1993 f150 5.0 2wd e4od

Hey guys. Just a few questions here. First, my truck has a new coolant temp sensor (both for comp and gauge) and it reads usually between the R and M in NORMAL. When it is hot out it can get as high as the M. I have noticed that coolant will not stay in the reservoir. If I fill it within a few days it will be bone dry. No leaks anywhere. No signs of head gasket trouble whatsoever.

This is not the first truck I have had this problem with. My 85 I had before this had the same problem. I rebuilt that one so it had a new gaskets everywhere- water pump, head gasket, thermo housing, etc. and still did it. Is this a common trouble? What could cause this? This is weird because it has happened to my last 2 trucks and I believe both head gaskets good.

 

I have never been a fan of the exterior overflow tanks, all seem to mysterious coolant leaks. When Ford made the change to the integral overflow tanks, all is well. If you have a radiator cap on the radiator, thats what I am calling the exterior overflow tank. If the cap is on the bottle and no cap on the radiator, thats the integral type. My 73 F250, my 88 BII and my 96 expolorer all use the exterior type reservoir, all of them suck. No issues with the 02 and the internal tank.

 

I have the same issue, very upsetting.

 

So you get this too? Every few days coolant is dry on tank right?

 

I used to get that until I flushed my coolant out a couple summers ago, my guess is that the concentration of water/coolant was off and a majority of the water as evaporating.

So got rid of the brown nasty stuff in the rad and put in some fresh coolant and now I only top off the res. tank every other month or so, and I always put a little bit over the fill mark just in case.

Check/replace your rad cap is also releasing pressure when its supposed to.

 

Yea, I think sylver is on to something. I'll probably get a new rad cap. What pressure should I run?

 

New rad cap and I flushed it not that long ago. Same result. Where does your gauge sit on NORMAL???

 

Mine rides between O and R (when my temp sensor is working properly). I think 13 Psi is the rad cap spec. Its cheap insurance and seemed to fix my problem.

Even if you can't see or track a leak, I'd still try to pressurize the rad and see if you missed something and the overflow tank and lines aren't cracked or loose.

 

Thanks meng, I recently stopped a leak, thinking about a whole new bucket as well