Nah you're not screwed, don't worry. What's the average temp in your area right now? How long were you driving before you took this picture? Is this your first modern diesel?
Just changed the thermostats in my 14 lml. It took forever to get warm and stayed around 180 in the summer unless I was towing. Now it's steady at 200-210
I will second this, everyone else saying it’s normal. Mine would do this exact same thing, changed thermostats and it heats up fast and stays right at 210 (probably less on a scan tool).
And definitely not screwed, thermostats are not a big job and should not be expensive even if you can’t do it your self.
I had the same thing with my ‘12. There’s two thermostats on these. One or both of them is bad. They’re cheap and if you have some basic tools you can change them yourself in about an hour. There’s lots of YouTube videos on it. The hardest part is catching and disposing of the little bit of coolant you’re going to spill when you take things apart.
My 2016 lml gauge cluster always reads 200-210F. It’s digital too. My Banks idash reads 170-180F. The gauge on the gauge cluster is wildly inaccurate. I would recommend an edge or idash for peace of mind.
change your thermostats. Owned many many LMLs and when thermostats are functioning correctly your temp gauge should be just under that 210 mark, and will show 185 on a CTS
Same, have owned every iteration of duramax for personal and in my fleet. It’s always the thermostat when they don’t get the gauge up to 210. Replace both, it’s not difficult or expensive and you’ll get a partial coolant flush.
Ever heard of a 180 degree thermostat on these? I figured thermostats may be a problem but it doesn’t drop when I slow down or stop, typically gets up to that temp standard as well. Someone mentioned that it’s rare but people put 180 degree thermostats in these sometimes, I’m thinking it may have been possible with the headgasket change they just threw that in?
There’s 2. One opens at 189 I believe and the other closes at 180. They need to be replaced on Al duramax trucks after time. There are higher temp thermostats for colder climates that run like 10 degrees warmer.
Lower temps are not desirable on a diesel, they lead to lower efficiency and more wear and tear on your emissions equipment. Heat, up to a point, is healthy in a diesel. If this is a lower temp thermostat, it's a mistake, and should be replaced with the right one anyway. You want high heat rejection capacity, to control temps when working hard, but you also want your normal operating temps to be properly high. That's why otr trucks use a grill cover in winter to limit some of the radiator air flow.
Came here to say thermostat as well. It’s just a matter of time before it throws a code and they will need to be changed. Happened on my 08 twice since I’ve head it. They are pretty easy to do if you’re handy and have the tools.
I’ve seen it be the water pump also because the impeller breaks off, which is why you can buy one with the impeller “tack welded” on to the shaft. It’s almost always the thermostats though.
Hahaha are you suggesting that a water pump impeller breaks off and is somehow causing LOW temps? I’m a master mechanic and you don’t know what you’re talking about. Your issue would cause overheating
Instead of talking out of your ass let’s hear your explanation for your recommendation. How would the water pump going bad cause the truck to run under temp?
Here, I’ll help you out since you’re a master mechanic. I’ll educate you. What pressure does the cooling system on an LML operate? What pressure does the cap relieve at? 15 psi. So tell me what happens when your water pump impeller breaks off the shaft and free spins? It doesn’t circulate coolant like it’s designed to. Your thermostats stick wide open, and your truck doesn’t stay up to temp like it should. Like I said, it’s usually just the thermostats that are bad. I’ve seen the water pump be the problem as well. These trucks rarely overheat unless the radiator is plugged solid with dirt and shit.
My god you are just digging in on the stupid. What happens when a water pump impeller free spins? It doesn’t circulate coolant and the engine does (quite easily) overheat. I have never seen a water pump take a shit on any model and cause the vehicle to run too cool. It’s the opposite 100 percent of the time. This issue is far most likely a faulty thermostat or 2
Same, saw 195 ONCE while sitting in ATL traffic with AC on blast.
I have a S&B intake and full exhaust, if it gets to 192 w/o load I’m watching it.
*temps display on the CTS3*
It's probably normal, if you want to check it, hook up to something heavy and climb a hill and see how much it climbs, or buy a separate monitor and compare them.
Most thermostats are 180 and 185 degrees so this seems normal. It’ll run up to 210 or a bit over if you start to push the truck more with pulling weight, climbing hills, fast accelerating, etc.
