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heater core replacement


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jack frausto
User

Dec 23, 2009, 1:26 PM

Post #1 of 19 (2775 views)
post icon heater core replacement Sign In

1989 chev 1500 5.7 4x4, replaced the therm but no heat. I even sprayed water into the posts of the heater core, still mounted. Reconnected hoses,ran the truck for half hour topping off the radiator along the way. Still no luck. So now I am going to replace the heater core. I have watched a few videos online on the replacement to many vehicles and a few on chevy pickups(Do I need a site with pictures or video of how to do this?), if I was to replace the heater core I think someone could simply walk me through no problem. So, if anyone can tell me the easiest, fastest, least painful way to do this replacement I could sure use it asap!Thanx.

(This post was edited by jack frausto on Dec 28, 2009, 5:16 PM)


chickenhouse
Enthusiast

Dec 23, 2009, 2:05 PM

Post #2 of 19 (2768 views)
Re: heater core replacement Sign In

Are you saying you disconnected the heater hoses and sprayed water into the heater core? If so, was it plugged up? If not, is it leaking inside the truck? If not, the heater core may not be the prob. The heater/ac door may not be working or opening. I would look into that before I changed out a good heater core.


jack frausto
User

Dec 23, 2009, 2:42 PM

Post #3 of 19 (2767 views)
Re: heater core replacement Sign In

Where are these doors located and what do I need to remove to get to them?
Water got into the truck but not a flood of water.
Used water hose with hand spray gun,spayed water into the output, water came out the other one. I then sprayed water into the input and watched water flow out the otherside. I repeated these steps afew times to maybe free up anything that maybe lodged. Like I said water was on the floor mat, just not an excessive amount.


chickenhouse
Enthusiast

Dec 23, 2009, 4:23 PM

Post #4 of 19 (2758 views)
Re: heater core replacement Sign In

O K, maybe it's time to do a pressure test. Fill it with coolant and pressurize the radiator. I think Auto Zone may have one you can use if you don't have one. Do not exceed the pressure of the radiator cap. While you are at it, the pressure tester has an adapter that will check your cap. While under pressure see if coolant is leaking onto the passenger floor mat.


jack frausto
User

Dec 23, 2009, 5:37 PM

Post #5 of 19 (2756 views)
Re: heater core replacement Sign In

ok i'll try the pressure test. Now, the core doesn't leak radiator fluid when the truck is or has been running with the heat on. Only cold air blasts out. If you could also explain to me where & how to adjust the heat/ac door. I want to check this to eliminate one more thing on the list.


chickenhouse
Enthusiast

Dec 23, 2009, 8:40 PM

Post #6 of 19 (2749 views)
Re: heater core replacement Sign In

Sure, we can try to help there also. The door is under the dash and works by vacuum when you change from heat to a/c or defrost (a/c kicks on when in the defrost mode. Electronic dash control, so when switching from one mode to another, listen under the dash for any vacuum leaks and note that the blower should switch from say defrost to lower heat. It is incorporated in the heater-a/c housing. Just switch your heat settings around and note if the door moves accordingly. Still not convinced the heater core is not leaking. Let us know what you find, we'll go from there. Merry Christmas to you and yours.


chickenhouse
Enthusiast

Dec 23, 2009, 9:03 PM

Post #7 of 19 (2748 views)
Re: heater core replacement Sign In

Replacing the core is taking the heater hoses off, take the glove box liner out. Take the bolts loose from the firewall that hold the heater box in place. Go under the dash and get the heater/ac housing to come loose from the firewall. When you get it out and on the bench, take the cover off the heater core. The core can then be removed. The pipes of the core can swivel so you can line them up with the holes in the firewall. Just reverse the procedure for install. Let us know if we can help. Others here know more than me and can direct you to any problems I missed.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 24, 2009, 3:06 PM

Post #8 of 19 (2737 views)
Re: heater core replacement Sign In

Going blind reading posts - sorry if I missed something. You said you found water on floor when flushing back and forth but not with a pressure test??

If coolant is in system - have you found coolant or plain water from flushing on the floor?

Not sure but in 89 the door that blends to a range of heat output may be a cable, not vaccuum or electrically actuated blend door. You would feel resistance moving the temp request moving a diverter door if cable,

T



re-tired
Veteran / Moderator
re-tired profile image

Dec 27, 2009, 12:04 PM

Post #9 of 19 (2715 views)
Re: heater core replacement Sign In

Good call on the cables Tom . The 89 did indeed have cable controls . The temp cable was known to break or come loose at it's anchoring clip. Here's a pic for the poster.


