[Bearhawke]

Note I'm a brake and suspension tech so my knowledge of underhood repair is limited at best,

My G/F's 2000 Suzuki Grand Vitara 2.5L V6 2WD 5 spd stick is starting to run rather hot and once the temp gauge gets much past the 1/2 mark, the AC quits blowing cold. Yes; both the electric pusher and mechanical fans remain on; however, unbeknownst to me, the pusher was disconnected so I plugged it back in. Truck has about 115K miles on it.

I 'hit' the upper and lower radiator hoses with a temp gun and the upper is ca. 190F (200F at the radiator proper by the upper hose) with the lower coolant pipe about 150F or thereabouts. I suspect thermostat which is where the lower coolant pipe goes back into the motor but want to make reasonably sure before I start throwing parts at this thing.

What does concern me is a possible blown head gasket.

 

[TWX]

Well, In your shoes I'd pressure-test the cooling system and possibly do a pressure leak-down test of each cylinder, pressurizing with an air compressor and seeing if that pressure is lost, and if so, trying to figure out if it's out through somewhere that could be the head gasket.

I did some Internet searching, and it does not sound like the temp ranges that you mention are really all that out-of-whack for normal driving. Remember, there are a lot of thermostats that do not even open up until 160°F, 180°F, or higher.

It's possible that there's a coolant temp sensor problem, rather than an actual fault. I don't know how the Suzuki save-the-engine systems work with regard to temperature and electronically cutting off the air conditioning. I would hope that if there is a fault that causes the computer to cut off the AC that it'd store a code in the process.

Unfortunately Dad's '99 Chevy Tracker is the 4cyl, so there's not a lot that I can suggest that direction.

Has the coolant ever been changed, and if not, what kind of coolant is it?

 

[Bearhawke]

Tannon: I suspect it may indeed be a real problem since I loosened the radiator cap and coolant came flying out of there...........plus the overflow reservoir was empty. Too; even with the GV sitting for over an hour turned off, once started back up, it gets hot real fast again. Yes; I realize this is Bullhed City ar over 100F but still. Something seems amiss.

Side note: no 'Check Engine' light.

 

[TWX]

Remember that cooling systems are pressurized, and between the pressure and the non-water part of the coolant, it's possible for coolant to exceed the normal boiling point of water by a considerable amount, and releasing the radiator cap while hot can shoot the hot coolant out and cause steam burns. I would not be surprised if you opened the radiator cap and got at least some coolant to come out if the system was hot.

What did topping up the radiator and adding coolant to the overflow bottle do?

I'd still check codes even without the light. Might not help, but wouldn't hurt.

 

[Bearhawke]

Remember that cooling systems are pressurized, and between the pressure and the non-water part of the coolant, it's possible for coolant to exceed the normal boiling point of water by a considerable amount, and releasing the radiator cap while hot can shoot the hot coolant out and cause steam burns. I would not be surprised if you opened the radiator cap and got at least some coolant to come out if the system was hot.

What did topping up the radiator and adding coolant to the overflow bottle do?

I'd still check codes even without the light. Might not help, but wouldn't hurt.

No change.

 

[TWX]

Well, when the Stratus had a head gasket go bad it only showed strong symptoms while idling for an extended period of time, like in a slow drive-through or in heavy stop-and-go traffic. It would rolling-boil hot exhaust gases through the coolant overflow bottle.

How's the exhaust smell? Coolant can only go a few places if it leaves, and generally that means either out and on to the ground, out through a pin-hole leak in a hose that almost mists the coolant, into a cylinder to be vaporized through the exhaust, in to the crankcase, or in to the radiator via the transmission fluid heat exchanger. That's really about it.

 

[Bearhawke]

Another mechanic stated the temp difference between the two hoses was way too much and advised a new thermostat------------that solved the overheating/failing AC problem.

 

[TWX]

Good. nice when it's a relatively cheap fix.