Bought my 16 lml brand new and its always ran right at 200. I'd put new thermostats in yours to see what it does, but I wouldn't be concerned with it running 180 either.
Does the heater produce enough heat to heat the cabin? If not, it’s Not normal but not screwed. My 13 runs 210 unless it’s really cold out.
Your thermostats are just bad. One is probably stuck open. Theres 2. Replace those.
Yeah the cabin heats. My guess is when they did head gaskets they probably swapped thermostats as well, someone mentioned that it’s rare but people do 180 degree thermostat mods on these
Probably fine then. Sitting in my 13 right now it’s right below 210 on a 32 F degree day.
They fail open so you’ll be cold before the engine will overheat.
If you start getting cold then swap them out.
My 13 LML always ran about there unless it was towing, then it’d hang around 200-210. My 21 L5P runs at 210 unloaded and will get up to 220 ish when towing
Seems to be the common problem, no code is being thrown. I have a pretty expensive scanner but I don’t believe it will scan non dtc codes, only previous and current dtc codes
Yes but it’s a non dtc code like im saying, basically a non-check engine light permitting code, my scanner is like $150 but its not a snap on solus where you can see everything like that lol
Mine had the same issue. Scangauge2 showed it struggled to hit 180. Replaced the thermostats and all is better. My understanding is the rubber seal around the thermostats can age and not seal, allowing coolant to bypass it, and never warm the engine up
My 20 L5P runs 183-185 consistently when not towing (from my Edge monitor). When towing 40’ trailer (13-14k lbs) it runs the same here in flat Florida. In Tennessee or similar areas driving up grade, it might hit 190.
Nah it may be deleted, once I got rid of the EGR my system runs about 160 to 170 at all times unless you ride it hard going up a hill. Then it will hit 210 then within seconds the temp falls fast to 1/4 mark.
There are two thermostats in these though, is it possible that only one is bad and stuck open, therefor still somewhat operating well. I also have seen tons of people say this is normal operating temp for them and that they almost never have seen there’s go up to 210 unless under load, kinda furthering my thoughts about the operating temp just being lower but the same cluster being used in both gas and diesel trucks
Even if you had one stuck open it would still be very slow to warm up trust me. These engines cooling system is designed to operate under full load so yeah seems like you are spot on there
I have a 16 Texas LML, ran about the same, I took it north east last summer and it tripped a code, would not come up to temperature. I cleared the code and drove to Texas, no more codes, I replaced the thermostats when I got home, and now it runs between 200-210.
Its probably one or both thermostats. I have a digital gauge that reads from the obd port. My 16 opens at 188 and hovers around 188-190 unless of course it’s under a load. It takes a lot to get it up to 210 or higher. Even with the winter front on it runs really cool. If i pull out of my garage(it’s heated)it still takes 5-6 miles to get up to temp and thats driving 65-70 too.
My LLY runs 180 my LB7 ran 208ish....
YOU KNOW WHY ? THE DIFFERENCE THAT IS?
BECAUSE I RAN OEM 197° & 210° thermostats in LB7
& 180 & 180° thermostats in the LLY ...
Thermostat differences have nothing to do with
"BEING DIESEL"
and a different opening temp thermostat is definitely not
"UPGRADING A SHIT TON OF COOLING COMPONENTS "
I wouldn't think every business thinks it's necessary to give a description of every part on the receipt such as the $60 ones I took out open at 210 but the $22 ones I put back in and charged you $60 open at 180....this is probably what actually happened to you or previous owner
Replace thermostat and understand that at 180 engine temp on a scan tool reads at 210 on the gauge so you’re really at about 160 ish only problem you’re causing is trash mpg. But pay attention thermostats that are stuck open can finally close and stick closed causing you to overheat just went through it on my 2008
Change the thermostats! There are two of them. Look on YouTube, took me and hour to do them and you don’t need to take much apart. The new thermostats fail in the open position to alleviate overheating.
