Temp problems

[Jason Glover]

Passenger head:

Engine Cooling Fan Switch Right ACDelco GM Original Equipment 15-4457

Drivers side head:

ACDelco GM Original Equipment 213-78 Engine Coolant Temperature Sensor​

Edit: To clarify, these are the parts for the 1991-1995 trucks with 454 tbi (L19) engines. Most autopart stores only list the sensor by the thermostat. I wanted to share this for someone else who needs to replace these parts, as it took a lot of error and guesswork to find the correct parts. I have been informed the RVs with the same engine may have used a different fan switch, but I cannot confirm that.

Thank you so much, this is helpful and I greatly appreciate it!

 

[Jason Glover]

Passenger head:

Engine Cooling Fan Switch Right ACDelco GM Original Equipment 15-4457

Drivers side head:

ACDelco GM Original Equipment 213-78 Engine Coolant Temperature Sensor​

Edit: To clarify, these are the parts for the 1991-1995 trucks with 454 tbi (L19) engines. Most autopart stores only list the sensor by the thermostat. I wanted to share this for someone else who needs to replace these parts, as it took a lot of error and guesswork to find the correct parts. I have been informed the RVs with the same engine may have used a different fan switch, but I cannot confirm that.

When I change them out what should I expect as far as coolant leakage? The truck hasn’t ran for a few months, should I pop the radiator cap off first?

 

[Supercharged111]

When I change them out what should I expect as far as coolant leakage? The truck hasn’t ran for a few months, should I pop the radiator cap off first?

It'll leak even if you drain the radiator, I think. You'd have to drain radiator and block to eliminate leakage. Shouldn't be more than about a half gallon or so. If you're parked on dirt just yank the thing.

 

[Schurkey]

The radiator drains the engine down to the water pump level. Draining the rad is enough for temp sensors in the intake and heads. There might be some coolant loss, but it wouldn't be much.

It wouldn't be enough if you were removing the knock sensor on a small-block, for example.

How old is the coolant? Now would be a good time for a flush 'n' fill with fresh coolant and distilled water. In that case, you'll want to remove the block drains so all the flush water is removed. On a 5.0, I'd expect the knock sensor on the right side, and a steel/iron hex-head plug on the left side. Both will pour out some coolant, but there's no other way to drain the lower block. The knock sensor will need to be torqued back into position when you install it; and both the sensor and the plug should have some sealant on the threads.

When it's my vehicle, I scrap the steel/iron block plug, and replace it with either a brass plug, or a brass draincock.

 

[Jason Glover]

The radiator drains the engine down to the water pump level. Draining the rad is enough for temp sensors in the intake and heads. There might be some coolant loss, but it wouldn't be much.

It wouldn't be enough if you were removing the knock sensor on a small-block, for example.

How old is the coolant? Now would be a good time for a flush 'n' fill with fresh coolant and distilled water. In that case, you'll want to remove the block drains so all the flush water is removed. On a 5.0, I'd expect the knock sensor on the right side, and a steel/iron hex-head plug on the left side. Both will pour out some coolant, but there's no other way to drain the lower block. The knock sensor will need to be torqued back into position when you install it; and both the sensor and the plug should have some sealant on the threads.

When it's my vehicle, I scrap the steel/iron block plug, and replace it with either a brass plug, or a brass draincock.

I’m not sure how old it is in there, probably 2 years. Levels always been good so I haven’t really messed with it.

 

[alpinecrick]

Thanks for the info! I’ve gotta ask, should the sensors be the same identical part? As far as I can tell, the connectors look pretty close to the same.

To my knowledge, all the connectors under the hood are unique to one another with the Vortec 5.7/5.0. I've had them all disconnected at one time or the other. They're the same sensor because all the sensors--including the two temp sensors--do a different job, and send different signals/voltage.

Different years, different motors may use the same connector for different sensors though.

 

[Volunteer454]

Thank you so much, this is helpful and I greatly appreciate it!

I lost maybe half a gallon when I did them. Make sure the truck is cool and work fast. Overall easy job. Took me 20 mins to do both and top off the system. Good luck

 

[someotherguy]

Just wait until the engine is cold, have the new sensor/sender/switch ready to go and once you turn the old one the last few threads to remove, have the new one in the other hand ready to go in. You'll lose no significant amount of coolant at all.

Richard

 

[Casey916]

Well, thats a pretty important sensor, if its not working your engine will always be in open loop meaning t s running off a program rather than taking info from all of the other sensors and optimizing.

So to answer your question about what other sensors are effected by the temp sensor... All of them.

Your setup is a little different than the original poster - he has a Vortec small block.

On your TBI big block, the one in the intake near the thermostat is for the computer input. This is the only sensor on your TBI engine that tells the computer the coolant temperature.

The one on the driver's side head is for the dash gauge.

The one on the passenger side head is for the auxiliary fan that should be mounted ahead of the A/C condensor.

(By the way the Vortec big blocks are pretty much set up the same way though they have the IAT of course in the air intake tube.)

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Richard

Auxiliary fan my '98 Chevy doesn't have no auxiliary fan do all of them have that

 

[Schurkey]

Auxiliary fan my '98 Chevy doesn't have no auxiliary fan do all of them have that

WHICH " '98 Chevy" are you talking about? What engine? What platform?