1989 Dodge Caravan Heating issue

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  #1  
Old 12-12-11, 06:46 AM
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1989 Dodge Caravan Heating issue

I have a 1989 Dodge Caravan with the 3.0L engine.
My problem is that the engine doesn't heat up sufficiently for the heater to be very effective.... and we're in Michigan now.
I thought the problem might be that the thermostat was stuck open. So I put in a new thermostat yesterday but I'm still having the same issue. The temp gauge stays closer to cold than in the middle of the range.
Because of the anemic heat coming out of the heater I'm almost sure the problem is not the temperature gauge sender.
I'm assuming the heater would work better if the engine were at the normal temperature.
Any thoughts as to why the temp is staying low???
 
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  #2  
Old 12-12-11, 07:14 AM
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Just a thought....does it have an electric fan or maybe two? It shouldn't be running most of the time. If it is, it will overcool. Normal problem is it WON'T run...but it could be on all the time.
 
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Old 12-12-11, 07:29 AM
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Hi. Thanks. One of the fans was replaced back in September. I was told it wasn't working.. the normal problem, as you said. Don't know which one they replaced.
I'll take a look and see if they're always running. Thanks.

Originally Posted by Gunguy45 View Post
Just a thought....does it have an electric fan or maybe two? It shouldn't be running most of the time. If it is, it will overcool. Normal problem is it WON'T run...but it could be on all the time.
 
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Old 12-12-11, 07:58 PM
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take piece of cardboard, wide enough to cover half radiator, and fix ti to it. old Russian way. we used to have manually operated "blinds" in front of radiator, to control cold air flow.
of course, this is just to get you by.
did you purge air out of the system after t0stat replacement?
 
  #5  
Old 12-12-11, 08:27 PM
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If in fact the coolant is getting sufficiently hot enough the next place to think about is having a partially blocked heater rad. I am thinking that this is still a very good possibility and the level on the temp guage may not be telling the real story around the lack of cabin heat. This is a pretty old vehicle. When was the last time the entire system was flushed properly and coolant replaced? How many times has it been flushed and cleaned out in the past 20 years? If it really is coolant temperature related and this is also not caused by a fan running issue as Gunguy45 mentions, it could potentially be that there are parts of the engine actually getting too hot due to poor circulation of coolant from passage blockages, and because of this the coolant itself is not heating up enough to bring the operating temperature up to the 190 deg or so that it should normally reach. In my opinion unless the coolant system has recently been flushed, I would have it done, and separately flush and backflush the heater rad. This could solve either or both of the above issues if you have them.
 
  #6  
Old 12-13-11, 06:33 AM
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I noticed yesterday that the temperature gauge was creeping up from the COLD line to just below the normal range. Then it would drop quickly back down to the COLD line. Seems like it now cycling like this. I haven't turned the heater on to see what the temperature is like when this happens. The radiator fan doesn't come on when I first start the engine but it was running when I got home yesterday... normal. I might experiment with disconnecting the fan and see what the temperature does.
I don't remember when the cooling system was flushed last. I may take it in next week and have that looked at.
Originally Posted by equinox View Post
If in fact the coolant is getting sufficiently hot enough the next place to think about is having a partially blocked heater rad. I am thinking that this is still a very good possibility and the level on the temp guage may not be telling the real story around the lack of cabin heat. This is a pretty old vehicle. When was the last time the entire system was flushed properly and coolant replaced? How many times has it been flushed and cleaned out in the past 20 years? If it really is coolant temperature related and this is also not caused by a fan running issue as Gunguy45 mentions, it could potentially be that there are parts of the engine actually getting too hot due to poor circulation of coolant from passage blockages, and because of this the coolant itself is not heating up enough to bring the operating temperature up to the 190 deg or so that it should normally reach. In my opinion unless the coolant system has recently been flushed, I would have it done, and separately flush and backflush the heater rad. This could solve either or both of the above issues if you have them.
 
  #7  
Old 12-13-11, 06:39 AM
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I didn't purge the air out. I'll open it up tonight maybe and do that... although I did fill the radiator completely and flexed the top hose to try and make sure it filled completely. I might try the cardboard trick too. Thanks.
Originally Posted by ukrbyk View Post
take piece of cardboard, wide enough to cover half radiator, and fix ti to it. old Russian way. we used to have manually operated "blinds" in front of radiator, to control cold air flow.
of course, this is just to get you by.
did you purge air out of the system after t0stat replacement?
 
  #8  
Old 12-13-11, 05:12 PM
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Shouldn't have to resort to cardboard, only as a last resort. Make sure you bleed air out good. I normally will start engine cold, remove rad cap , turn heater ( not defrost) on, and let it run up to temperature and add coolant as needed during. I will wait until cooling fan kicks on and off 2 or 3 times to be sure all air is out and things are circulating properly by looking in rad. Feeling the temperature of heater hoses at firewall where they attach to core, is a real good indicator as well. In the past I have even resorted to flushing core using a drill pump and a pail of CLR. ( calcium, lime, rust remover) I flushed it back and forth, then made sure core was full and pinched it off to make sure it stayed full and let it sit all night in the core. Flushed it a few more times, then hooked heater hoses back up and bled system again. I got much better heat and circulation through core, which saved me changing core.
 
  #9  
Old 12-13-11, 07:06 PM
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you Canooks are so un adventurous... I thought you have more of exploration spirit left in you.
But Mike took it out of my mouth. You do need to check both heater core hoses and upper and lower radiator hoses, AFTER T-STAT OPENED for being very close to same temperature. if you have them both "right" then another venue might be your air blender doors. simply not mixing air right.
that you replaced t-stat does not exclude it being bad and semi stuck open.
also, you pump might be getting there.
but 1st of all - do hoses temp check.
oh, and cardboard works fine. even newspaper. you guys forget that it's December, and it's no fun to mess with coolant drains. of course, fella might have super well insulated garage equipped for this type of mess. but so do doubt I somehow...

oh, and if you have them both not hot enough - your t-stat IS stuck open.
temp jumping up and down is pretty good sign of air bubble in the system on my book.
 
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