1994 Chevy S-10 No heat but heater core has been changed.

Tiny
TOMMYTX
  • MEMBER
  • 1994 CHEVROLET S-10
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 110,000 MILES
Someone had cut of the heater hoses and capped both ends off for years. No bypass was used just cap off.

I assumed the heater core was leaking due to the cap off and changed the heater core.
Still no heat.
Can you give suggestions for what I can check?

Thanks.
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Saturday, September 12th, 2009 AT 9:05 PM

6 Replies

Tiny
JDL
  • EXPERT
Did you check for flow through the heater hoses? You can take return line loose from engine, aim the hose into container, just bump the starter, don't start it, disable the ignition if you have to. There should be flow coming from the hose? Are the heater hoses getting hot?
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Sunday, September 13th, 2009 AT 11:26 AM
Tiny
TOMMYTX
  • MEMBER
Thanks for your offer to help, but I have solved the problem and boy am I confused. First vehicle I have ever seen that would not overheat with the water pump completely dead.
New water pump is installed and heating like a big dog.

For those reading here is the blow by blow:
1. Flushed out the old heater core that was removed.
2. Actually it was just fine.
3. Disconnected both hoses at the firewall.
4. Connected the hoses to the old core laying on the fender of the truck.
5. Started the motor and at 200 degrees on the intrument cluster. Zero zilch heat on the hoses or on the heater core. Okdokye I am on a roll now.
6. Remove radiator cap. After engine shutdown.
7. Disconnect both hoses from core.
8. Use water hose and flush water into hose 1.
9. Success. Water flows out the radiator cap.
10. Force water down the hose connected to top of water pump.
11. Success 2. Water flows from the cap again.
12. Fill radiator to brim and start motor.
13. Water flowing from either hose. Whopping Zero.
14. Now here is a 1/2 inch hose connected direct to the top of the water pump and zero water flow.
15. Hell even the slighest rotation of the vane of the water pump should have blown water all over the place.
16. I would never have suspected this as I have never seen a motor run with a completely dead water pump and run below 200 degrees. A first for me.
17. Change water pump. Heats like a big dog.

Has anyone ever seen this. Hell there was not thermostat so I put a new one there also. And a new serpentine belt to make it all look pretty.

If someone had said water pump while the engine was cooling just fine, I would have said Bull.

Hopefully this will help some other soul out there in the future.

Now the darn horn does not work. Must have broken a wire during the major dash rip off to replace the non bad heater core. Anyone need a good use heater core. Actually the removed unit looks relatively new. I suspect someone had replaced in the past trying to fix the heater problem with no success. So both cores are good now.

So no longer will I automatically suspect a leaking heater core when the core has been bypassed or capped off as this one was.

Thanks for the help. But I just saw your input tonight.

One final note: I purchased the one month access to the data on this truck so I guess I will not look up the schematics and parts lay out and get to work on the darn horn. Hopefully some of you nice folks will read this and comment. That will give me an email reminder that a comment has been made and I will return to tell you which wire I pinched or broke during the dash removal for the core change that I did not need. Oh well. Its done. Almost once I figure out this freaking horn thingy.
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Sunday, September 13th, 2009 AT 7:46 PM
Tiny
JOERIN42
  • MEMBER
After reading someone elses post here, I've learned that there is a series of relay switches that operate the fuel pump and/or horn located in the glove box. Maybe with your year, out on the firewall above distributor. Switch them out and try the horn, then try to start the truck. It may be your problem since your horn hasn't worked after tearing into the dash/glovebox to get to your heater core.
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Sunday, September 13th, 2009 AT 10:16 PM
Tiny
TOMMYTX
  • MEMBER
Thanks for that suggestion but the horn works now.
Actually when I reinstalled the battery as I got hit by the inspector not only for disconnected heater core, he zapped me on no battery hold down. That is why the battery was completely removed.
Ok but during battery installation I accidentally set the battery back in the case in reverse. After spreading the fat post wider to make it fit, I ended up hooking the battery up backwards. Guess what happened?
1. The horn sucked.
2. The lights cast a shadow and
3. The radio listened.

Know how I knew the radio was listening. It sat there quietly and smoked. Hee hee just kidding. Don't try this at home.

Hell it even made the engine start up rotating backward and I then had 3 reverse gears and 1 forward.

Ok. Enough with the jokes. Back to the horn and another more weird problem than with the bad water pump.