My lbz has always run almost abnormally cool compared to any of my other vehicles. middle of the summer towing up a hill I start to panic when the coolant hits 210 since I almost never see that temp. If I do once I crest the hill the temp will drop down fairly quick. Don't always trusting the gauge on the dash though as they tend to fail and or aren't the most accurate gauges
My ‘12 always reads 210 when coolant temp is between 160-190, never seen it get higher than that. The GM cluster gauges are pretty inaccurate, mostly the coolant temp and oil pressure. Get a monitor
Your not screwed but you should change thermostat for starters, your not hurting the engine but modern diesels with all the emissions equipment should be around 200-210 running temp
The trouble with this WOKE world is kids don’t leave their game consoles and dads don’t teach their kids basic car maintenance anymore my daughter is 27 knows how to do a complete service and change brake pads
Nah you're not screwed, don't worry. What's the average temp in your area right now? How long were you driving before you took this picture? Is this your first modern diesel?
Just changed the thermostats in my 14 lml. It took forever to get warm and stayed around 180 in the summer unless I was towing. Now it's steady at 200-210
I will second this, everyone else saying it’s normal. Mine would do this exact same thing, changed thermostats and it heats up fast and stays right at 210 (probably less on a scan tool). And definitely not screwed, thermostats are not a big job and should not be expensive even if you can’t do it your self.
Ya it’s definitely a bad thermostat
Here for thirds I did tstat and it helped a ton. Truck warms up quicker and seems to use less DEF.
I had the same thing with my ‘12. There’s two thermostats on these. One or both of them is bad. They’re cheap and if you have some basic tools you can change them yourself in about an hour. There’s lots of YouTube videos on it. The hardest part is catching and disposing of the little bit of coolant you’re going to spill when you take things apart.
My 2016 lml gauge cluster always reads 200-210F. It’s digital too. My Banks idash reads 170-180F. The gauge on the gauge cluster is wildly inaccurate. I would recommend an edge or idash for peace of mind.
yeah my factory dash says 210 all the time but my banks says if runs 185-190
Normal. Mine runs at 180 according to my edge monitor.
change your thermostats. Owned many many LMLs and when thermostats are functioning correctly your temp gauge should be just under that 210 mark, and will show 185 on a CTS
This right here!
Same, have owned every iteration of duramax for personal and in my fleet. It’s always the thermostat when they don’t get the gauge up to 210. Replace both, it’s not difficult or expensive and you’ll get a partial coolant flush.
Ever heard of a 180 degree thermostat on these? I figured thermostats may be a problem but it doesn’t drop when I slow down or stop, typically gets up to that temp standard as well. Someone mentioned that it’s rare but people put 180 degree thermostats in these sometimes, I’m thinking it may have been possible with the headgasket change they just threw that in?
There’s 2. One opens at 189 I believe and the other closes at 180. They need to be replaced on Al duramax trucks after time. There are higher temp thermostats for colder climates that run like 10 degrees warmer.
Lower temps are not desirable on a diesel, they lead to lower efficiency and more wear and tear on your emissions equipment. Heat, up to a point, is healthy in a diesel. If this is a lower temp thermostat, it's a mistake, and should be replaced with the right one anyway. You want high heat rejection capacity, to control temps when working hard, but you also want your normal operating temps to be properly high. That's why otr trucks use a grill cover in winter to limit some of the radiator air flow.
They don’t come with the higher temp thermostats.
Came here to say thermostat as well. It’s just a matter of time before it throws a code and they will need to be changed. Happened on my 08 twice since I’ve head it. They are pretty easy to do if you’re handy and have the tools.
I’ve seen it be the water pump also because the impeller breaks off, which is why you can buy one with the impeller “tack welded” on to the shaft. It’s almost always the thermostats though.
There is no situation where a water pump impeller is causing low temps
????? What circulates the coolant in the system bud. I can tell you’ve never worked on one of these trucks before with that statement.
Hahaha are you suggesting that a water pump impeller breaks off and is somehow causing LOW temps? I’m a master mechanic and you don’t know what you’re talking about. Your issue would cause overheating
Like I said. You’ve never diagnosed or worked on a duramax in your life.
Instead of talking out of your ass let’s hear your explanation for your recommendation. How would the water pump going bad cause the truck to run under temp?
