4.9L 2nd Temp Sensor Location
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New User
Joined: Dec 2016
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From: Thousand Oaks, CA
4.9L 2nd Temp Sensor Location
Good day all, total newby here. Built a 300 engine (72 F100 2WD) which, due primarily to info found trolling FTE, is an excellent runner. I moved to FiTEch Go EFI this week to further improve driveability. Will post once measurable results are known.
I have struggled with finding a 2nd temp sensor location. There appears to be no location in the head, Offy DP intake doesn't have one. I ended up putting one inline on a heater hose but temp is WAY off. EFI can't "Learn" under 120 degrees (sensor hasn't gone above 95 but infrared guage says block is 190).
Is there a threaded plug in the block I can't find? Online schematics appear to be from later models with water port under #6 Cyl. Mine does not have that. I found a small threaded plug near the starter but seems too small (5/16?). My searches here and elsewhere did not yield result. Any help will be appreciated.
Probably irrelivant but this was a 240 block converted to 300 via crank/rods, etc.
PK
I have struggled with finding a 2nd temp sensor location. There appears to be no location in the head, Offy DP intake doesn't have one. I ended up putting one inline on a heater hose but temp is WAY off. EFI can't "Learn" under 120 degrees (sensor hasn't gone above 95 but infrared guage says block is 190).
Is there a threaded plug in the block I can't find? Online schematics appear to be from later models with water port under #6 Cyl. Mine does not have that. I found a small threaded plug near the starter but seems too small (5/16?). My searches here and elsewhere did not yield result. Any help will be appreciated.
Probably irrelivant but this was a 240 block converted to 300 via crank/rods, etc.
PK
Fleet Mechanic
Joined: Nov 2002
Posts: 1,643
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I use the one above the starter. I just made an adapter for the temp probe from a hardware store brass reducer bushing soldered to a short pipe nipple.
The smaller plug further forward gets a drain **** with a nipple to attach a hose for mess-free draining.
The smaller plug further forward gets a drain **** with a nipple to attach a hose for mess-free draining.
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New User
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From: Thousand Oaks, CA
Thanks FF, I do not have the closer hole you have the brass fitting in up near the head. I do have the smaller one you now drain from. Since I now know the smaller is water not oil, I can give it a try.
Peter
Peter
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Joined: Sep 2014
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From: like subarctic, brrr man!
Check out the EFI blocks Thermostat housings. Some of those have two boses for two sensors.
I eventually swapped out the ford types with my EFI for GM styles. Echlin TS4052 (and TSC200 pigtail) are what I swapped to.
I eventually swapped out the ford types with my EFI for GM styles. Echlin TS4052 (and TSC200 pigtail) are what I swapped to.
Cross-Country
Joined: Aug 2013
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1985 thermostat housing has a sensor location drilled and tapped already. Not all the EFI housings are drilled it seems, but same casting.
FITECH had a bad batch of temp sensors. Contact them and get a new one, or go to the parts store and grab one for a few bucks. If the heater lines are looped and flowing, you shouldn't have a huge temp difference between there and the block.
FITECH had a bad batch of temp sensors. Contact them and get a new one, or go to the parts store and grab one for a few bucks. If the heater lines are looped and flowing, you shouldn't have a huge temp difference between there and the block.
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From: Thousand Oaks, CA
Thanks all for the input.
Frenchtown - as you and others may have known, I did in fact have that opening directly under cyl #6. I pulled the factory sensor from there and connected my efi sensor to get it set up.
ZarK-eh - good idea, parts store came up short on my 1st attempt.
Guhfluh - this Was the ticket. Ordered my 85 therm housing as 2nd location. Upon relocating sensor from heater line to block, temp is now spot on. Must have been my Mickey Mouse rigging rather than sensor error.
Cheers all and thanks again.
Frenchtown - as you and others may have known, I did in fact have that opening directly under cyl #6. I pulled the factory sensor from there and connected my efi sensor to get it set up.
ZarK-eh - good idea, parts store came up short on my 1st attempt.
Guhfluh - this Was the ticket. Ordered my 85 therm housing as 2nd location. Upon relocating sensor from heater line to block, temp is now spot on. Must have been my Mickey Mouse rigging rather than sensor error.
Cheers all and thanks again.
Cross-Country
Joined: Aug 2013
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It was probably a poor ground being in the heater lines. The sensor is grounded through the body and threads. If you put it in the heater lines, you need to add a good ground wire from there to something else, or use a 2 wire sensor that has the same curve.
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