Dumb cooling question

[Krawler68]

Robert and I reached a small conclussion on this issue last night, but I'm not sure I know the final answer.

I was overheating in llano and my water temp gauge was not acurately reflecting my water temp. I assumed it was because the sending unit wasn't screwed in enough...

I screwed it in last night and while the needle seems to be moving more I'm not sure it's an accurate reflection of my water temp. It fluctuates quite a bit, and climbs under acceleration (normal I think), but drops quickly as I let off the gas. It starts around 150 at startup... after driving it with the fans off it sits around 180 and then as soon as I turn on the fans I get it to drop well below 180 and sit around 160 or so.

The themostate I am using is a 180* one with a 16lb radiator cap... I was boiling out the radiator frequently in llano, but was at high RPM with effectively no fans... now that all 3 of my fans are working I am wondering if it is REALLY this cool, or if there could be something wrong with my gauge.

Doug

[Chadnutz]

Is this gauge in a radiator hose or in some metal part of the motor. The sending unit must have a good ground and I don't think you should use teflon tape unless you can't keep it from leaking. I don't think one off road trip was worth risking a cracked or warped block/head/intake.... Be careful next time.

Y'all all know of my Mazda overheating problems. Now that it is going to be an off road rig, I am going to buy an extra fan clutch and lock it up where the fan will spin at the same RPM as the truck (not counting pulley size). If I don't do this, I am gauranteed to ruin a weekend of wheeling in the middle of summer.

[Krawler68]

I probably warped it pretty well, we shall see... I didn't use teflon... It's screwed into the intake.

I am wondering how low on the post the two nuts should sit... does it need to be flush against the base of the sending unti or do they "float" up higher?

Doug

[stinger7401]

I dont think it has anything to do with depth of sending unit or anything like that unless the sender or guage is bad. I would look more twords proper air travel across the radiator, possible restricted water flow through the radiator or a bad thermostat.

[AgDieseler]

My temp sender is in the head, and it didn't require teflon, but instead came with some other high temp sealant already on the threads.

If I really get on it, water temps will climb from about 140 to 150ish. This only occurs when I'm doing 3/4 or WOT; not regular driving around. Currently, I'm running 160 and 180F thermostats, and both seem to be working fine. A mild increase in temperatures under hard acceleration isn't out of the ordinary.

There is a "magical" coolant temp that creates max power. The norm seems to be around 190 for gassers and diesels, but I'm not sure what the prime temp is for propane. Generally, you can't go wrong with a 180 t-stat.

[Krawler68]

OK...Apparently my question was misunderstood.

I am wondering why my temp gauge isn't reading what my coolant is doing... it's a brand new sending unit... I KNOW why it overheated... I didn't have my fans turning efficiently... I also don't feel like it will overheat now... but I want to be able to watch my temp gauge and know it's working.


My question was would iot seem anywhere near normal for my fans to work well enough to bring down the temp 10-15* nearly instantaneously? It's not a drain on the power... it's a genuine drop of the gauge.

Doug

[AgDieseler]

Originally posted by Krawler68
My question was would it seem anywhere near normal for my fans to work well enough to bring down the temp 10-15* nearly instantaneously?

I think that's pretty normal. It seems similar to what happens when a fan clutch engages, and the temps seem to drop like there's no bottom.

[Krawler68]

gracias... I imagine I've fixed the problem then. We'll see.


Doug

[BigRedFord04]

Originally posted by Chadnutz
Y'all all know of my Mazda overheating problems. Now that it is going to be an off road rig, I am going to buy an extra fan clutch and lock it up where the fan will spin at the same RPM as the truck (not counting pulley size).

Fan clutches are the debil!!

Originally posted by Chadnutz
My question was would iot seem anywhere near normal for my fans to work well enough to bring down the temp 10-15* nearly instantaneously? It's not a drain on the power... it's a genuine drop of the gauge.

If i have my fans off and the motor gets hot, when i turn them on it will usually drop back to normal temp within 30 seconds. Not anywhere NEAR as quick as when i forgot to turn them on pulling the h.s. kids, the motor got hot, and i dumped the front end into the river last weekend. holy crap, i've never seen anything like that...it went from the top of the gauge to the bottom in like 10 seconds!

[Chadnutz]

Does anyones motor ever crack from driving through rivers are normal operating temperature?

[BigRedFord04]

nope, never

[Krawler68]

I don't know... mine didn't this weekend... of course I was neck deep in river water several times and didn't even have my distributor hiccup... nice huh?

Doug

[mark]

Originally posted by Krawler68
My question was would iot seem anywhere near normal for my fans to work well enough to bring down the temp 10-15* nearly instantaneously? It's not a drain on the power... it's a genuine drop of the gauge.

Doug

Sounds like you have a slightly screwy thermostat. Your temp should be rock steady. There is also a possibility of some trapped air in the cooling system, but that would pass quickly.

-Mark