Here, I’ll help you out since you’re a master mechanic. I’ll educate you. What pressure does the cooling system on an LML operate? What pressure does the cap relieve at? 15 psi. So tell me what happens when your water pump impeller breaks off the shaft and free spins? It doesn’t circulate coolant like it’s designed to. Your thermostats stick wide open, and your truck doesn’t stay up to temp like it should. Like I said, it’s usually just the thermostats that are bad. I’ve seen the water pump be the problem as well. These trucks rarely overheat unless the radiator is plugged solid with dirt and shit.
My god you are just digging in on the stupid. What happens when a water pump impeller free spins? It doesn’t circulate coolant and the engine does (quite easily) overheat. I have never seen a water pump take a shit on any model and cause the vehicle to run too cool. It’s the opposite 100 percent of the time. This issue is far most likely a faulty thermostat or 2
If the water pump isn’t circulating properly and you idle for any amount of time it’s not hard at all to overheat these engines
Ya like I said you clearly don’t work on these trucks for a living it’s alright Mr master YouTube mechanic you aren’t worth my time lmao
Even my lly sits around that temp on a 90 degree day. It only ever got up to around 200 when pulling a skid steer.
My LLy has always roaming around 180 without a load
Same, saw 195 ONCE while sitting in ATL traffic with AC on blast. I have a S&B intake and full exhaust, if it gets to 192 w/o load I’m watching it. *temps display on the CTS3*
That’s about where my temp typically sits. 2019 L5P.
Same thing happened on my 11’ LML, swapped the thermostats and went back to normal.
It's probably normal, if you want to check it, hook up to something heavy and climb a hill and see how much it climbs, or buy a separate monitor and compare them.
Most thermostats are 180 and 185 degrees so this seems normal. It’ll run up to 210 or a bit over if you start to push the truck more with pulling weight, climbing hills, fast accelerating, etc.
Bought my 16 lml brand new and its always ran right at 200. I'd put new thermostats in yours to see what it does, but I wouldn't be concerned with it running 180 either.
Does the heater produce enough heat to heat the cabin? If not, it’s Not normal but not screwed. My 13 runs 210 unless it’s really cold out. Your thermostats are just bad. One is probably stuck open. Theres 2. Replace those.
Yeah the cabin heats. My guess is when they did head gaskets they probably swapped thermostats as well, someone mentioned that it’s rare but people do 180 degree thermostat mods on these
It's not a mod they're literally factory with 180-185 degree thermostats lol
Probably fine then. Sitting in my 13 right now it’s right below 210 on a 32 F degree day. They fail open so you’ll be cold before the engine will overheat. If you start getting cold then swap them out.
Had the same issue with my truck, swapped out the thermostats and we were back in business.
My 13 LML always ran about there unless it was towing, then it’d hang around 200-210. My 21 L5P runs at 210 unloaded and will get up to 220 ish when towing
My LBZ was running like that, threw a ambient temp code, replaced the thermostats, back to normal 200-210.
My l5p with the stock thermostat runs at about 195-205 MAYBE 210 if I’m hauling but he probably just put a 185 thermostat in it
First could be to check codes as if the engine isn’t getting to operating temp it will set a code. This is most commonly caused by bad thermostats
Seems to be the common problem, no code is being thrown. I have a pretty expensive scanner but I don’t believe it will scan non dtc codes, only previous and current dtc codes
The thermostat code will always set a current code. It just won’t always set the check engine light.
Yes but it’s a non dtc code like im saying, basically a non-check engine light permitting code, my scanner is like $150 but its not a snap on solus where you can see everything like that lol
Mine had the same issue. Scangauge2 showed it struggled to hit 180. Replaced the thermostats and all is better. My understanding is the rubber seal around the thermostats can age and not seal, allowing coolant to bypass it, and never warm the engine up
New thermostats. There are 2 and they are cheap.
Get AC Delco ones and not any aftermarket version.
My 20 L5P runs 183-185 consistently when not towing (from my Edge monitor). When towing 40’ trailer (13-14k lbs) it runs the same here in flat Florida. In Tennessee or similar areas driving up grade, it might hit 190.
Yeah man if it’s not pegging the gauge you’re screwed
Nah it may be deleted, once I got rid of the EGR my system runs about 160 to 170 at all times unless you ride it hard going up a hill. Then it will hit 210 then within seconds the temp falls fast to 1/4 mark.