LIFE'S SHORT GO FISH


jack frausto
User

Dec 28, 2009, 4:11 PM

Post #10 of 19 (2692 views)
Re: heater core replacement Sign In

Thank you all for the responses. I would like to answer a few of the questions that may have confused some of you. I flushed the heater core and found water not antifreeze. The heat / ac is electronic not manual. I have not taken any of the dash apart yet, and have been driving with no heat. I do have a constant cold air blowing in by my feet. May have something to do with the 15 degrees outsideCrazy. I did feel the hoses after I tried flushing the heater core and the input was warm and the output was cold. So I am to asume the heat is going somewhere, correct? Well I hope someone can get heads or tails of this. Thanks again for your help so far.


re-tired
Veteran / Moderator
re-tired profile image

Dec 28, 2009, 5:18 PM

Post #11 of 19 (2686 views)
Re: heater core replacement Sign In

Sorry for the confusion on the controls ,my manual showed cables . But thats irrevelent if there is no heat to control. Is the eng getting up to operating temp 180-190 degree's ? You may have a stuck open thermostat.


LIFE'S SHORT GO FISH


Loren Champlain Sr
Veteran / Moderator
Loren Champlain Sr profile image

Dec 29, 2009, 5:15 PM

Post #12 of 19 (2677 views)
Re: heater core replacement Sign In

jack; From what I can tell, this is a blend door type system (no external heater control valve)...so, both heater hoses should be equal temperature at all times. If not, then there must be a blockage in the heater core. Try flushing it in both directions, several times. If this doesn't work, then.....Sorry. As CH suggested, make sure the engine is getting up to temp, as well. This engine should have a 195F thermostat, meaning, at normal operating temp, the engine shouldn't be running cooler than that.
Loren
SW Washington


jack frausto
User

Dec 30, 2009, 8:05 AM

Post #13 of 19 (2658 views)
Re: heater core replacement Sign In

Yes I have flushed the heater core in both directions multiple times. The first and least expensive thing I did was to replace the thermostat. To answer the other question about the operating temp. Yes I get it up to operating temp I have to drive the truck 40 min to work everyday. There is no sweet smell, and there is no leaking of fluid in or out of the truck. There seems to be a vent open because my feet get Ice cold from air blowing in from the heater even with it off. This is why I was looking to find the door to repair or replace. I do have a small warm feeling of air from the dash right before I try the defrost,but that is quickly replaced with cold air almost immediately.


re-tired
Veteran / Moderator
re-tired profile image

Dec 30, 2009, 9:37 PM

Post #14 of 19 (2647 views)
Re: heater core replacement Sign In

Apparentlyyou have two different post running about the same truck check my answer on other post . Hope it helps.


LIFE'S SHORT GO FISH


jack frausto
User

Jan 5, 2010, 3:04 PM

Post #15 of 19 (2626 views)
Re: heater core replacement Sign In

removed and closed the door manually and still no heat.Frown
Is there a coolant sensor, if so where is it and how do u remove and replace?

(This post was edited by jack frausto on Jan 5, 2010, 3:45 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 6, 2010, 9:41 AM

Post #16 of 19 (2612 views)
Re: heater core replacement Sign In

SEARCHED FOR Heater control valve Showing 1 - 1 of 1 parts
AutoZone does list a heater control valve?? If it has one it would be like that in pic. Not sure if so how it's controlled but hose would be much cooler on firewall side if it has this and could cause no heat or very poor heat. Long time ago - those could be electrically or vaccum actuated. AZ isn't always right - just it showed one??

Here's the link..... http://www.autozone.com/...p;_requestid=1974986


T



jack frausto
User

Jan 6, 2010, 9:00 PM

Post #17 of 19 (2603 views)
Re: heater core replacement Sign In

Well I feel like an idiot. I replaced the water pump and just removed the input hose to the heater core to see if the fluid would pump through. Wouldn't you know it there was no fluid coming out of the hose. Now I have all these new parts and one of two problems. Bad or clogged hose, or the gasket is old and the coroded pieces are blocking the flow of fluid. If these are the only possibilities please let me know as I feel I have isolated the problem.Blush


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jan 6, 2010, 10:44 PM

Post #18 of 19 (2600 views)
Re: heater core replacement Sign In

?? Hose doesn't generally clog. Getting air out can be a pill. Can you feel (careful) warm to hot coolant to and from heater core?

Tired - near brain dead for now but know that there are counter rotating engines in some of these critters but I don't think the water pump is directional - could be wrong.

Just tossing out ideas. Didn't think these were the tricky ones??

T



chickenhouse
Enthusiast

Jan 7, 2010, 4:15 PM

Post #19 of 19 (2594 views)
Re: heater core replacement Sign In

I might be mistaken but I think some of the 350's are counter rotational. What I mean is if you install a water pump on your 89 that was meant for say an 86- without the serpentine belt, the pump may be running backwards. Check to see if this could be the prob.






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