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Ok so there is alot of information about this out there! I had the issue with my heater sucked! My AC works great and as far as I could tell everything else in the system worked fine. I got cold air, then when I switched to hot, I received a brief glimpse of hot air. I went ahead and flushed out the heater core using a hose, got all kinds of brown crap out of there. And the flow of clear water was great before I finished up. And the heater worked great. I did the flush probably 3 times before I got good at it and was able to get noticeable effects. I put a thermometer in my vent and was able to read about 120°and the factory service manual declares 120° from your vent as proper operation. I didn't like this, my Dodge blows out air so hot that I cannot bear it for very long; it burns me. So a month or two goes by and one night my heater seems to be not working effectively, it got cold at idle. So I blasted that thing out again with the hose. Again I saw brown crap come out. This all makes me wonder if my heater core has such an issue, why not my radiator? But the system runs super cool all the time! So I tested my heater again, and this time it's blowing like it's from Hell! I temped and was reading 137.7°and I felt the heat! I mean this thing is hot now! I just wonder what everyone else is reading out there for their heater temperatures. Oh and I should mention I changed the thermostat out right away, since that is the standard fix for this issue. But in this vehicle, coolant is always running to the heater core, and I don't think the thermostat would make a difference in this issue. Anyone else out there temp their heater?
 

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I have not checked the temp of my heater and it wouldn't matter if I did anyways as i'm running a 160* t-stat which will naturally not allow as hot a temp from the heater. What temp t-stat are you running?
 

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I've measured 167°F out of my dash vents with my IR temp gun.
 

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Discussion Starter #4
Hot!

I've measured 167°F out of my dash vents with my IR temp gun.
Holy **** that is hot! Now I have something to strive for. Though, I am curious about the difference between my thermometer and your IR gun, I don't they would be scientifically comparable. I am thinking my method measured the air temperature whereas the IR gun would have measured the temp. on some surface. Regardless, your heat is hot!
 

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Discussion Starter #5
Update

Ok so my 140 degree heat didn't last very long. I read another post about someone flushing out their core over and over and over again. Almost makes me want to get a new heater core if this is what I have to look forward too. The heater works still, but not like I want it too. So I am going to flush it out again, that Dex-Cool stuff really sucks! I wonder what would happen if I flushed the 50/50 and used dex-cool again, but I think the consensus on that stuff is that it is no good.

So what temp. are you rockin'?
 

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Discussion Starter #6
Stat

I have not checked the temp of my heater and it wouldn't matter if I did anyways as i'm running a 160* t-stat which will naturally not allow as hot a temp from the heater. What temp t-stat are you running?

I am running OEM thermostat I believe is 180°F. I'm not sure if that thing kicks in very often. I check the temperature readings using the A/C Diagnostics and the hottest I've seen is 170° and maybe at most close to 90° at the cylinder head, I'm not sure if that's where it's supposed to be, but I can say my cooling system works like a champ! I know alot of people put a 160 thermostat in, I really don't see an advantage to that just yet. And like I said coolant is running through the heater core at all times, so I hardly believe the thermostat has much effect on my heater, unless your system is running cooler all the time, which would only negatively effect the heater system.

On a side note, if you ever replace your coolant, you are supposed to leave the cap off the recovery reservoir, fill it cold, then heat the vehicle up to the point where the thermostat kicks in, then add more coolant to the reservoir. But I don't know if my thermostat ever kicks in, how is this possible that our cooling systems work so well that they seem to not ever need a thermostat?
 

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how is this possible that our cooling systems work so well that they seem to not ever need a thermostat?
If it's a '94 with two hoses going to the expansion tank, the hoses were arranged in a way that bypassed the thermostat. There was a recall about it to block off one of the hoses.
 

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If it's a '94 with two hoses going to the expansion tank, the hoses were arranged in a way that bypassed the thermostat. There was a recall about it to block off one of the hoses.
You are supposed to remove the hose that goes to the top of the radiator from the expansion tank and cap both ends off if you have a 1994.

