who left the plug in) told me before he started that he was going to first take off the degas bottle. In no time he found the plug left in the hose pipe. I am trying to learn from this mishap. Can someone please tell me what I could have done to diagnose the coolant system (no heat was the symptom but would feel a touch of heat when revving at high RPM and cold outlet hose coming out of heater core) to immediately find the plug at the end of the heater core outlet hose (furthest away from the heater core)? Thanks...
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Joined: Sep 2022
Posts: 248
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From: Burlington, Vermont
Thread Starter
Senior Member
Joined: Sep 2022
Posts: 248
Likes: 14
From: Burlington, Vermont
Post mortem it made sense to you...you should have simply employed that line of thinking earlier, e.g. "heat was working fine prior to repair, ergo problem is DUE to repair...so what changed". I have found that using logic paths like this ultimately shortens up the diagnostics. But then sometimes in your head you 'add 2 and 2 and get 5', and are going down the wrong path from the get-go.
Personally that mechanic that put it in would be wearing it as a butt plug, especially considering the attitude he copped with you!
Personally that mechanic that put it in would be wearing it as a butt plug, especially considering the attitude he copped with you!
Thread Starter
Senior Member
Joined: Sep 2022
Posts: 248
Likes: 14
From: Burlington, Vermont
How would I go about my diagnosis to find the plug in the hose? It was so well concealed. I never expected something like that from a professional. The chances of that happening were so remote I ignored that scenario and moved on. Thanks for your feedback!
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Joined: Sep 2022
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From: Burlington, Vermont
Paragraphs needed in long posts
Thread Starter
Senior Member
Joined: Sep 2022
Posts: 248
Likes: 14
From: Burlington, Vermont
The IP sure is easier going IN rather than OUT. This was my 2015 being assembled. That's the HVAC unit bolted to the firewall before the IP is installed.
https://youtu.be/pExCIOu4m-Q?si=W6jYmku4MkCfD_yK
https://youtu.be/pExCIOu4m-Q?si=W6jYmku4MkCfD_yK