more chevy crap

[CaptainMikey]

Ive got a chevy 305IN V8 5.0L in a conversion van.
Im loosing coolant but cant find out where. There are no puddles in the drive way, no puddles where i park at work, no leaks that are visable, thermostat is working, hoses are in good condition, and radiator is perfectly fine, and the radiator cap is brand new and in working condition. I pulled the dog house and didnt see any leaking around the engine at all. The only thing that I can find is that there is evedence that coolant is being expelled out the overflow tube from the res. tank. I ran it for a full hour and let it get hot, checked everything again, and found nothing.

Here is what happens. I lost my heater and within 30sec-1 min the temp rises to 235, doesnt over heat but it gets hot and. I pulled over and had to add about 1.5gal of 50/50. Got all the bubbles out, the thermostat opened and the heater worked. Fastforward 3 weeks. Sam thing again, this time almost 2 gallons gone. But no signs of leakage or failure of items. Pulled the waterpump and it is in perfect condition. Drained the oil to rule out coolant leaking into crankcase and didnt find any in the oil.

Kind of stumped.

[LVFD301]

I am no mechanic. I don't even play on on TV.

But... Could it be head gasket leak?

[mcaldwell]

I am no mechanic. I don't even play on on TV.

But... Could it be head gasket leak?

Possibly internal, check exhaust for signs of coolant.

[GFDSlappyRob]

yeah dude if you were leaking that much coolant through your head gasket you'd more problems than just losing coolant... your engine wouldn't runwell if at all. Just take it in and get it looked at bro...

[MalahatTwo7]

I am no mechanic. I don't even play on on TV.

But... Could it be head gasket leak?

I have an '85 Blazer, 2.8 litre with a similar problem. The leak is actually right at the junction of the upper rad hose, where it leads into the top of ot radiator. Also leaked a bit around the thermostat. Both leaks come when the motor is running hot, and the only way that I ever saw the "problem" was the bit of green residue around both points. New hose, new thermostat 'n gasket and alumi-seal never did truly fix the problem. Just one 'o them Chevy Gremlins, I guess.

[EFD840]

You've probably already checked but just in case...

Lift the floor mat on the passenger side and feel the carpet. If it is damp or smells of antifreeze, you've got a leaking heater core.

[ThNozzleman]

Pull your plugs and look for discoloration on one or two of them. Do a leak down test of each cylinder with the valves closed (TDC). Listen for air escaping from the radiator. Also, pressure check the radiator and look closely for external leaks at the head gaskets and "freeze plugs" that may be evaporating on exhaust members and other hot surfaces instead of hitting the ground. You should be able to smell that, though.

[DaSharkie]

If you have a friend with a black light (or have a teenage child ) you can get a bottle of dye to see where any coolant leaks out. If I recall my days of working for a car dealer correctly.

Might be worth replacing the thermostat anyway. If something is causing the engine to heat up that badly that you lose so much coolant, it could be getting clogged or just plain not working properly in general. Especially if you are only seeing coolant residue at the overflow port.

I had an '01 Impala with a 3.6 in it that would sound like a coffe percolator after driving for a bit and we had to keep a closer eye on the coolant. I suspect it was probably a similar issue. Have since replaced this Chevy Crap with an '07 Toyota Highlander after $1,500 in sensors, components, and a new catalytic converter, traction control problems, airbag sensor malfunctions, and with the suspension shot at 59,000 miles.

Much better now.

[ntmd8r38]

On a 305 it's more likely cracked heads, probably near the exhaust valve seats, very common in those engines.

[MalahatTwo7]

On a 305 it's more likely cracked heads, probably near the exhaust valve seats, very common in those engines.

Hmm sounds like the 2.8's too. They have a habit of throwing #'s 5 and 6 cyls.

[LeeJunkins]

Ive got a chevy 305IN V8 5.0L in a conversion van.
Im loosing coolant but cant find out where. There are no puddles in the drive way, no puddles where i park at work, no leaks that are visable, thermostat is working, hoses are in good condition, and radiator is perfectly fine, and the radiator cap is brand new and in working condition. I pulled the dog house and didnt see any leaking around the engine at all. The only thing that I can find is that there is evedence that coolant is being expelled out the overflow tube from the res. tank. I ran it for a full hour and let it get hot, checked everything again, and found nothing.

Here is what happens. I lost my heater and within 30sec-1 min the temp rises to 235, doesnt over heat but it gets hot and. I pulled over and had to add about 1.5gal of 50/50. Got all the bubbles out, the thermostat opened and the heater worked. Fastforward 3 weeks. Sam thing again, this time almost 2 gallons gone. But no signs of leakage or failure of items. Pulled the waterpump and it is in perfect condition. Drained the oil to rule out coolant leaking into crankcase and didnt find any in the oil.

Kind of stumped.

You did not say what year yours is, but if it is a vortech 305 or 350 the head gaskets have a restricktor plate over one of the water jackets on each side, these have about an 1/8 inch hole for the water to circulate through and if they rust through the water will circulate too fast and when you run pretty hard and then let off, it will shoot out the over flow tube. This is a very common problem in areas that have hard water.
The vortech engine will be 1987-up

[CaptainMikey]

I gave it to a mechanic today. Hopefuly it wont put a hole in my wallet. Hope to be in a actual car in a year that I can work on.