Engine will not maintain temps

[PJ Walters]

Ok both of my sensors are in the intake. I will call holley and see if they recommend putting the sensor in another location? Interesting concept that it could be operating fine and the sensor location is the issue. I will investigate this. Thank you and I will advise what i find out.

 

[bp71k5]

Ok both of my sensors are in the intake. I will call holley and see if they recommend putting the sensor in another location? Interesting concept that it could be operating fine and the sensor location is the issue. I will investigate this. Thank you and I will advise what i find out.

I might measure the area right next to the sensor and see if that jives with what the sniper is seeing. Just don’t measure any old spot on the motor and assume it’s all the same temperature.

 

[bp71k5]

I might measure the area right next to the sensor and see if that jives with what the sniper is seeing. Just don’t measure any old spot on the motor and assume it’s all the same temperature.

Also any chance the sensor is loosing contact with the coolant when it reads cold? An air bubble perhaps? I know if you use those NPT reducers that can sometimes prevent the sensor from penetrating far enough into the threaded hole to make good contact.

 

[PJ Walters]

Also any chance the sensor is loosing contact with the coolant when it reads cold? An air bubble perhaps? I know if you use those NPT reducers that can sometimes prevent the sensor from penetrating far enough into the threaded hole to make good contact.

HEY you may be on to something here!!! I had to use an adapter for me mechanical temp gage and it lifts the actual resistor up a good ways. I'm wondering if putting these sensors in the head can alleviate that possibility? That actually makes sense and I am out of other ideas.

 

[dyeager535]

If your IR gun is reading the same temps somewhere you know coolant is hitting (not where a bubble may form) then I don't see how sensor location is the issue. Yes, they will read wrong when not in coolant (why you don't pay attention to a water temp gauge when you have a coolant leak), and the head location is low enough that it won't hold air there, but it sounds to me like you've checked a few locations and the temp is consistently low.

Reverse flow waterpump will overheat with the engine under load, very doubtful that's the issue. Besides, the impeller on the pumps won't work turning in reverse (and thus no fluid velocity) hence why they overheat when turned the wrong direction. Even with the wrong pump it wouldn't do anything regarding the t-stat.

 

[Wes Harden]

Why would a t stat get up to its spec temperature and never close, when coolant temp drops below 160?

 

[PJ Walters]

Why would a t stat get up to its spec temperature and never close, when coolant temp drops below 160?

I do not know. I am going to put the sensors in the head and see what that does.

 

[Wes Harden]

How are the fans turned on? Do they have their own sensor and relays?
Does the Holley ecm control them.
You mentioned 2 senders, I am guessing 1 for gauge, and 1 for Holley ECM.
Been thinking about my t stat question. Possibly damage do to no bypass. Now that you have the bypass try a new stat. Inspect the old one for signs of over pressure damage. Please continue to run a bypass.
I think you have the correct rotation pump. It might be a high volume pump though.

 

[PJ Walters]

UPDATE: I started the truck and brought it to temp and I noticed something very peculiar; when shot with an IR gun, the Sniper bung and sensor that is screwed into to the intake, back by the distributor, read exactly what the gages in the dash read (155F). HOWEVER, when I shot the IR on the bottom of the tstat housing it read anywhere from 25 to 40 degrees hotter than bung and sensor near the read of the engine! I shot the front of the heads, the bottom of the tstat, rad hose and they were within 10 degrees of one another. When the front of the heads hit 200F I cut off the motor and could hear water boiling in the rad. I shot the rear bung and sensor again and it was almost 35 degrees cooler still. So BP71K5 I think you are on to something with a combo of placement of the sensor and Sniper being goofy. Back to the bung... I shot the rear Sniper bung and adapter and got another interesting read; the intake right where the bung connects read 177F, the adapter directly above was around 165F and the actual top of the sensor was around 155, the same reading as the dash gage. So what does that tell me??? Do I have air trapped in the system? Is the adapter lifting the sensor out of the fluid? Why is the rear of the motor so much cooler than the front of the motor? Is it because the cold water from the rad is dumping into the block somewhere near the rear of the truck keeping it much cooler than near the tstat/where the fluid exits the motor? Exercising this theory I should move the sniper bung to the front of the intake so that it gets a temp reading after water circulates through the block prior to before?

