What is normal coolant temperature? My heat is lukewarm.

[msnott]

I own a 2004 Buick Lesabre Limited.

I have noticed that when I am at idle, my heat is lukewarm. When I am driving and the RPMs are up, my heater’s air temperature rises but is still not what I would consider hot. My coolant level is and has been normal.

What I noticed was that my coolant temperature ranged from 178-185, never climbing above the 185 mark. Is this the reason for the lukewarm air temperature from my heater? Should the coolant temperature be more like 195-205 in order to provide hot air?

I also suspected a blend door issue, but I do hear the whizzing of the blend door when changing the digital temperature control from a/c to heat. Whether it is fully operational, I do not know. All I know is that I hear the whizzing and it does change from a/c to heat, even if it is only lukewarm heat.

I have ordered a new thermostat, but don’t know if it is the solution or if I should continue diagnosing the problem.

Any help is appreciated!

 

[MelsRegal]

You should have a 195 thermostat meaning the minimum operating temperature is 195 with the potential to going up to at least 215.

 

[Homer Jay]

Welcome.
Although you mentioned the coolant level is normal, I would confirm by removing the radiator cap (engine cold), coolant level should be at the filler neck. Next, bleed the system for trapped air.

 

[JGBuick]

Mine (factory thermostat) keeps my system average around 201-degs.

 

[BossHog39]

all above good but could also be a partially stopped up heater core had two to do that. Check while engine is warm feel of both heater hoses they should be real close to same temp if not core stopped up the two I have done I was able to resolve the issue by simply removing both heater hoses at engine side and back washing core with water hose the stuff was in the ones I messed with luckily was loose debris and man was there a lot.

 

[2004CSOTP]

I own a 2004 Buick Lesabre Limited.

I have noticed that when I am at idle, my heat is lukewarm. When I am driving and the RPMs are up, my heater’s air temperature rises but is still not what I would consider hot. My coolant level is and has been normal.

What I noticed was that my coolant temperature ranged from 178-185, never climbing above the 185 mark. Is this the reason for the lukewarm air temperature from my heater? Should the coolant temperature be more like 195-205 in order to provide hot air?

I also suspected a blend door issue, but I do hear the whizzing of the blend door when changing the digital temperature control from a/c to heat. Whether it is fully operational, I do not know. All I know is that I hear the whizzing and it does change from a/c to heat, even if it is only lukewarm heat.

I have ordered a new thermostat, but don’t know if it is the solution or if I should continue diagnosing the problem.

Any help is appreciated!

That does seem low compared to my own 04 Le slobber and it's only October. Back flushing the heater core can help as well. This involves disconnecting the heater hoses from the engine and rigging up something with a garden hose to run water through the core backwards from the usual direction. But, if you have an air compressor and you just like tools, this will work great.

Cooling System Power Flush Gun | OTC Tools

www.otctools.com

 

[BossHog39]

That does seem low compared to my own 04 Le slobber and it's only October. Back flushing the heater core can help as well. This involves disconnecting the heater hoses from the engine and rigging up something with a garden hose to run water through the core backwards from the usual direction. But, if you have an air compressor and you just like tools, this will work great.

Cooling System Power Flush Gun | OTC Tools

www.otctools.com

you do not not have to rig anything and do not not have to buy jack for the flush its not that dang hard take off hose hold garden hose to one then switch several times make a mountain out of a mole hill for a simple dang flush that requires only water. start costing them money on BS that it a waist of time.

 

[BuickGirlFromMars]

That does seem low compared to my own 04 Le slobber and it's only October. Back flushing the heater core can help as well. This involves disconnecting the heater hoses from the engine and rigging up something with a garden hose to run water through the core backwards from the usual direction. But, if you have an air compressor and you just like tools, this will work great.

Cooling System Power Flush Gun | OTC Tools

www.otctools.com

I did it on numerous vehicles, last 3800 was a 2006 la crosse, all you need is your mouth, ability to wrap your mouth on a towel or clean the hose end with some cleaner if you think its gross, then push. I would not use an air compressor due to the strength that would love to find a weak spot and crack etc. You can regulate sure but i found that with blockages they clear rather quickly and then the flow of a hose or placing water in the hose and a couple pushes is all that is needed. Going both ways of course.

 

[02LTD]

Just put in the 195 degree thermostat and see what happens. My last Buick (2001 LeSabre Limited) ran cool. When I would get off the highway I noticed the temp was 183 or thereabouts. When I took out the thermostat I found it was one of those “Failsafe” thermostats that was stuck in the open position. I put in a Stant 195 degree thermostat and everything was okay after that. Keep it simple!!!!!😉😎

BTW….Normal operating temperature is196 to 225. At 225 both fans are on and quickly cool the engine down to the low 200s.

 

[msnott]

Thanks everyone! Very appreciative of your comments and suggestions.

@Homer Jay Prior to my post, to confirm that I had proper coolant level, I did remove the radiator cap. The coolant was full and overflowing.

Based on a couple posts, it does sound like my coolant temperature is low. I plan to change the thermostat but also flush the heater core. It's probably due for that maintenance anyway. Between the two, hopefully this will resolve the issue.

Again, grateful for your help.

 

[BuickGirlFromMars]

Thanks everyone! Very appreciative of your comments and suggestions.

@Homer Jay Prior to my post, to confirm that I had proper coolant level, I did remove the radiator cap. The coolant was full and overflowing.

Based on a couple posts, it does sound like my coolant temperature is low. I plan to change the thermostat but also flush the heater core. It's probably due for that maintenance anyway. Between the two, hopefully this will resolve the issue.

