where is my coolant going?

[cherokeechief79]

my 86 monte w 350 vortec has always run cool even at idle.it has the stock rad and I run a 160 t stat.
the other day in the heat it started creeping up w the ac on and sitting still.once I started moving it crept back down again but soon as I sat again it started going up.
it was about a gal low on water (strange) so I added to it and it seemed fine.now a week later its doing the same thing and going way up at a standstill.
I did the dollar bill test in front of the rad and it did suck it to it but not with much force.i turned it off and checked the resistance on the fan and there was a bit I think it could have been way more.
I bought a new clutch last nite and ill put it in tonite but im wondering where the heck this coolant is going.
there are no visible leaks anywhere and I see nothing coming from the exhaust.
I was thinking of putting a pressure gage on the rad to see if it holds.
any ideas?

 

[pontiacgp]

have you checked your oil to make sure no coolant in the oil?

 

[Jeff L]

Check the radiator cap. Had similar issue using ac and temp going up at stop lights. Both cars problems were failing radiator caps. Changed those and problem was solved.

My Monte had the cooling issue because of a bad fan clutch like you mentioned. Mine was not coupling and was loose all the time. Had overheating in city traffic. Changed it and problem solved.

I agree with pontiacgp and check your oil level. When big problems are beginning the coolant starts getting into the oil.

Had another time my thermostat was not working right and water was boiling off in the radiator because it was not flowing correctly and I do not think I had a proper 50/50 coolant mix. It was my Winter car and I was getting it ready before the bad weather. Changed thermostat and put in proper coolant and loss went away. This was an older car with just idiot lights so I had no idea how bad it was getting until the issue boiled over! No pun intended. I think the radiator cap was also bad in this instance too?

As I always write I am not sure any of these are your causes but it sometimes helps looking at them because you never know?

Good luck.

 

[pontiacgp]

what is the operating temperature and what does it get up to?

 

[cherokeechief79]

thanks.
the oil level and color look fine.
the temp has always stayed below 180(stock gage)right now it will climb up to 220 before I have to move to get air going thru the rad.im sure it wld go higher.
last nite I added a gal of water so the system was full,then I sat idling for a long time and after a bit it started creeping up.this is leading me to believe the fan cluch is shot.
its only a yr old from autozone.
lifetime guarantee fortunately.
I just cant see how I can loose a gal of water in 2 weeks with no obvious symptoms or visible leaks.
I guess just hook the pressure tester up wo it running?
if it was running and there was an internal leak should I see the needle pulse?

 

[axisg]

by chance is it a little hard to start when cold ? Like its running on 6 or 7 cylinders ? After looking at the obvious I would suggest you test or have the coolant system pressure tested ( do it cold then again when hot ). That should give you a good indication of where the coolant is going. I have 3 internet dollars bet on a leaking intake gasket. Clutch fan slipping may explain why its slowly creeping up in temp but not where the coolant is going. Your engine can burn off a lot of coolant without noticing that its being burned off and as the coolant disappears you are losing that heat exchange making it run hotter.

 

[pontiacgp]

You don't mention an overflow container for the coolant.....I agree with Axisg on the intake gaskets for the vortec heads. What style of gasket are you using and what have you torqued the 8 bolts to

 

[cherokeechief79]

I have a stock overflow tank which is usually full and never changes but recently its ben empty.
about 2/3 yrs ago I tightened the stock intake gaskets too much and cracked the plastic which caused an oil leak internal and blue smoke.
I replaced them with the felpro problem solvers(metal) at that time and never had a problem.

 

[oldmansmonte]

Not to highjack your thread, but I have a Vortec engine as well. But my overflow starts out empty, but is 1/3 or so full when hot. I never understood this. I also get the smell of coolant around the front of the car when its hot. Never see it in the oil, but then again it get's changed at like 1,500 miles(annually). Never see leaks. Anyone know what's up with that?

 

[pontiacgp]

if you get a smell of coolant then you have a leak, it's a closed system