Slow coolant leak, now engine almost overheats before t stat opens

[TrevoJreal429]

my 2000 Sohc has always had a really slow coolant leak, maybe a pint a week. The past few week since it went from being in the 80's all the time to in the 50's my engine has been getting really hot, maybe 3/4 up the heat guage before the thermostat opens and it cools off. I replaced the t stat earlier this year, Because my mechanic said the truck was running too cool and I'd get better mileage if it ran warmer. I haven't had any problems until now. I've checked everywhere to find the leak and i've never been able to pinpoint it, I replaced the radiator cap and put hose clamps where I thought steam could be getting out of aswell.
Any ideas?
Sorry about the run on sentences I'm posting this from my phone at work.
Thanks, Trevor.

 

[RangRayy]

check the two lines running into the firewall. these run to your heater core i believe. check for wet looking areas and the pressure of the hose when its running. also when my thermostat went out i noticed i had a leak somewhere. Jon and I could only come up with a gasket blowing...still not sure on that one lol. i had fluid running down off the back of the motor and down onto the tranny. check there too.

he pointed me to some stuff at O'Reilys that contained liquid glass that pretty much stopped the leak. this stuff did wonders, the drain plug at the bottom of the radiator snapped off on me as i was draining mine to put this stuff in. i tightened the plastic nut too much so it dripped and after this stuff cycled through my cooling system it sealed that leak up.

my advice is get some off this stuff and see if that'll help solve your leak.
im trying to see if i can remember what its called. ill post back when i come across it.

 

[RangRayy]

http://www.barsproducts.com/1108.htm it looks like this stuff but dont get this stuff

 

[TrevoJreal429]

I did that over a year ago an it helped with the leak, Im not too concerned with the leak because it's slow and not got worse. But what would cause the thermostat to open at a much hotter temp then before?
I read something about a sending unit could that be the problem?
Thanks much.

 

[RangRayy]

now that im not sure about. thats after i replaced mine i noticed that the gauge went up higher than it did before. but it didnt go higher it was just that new thermostat and what temp it was set at.

might try and new tstat or check the seal around it. i know they arent too too expensive just a hassle to get to...

 

[YountExplr]

also check your water pump.

 

[gtyates]

Another place for leaks is the heater control valve. On my OHV engine it is loacted next to the blower fan box, in the engine bay. You will see a black part that has several hoses running to and from it. Mine was leaking. I noticed it when I started to get a slight hot coolant smell drifting through the cabin and I could also smell it when I parked in my garage at home. As far as running a little too hot, sounds like either your new thermostat is not working propoerly, you have one with too high of a temp set point before opening (maybe a 195 instead of 180 degree), or maybe the entire cooling system needs a flush due to build-up in the system. Just had mine flushed in conjunction with replacing a thermostat that was stuck open. Shop guys told me there was a bunch of "gunk" that flushed out of the system.

 

[specialized7]

i couldnt find where mine was leaking until i pressure checke the system in which it turned out to be a lower intake gasket.