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Mike V.
Mike V., Auto Service Technician
Category: Car
Satisfied Customers: 25667
Experience:  25 years of experience, Certified Subaru Technician and Nissan factory trained.
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voyager: heater core hoses, and flush the rust/debris

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1993 Plymouth Voyager 3.3 - My heater stopped heating all of a sudden. I get a bit of heat at 1st, but that dissipates quickly. I have been advised to remove the heater core hoses, and flush the rust/debris that might be blocking the heater ports. Another shade tree mech. advised me to reverse the hoses, but I think this is bad advice, because debris would just be relocated to another area (radiator) and cause further problems. any Advice, thanks!
HI there! If you feel the heater hoses going to the heater core in the firewall are they hot?
Customer: replied 8 years ago.
I have not started the troubleshooting, yet. I will start the car now.

I did read that they should both be hot. BRB
Before you start the car,make sure the coolant level is full in the radiator and overflow jug.
Customer: replied 8 years ago.
Ok. Car is warming up. Only needed antifreeze in reservoir

Do I need to have heater on or off when checking these hoses.
ok. do you get any heat when going down the road or just that quick little bit and that is all? Also, is the van running at normal operating temps? I know it's alot of questions!
Customer: replied 8 years ago.
No heat on road...Just a little bit. Van operates normally.

Ask away. Going out to check those heater hoses now
ok let me know on those heater hoses when you can. Thanks
Customer: replied 8 years ago.
Motor is still cold to touch, So of course hoses are still cold. waiting another 10 minutes, then will message you back.

Don't go away

You didn't say whether I should have heater on or off

Heater on would be best. Want to make sure you have hot coolant making it to the heater core. I'll be here.
Customer: replied 8 years ago.
Well such is my luck. while inside chatting with you, my serpentine jumped(bad frt main seal)off pulley's. I just changed to old clothes in order to re-install. Greasy arms you know. Back asap, OK?
Customer: replied 8 years ago.
I have got the serpentine back on. what a mess. It jumped because after I filled the coolant tank it overflowed making belt super greasy.
Anyway; belt back on and as far as heater hoses.

They are still cold to the touch. shouldn't 10 minutes or so be long enough for this test/

So for re: temp gauge says dead center, (normal), engine is heating. Coolant seems to be warm/hot, but heater hoses at firewall are cold.

going back out to make sure belt hasn't jumped again, and to check hoses once again.
awaiting your reply, thanks
OK. Check the other hoses, at least upper radiator hose and see if it is getting hot. Also, give it some gas and see if the heater hoses start to get hot. Let me know. If the van is at operating temp those hoses should have some heat.
Customer: replied 8 years ago.
Upper hose is hot, will go rev engine, and come back.
Customer: replied 8 years ago.
Upper hose is hot, will go rev engine, and come back.

Drove van around the block. Looking into engine compartment from the front...Left hose that has a valve or vacuum device is starting to warm up. the right side hose Plain hose, no interruptions, is cold!

sounds like a clogged core, huh?
OK, that vaccum device is the valve that opens to allow the coolant into the heater core. Make sure there is vaccum and get a helper to change from the heater coltrol from hot to cold. You should see a lever moving in there. If you are not getting vaccum when you switch it will not move the lever. Sorry, I don't have a diagram to help. I am doing this from memory. I have seen alot of these valves go bad and not switch over. The other hose is cold because it isn't letting anough hot coolant into the heater core. You may be able to manually move the lever to determine if we are correct. Let me know!
Customer: replied 8 years ago.
OK. 1st I have vacuum at valve. Changed lever on control from hot to cold and back, could here a door??? opening closing, and the lever is moving in out when moving from hot to cold...
OK. If there is no change in the heat,then either the valve inside the hose is hot,or the heater core could be plugged. You can try back flushing the heater core and do not just hook the hoses up backwards. Actually disconnect them both and use a garden hose. I tend to lean more towards the valve based on the fact it happened to you so quickly. If the back flushing doesn't work then pull the valve and take a look at it.
Customer: replied 8 years ago.
.Well I pulled the hoses from core, but my garden hose is frozen. I am going to accept your answer, because you basically confirmed what I was aware of, and I believe it comes down to the valve. When I pulled hoses, there was no debris, and as an afterthought, as you say it happened suddenly instead of providing poor heat before failing, so I am buying a valve, and if I have a problem after that, I will come back

Peace God Bless, Roger

p.s. I wanted to say thanks. I was surprised at how well this went.

I will leave you an excellent feedback, I learned a good deal of useful info today. In these tight times, doing my own car repairs, I will gladly pay for this service, on occasion.

rsvp, and I will "accept" thanks carguy

Thanks for the kind words. I am glad to be able to assist you with your car! Thanks for using JA and God bless to you as well.
Mike V. and 7 other Car Specialists are ready to help you
Thaks so much for the accept and the bonus!! Have great day!