Low EOTs...
Thread Starter
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Fleet Mechanic
Joined: Apr 2019
Posts: 1,737
Likes: 661
From: South AR
Low EOTs...
My truck runs a little cool compared to what I’ve seen on here. It just doesn’t seem normal.
I monitored it both on my CTS2 and FORScan tonight on a 45 min Highway drive.
Crank the truck EOT was at 55F.
Idle for a few minutes while the kids and wife loaded up.
Drive unloaded..
3 miles to the highway at 55mph. EOT 141F
45 miles on interstate at 70ish. max EOT at about 40 min in was 175F (hilly area toward end) but mostly was around 160F.
Pulled off interstate and drive 3 miles at 55mph and EOT already back down to 155F when 170F when came off interstate.
thoughts?
bad thermostat?
bad EOT sensor?
bad fan clutch?
just fine???
I monitored it both on my CTS2 and FORScan tonight on a 45 min Highway drive.
Crank the truck EOT was at 55F.
Idle for a few minutes while the kids and wife loaded up.
Drive unloaded..
3 miles to the highway at 55mph. EOT 141F
45 miles on interstate at 70ish. max EOT at about 40 min in was 175F (hilly area toward end) but mostly was around 160F.
Pulled off interstate and drive 3 miles at 55mph and EOT already back down to 155F when 170F when came off interstate.
thoughts?
bad thermostat?
bad EOT sensor?
bad fan clutch?
just fine???
Cargo Master
Joined: Aug 2003
Posts: 2,332
Likes: 442
From: Eastern Washington
Does the Engine oil cooler have a thermal valve? I don't know. I know my EOT runs a couple degrees above my coolant temps, about 215 IIRC.
If your coolant temps are staying in line I wouldn't think the fan clutch or engine tstat are faulty.
140-175 doesn't seem bad to me, These are for sure oil temps, not trans temps, right?
If your coolant temps are staying in line I wouldn't think the fan clutch or engine tstat are faulty.
140-175 doesn't seem bad to me, These are for sure oil temps, not trans temps, right?
Banned
Joined: Dec 2018
Posts: 3,541
Likes: 458
I doubt the sensor is bad. Seems to be doing what it is supposed to do. You could have a thermostat stuck open and it might be worth replacing preventatively. Fan clutch is kind of a tough one to diagnose. It should allow the fan to turn with the engine off but with significant viscous resistance even on a brand new one in my experience. If it is locked up solid and not allowing the fan to spin at all that is probably a good indication it has failed. Take the fan off if that is the case and see what the temps do driving around. Wont hurt anything especially this time of year, just don't try to tow anything heavy. I don't really like these style of fan clutches because they are basically always spinning (and robbing power) even when the cooling is not needed or maybe even wanted.
Mine will maybe make it up 180* in cold weather on a short drive to town ~10 miles. To get it up to 190+ requires an extended drive on the interstate. Obviously in summer it is easier to get it up around 195-200* but you have to factor in ambient temperatures a little before deciding your truck is broken.
Mine will maybe make it up 180* in cold weather on a short drive to town ~10 miles. To get it up to 190+ requires an extended drive on the interstate. Obviously in summer it is easier to get it up around 195-200* but you have to factor in ambient temperatures a little before deciding your truck is broken.
Thread Starter
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Fleet Mechanic
Joined: Apr 2019
Posts: 1,737
Likes: 661
From: South AR
I doubt the sensor is bad. Seems to be doing what it is supposed to do. You could have a thermostat stuck open and it might be worth replacing preventatively. Fan clutch is kind of a tough one to diagnose. It should allow the fan to turn with the engine off but with significant viscous resistance even on a brand new one in my experience. If it is locked up solid and not allowing the fan to spin at all that is probably a good indication it has failed. Take the fan off if that is the case and see what the temps do driving around. Wont hurt anything especially this time of year, just don't try to tow anything heavy. I don't really like these style of fan clutches because they are basically always spinning (and robbing power) even when the cooling is not needed or maybe even wanted.
Mine will maybe make it up 180* in cold weather on a short drive to town ~10 miles. To get it up to 190+ requires an extended drive on the interstate. Obviously in summer it is easier to get it up around 195-200* but you have to factor in ambient temperatures a little before deciding your truck is broken.
Mine will maybe make it up 180* in cold weather on a short drive to town ~10 miles. To get it up to 190+ requires an extended drive on the interstate. Obviously in summer it is easier to get it up around 195-200* but you have to factor in ambient temperatures a little before deciding your truck is broken.
Just figured it was a little on the low side considering what I keep seeing as “normal” operating temps listed. Just being paranoid and OCD to head off any issues.
I would’ve already replaced it (thermostat), but I’m not looking forward to the bolts shearing off and then having to pull the whole pump in all likelihood.. So I’ve been putting that off and trying to see if actually has normal function and diagnose without going down that rabbit hole.
It mainly got me to thinking on temperatures when I drove my father-in-law‘s 6.0 a month or so ago when I was doing a cooler backflush and coolant flush change to ELC for him for his Christmas present. An 03 with ORGINAL coolant... 😬... boy was it nasty inside BUT
he had great deltas (8F)... luckily best ONLY has 35k miles on it!!! I noticed his temps came up super fast and hovered around 180-190 within 10 miles on freeway. I know dif engines but still similar.
