Running hot FJ40 (1 Viewer)

[Buffchief]

Fan clutch, or older style water pump? Also, I have a used water pump on the bench. Precipitate collects on the impeller, can that reduce efficiency?

I'm still thinking that 220F isn't that hot, based on a few web searches.

Oil viscosity changes a couple of things. Thick oil adds to friction, despite the lower levels of wear, and it transfers heat slower. That might not affect thermals in the head, but it reduces power output. But still, oil is an interesting topic to me; are you running 20W-50?

More coolant means better corrosion and freeze / boil-over protection. Water is better at heat-transfer than ethylene glycol coolant. 50/50-mix?

20w-40 on the oil coolant is 50/50

 

[Buffchief]

20w-40 on the oil coolant is 50/50

Good fan clutch. Water pump is OEM that was in installed when I purchased it.

 

[Buffchief]

Are you sure its running hot? Maybe you got a vacuum leak, that could make it run hot. Maybe they didn't get the new head cleaned out good so it has poor coolant flow. Head Gasket could be blocking ports. Crap got into the cooling jacket and is restricting the water pump inlet/outlet or the cores in the radiator. Big air bubble not allowing coolant flow

Well it looks hot by the gauges...but I'm sure of NOTHING!! Lol. Just aggravated

 

[Buffchief]

Are you sure its running hot? Maybe you got a vacuum leak, that could make it run hot. Maybe they didn't get the new head cleaned out good so it has poor coolant flow. Head Gasket could be blocking ports. Crap got into the cooling jacket and is restricting the water pump inlet/outlet or the cores in the radiator. Big air bubble not allowing coolant flow

Not sure about a vacuum leak. Fully smogged with all new OEM hoses. Wouldn't even know where to start and with what .

 

[Buffchief]

Are you sure its running hot? Maybe you got a vacuum leak, that could make it run hot. Maybe they didn't get the new head cleaned out good so it has poor coolant flow. Head Gasket could be blocking ports. Crap got into the cooling jacket and is restricting the water pump inlet/outlet or the cores in the radiator. Big air bubble not allowing coolant flow

I don't remember the letter/number on the head but the new one I bought had the same one. The head gasket is OEM. I do know there were some passages in the head and block that the gasket seemed to cover. I read that I shouldn't open them for whatever reason/by design (?) did t make since to me but I left them intact. The gasket IS OEM. For that head.

 

[charliemeyer007]

Stuff gets miss labeled all the time. #'s at the parts store get jumbled in the computer. It took my neighbor 3 trips to Autozone to get the correct pucks for the rear brakes on his Tahoe. That third trip the store manager gave him the disks for free to offset the time and gas money down the drain just for something as simple 2007 break disks.

I like KISS principle for problem solving. You changed heads and now it runs hot. Lean mixture from leaking manifold gasket could do it. Maybe your timing got retarded from vacuum advance isn't working now. Maybe the "new" head is the problem, could be the gasket ports. Could be some other issue.

 

[Pighead]

The gauge I bought for under dash came with a sensor to install in the head. I didn't swap it yet hoping it was just the 40s temp gauge.

Traditionally, you need to match your gauge and sender. I think you need to get an accurate engine temp before you do anything expensive.

 

[Buffchief]

Traditionally, you need to match your gauge and sender. I think you need to get an accurate engine temp before you do anything expensive.

How do I get an accurate temp of not by use of the two different gauges ive used ?

Traditionally, you need to match your gauge and sender. I think you need to get an accurate engine temp before you do anything expensive.

So I pulled the OEM sender out and replaced it with the one that came with the under dash gauge I bought from O'Reilly's. Temp went up to about 190° on new gauge and stayed pretty steady. This is all while setting parked on an incline with a radiator fill/bubbler installed working the bubbles out. Seems to be good. Noticed that the OEM sending unit had what looks like a clear coat on it!! So that would not be a good connection. It was flaking off when I removed the wire. Also, not sure what these numbers on the side represent.

 

[Ocho77]

Glad you potentially have it sorted! The IR guns are super helpful.

FYI - I flew Buff's out of Barksdale (20th BS) from 04-10. Loved it there!

 

[Buffchief]

Glad you potentially have it sorted! The IR guns are super helpful.

FYI - I flew Buff's out of Barksdale (20th BS) from 04-10. Loved it there!

I was a Crew Chief on the BUFFs for about 17 years and the fleet manager of all 76 B-52's while at Global Strike Command Headquarters A/4 for a few years. Retired a couple years ago from the 307th BW/ 93rd with a total of 32 years. Crewed A-10's for a few years as well. Only planned to do 4 years!! lol

 

[Ocho77]

I was a Crew Chief on the BUFFs for about 17 years and the fleet manager of all 76 B-52's while at Global Strike Command Headquarters A/4 for a few years. Retired a couple years ago from the 307th BW/ 93rd with a total of 32 years. Crewed A-10's for a few years as well. Only planned to do 4 years!! lol

Awesome. I'm guessing we ran into each other on the flight line a time or two...

