Engine underheating?

[Flash]

it's not really a sealed system. if you don't want to worry about moisture, you can switch to silicon brake fluid (i use it in my classic cars) but you have to replace pretty much the entire brake system as DOT 3 and silicon fluids don't play well together.

When water gets into the system it will mix with the DOT3 and reduce its boiling point a bit. If a lot of water gets in the boiling point will reduce a lot.

This will make steam which is a compressible gas until the brake fluid which isn't.

The trouble with using silicon is that water won't mix in leaving the water to sink to the bottom of the system, the calipers, where it will boil at a paltry 100 degrees C, make a compressible gas and you'll have no brakes.

I prefer to just change the DOT3 regularly.

 

[kvanmet]

Wow some great info was posted while I was dog sick. Thanks for your replies. I've had a recent development. I'm getting somewhat consistent warm air, but only when I use the max ac setting. Makes no sense to me. Sometimes I have to push off, push max ac, repeat until I get hot air, but while I was driving on the highway I just about got sweated out. Still though, on any other setting I get nothing but cold air. I still don't think the hot air I'm getting is as hot as it could or should be though. As outside temps keep dropping coming into winter I'm afraid the heat I'm getting won't be enough

 

[AeroRamer]

I've had a recent development. I'm getting somewhat consistent warm air, but only when I use the max ac setting. Makes no sense to me. Sometimes I have to push off, push max ac, repeat until I get hot air,

Few days ago as we start getting into the 50’s and 40’s in the evening and morning hours here in florida I started noticing the same problem with the heater been only luke warm. I posted a new thread (Heater air only luke warm (?)) to not threadjack this one but I am using the tips here to troubleshoot my problem.

But on your comment about using the MAX A/C setting, I too noticed a tiny little increase in heat but not something that would make the interior cabin any more comfortable as it was in the past. I wonder if the reason is because the MAX A/C setting is most likely set at 60 degrees and cold air is mixed with the luke warm air on other settings (ie. Vent, Panel/Floor). When using the MAX A/C you have to set the temp to hot or 90 degrees.

 

[vegasmax]

When I install a new thermostat I do a couple of things extra...First I put the new one in a pan of hot water on the stove and turn on the burner. I put a temperature gauge or thermometer in and watch when the thermostat really opens. If it is very close to what it is advertised to be OK. The next thing is I drill a 1/8" hole just above the center part that opens when hot. The reason I do this is to allow for trapped air to escape while filling. The hole is small so you'll still have to watch to see when the thermostat opens and then add more coolant. I use anti-freeze in a 60/40 mix and us R/O Water in the system. May not be the best way it is just the way I've done it for years.

 

[blakshukvw]

Come on guys this is pretty easy. My 5.0 does this to and I'm sure my fan clutch is the cause. If your fan clutch is fully locked up or just enough to run faster than it should when the rad and engine are not at full operating temp, then this the exact scenario you will get. I don't really mind it cause my truck runs real cool in the summer time and I still have good heat in winter. However when it's below about 15 degrees when I'm driving I can actually see the gauge move rapidly towards cold when accelerating from a stop and it will stay pretty cool until it shifts into OD. That's because in OD the engine RPMs go low enough that the fan speed slows down enough for it to allow some heat to build in the system.
OP, get yourself a new fan clutch.