In investigating the failed horn, I dived under the dash again with the following results. Previously while under the dash I had a left flasher lite out and so I replaced that one. Also I had a steady lite on the dash saying "anti-lock" problem. The inspector did not fail me for this, but since I had to go back for the re-inspection I did not want that staring him in the face. So I removed that bulb so it don't stay on. Some how that completed a ground somewhere to the horn, becasue when I put the bulb for antilock back in the horn worked. But now I got the antilock light again. So I replaced the good bulb with the burned out buld I removed from the left turn light and bingo I now have no antilock lite and the horn is working fine. Bingo.

I am not suggesting anyone do this, as it is a safety violaton to disable the anti-lock lite. And I am not teaching law breaking. As I am not a member of ACORN.

K- let me qualify this. Just in case someone is very knowledgable and says bull. The flasher lite will not fit in the slot for the anti-lock socket. The actual work on this was done by my mechanic. And I also though it weird, but he did not charge me as he said the horn fail was caused by himself.

IF anyone knows or has ideas please enlighten me as I am not sure I believe that whole story, but he had no resason to make it up. Either way I did not pay for the service.

Also I think I got a pretty good deal as professional shops claim 7.5 hrs for the core change. And most charge from 60 to 90 dollars and the chevy dealer is around 110 an hour. I paid 250 + parts. I think that is fair. If you are in the Norfolk, Va area and need a quick core change even if its not bad get a hold of me.

So what the hell I got a new core and new water pump. Live and learn. So as the story goes. Never assume obvious (most likely).
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Monday, September 14th, 2009 AT 8:16 PM
Tiny
TOMMYTX
  • MEMBER
While I am on a roll, let me give some well learned advice that I learned from the very expensive lesson where I paid 250 + parts and most of you would pay 450 + parts. To change a totall good core when the actual problem is water pump.

So why the hell would anyone change a core when the water pump fails.
1. Core was bypassed. Almost always means the core is leaking into the passenger compartemnt. Wrong.
2. The engine temp had been completely normal around 225 max for the last year even during 100 degree outside temp.

3. But I learned one hell of a lesson. Never make obvious assumptoins. Instead. Test. Test. Test.

Now here is what I should have done.
1. With engine at normal temp touch both hoses to the core. With heat on both should be similarly hot.
One may be slightly hotter than the other as it goes into the core and comes out the other may cool slightly.
2. If the entire engine compartment is extremely hot this may be a difficlult test. To determine.
3. But never buy a core until you do this.
4. Wait for the engine to cool, or pour cold water on the hoses. Messy. To speed cooling.
5. Remove the hose at the firewall (where the hoses connect.) The larger of the two. Normally the small is in and the fat is out.
6. OOPS! Watch out. Any water coming out may be rusty and if you are on the drive or in the garage. The wife will beat the living hxll out of you as that rust will stain anything.
7. Take a water hose and force water into the small host. And you will see water come out of the core where you removed the hose. It may be slow but should be a steady flow. Watch for the rust flying out its bad on the eyes so apply the water slow at first.
8. After the rusty water is purged the water shoud become clear. May take quite a while to get clean.
Again might be a little slow as it is being forced thru tiny vanes.
9. So what is going on. You are forcing water into the small hose which should be connected to the water pump which will go thru the pump oh what the hell I just realized it your engine is cooled down your thermiostat will be closed and my not go thru.
10. A better way would be to disconnect both hoses and purge the core both ways to make sure all is well. If the core allows water thru without leaking in the car it should be ok. As that is all it does.
11. Hell I am tired of writing. Just go back to my initial troubleshooting above as it give a step by step test. That should be done before changing the core not after.
Bye for now.
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Monday, September 14th, 2009 AT 8:34 PM
Tiny
TOMMYTX
  • MEMBER
Hey CarPro Guys. You are on a roll. Only been posted for 2 days and you are now #1 on google for the search term "1994 Chevy S-10 No heat"

I wish to hxll someone had written this before I got here. But maybe it will help someone else. Actually I a not a mechanic, I am a Web designer for Real estate agents and you can find me and thanks again for setting up this web site. I did not do a donation yet but I will, and I did buy your auto repair data for this model car and I do recommend anyone having problems its worth the 15 bucks to have access for a month.
I will keep coming back as I have more problems. Thanks again Carpro guys.
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Monday, September 14th, 2009 AT 8:41 PM

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