on a 1988 pontiac tojan which is mechanically a pontiac transam with the 5.0l V8, I have had a constant coolant leak that cannot be located, hoses have been replaced, thermostats, 4 of the 6 freeze plugs, spent a lot of money and none of the fixes have fully resolved the problem, it still leaks about 1 gallon of coolant every couple of weeks and there are no puddles anywhere when car is parked, i have had 2 different mechanics try and resolve, and no luck....have owned and own many cars with the same engine, never see this problem before...water pump i was told was fine, and if that were leaking, it would leave a puddle, but there is no puddle...HELP!!

 

Your problem is a simple one , and one simple diagnostic procedure will tell you exactly where your coolant is going . Have you done a "cooling system pressure test" yet ? Because your loosing one gallon every two weeks with none hitting the street then the obvious answer is that your burning it through the engine in one of three places ;

#1 A bad intake manifold gasket .

Or

#2 A bad head gasket .

Or (hopefully not and thankfully VERY rare compared to numbers 1 and 2) A crack in either one cylinder head or the block itself .

Like i said , #1 is by far the most common reason for your problem , with #2 also a distinct possibility , and of course #3 being seen in only a very small percentage of these mysteriously missing coolant situations .

Now I know your gonna ask "But if it's burning it , shouldn't I be seeing billowing clouds of white smoke from the exhaust ?" .... Nope , I will tell you from personal experience that my 305 burnt antifreeze , slowly at first and got progressively worse . Like you , every couple or few weeks I'd be adding coolant with no trace of where it was going . A pressure test revealed pressure loss with gurgling heard near the top rear of the engine , classic intake manifold gasket failure . It took till it was burning over a quart a day before the white clouds appeared from the exhaust and the sticky sweet smell of burning coolant could be smelled from the exhaust !

Providing your passenger's side carpet isn't soaked with coolant , I'd say you've very likely got an intake manifold gasket or a head gasket job in your car's future ....

 

have you replaced the water pump - i had a similar issue that got worse and worse, basically there was a leak behind the pulley and was being sprayed as a fine mist constantly

 

I would bet coolant leak as well. Had one on my L-98 motor.... it wicks down onto the engine and evaporates, but never a puddle. Do you have a burnt coolant smell in the engine compartment after driving it for a while?

 

I got the same issue but maybe a quart every few trips out. My anti freeze has a rusty look to it also. I'm thinking 350 swap in near future I hope.