 

[Buffchief]

I was a Crew Chief on the BUFFs for about 17 years and the fleet manager of all 76 B-52's while at Global Strike Command Headquarters A/4 for a few years. Retired a couple years ago from the 307th BW/ 93rd with a total of 32 years. Crewed A-10's for a few years as well. Only planned to do 4 years!! lol

I came here after the gulf war and was stuck....Barkatraz

 

[Pighead]

How do I get an accurate temp of not by use of the two different gauges ive used ?

So I pulled the OEM sender out and replaced it with the one that came with the under dash gauge I bought from O'Reilly's. Temp went up to about 190° on new gauge and stayed pretty steady. This is all while setting parked on an incline with a radiator fill/bubbler installed working the bubbles out. Seems to be good.

Did you answer your own question here? After you hooked the correct (matched) sender to your aftermarket gauge you get a more reasonable, and, theoretically more accurate, reading.
You might have had two temp senders on the top rear of your cylinder head, one for the dash gauge and one for the emissions control. they each put out different amounts of whatever it is that they put out (I don't know much about electricity). The markings on the sender might tell you what that sender was sending if you could read that code. Figure out which sender does what and you can run your stock temp gauge and your new temp gauge. That's what I do.
I like gauges, I like mechanical gauges better than electric gauges.

 

[Buffchief]

Awesome. I'm guessing we ran into each other on the flight line a time or two...

...or tdy's to Diego Garcia during the

Did you answer your own question here? After you hooked the correct (matched) sender to your aftermarket gauge you get a more reasonable, and, theoretically more accurate, reading.
You might have had two temp senders on the top rear of your cylinder head, one for the dash gauge and one for the emissions control. they each put out different amounts of whatever it is that they put out (I don't know much about electricity). The markings on the sender might tell you what that sender was sending if you could read that code. Figure out which sender does what and you can run your stock temp gauge and your new temp gauge. That's what I do.
I like gauges, I like mechanical gauges better than electric gauges.

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View attachment 3784984

Did you answer your own question here? After you hooked the correct (matched) sender to your aftermarket gauge you get a more reasonable, and, theoretically more accurate, reading.
You might have had two temp senders on the top rear of your cylinder head, one for the dash gauge and one for the emissions control. they each put out different amounts of whatever it is that they put out (I don't know much about electricity). The markings on the sender might tell you what that sender was sending if you could read that code. Figure out which sender does what and you can run your stock temp gauge and your new temp gauge. That's what I do.
I like gauges, I like mechanical gauges better than electric gauges.

View attachment 3784982

View attachment 3784984

That is my plan to use both, but I don't know that there is another point of contact for another temp sender install. I don't want the oem temp gauge dead in place.

 

[Buffchief]

Awesome. I'm guessing we ran into each other on the flight line a time or two...

Most likely! Been here 30 damned years!! Maybe even Diego Garcia during the missions north into Afghanyland after 9-11 or one of the 100's of global Air shows. Who knows.

 

[Pighead]

That is my plan to use both, but I don't know that there is another point of contact for another temp sender install. I don't want the oem temp gauge dead in place.

There might be a couple other places to install a water temp sender. Are you still using your stock emissions "computer"? Are you running an oil cooler?

 

[Buffchief]

There might be a couple other places to install a water temp sender. Are you still using your stock emissions "computer"? Are you running an oil cooler?

yes. all oem parts with coolers etc.

 

[Pighead]

OK, I have heard (or read) about a bit of pipe, or tubing, with a threaded bung, that fits inside one of your larger coolant lines and takes the place of a couple inches of coolant line that you can thread an aftermarket sender into. I've not had to use one, perhaps search the 60 tech section.

 

[Roastchestnuts]

I didn’t read all your details, but I may have had a similar problem. I have a newly rebuilt FJ60 engine and head (Thanks FJ40Jim!). This was installed in my ‘76 FJ40 this fall ‘24. The FJ60 OE temp sender (top rear driver side cylinder head) was reused during the rebuild. FJ40 factory gauge was reading abnormally HOT and didn’t seem right. I ended up pulling the old sender from my original FJ40 head and swapped it onto the new FJ60 head. Works great. I never researched whether or not this is a sender/guage incompatibility from the 40 to the 60 series, but this may be the case. Whatever your setup is, try a different sender before you start digging too deep.

This is similar to my temp gage - the earlier gages from early fj40s (mine is a 1964) do not play well with the sendors from the 2f engines. I found that out when I swaped in a 2f in my fj40.

 

[Buffchief]

This is similar to my temp gage - the earlier gages from early fj40s (mine is a 1964) do not play well with the sendors from the 2f engines. I found that out when I swaped in a 2f in my fj40.

I believe that you're correct. Same thing here. I had the 60 sender going to my 40 gauge and it showed hot. Added an under dash gauge and plugged it into the 60 sender and it showed hot! Removed the 60 sender and replaced with the sender from under dash gauge kit and it shows just right. I plan on finding an fj40 sender for my 1980 40 to install and keep my original gauge working as well as using the extra gauge as a back up under dash once i figure out where to install the sender. I don't like deviating from the original oem but an extra temp gauge can only help!