Occasional High ECT/EOT Spread
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Junior User
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Occasional High ECT/EOT Spread
SO, I was driving home from work tonight (no load, flat ground,41 deg, "moist" weather), looked down at my SG's and saw that my ECT/EOT spread was approaching the 15* spread mark. The truck had only been running for around 15 minutes so I chalked it up to it not being fully warmed up. A few minutes later I saw that the spread was getting higher. Now the thing was, the ECT was only 150*. Normally around the same point in my trip the ECT/EOT is around 172/176.
This has happened a couple of times before in the last year. Funny thing is it happens typically when the OS temps are 40-50 and had been raining. I decided to take the long way home and the spread hit 25* at one point.
I know some will say I need to change my thermostat out and I do agree. But, can that really be the only cause or can the Coolers act up just occasionally as they are going TU? I took a look at the EC Sensor and seemed to be okay.
No codes, no other odd behavior. No mods either.
Any ideas or suggestions would help. Thanks.
This has happened a couple of times before in the last year. Funny thing is it happens typically when the OS temps are 40-50 and had been raining. I decided to take the long way home and the spread hit 25* at one point.
I know some will say I need to change my thermostat out and I do agree. But, can that really be the only cause or can the Coolers act up just occasionally as they are going TU? I took a look at the EC Sensor and seemed to be okay.
No codes, no other odd behavior. No mods either.
Any ideas or suggestions would help. Thanks.
I'm hitting easy street
Joined: Nov 2009
Posts: 6,395
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From: Central Oregon
You haven't hit 190*?
And when you see the spread, what is the EOT reading? I haven't really seen any figures that you have spoken about.
Is the ECT 150* and EOT 175*?
Need a little more to go on.
You need to be "hot"--190* ECT to get an accurate read on the spread. Doing 60 mph.
And when you see the spread, what is the EOT reading? I haven't really seen any figures that you have spoken about.
Is the ECT 150* and EOT 175*?
Need a little more to go on.
You need to be "hot"--190* ECT to get an accurate read on the spread. Doing 60 mph.
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Junior User
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I rarely hit 190 in the winter unless I am on the freeway for a long distance. 170-180 ect is my norm. My commute home is only 20-25 minutes in town. (30-45 mph). The last part of the trip tonight the temps read 163 ect/188 eot.
No coolant filter but was planning to add one before camping season started.
No coolant filter but was planning to add one before camping season started.
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Junior User
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I kind of thought the t-stat could be the issue. Been telling the wife for two months I need to get it changed out when I get some free time. Just, thought I would put it out there to see if anyone had any other thought. Thanks. I will change it out and post my findings.
Hotshot
Joined: Apr 2010
Posts: 19,072
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From: Saratoga Springs,UT
And you need to clean the EGR Valve because you dont have proper combustion at 163 ECT. Its very very important to run at 190ECT or better
Mine was running at 173 ECT I was only getting 300 miles to a tank of fuel
Now that I have changed it and ECT is Back to 190 ECT Minimum Im back to 360 miles per tank of fuel
I bet your fuel milage will increase with a new thermostat
Now the BAD part IMO even though you have a Bad thermostat your OIL Cooler is shot and needs to be replaced
I have yet to see anyone change there thermostat and bring the spread closer together it dont work like that
From what Iv seen the new Thermostat will just make the temps Hotter but It Will NOT Bring them closer together
Change that Oil Cooler Soon before that EGR cooler pops and lifts the heads
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Hotshot
Joined: Apr 2010
Posts: 19,072
Likes: 242
From: Saratoga Springs,UT
Oh 1 more thing when My thermostat was running cold I still had the same ECT vs EOT spread as I did with the New Thermostat
The spread stayed the same Good or Bad ThermostaT
One thing you have to keep in mind is
the thermostat controls the Temps (thats figuring you have a good water pump)
And the OIL Cooler controls the Spread
Good Luck with it
The spread stayed the same Good or Bad ThermostaT
One thing you have to keep in mind is
the thermostat controls the Temps (thats figuring you have a good water pump)
And the OIL Cooler controls the Spread
Good Luck with it
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From: KCMO
Blade, I'm not going to say you're wrong but I have a theory.
