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since you could not drain the block due to the KS being locked in place then the core may be restricted again so remove hoses from the block and using a water hose and a bucket to capture the coolant see if crap comes out .. IF crap comes out of the heater core then you best get 2 new KS and take out the seized ones flush out the block and do not use any drinking water MUST USE distilled water only.. also if it is crapped up make sure the pressure cap is working properly these can cause high pressure effecting coolant flow.

very possible the KS were installed with some loctite ... the first time I removed them that was tough because I noticed some coating on the threads. hard coating..
I use a white Teflon paste on the threads and the amount is very small and thin but I do not have to tighten them down much about 10ft lbs snug never leaked and easy to remove every 3-4 yrs........
if this is not with any crap then the temp door may not fully move could be something got in there like acorns etc...
 

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Discussion Starter #22
J Cat,

Destroying old knock sensors could be a good idea, but I am pretty much done with the repairs this year. The heat issue will have to wait. Will check out the operation of the air mix door, though for it is an easy job. Will report back if I find out something interesting. Thanks again for the advice!
 

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Happy

I am so happy with my VERY HOT HEATER,2 years ago I flushed the core then installed a water filter and reversed the flow...Old hot head
 

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Dont scold me if it was covered, but have you tried taking the glove box off the dash to check the blend door actuator function? It has a little index on it to show heat 50/50 and cold. So it's easy to tell if it's working or not.

Per your statement, '...at 90 I get some heat, and 60 I get much less heat...'

Do you have the AC on? Or is it turning on?

Reason being, at 90, I'm pretty sure the AC gets turned off(CC vehicles) and at 60 the AC is on. So if your blend door is stuck(seized up a little), like mine just did the other day, the door might be stuck in some mode between hot and cold and the difference in vent temp is because the AC is on or off. All you have to do is pull the glove box off and tap the BDA with a metal something and it will probably go to working. It's what I did to mine. Now I do know I will have to replace the BDA at some point because getting stuck is usually what they do right before they fail entirely.

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Discussion Starter #25
Dont scold me if it was covered, but have you tried taking the glove box off the dash to check the blend door actuator function? It has a little index on it to show heat 50/50 and cold. So it's easy to tell if it's working or not.

Per your statement, '...at 90 I get some heat, and 60 I get much less heat...'

Do you have the AC on? Or is it turning on?

Reason being, at 90, I'm pretty sure the AC gets turned off(CC vehicles) and at 60 the AC is on. So if your blend door is stuck(seized up a little), like mine just did the other day, the door might be stuck in some mode between hot and cold and the difference in vent temp is because the AC is on or off. All you have to do is pull the glove box off and tap the BDA with a metal something and it will probably go to working. It's what I did to mine. Now I do know I will have to replace the BDA at some point because getting stuck is usually what they do right before they fail entirely.

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Smelonas,

Thank you for the input. I know how the airmix door operates and it is fine. The issue is clearly the heater core getting clogged within a couple of days after flushing.
 

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The issue is clearly the heater core getting clogged within a couple of days after flushing.
If this is true, you may need to remove the knocksensors / drainplugs during your next flushing to really get the crud out of the system.

Just in case, some people only flush in one direction. Especially with our cooling systems, it's worth the extra trouble to backflush, then flush, then backflush.
If you're also removing the knocksensors, this should clean it out really well.

Lastly, I [and others] very highly recommend
RMI-25.
 

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Smelonas,

Thank you for the input. I know how the airmix door operates and it is fine. The issue is clearly the heater core getting clogged within a couple of days after flushing.
Glad to hear you have the problem pinpointed.

I used some aggressive cleaning to get my system to clear up. Between a backflush tool, removing the reservoir several times for cleaning and adding a coolant filter to my system, I have achieved relative cleanliness in my engine. A TON of stuff came out of my motor over a couple weeks of cleaning.

I suggest adding a dedicated coolant filter to keep any and all contaminants cleared out. The coolant was cloudy even after many attempts to get it clean, but the coolant filter changed all of that.

I have never removed the knock sensors on my car either. But I did every thing the long, lazy, easy way.

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