Mike--Hamilton Chevy
 

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Discussion Starter #9
You are supposed to remove the hose that goes to the top of the radiator from the expansion tank and cap both ends off if you have a 1994.

Mike--Hamilton Chevy


I have never heard of this, I had a '94 and I put that engine into a '95, everything bolted up correctly, but maybe my '94 was a '94.5? How do you forget to run everything to the thermostat? But my current ride is a '95, another one, and I guess I am going to take a look at the reservoir. Is there a service bulletin for this?
 

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Doubt it since there were so few '94's produced. Plus,the replacements for the reservoirs only had one port anyway...
 

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I have never heard of this, I had a '94 and I put that engine into a '95, everything bolted up correctly, but maybe my '94 was a '94.5? How do you forget to run everything to the thermostat? But my current ride is a '95, another one, and I guess I am going to take a look at the reservoir. Is there a service bulletin for this?
The year of the motor has no bearing on this. The expansion tank in 1994 and part of 1995 came with 2 nipples. There was also a nipple on the passenger side top corner of the radiator that the extra hose connected to. GM found this to be not required and did issue a TSB to remove and cap the second line. That is why the 1996 and all the current replacement tanks have only 1 nipple. I do not remember the TSB number for this but since I owned a 1994 for 18 years I sure do remember the change.

Mike--Hamilton Chevy
 

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Your crud is hiding in your block. You can keep flushing the core till the cows come in but until you get the brown goop out of your whole cooling system you mind as well pizz up a waterfall.

There are numerous threads on pulling the knock sensors and flushing the block.

Good luck and stay away from waterfalls.
 

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Discussion Starter #13
Nipple

The year of the motor has no bearing on this. The expansion tank in 1994 and part of 1995 came with 2 nipples. There was also a nipple on the passenger side top corner of the radiator that the extra hose connected to. GM found this to be not required and did issue a TSB to remove and cap the second line. That is why the 1996 and all the current replacement tanks have only 1 nipple. I do not remember the TSB number for this but since I owned a 1994 for 18 years I sure do remember the change.

Mike--Hamilton Chevy

You talk a lot about nipples.
 

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That crud is insanely hard to rid yourself of, and for many reasons, the heater core is a very good place for it to hide.

You need to flush everything out with your thermostat, block plugs (knock sensors), and radiator petcock removed. You'll see where that crud has indeed been hiding in your radiator then.

Flush the heater core forwards and backwards to free the most garbage.

Dump in a double dose of radiator flush, run the engine hot and at elevated rpms for 15 minutes.

Take everything off and manually flush again very well.

Allow everything to drain completely, and fill with distilled water.

If you want maximum protection from a resurgence, add a coolant filter to your system.

I added one to my 92 wagon after doing multiple flushes and still seeing gold flakes from some person's use of Bar's Stop Leak. Now, I never see anything but crystal clear coolant.
 

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I have never heard of this, I had a '94 and I put that engine into a '95, everything bolted up correctly, but maybe my '94 was a '94.5? How do you forget to run everything to the thermostat? But my current ride is a '95, another one, and I guess I am going to take a look at the reservoir. Is there a service bulletin for this?
I have a 180 deg F T stat . air temp out heater core in winter is 140deg f. never check it when 80 deg F outside temp.

the heater core was blocked when I only had the car 9 months back in 1996. GM sealant pellets ... I still find some traces of these in my purge bucket every time I do the coolant changes.

I run dexcool but I have 65% dexcool to 35% distilled water .. also I do drain the block , flush out the heater core,wash out the pressure tank and wash the pressure cap as the cap can get plugged up and over pressure the system [I had that happen once ]..serviced every 4 years . never had any heat problems to this day. the heater core acts like a filter , I also had this occur in my 2000 silverado when it was new ... no problems now.
 
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