Engine Overheating/No Heat

[JTsYUKON]

My 2014 GMC Yukon SLT is running hot (235*), and there’s no heat blowing out the vents. Is this a thermostat issue? Is it stuck closed? Or possibly something else? If it’s the thermostat what brand do I need?

Thanks! You guys have been helpful in the past.

 

[B-train]

It sounds like the thermostat. Is there coolant in the reservoir? Low coolant level will cause the no heat issue and can cause an overheating problem too.

Are there any signs of coolant leakage anywhere? How many miles? Once these questions are answered, we can suggest better solutions.

But, off the cuff:
1) if coolant level is full and appears in good condition (not cloudy, gunky, etc) then I would assume there are no leaks and replace the thermostat and top off with new coolant and give it a try.
2) if coolant is low or nonexistent in the reservoir, then inspection of radiator, water pump, and hose connections for leakage or damage. Then fix accordingly and replace thermostat as well.

 

[JTsYUKON]

It sounds like the thermostat. Is there coolant in the reservoir? Low coolant level will cause the no heat issue and can cause an overheating problem too.

Are there any signs of coolant leakage anywhere? How many miles? Once these questions are answered, we can suggest better solutions.

But, off the cuff:
1) if coolant level is full and appears in good condition (not cloudy, gunky, etc) then I would assume there are no leaks and replace the thermostat and top off with new coolant and give it a try.
2) if coolant is low or nonexistent in the reservoir, then inspection of radiator, water pump, and hose connections for leakage or damage. Then fix accordingly and replace thermostat as well.

Ok, I’ll check the coolant level in the overflow and radiator first thing this morning. I haven’t noticed a leak, but it’s my wife’s vehicle. I’ll report back.

The rig has 157,000mi.

Thanks.

 

[Foggy]

COOLANT LEVEL IS LOW

 

[Fless]

It's likely that the radiator doesn't have anywhere to check the level. Top off the surge tank and fill the system from there.

 

[JTsYUKON]

It sounds like the thermostat. Is there coolant in the reservoir? Low coolant level will cause the no heat issue and can cause an overheating problem too.

Are there any signs of coolant leakage anywhere? How many miles? Once these questions are answered, we can suggest better solutions.

But, off the cuff:
1) if coolant level is full and appears in good condition (not cloudy, gunky, etc) then I would assume there are no leaks and replace the thermostat and top off with new coolant and give it a try.
2) if coolant is low or nonexistent in the reservoir, then inspection of radiator, water pump, and hose connections for leakage or damage. Then fix accordingly and replace thermostat as well.

Here’s where I am.
Coolant was low. Nothing visible in the surge reservoir. I had some on hand and followed the instructions in owner manual to add to cold full mark. When I cranked it the level dropped and I added more. I didn’t have enough to bring to the cold full line, but I allowed the engine to heat up with the cap off till the upper radiator turned hot, affirming the thermostat and water pump are operational. The air was at least warm in the car with engine temp at 195 in a cold driveway.

I did notice about a tablespoon of coolant under the passenger side. I didn’t think I missed when adding to the surge reservoir, but no more drips as I watched it for 10-15 min.

My plan is to go get some more coolant to bring it up to the cold full line. I’m open to more advice. Thank you so far! Great stuff.

Here are a few pics.

 

[Geotrash]

Here’s where I am.
Coolant was low. Nothing visible in the surge reservoir. I had some on hand and followed the instructions in owner manual to add to cold full mark. When I cranked it the level dropped and I added more. I didn’t have enough to bring to the cold full line, but I allowed the engine to heat up with the cap off till the upper radiator turned hot, affirming the thermostat and water pump are operational. The air was at least warm in the car with engine temp at 195 in a cold driveway.

I did notice about a tablespoon of coolant under the passenger side. I didn’t think I missed when adding to the surge reservoir, but no more drips as I watched it for 10-15 min.

My plan is to go get some more coolant to bring it up to the cold full line. I’m open to more advice. Thank you so far! Great stuff.

Here are a few pics.

When filling the coolant tank, it's easy to slosh it around the threads in the opening. There's a hidden drain where the radiator cap seats to safely capture any coolant that might escape when the pressure in the system causes the cap to release pressure and vents it safely out the bottom. So it's normal to have coolant under the pax side of the car after dumping some into the reservoir unless your aim is improbably perfect and none of it touches the threads.

 

[JTsYUKON]

When filling the coolant tank, it's easy to slosh it around the threads in the opening. There's a hidden drain where the radiator cap seats to safely capture any coolant that might escape when the pressure in the system causes the cap to release pressure and vents it safely out the bottom. So it's normal to have coolant under the pax side of the car after dumping some into the reservoir unless your aim is improbably perfect and none of it touches the threads.

I’m heading home in a minute with the extra coolant. I bought concentrate bc I already have some distilled water on hand and now I’ll have plenty.

One question I have is where did all that coolant go? Did it boil and overflow out the pressure release?

 

[Doubeleive]

I’m heading home in a minute with the extra coolant. I bought concentrate bc I already have some distilled water on hand and now I’ll have plenty.