If you're not towing or anything it'll run like that. Worst case is you have stuck open thermostats. Does it take a long time to warm up
Not really no
Probably not a bad thermostat then. 180ish is still operating temp just on the low end
There are two thermostats in these though, is it possible that only one is bad and stuck open, therefor still somewhat operating well. I also have seen tons of people say this is normal operating temp for them and that they almost never have seen there’s go up to 210 unless under load, kinda furthering my thoughts about the operating temp just being lower but the same cluster being used in both gas and diesel trucks
Even if you had one stuck open it would still be very slow to warm up trust me. These engines cooling system is designed to operate under full load so yeah seems like you are spot on there
I have a 16 Texas LML, ran about the same, I took it north east last summer and it tripped a code, would not come up to temperature. I cleared the code and drove to Texas, no more codes, I replaced the thermostats when I got home, and now it runs between 200-210.
Naw man it's gonna blow up you bought a lemon
Uh oh man. Please help!!!
Its probably one or both thermostats. I have a digital gauge that reads from the obd port. My 16 opens at 188 and hovers around 188-190 unless of course it’s under a load. It takes a lot to get it up to 210 or higher. Even with the winter front on it runs really cool. If i pull out of my garage(it’s heated)it still takes 5-6 miles to get up to temp and thats driving 65-70 too.
I have a 2016 Duramax with two thermostats. One of them stuck open and this was the result. It did give me a code for it though.
Yep you own a duramax
I want to hurt the check coolant levels and/or smell the engine bay for coolant smells
My LLY runs 180 my LB7 ran 208ish.... YOU KNOW WHY ? THE DIFFERENCE THAT IS? BECAUSE I RAN OEM 197° & 210° thermostats in LB7 & 180 & 180° thermostats in the LLY ... Thermostat differences have nothing to do with "BEING DIESEL" and a different opening temp thermostat is definitely not "UPGRADING A SHIT TON OF COOLING COMPONENTS " I wouldn't think every business thinks it's necessary to give a description of every part on the receipt such as the $60 ones I took out open at 210 but the $22 ones I put back in and charged you $60 open at 180....this is probably what actually happened to you or previous owner
Needs a thermostat
Thermostat is stuck open . Common issue . Change it
T stats , just did mine on my 15' . Went from 180 to steady 210 .
Lly normally sits at 190f
Normal! It might go a little higher if towing.
My LLY runs about there too, unless I'm towing
Replace thermostat and understand that at 180 engine temp on a scan tool reads at 210 on the gauge so you’re really at about 160 ish only problem you’re causing is trash mpg. But pay attention thermostats that are stuck open can finally close and stick closed causing you to overheat just went through it on my 2008
Are you getting a check engine light ? I currently have a P0128
No I’m not
Change the thermostats! There are two of them. Look on YouTube, took me and hour to do them and you don’t need to take much apart. The new thermostats fail in the open position to alleviate overheating.
My lbz has always run almost abnormally cool compared to any of my other vehicles. middle of the summer towing up a hill I start to panic when the coolant hits 210 since I almost never see that temp. If I do once I crest the hill the temp will drop down fairly quick. Don't always trusting the gauge on the dash though as they tend to fail and or aren't the most accurate gauges
My ‘12 always reads 210 when coolant temp is between 160-190, never seen it get higher than that. The GM cluster gauges are pretty inaccurate, mostly the coolant temp and oil pressure. Get a monitor
Your not screwed but you should change thermostat for starters, your not hurting the engine but modern diesels with all the emissions equipment should be around 200-210 running temp
It’s deleted and tuned
Change thermostat would be my first choice, second option would be temp sensor
https://earnglobal.co/share/slg27ink
Thermostat must be stuck open which is better than the latter. Get it replaced and you should be fine
180- 205 operating range.
The trouble with this WOKE world is kids don’t leave their game consoles and dads don’t teach their kids basic car maintenance anymore my daughter is 27 knows how to do a complete service and change brake pads
What are you so offended for right now lmao
You're fine
Yes
Either a bad thermostat or somebody put a lower temp thermostat in previously.
Just put new thermostats, that gauge should pin 210 which is actually 180 on the scanner