If the t-stat is stuck open, the coolant is constantly circulating through every component. I'm wondering if the coolant moving through the oil cooler is not allowing adequate time for the heat to transfer from the fins into the coolant. The coolant needs to "sit" in there for proper heat transfer, then is cycled out and lower temp coolant takes it's place, etc etc.
Plausible?
I have a similar issue, my ECT will not get over 182 even running down the highway at 75. Well, it will go up a couple if I lay into it but then goes back to 182 within a few seconds. A new t-stat is going in probably this weekend so I'll see what happens.
If the t-stat is stuck open, the coolant is constantly circulating through every component. I'm wondering if the coolant moving through the oil cooler is not allowing adequate time for the heat to transfer from the fins into the coolant. The coolant needs to "sit" in there for proper heat transfer, then is cycled out and lower temp coolant takes it's place, etc etc.
Plausible?
I have a similar issue, my ECT will not get over 182 even running down the highway at 75. Well, it will go up a couple if I lay into it but then goes back to 182 within a few seconds. A new t-stat is going in probably this weekend so I'll see what happens.
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Junior User
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That makes sense about the EGR now. I cleaned it a while back ago, a few months went by and decided to pull it and do a visual on it. It was a bit more coked up than I thought it should have been. I don't know why the low temps causing it didn't dawn on me.
I am going to replace the stat this weekend and monitor the temps. I have a non factory warranty on the thing and will just have to convince them that the cooler is going bad, or hope the spread is off when I take the truck in. Otherwise ill have to replace it on my dime which i prefer not tondo until the warranty is up. Isn't that hard to do if it is an intermittent problem? I was actually hoping the cooler would go bad before the warranty was up so I could get the heads done and studs installed as well.
I am going to replace the stat this weekend and monitor the temps. I have a non factory warranty on the thing and will just have to convince them that the cooler is going bad, or hope the spread is off when I take the truck in. Otherwise ill have to replace it on my dime which i prefer not tondo until the warranty is up. Isn't that hard to do if it is an intermittent problem? I was actually hoping the cooler would go bad before the warranty was up so I could get the heads done and studs installed as well.
Hotshot
Joined: Apr 2010
Posts: 19,072
Likes: 242
From: Saratoga Springs,UT
Blade, I'm not going to say you're wrong but I have a theory.
If the t-stat is stuck open, the coolant is constantly circulating through every component. I'm wondering if the coolant moving through the oil cooler is not allowing adequate time for the heat to transfer from the fins into the coolant. The coolant needs to "sit" in there for proper heat transfer, then is cycled out and lower temp coolant takes it's place, etc etc.
Plausible?
I have a similar issue, my ECT will not get over 182 even running down the highway at 75. Well, it will go up a couple if I lay into it but then goes back to 182 within a few seconds. A new t-stat is going in probably this weekend so I'll see what happens.
If the t-stat is stuck open, the coolant is constantly circulating through every component. I'm wondering if the coolant moving through the oil cooler is not allowing adequate time for the heat to transfer from the fins into the coolant. The coolant needs to "sit" in there for proper heat transfer, then is cycled out and lower temp coolant takes it's place, etc etc.
Plausible?
I have a similar issue, my ECT will not get over 182 even running down the highway at 75. Well, it will go up a couple if I lay into it but then goes back to 182 within a few seconds. A new t-stat is going in probably this weekend so I'll see what happens.
I see what you mean but regaurdless of the thermostat Open/Closed/Stuck open whatever there is Constant Coolant flow threw the Block!
