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no heat ? flush heater core ?

24K views 20 replies 12 participants last post by  pharmgdb 
#1 ·
hey guys, my 93 grand cherokee doesnt have very warm heat. It has new heater hoses, new coolant and a new 195 degree thermostat, its leaking a tad bit of coolant from the drain **** but nothing to get in a pinch about.

I am thinkin maybe my heater core is possibley plugged up, what would be the best way to flush it ?? i was thinkin of removing the heater hose lines and using a pressure washer ?? but would a pressure washer cause damage to the heater core?? i dont wanna pull the dash at all...i just want to try to flush it out , i have tried with a garden hose twice, the heat comes back for 1 day good as new, then slowly fades,

any ideas on whats the best way to flush the heater core guys ?

also could the rad cap have anything to do with temp of heat ?? like pressure in the system ?? my dad put a different rad cap on it cause the old ones spring was weak and leaking a tad bit of coolant ?? could a cap be the cause of no heat ??

also the jeep gets up to operating temp everytime i drive it , and there are no overheating problems what so ever.
 
#2 ·
anybody chime in ?
 
#3 ·
jeepunlimited said:
hey guys, my 93 grand cherokee doesnt have very warm heat. It has new heater hoses, new coolant and a new 195 degree thermostat, its leaking a tad bit of coolant from the drain **** but nothing to get in a pinch about.

I am thinkin maybe my heater core is possibley plugged up, what would be the best way to flush it ?? i was thinkin of removing the heater hose lines and using a pressure washer ?? but would a pressure washer cause damage to the heater core?? i dont wanna pull the dash at all...i just want to try to flush it out , i have tried with a garden hose twice, the heat comes back for 1 day good as new, then slowly fades,

any ideas on whats the best way to flush the heater core guys ?

also could the rad cap have anything to do with temp of heat ?? like pressure in the system ?? my dad put a different rad cap on it cause the old ones spring was weak and leaking a tad bit of coolant ?? could a cap be the cause of no heat ??

also the jeep gets up to operating temp everytime i drive it , and there are no overheating problems what so ever.
With the engine up to temperature, feel the heater hose to see if they are hot. If they are, you are getting a flow thru the heater core & flushing will not cure the problem.
You can flush the heater core via the heater hoses, but DON'T use a pressure washer, or you'll be soaking up water from the passenger's floor, after you blow out the heater core. Use a garden hose & don't do anything that could build up pressure in the system > ~18#.

In my opinion, you probably have an issue with the positioning of your mixing/blend doors. The heater core is getting hot, but the air isn't being channeled into the cabin.
 
#4 ·
Are you getting any air flow from the vents at all?
 
#7 ·
i get air through the vents all the time, just sometimes it isnt hot, the heater hoses are burning hot, i cant hold them for very long at all, and they are both hot as hell...feed and return to the heater core

how would i go about checking the doors to the cabin ?? is there a way to open them to heat and leave it on it , like dissconnect the doors soo they cant close ?? is there any way i can work with the doors to get maximum heat out of it , i dont have AC soo im not worried about it , the old owner removed the AC compressor and idont mind not having ac at all, i just want heat!!!

would there be a explanation as to why it wont be that warm but then after driving it for a bit, it starts to heat up the dissapears again when i shut it down and start it back up ???? , would the digital unit in the dash have anything to do with doors not opening correctly ?? or should i dig under the dash to figure it out

also the positioning of the heat doesnt change at all, if i have it on floor, its on the floor, if i have it on defrost, its on defrost , , doesnt move the air flow until the dial is turned

any help would be great

thanx guys
 
#11 ·
Google is your friend Clash - search finding a vacuum leak and you'll find loads of resources.

Search the forum too.
 
#15 ·
So.....I know this is a really old thread, but i have to ask.....what do you do if the previous owner put a few (more than 2) tubes of stop leak in there? ...my buddy is having this problem right now. Thermostat was plugged up, heater core is plugged up...there was even a glob on the back of the radiator cap....WOW..... is there an easy solution to clean all that crap out so that the heater will work again
 
#16 ·
I know this is an old thread but I was having issues with engine temp and overheating. I replaced my fan clutch, thermostat, water pump flushed the radiator. Still had issues so I replaced the radiator. This seemed to resolve the issue but I was getting no heat inside. I removed the hoses going to the heater coils but could not put water through. I ran water from the other hose and this forced brown sludge to come out. I kept flushing by alternating the hoses to input water till clear and I could not see much brown water after several alternating flushings. The heater works very well now.
 
#18 ·
If your careful not to leave it in very long, I have had great results with running CLR through to clean out my heater cores. Its best to disconnect the entry and return lines to limit the exposure of the CLR to just the heater core itself, don't run it through your engine. 5 minutes of soaking will do wonders for your core flush.
 
#19 ·
It is easy. my hose has a nozzle end that rounded so it sealed well on the end of the heater core hoses. At first I could not flush in the normal direction of flow, it was blocked. I flushed from the other end and brown muck came out. I flushed till clear then flushed from the other hose until it was clear. I kept alternating untill I did not see the brown. Heat is wonderful when you need it. I would like to do something like what dirtybobby423 described but it worksnow so I will wait till it is broke to run the chemical cleaning. I have other projects taking priority. Paint job, and I think I will do a bearing job. there are some squeaks so I will try to narrow it down. The sway bar links were part of the issue but not any more. Take care.
 
#20 ·
Had the same problem and here is how I fixed it even though it was pressurized.

I was having hot air for a while and then it started blowing lukewarm so what I did to fix it is disconnected my lower radiator hose to let all the coolant out and then I disconnected the heater core lines and blew it with some shop air huge compressor. The most brown I have ever seen come out of any car looked like a crime scene. After about 2 weeks I did it again and all is good now. Everyone said to replace it but if I was going to anyways I figured why not give it a shot and it worked

Just remember to burp your lines and park on a steep incline and pinch your hoses to get all the bubbles out

Quick edit I also flushed in both directions normal flow and reverse
 
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