Losing Coolant

[DIALSDIESEL]

99 CH613 E7-350 COOLANT LEVEL DROPS BUT NO SIGN OF LEAKAGE ANYWHERE, OIL IS NOT MILKY, BUT COOLANT IS "VERY RUSTY".

ANY IDEAS? OIL COOLER OR LINERS, ANY EASY WAY TO DETERMINE? SEEMS TO HAVE STEAM MIXED WITH BLOW BY COMING OUT OF PIPE.

THANKS IN ADVANCE FOR HELP.

[fjh]

99 CH613 E7-350 COOLANT LEVEL DROPS BUT NO SIGN OF LEAKAGE ANYWHERE, OIL IS NOT MILKY, BUT COOLANT IS "VERY RUSTY".

ANY IDEAS? OIL COOLER OR LINERS, ANY EASY WAY TO DETERMINE? SEEMS TO HAVE STEAM MIXED WITH BLOW BY COMING OUT OF PIPE.

THANKS IN ADVANCE FOR HELP.

My first guess would be liners leaking.You could try some repair in a can, like alumiseal ect. Do not use barsleak !

[bbigrig]

Keep an eye on the coolant color/texture. At an almost all mack fleet I worked at we had lots of (plate type) oil cooler failures. probably over 1/4 of our 1999/2000 model year trucks (over 100 macks in the fleet) had the coolers replaced and an updated coolant bybass hose installed.

We also had 4 engine blocks that the casting dust was not cleaned out properly causing the dust to settle in the air compressor coolant passage, causing cooling system problems to the compressor.( would melt the plastic air line for unloader signal at the compressor)

It will look like dirt in the coolant and our trucks didn't have the cooling system filters to strain it out in time.

If the color/ texture of the coolant doesn't change I would suspect liner/head area problems aswell. How is the engine temp on a hard pull etc?

is the cooling system building up pressure faster then normal, before the engine temp. comes up?