The Coolant Does NOT just sit there untill the thermostat opens
its always Circulated threw the Moter via the water pump
A Heater Core in the truck is a GREAT example here Have you noticed you can Feel heat coming out the Heater Vents Long before the Truck reaches 190 ECT thats because its circulating coolant
Now will it circulate Faster with a stuck open thermostat I dont think it would. I beleive the water pump circulates the SAME Gallon Per Minute no matter the position of the thermostat
Now there have been a few cases of a Bad water pump not circulating enough coolant and causes the EOT to be Higher temp
Former Vendor
Joined: Feb 2010
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I had a 14° spread on mine and did a flush. Now I'm at a 3° spread. 
Condensed Steps:
1. Regular flush n fill process using tap water as with 'normal' vehicles until no slimy feeling water remained.
2. VC-9 with tap water. Flush until clear.
3. Restore + with tap water. Flush until clear.
4. Backflush oil cooler with tap water. Collect multiple tablespoons of sand.
5. Backflush heater core with tap water.
6. Drain block
7. Add distilled. Run truck to operating temp. Drain via lower rad hose/petcock valve.
8. Repeat step 7 five times to get 98% or so of tap water out.
9. Drain yet again.
10. Install coolant filter
11. Add Delo ELC concentrated coolant in quantity equal to 50% of system capacity.
12. Top off with distilled.
13. Wipe brow and have a beer.
I used the directions at http://home.comcast.net/~lyon.family...ush%20v1-0.pdf as a general guide.
Good luck, but I wouldn't wait on it...
Ed
Ed@ficmrepair.com
Condensed Steps:
1. Regular flush n fill process using tap water as with 'normal' vehicles until no slimy feeling water remained.
2. VC-9 with tap water. Flush until clear.
3. Restore + with tap water. Flush until clear.
4. Backflush oil cooler with tap water. Collect multiple tablespoons of sand.
5. Backflush heater core with tap water.
6. Drain block
7. Add distilled. Run truck to operating temp. Drain via lower rad hose/petcock valve.
8. Repeat step 7 five times to get 98% or so of tap water out.
9. Drain yet again.
10. Install coolant filter
11. Add Delo ELC concentrated coolant in quantity equal to 50% of system capacity.
12. Top off with distilled.
13. Wipe brow and have a beer.
I used the directions at http://home.comcast.net/~lyon.family...ush%20v1-0.pdf as a general guide.
Good luck, but I wouldn't wait on it...
Ed
Ed@ficmrepair.com
Hotshot
Joined: Apr 2010
Posts: 19,072
Likes: 242
From: Saratoga Springs,UT
Guess I shouldnt say a bad oil cooler just yet
Couple other thoughts was a bad temp sensor if you only have a random BAD Spread
Does one of the temp readings jump around alot with a BIG diffrence could be a bad sensor
And are the gauges reading the same after a 12 hour cold soak
Also driving around town doesnt count to much stop and go
It needs a steady 60-65mph drive for 30-45 minutes or untill both temps reach there high then at this point the spread would be taken
Couple other thoughts was a bad temp sensor if you only have a random BAD Spread
Does one of the temp readings jump around alot with a BIG diffrence could be a bad sensor
And are the gauges reading the same after a 12 hour cold soak
Also driving around town doesnt count to much stop and go
It needs a steady 60-65mph drive for 30-45 minutes or untill both temps reach there high then at this point the spread would be taken
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Junior User
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Yeah, a flush and an addition are going to have to happen within the next few weeks as well.
No the temp doesn't jump around, temp goes up gradually like you expect. For now I ruling the sensor out, maybe i will change it out for the heck of it.
I do a cold soak check on the gauges from time to time and the readings have been good.
Thanks for your input so far guys.
Couple other thoughts was a bad temp sensor if you only have a random BAD Spread
Does one of the temp readings jump around a lot with a BIG difference could be a bad sensor
And are the gauges reading the same after a 12 hour cold soak
Does one of the temp readings jump around a lot with a BIG difference could be a bad sensor
And are the gauges reading the same after a 12 hour cold soak
I do a cold soak check on the gauges from time to time and the readings have been good.
Thanks for your input so far guys.