It's a Van Gogh
Joined: Feb 2010
Posts: 7,813
Likes: 1,335
From: Elk Grove, CA
That looks low IMHO. I'd guess stuck thermostat too. If it was bad fan clutch you'd hear it all the time, it's not a normal sound.
Unless miles are low on everything I'd do waterpump as well as new thermostat and billet water neck, bottom hose and neck, plus top hose that goes around serp belt. Maybe do ELC. One fell swoop to renew the whole system and not worry about it for 5 years. Maybe even a belt tensioner.
Maybe I'm advising this cuz I'm getting older and if I'm working on the truck it's going to be Sherman's March to the Sea.
Unless miles are low on everything I'd do waterpump as well as new thermostat and billet water neck, bottom hose and neck, plus top hose that goes around serp belt. Maybe do ELC. One fell swoop to renew the whole system and not worry about it for 5 years. Maybe even a belt tensioner.
Maybe I'm advising this cuz I'm getting older and if I'm working on the truck it's going to be Sherman's March to the Sea.
Banned
Joined: Dec 2018
Posts: 3,541
Likes: 458
I would say don't attempt the thermostat until you have some time to mess with it and a new pump in hand because those bolts probably will break off in the old one. If all that stuff is original I would just plan on replacing it all. You can take the fan off easily with the right wrench (big) and a some taps with a 2lb sledge. The fan/ fan clutch and shroud all have to come out together (an go back in together) so an extra pair of hands helps but I've done it myself. You have to do that anyway to replace the water pump if the thermostat bolts break off in it, so I would just do that and then observe how the truck runs for awhile to do a little trouble shooting. If you do end up doing the thermostat I would also replace everything. Pump, T-stat, aluminum t-stat housing, upper and lower hoses and the metal pipe piece that sits between the pump and lower hose. Obviously get the upper hose that goes behind the serpentine belt if you don't already have that. (They make colored silicone hoses if you want to get fancy.) I got rid of those original spring clamps for the hoses also. Those are real knuckle busters.
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Fleet Mechanic
Joined: Apr 2019
Posts: 1,737
Likes: 661
From: South AR
Yeah I’m probably going to go ahead and just get everything when I get the money together and plan to change it all. I suspect it’s all original except for the hoses 150,000 miles 2000 model.
i’ll just add it to the list ☺️
i’ll just add it to the list ☺️
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Cargo Master
Joined: Aug 2003
Posts: 2,332
Likes: 442
From: Eastern Washington
I took my truck for a drive today (empty/unloaded) and monitored EOT. 10-15 miles to get to 190 from about 30 with a 5-10 minute warm up.
It stuck to 190 in the flats, climbed a bit uphil and dropped a bit coasting/descending. 40 miles total, 188 when I parked it.
I didn't have ECT info, but I'm assuming that it's following coolant temp and there is not a oil cooler thermostat.
It stuck to 190 in the flats, climbed a bit uphil and dropped a bit coasting/descending. 40 miles total, 188 when I parked it.
I didn't have ECT info, but I'm assuming that it's following coolant temp and there is not a oil cooler thermostat.
Logistics Pro
Joined: May 2017
Posts: 3,523
Likes: 483
From: Southern OH
My truck runs a little cool compared to what I’ve seen on here. It just doesn’t seem normal.
I monitored it both on my CTS2 and FORScan tonight on a 45 min Highway drive.
Crank the truck EOT was at 55F.
Idle for a few minutes while the kids and wife loaded up.
Drive unloaded..
3 miles to the highway at 55mph. EOT 141F
45 miles on interstate at 70ish. max EOT at about 40 min in was 175F (hilly area toward end) but mostly was around 160F.
Pulled off interstate and drive 3 miles at 55mph and EOT already back down to 155F when 170F when came off interstate.
thoughts?
bad thermostat?
bad EOT sensor?
bad fan clutch?
just fine???
I monitored it both on my CTS2 and FORScan tonight on a 45 min Highway drive.
Crank the truck EOT was at 55F.
Idle for a few minutes while the kids and wife loaded up.
Drive unloaded..
3 miles to the highway at 55mph. EOT 141F
45 miles on interstate at 70ish. max EOT at about 40 min in was 175F (hilly area toward end) but mostly was around 160F.
Pulled off interstate and drive 3 miles at 55mph and EOT already back down to 155F when 170F when came off interstate.
thoughts?
bad thermostat?
bad EOT sensor?
bad fan clutch?
just fine???
Thread Starter
|
Fleet Mechanic
Joined: Apr 2019
Posts: 1,737
Likes: 661
From: South AR
I need to reseal the oil cooler anyway, so I guess I’ll plan to get water pump and billet housing and do this at the same time, so I don’t have to drain coolant twice,etc. Good timing, just bad timing on the pocketbook. “As usual”. 😣
Logistics Pro
Joined: May 2017
Posts: 3,523
Likes: 483
From: Southern OH
55F. Took another 45 min drive tonight and never got over 170. I figure thermostat is stuck open. Thanks everyone for confirming what theirs are doing. Don’t think it is “hurting” anything. Just not the most efficient.
I need to reseal the oil cooler anyway, so I guess I’ll plan to get water pump and billet housing and do this at the same time, so I don’t have to drain coolant twice,etc. Good timing, just bad timing on the pocketbook. “As usual”. 😣
I need to reseal the oil cooler anyway, so I guess I’ll plan to get water pump and billet housing and do this at the same time, so I don’t have to drain coolant twice,etc. Good timing, just bad timing on the pocketbook. “As usual”. 😣
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