 

[PJ Walters]

How are the fans turned on? Do they have their own sensor and relays?
Does the Holley ecm control them.
You mentioned 2 senders, I am guessing 1 for gauge, and 1 for Holley ECM.
Been thinking about my t stat question. Possibly damage do to no bypass. Now that you have the bypass try a new stat. Inspect the old one for signs of over pressure damage. Please continue to run a bypass.
I think you have the correct rotation pump. It might be a high volume pump though.

Holley ECM control the fans. They do work as when the temps are up they kick on and off as expected. However, they never turn on due to the ECM always reading low. I will not be removing the bypass and I am going to get a 5th tstat. haha my auto parts store(s) must think I am nuts!

 

[Wes Harden]

An odd spot for a coolant sensor. There is no flow there, at least with any intake manifold I am familiar with.
2 things, I see teflon tape or sealent. These interfere with heat and ground transfer. The sensors should be pipe thread and need very little or no sealer
2nd move that sender to driver side cylinder head between spark plugs 1 and 3 this is the best spot for engine temp.

 

[Wes Harden]

After the sensor post there may be nothing wrong with the t stat. It might be all the location of the sender

 

[PJ Walters]

An odd spot for a coolant sensor. There is no flow there, at least with any intake manifold I am familiar with.
2 things, I see teflon tape or sealent. These interfere with heat and ground transfer. The sensors should be pipe thread and need very little or no sealer
2nd move that sender to driver side cylinder head between spark plugs 1 and 3 this is the best spot for engine temp.

I will be doing this asap and will reply.

 

[Fastereddie]

The boiling water sound in the radiator seems off to me. Nothing should be boiling at 200 even if you have straight water. Maybe your hearing air pockets trapped?

 

[PJ Walters]

The boiling water sound in the radiator seems off to me. Nothing should be boiling at 200 even if you have straight water. Maybe your hearing air pockets trapped?

That absolutely could be. There was definitely something rolling around in there.

 

[Fastereddie]

Also, an ir temp gun is not as accurate as you might think when trying to get water temp. Every different surface you check has different emissivity.

 

[Fastereddie]

I’m not sure what your elevation is but It could be boiling

 

[ridenby]

I’m not sure what your elevation is but It could be boiling

No elevation to speak of in PA.

 

[bp71k5]

UPDATE: I started the truck and brought it to temp and I noticed something very peculiar; when shot with an IR gun, the Sniper bung and sensor that is screwed into to the intake, back by the distributor, read exactly what the gages in the dash read (155F). HOWEVER, when I shot the IR on the bottom of the tstat housing it read anywhere from 25 to 40 degrees hotter than bung and sensor near the read of the engine! I shot the front of the heads, the bottom of the tstat, rad hose and they were within 10 degrees of one another. When the front of the heads hit 200F I cut off the motor and could hear water boiling in the rad. I shot the rear bung and sensor again and it was almost 35 degrees cooler still. So BP71K5 I think you are on to something with a combo of placement of the sensor and Sniper being goofy. Back to the bung... I shot the rear Sniper bung and adapter and got another interesting read; the intake right where the bung connects read 177F, the adapter directly above was around 165F and the actual top of the sensor was around 155, the same reading as the dash gage. So what does that tell me??? Do I have air trapped in the system? Is the adapter lifting the sensor out of the fluid? Why is the rear of the motor so much cooler than the front of the motor? Is it because the cold water from the rad is dumping into the block somewhere near the rear of the truck keeping it much cooler than near the tstat/where the fluid exits the motor? Exercising this theory I should move the sniper bung to the front of the intake so that it gets a temp reading after water circulates through the block prior to before?

View attachment 388845

If that’s a regular GM sensor, it should really be deeper in that hole. I had to tap my adaptor deeper with an NPT tap to get the sensor to sit lower. See if you can find a lower profile reducer.

 

[Fastereddie]