One question I have is where did all that coolant go? Did it boil and overflow out the pressure release?

you have a leak, coolant does not just evaporate or magically disappear, just a matter of finding the leak.
my best advice is get under it with a flash light and look up. all over but concentrate more on the passenger side
look all over and both sides left/right/front/rear and under radiator
look under water pump, you may need a mirror to see properly they have the telescoping ones at any auto parts store for cheap
if you can't find anything obvious then park it on a level surface and place a piece of cardboard under it as big as you can find and then leave it overnight and look under it in the morning and look up directly from any "wet spot"
the heater hose's, firewall T's are places to check
sometimes the reservoir tank can crack

 

[JTsYUKON]

you have a leak, coolant does not just evaporate or magically disappear, just a matter of finding the leak.
my best advice is get under it with a flash light and look up. all over but concentrate more on the passenger side
look all over and both sides left/right/front/rear and under radiator
look under water pump, you may need a mirror to see properly they have the telescoping ones at any auto parts store for cheap
if you can't find anything obvious then park it on a level surface and place a piece of cardboard under it as big as you can find and then leave it overnight and look under it in the morning and look up directly from any "wet spot"
the heater hose's, firewall T's are places to check
sometimes the reservoir tank can crack

Ok, will do. Thank you.

I hope it's something simple like a hose or the surge reservoir tank and not the radiator. Although, this thing is at 157,000miles and I think 150,000 is when you start having issues with the the cooling system.

Y'all are a great group on this forum. A lot nicer than the folks on my Jeep forum, though they are pretty easy going with engine problems. When it comes to mods it can get nasty.

 

[mattbta]

While a free but pricey deposit rental, AutoZone has a pressure test kit that might make quick work out of finding the leak if initial visual inspection doesn't come up with much.

 

[Geotrash]

I agree with Wes. And I'll add an opinion that the most likely culprits at your mileage, in order (always debatable) are:
1/ The radiator - check around the plastic end tanks for any wetness and sniff for that sweet coolant smell. It's common for them to crack and seep coolant.
2/ The plastic tees where the heater hoses connect to through the firewall
3/ The water pump shaft seal
4/ A crack in the coolant tank
5/ A leaking hose connection

One final check to make sure it's not a blown head gasket or cracked cylinder head (both rare on these), check the oil dipstick to make sure the oil looks like oil should and isn't milky. Also check the oil filler cap and make sure it's not covered in a milky slime. If you find either one, then you have a problem.

Finally, if after all of that you can't find the leak, have a shop perform a pressure test on the cooling system, along with possibly a leak down test.

 

[JTsYUKON]

While a free but pricey deposit rental, AutoZone has a pressure test kit that might make quick work out of finding the leak if initial visual inspection doesn't come up with much.

I agree with Wes. And I'll add an opinion that the most likely culprits at your mileage, in order (always debatable) are:
1/ The radiator - check around the plastic end tanks for any wetness and sniff for that sweet coolant smell. It's common for them to crack and seep coolant.
2/ The plastic tees where the heater hoses connect to through the firewall
3/ The water pump shaft seal
4/ A crack in the coolant tank
5/ A leaking hose connection

One final check to make sure it's not a blown head gasket or cracked cylinder head (both rare on these), check the oil dipstick to make sure the oil looks like oil should and isn't milky. Also check the oil filler cap and make sure it's not covered in a milky slime. If you find either one, then you have a problem.

Finally, if after all of that you can't find the leak, have a shop perform a pressure test on the cooling system, along with possibly a leak down test.

I have about an hour to get to this before the vehicle is gone to my wife's hair appointment. I'll get under there and do some snooping with my headlamp and flashlight. I'll also clean everything up so that I can identify any new coolant tomorrow. I have lots of cardboard, so i can slip some of that under the rig.

Thanks for help. Great ideas.

 

[Doubeleive]

I have about an hour to get to this before the vehicle is gone to my wife's hair appointment. I'll get under there and do some snooping with my headlamp and flashlight. I'll also clean everything up so that I can identify any new coolant tomorrow. I have lots of cardboard, so i can slip some of that under the rig.

Thanks for help. Great ideas.

it's usually ok to drive it as long as you keep an eye on the coolant level, if it was leaking out so fast that it had to be refilled going a couple miles down the road then no.

 

[JTsYUKON]

it's usually ok to drive it as long as you keep an eye on the coolant level, if it was leaking out so fast that it had to be refilled going a couple miles down the road then no.

Ok, great. I just drove her and left the Yukon at home. I got under it, removed the plastic engine skid and took pics before cleaning it all so I can get a fresh look. It’s all along the bottom of the fan shroud which is just behind the radiator. I couldn’t any in other places. Mostly here and some dripping down passenger side. Found a dead bird. LOL

 

[Foggy]

By your pics, my guess is the radiator itself or the water pump. Stuff get splashed !
Check your end tanks on the radiator- they are plastic.. That's prob where you'll find
the leak. Good Luck.. Radiator Job is fairly easy on these

 

[Doubeleive]

I bet it's a cracked plastic side tank, par for the course on these.
not sure where you sit on money but don't cheap out on the radiator it just causes more headaches
if you can do those heater hose "T"'s at the same time because those will break next may as well get it out of the way.

 

[Geotrash]

I bet it's a cracked plastic side tank, par for the course on these.
not sure where you sit on money but don't cheap out on the radiator it just causes more headaches
if you can do those heater hose "T"'s at the same time because those will break next may as well get it out of the way.

+1 on the heater tees.

 

[Foggy]

Yup +2 on the heater Tee's
If you just want a stock replacement, the GM ones are fine.. Apparently they
have been updated (that's what my parts guy told me) and they had them
in stock... Not very expensive.. Just a ***** to take the old ones out. New ones go in easy.
And ++ on getting a GOOD radiator.. There are some decent aftermarket ones, but not
very many so be careful or get the GM one

 

[89Suburban]

Ok, great. I just drove her and left the Yukon at home. I got under it, removed the plastic engine skid and took pics before cleaning it all so I can get a fresh look. It’s all along the bottom of the fan shroud which is just behind the radiator. I couldn’t any in other places. Mostly here and some dripping down passenger side. Found a dead bird. LOL

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Good job with the pics. Helps a lot with looking for the the problem. Keep at it.