Losing Coolant Fast

I have a 1997 GMC Sonoma with a V6 Engine (4.3L I believe).

I had a slight coolant leak for about a year. I thought it was the intake manifold gasket, since I've read a lot about that known issue with Dex-cool. I used a stop leak additive and the problem seemed to be better.

Now a year later, I'm losing coolant like it's nobody's business. Every 3 days I'm putting a gallon+ of water (since it's so expensive, I can't afford to waste coolant at these rates) in the radiator at a time. The funny thing is, the reservoir tank is full, and it even has actual coolant in it still. Before when I was losing coolant, I was having to replace it everywhere, but now I'm only having to fill the radiator.

The other day my temperature gauge was reading about 3/8 (it's usually about 1/4) so I thought I'd preempt a little and fill it up with some water. I heard sort of a hissing noise in the front driver's side corner of the hood where the radiator/front part of the engine is...some white steam/smoke was seen coming out of there just before/after I pulled over. That whole area seemed wet, so I guess water was leaking out to other areas of the engine and steaming?


A few days later I pulled into a parking lot, and just for giggles I was going to pour water into it again. The temperature gauge only showed 1/4 up, which is normal, but I know how fast things can go bad, so I went to put water in it after being stopped a few minutes.

I opened the radiator cap and water GUSHED all over my hand. It was luke warm at most, so it didn't hurt. That's never happened before, and I'm really confused as to why it would do that. (yes, I know that was very stupid of me to do!)

any ideas what my problem could be? I never see coolant really dripping from my car, and I'm only losing it directly from the radiator. The reservoir is still full! Could this be an intake manifold gasket problem like I originally thought? There's no way it could be a blown head gasket right?

I'm not TOO knowledgeable about this stuff, so I'm hoping I provided enough information. I want to get this fixed asap, but I want to educate myself enough so I don't get ripped off.

A few things come to mind here, How does your engine oil look? Does it look like oil or chocolate milk. Does it run on all 6 cylinders? You could have a bad head gasket or cracked head and your coolant is running out the exhaust. If your engine oil looks like chocolate milk it's definitely the intake gasket. If it look like regular oil than your problem is more severe and either a head gasket or cracked head. You should do a compression test and post your results.

You may have a craked head.

Run a pressure test on coolant system and see if you can spot leak.
And as said watch the oil for coolant/water in it.

They make a coolant leak dye for help with finding coolant leaks.

The easiest thing to do is when you first crank the vehicle is to go to the rear and look at the exhaust. If the head is cracked, it will show a white vapor comming out the exhaust and when you rev it up some, will even show droplets of water comming out the exhaust. Takes 2 mins. Then you know you have a cracked head........Happened to me !

The thing with a blown head gasket, cracked block, or a cracked head is that the vehicle does not always have the same symptoms or show all of the possible symptoms, it will show one or all of the following, milky oil, white exhaust, droplets of water in exhaust, high pressure in your coolant system, which is caused from the engines compression. you can also see the effects on your spark plugs, remove them and look for the odd one or ones out. Usually very clean plug will be the bank that has a head gasket leak. autozone has a block tester kit with a dye that will tell you if you are getting combustion gases into your coolant system. Its free and easy to use. another more obscure problem that I recently came across was a transmission cooler leaking into the radiator and it was causing the coolant system to over pressure causing coolant loss. this will result in milky transmission fluid and eventually hard shifting and other tranny problems. Do the test and determine if you have combustion gasses in your coolant system then I can give you some tips on how to isolate the problem.