Again, grateful for your help.

put a new cap on at the same time ac delco or stant only

 

[JGBuick]

Another vote for using an OEM Thermostat and radiator cap. Don't cheap-out on the thermostat.

 

[msnott]

So, I replaced the thermostat, which was easy enough. Then I turned my attention to flushing the heater core. The bolt that holds the coupling, which the outgoing coolant hose connects to at the sending unit, broke so that 3/4 of the bolt was still in the unit, while I was left holding the remaining top portion.

I did not see any way of realistically getting that remaining piece of bolt out of, what looks to be, the alternator unit. From my estimation, and I am not a mechanic, I figured I would have to take the entire alternator off in order to have a shot at extracting that bolt. After looking on YouTube, bolt extraction is not an easy endeavor.

With that in mind, I am taking the chance that the remaining portion of the bolt will be suitable to hold the coupling in place. The coupling is seated extremely tight into the sending unit even before the bolt, so I plan to keep an eye on it to ensure no leaking or loosening.

Can I simply ask. . . Why does every car repair want to throw a curve ball?

After the new OEM thermostat installed, the flush complete, new fluid in the cooling system, and the baby burped, I now have heat running around 145 degrees from the vents. The coolant temperature now gets into the 190s range, topping out above 200.

Thanks to everyone for their above advice as to how to deal with this issue. Problem solved. . . Hopefully.

 

[BuickGirlFromMars]

So, I replaced the thermostat, which was easy enough. Then I turned my attention to flushing the heater core. The bolt that holds the coupling, which the outgoing coolant hose connects to at the sending unit, broke so that 3/4 of the bolt was still in the unit, while I was left holding the remaining top portion.

I did not see any way of realistically getting that remaining piece of bolt out of, what looks to be, the alternator unit. From my estimation, and I am not a mechanic, I figured I would have to take the entire alternator off in order to have a shot at extracting that bolt. After looking on YouTube, bolt extraction is not an easy endeavor.

With that in mind, I am taking the chance that the remaining portion of the bolt will be suitable to hold the coupling in place. The coupling is seated extremely tight into the sending unit even before the bolt, so I plan to keep an eye on it to ensure no leaking or loosening.

Can I simply ask. . . Why does every car repair want to throw a curve ball?

After the new OEM thermostat installed, the flush complete, new fluid in the cooling system, and the baby burped, I now have heat running around 145 degrees from the vents. The coolant temperature now gets into the 190s range, topping out above 200.

Thanks to everyone for their above advice as to how to deal with this issue. Problem solved. . . Hopefully.

Ill share a secret dont tell your mom I told you it
I used zip ties. Sounds ghetto. The real fix means you need to pull the bracket off. If you cannot absolutely do that right now, get creative with thick , long zip ties. you justn eed to hold the pipe in the area. the o rings seal it. If you CAN do the repair right right now, the temp is right and the snow is not here yet, so I advise doing it. Your tensioner could be replaced as a whole unit for a new one if you wanted to get that refeshed. not cheap but it would mean little work too. keep it in mind. I used a small bracket off my alternator lower bolt (Near my supercharger, would be open area on a NA I think) and then used that to loop zip through. Get creative if you have to. If you do this, then elbows and water pump are naturally a great great idea because access.

And no, your coupling will pop out within minutes

also dont forget to use the bleeder to bleed, and hopefully you set your thermostat in facing 12 o clock looking at the engine.

 

[2004CSOTP]

Can I simply ask. . . Why does every car repair want to throw a curve ball?

Let's sit down and have a few beers. I'd like to tell you about the timing belt I did on an 04 Toyota Sienna.

 

[JGBuick]

In my experience, very few repairs (on any of my cars) have been 100% easy. It seems like when you are going down that path... something breaks or will not come apart, necessitating another round of repairs. Engineers NEVER make things easy. In reality, I don't even the slightest thoughts go into the "repair category". Nope... they want you to visit the showroom again... and that's how they get you.

Here's the plus-side... Today's cars are MUCH worse!!!!

 

[02LTD]

In regards to “curve balls” you must be willing to take a break for a few minutes to avoid breaking more stuff. I preferred the previous generation 92-99 as far as serviceability but even the last generation gives you plenty of room to work with.
If you get frustrated have a beer or a cup of coffee and try to relax a bit. Sometimes taking a break can help you approach something from a different angle and find a different solution to your problems.

 

[JGBuick]

Good advice. I know I often have to take a break and approach it from a different angle. I swore up and down when changing out the rear Firewall) plugs and wires. Getting leverage on those sticky boots was nerve racking. I finally took a break and was able to use some penetrate and a vice grip.

Good Lord was that a PITA!

 

[02LTD]

Good advice. I know I often have to take a break and approach it from a different angle. I swore up and down when changing out the rear Firewall) plugs and wires. Getting leverage on those sticky boots was nerve racking. I finally took a break and was able to use some penetrate and a vice grip.

Good Lord was that a PITA!

I hear you on the rear plugs. So far that was the most difficult task on my 2002. It was a lot easier on the previous generation.

 

[BuickGirlFromMars]

I hear you on the rear plugs. So far that was the most difficult task on my 2002. It was a lot easier on the previous generation.

the previous generation used multiple ribs on the plug porcelain up to the mid 90s for sure, and this helped how much force was needed to remove. but to increase the dielectric strength and of the boots, they made the porcelain flat. I know, it sucks after a lot of miles!! lol