Decreasing coolant levels

[Retire55]

Assistance please.

My 91 XLT (105,000 miles) keeps losing coolant fluid (close to a litre a month). There are no telltale signs of smoke from the exhaust and no visible leaks. I've had the coolant system pressure tested twice without identifying the problem. Next the dealer drained the oil, removed the oil filter, dropped the oil pan and left the vehicle sit overnight to see if any coolant made its way thru. Nothing. The used oil from oil changes looks normal and the vehicle runs fine. I'm concerned that if this situation isn't resolved, there will be serious consequences. Are there any tests that can be performed that might point to the potential problem? Or must I bite the bullet and have new manifold gaskets installed as a pre-emptive measure? I'm no mechanic - consequently all suggestions will be much appreciated. Thanks in advance.

 

[shamaal]

Personal Experience:

1. The aftermarket radiators are crimped on the side around a gasket. My first am radiator would leak only when cold, after warming up the leak was gone. Loss was about the same amount, only in Texas the leak was a quart.

2. Head gasket leaks vary from full blown steam shooting out the engine to little piddle ass leaks such as you describe. After I drained my system to replace the water pump I noticed a single drop of oil floating on top of the water in my bucket. Sure enough, I still had a persistent loss of around a quart a month. Changing the headgasket fixed it. Leaks into the cylinder may not translate into enough to get into the oil.

I've read in the forum some individual's been driving with a minor leak for years. I guess it depends on the severity. Other than a slow drop in engine performance and slow poisoning of the O2 sensor, I would think the greatest danger is getting enough water in the cylinder after a prolonged stationary period to cause hydraulic problems. A simple cylinder compression test would locate any problem with the head gaskets.

I once tracked down an annoying leak where the overflow hose attached to the tank, it was stretched and would leak an dinky amount only at certain times.

There is a fluorescent dye for coolant also, it would have pinpointed my first radiator leak.

Good Luck, search and ask questions.

 

[LXNavajo_94]

mine did the same thing for a while. I installed a new radiator, seems like there was a very small hair line crack that when under pressure would leak some. Once it cooled off it would seal back up. Plus with the air from the fan and such it blew the coolant away or something so you you wouldn't see it.

 

[Abom]

Mine leaks very very little at a metal pipe fitting at the top of the radiator, on the drivers side. It seems that it's leaking through the thead, I assume no one used any teflon tape when installing it. Anyways, it drips about 0.01 quarts every 4 weeks, as I said, very very little, but just an idea of where else to look.