Coolant Usage


New Member
I've got a 1998 FL50 with Cat 3126 and Allison with about 31,000 miles. I keep the coolant just above the site glass. I've recently -- over last few months -- noticed that after 1000-2000 the coolant drops just below the site glass. So I pour in a 1/2 quart or so. I don't see any leaks around any of the hoses or on the concrete pad. Engine runs fine. Just curious if others would consider this normal or if some problem deep inside the engine is lingering. I will be keeping an closer eye on the coolant usage.
Coolant Usage

Sounds like there is a problem lingering but a fairly simply one. Remove the engine and insert a Duremax.

All kidding aside but have you checked you pressure radiator cap. The seay wear out after a while and will let coolant bypass or vaprize while running down the road.

Another thought is Diesels are hard ond cooling systems due to the heat they produce. Have you changed out your coolant since you have had the truck, this stuff will breakdown.
Coolant Usage

You guys are good. May have found the problem as you suggested. Took the truck out for a spin today. Parked it on the pad afterward and saw a little puddle of coolant. Coming from overflow tube on the reservoir. Will swap out the cap and check again. Have changed the coolant with extended life stuff within the last 2 years. Also saw a couple of drops around the hose coming out of the radiator at the bottom. Tightened the clamp a tad.

What threw me off was noting the coolant down but didn't see any puddle. Must have been expelled before along the way home.

Nice when you find a simple fixe.