Loosing Coolant, mechanic stumped!

[thepload]

I own a 98 Firebird 3800 Auto, over the last month or so Ive been losing coolant and overheating. I dumped about 4-5 gallons of coolant in the last month. I took it to my mechanic the other day and he had the thing all day, did a pressure check, its not in the oil, ran it couldnt find any signs of leakage. Hes completly stumped, he was even amazed at how well the bird was running with over 100k miles on it.

My question, has anyone else had this problem?

[CDNFB]

Check out the latest posts on "POS starter, sounds bad",
http://www.camarov6.com/ubb/ultimate...c;f=1;t=016744

DZ

[CDNFB]

Yeah, I know the heading is about a starter, but it wanders off into a rather lengthy cooling issue that you may find helpful

DZ

[thepload]

They didnt think it was a t-stat issue and the water pump is good. All these things mentioned there were checked, hence the whole stumped thing. Starting to dislike modern cars again.

[camaro_speedemon]

If you're loosing coolant, and it's not dripping externally, or not going into the oil, then the engine is consuming it. It's probably a blown headgasket.

My old camaro ate coolant, nothing substantial like you though and it speced out fine in a compression test.

Is there white smoke coming from the exhaust after the engine is at temp?

It could be possible that the radiator cap isn't holding the pressure, so try changing that if you havent already.

[slow6]

I loose coolant. I used to think it was evaporating out, by some small leak somewhere. But looks like I'm going to have to tear into it to find out if I have a blown headgasket, a cracked block, or a bad intake manifold gasket(s).

[xFirex99]

I just went through this. Get under the car on the drivers side & look up by the motor mount. Check around the block heater for leaks. If your car doesn't have a block heater, check the frost plugs 'cuz they leak sometimes. Not often, but sometimes.

[iGoRa]

Offtopic:

Originally posted by xFirex99:

Hey where are you from? email me

[slow6]

Originally posted by xFirex99:
I just went through this. Get under the car on the drivers side & look up by the motor mount. Check around the block heater for leaks. If your car doesn't have a block heater, check the frost plugs 'cuz they leak sometimes. Not often, but sometimes.

In that case maybe put a little silicone RTV around the freeze plugs. I dont have a block heater either

[CDNFB]

XFireX99

I know what your talking about, but do the guys way south of the CAN/US boarder even know what a block heater is??

DZ

[xFirex99]

I bet if I sent a pic of my 'bird with two power cords hanging out the front, that would really throw them for a loop! (gotta have the battery warmer too)

[camaro_speedemon]

Originally posted by CDNFB:
XFireX99

I know what your talking about, but do the guys way south of the CAN/US boarder even know what a block heater is??

DZ

Probably something that keeps the block from freezing ;)

[CDNFB]

Yup, immersion heater put in place of one of the frost plugs.

I only have one cord that connects to:
1) block heater,
2) interior warmer

In the past I have had up to 3, the third one for the battery blanket!

I remember being in the states on holiday and the old man left the cord hanging out. Many people thought we had an electric car!!

Sorry getting off track here.

DZ

[camaronat]

You could have a problem like mine. I had a front cover seal fail at the water pump. It only leaked when the engine was warm, and the heat of the engine made the evidence dry up when the engine turned off. I found it when I tried replacing the pump, and it still leaked afterward.

Or you could have a cracked reservoir that leaks when you go through a turn. I had that problem for a while too. I found that problem when I was autocrossing, and someone saw liquid coming from the side of my vehicle.

[thepload]

Im going to bring up some of this stuff with my mechanic later, I dont have time to mess with the dang thing later. Theres no smoke or anything coming out of the exhaust, my mechanic just couldnt figure it out he ran it for hours drove it and there were no noticable stains anywhere. Im pretty sure its consuming the coolant so everything mentioned above in that area I'll look into. Thanks for the help guys I'll keep ya'll updated.