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Cat Man
Cat Man, Cat Engine Expert
Category: Boat
Satisfied Customers: 8813
Experience:  23 years Caterpillar Engine Experience
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one engine in my 2003 Cabo with 3126 B is loosing coolant from

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one engine in my 2003 Cabo with 3126 B is loosing coolant from the plastic reserve bottle. Half full when I leave for fishing and empty when I return. No signs of fluid anywhere that I can see. Engine level looks OK and no alarms or msg on the Cat electronic control. I put a pressure test on it at 15 lbs and it held steady. Thanks

Hi. Thanks for asking your question! I will try and help you out.

Most often when a 3126B engine is loosing coolant and it is not getting in the oil or leaking on the floor or ground, it's getting slowly burned in one or more cylinders. I have seen this before.

It not a large leak or else when shutnoff it will get on the piston and hydrolock the engine. To confirm its getting burned in the cylinder, the inside if the turbo outlet and exhaust piping will have a light white tint color to it. If you see this, it's getting burned in a cylinder.

This can be cause by a cracked head, or crack in one if the cylinders.

Please reply back if you need more help or have more questions. I am happy to assist.
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Customer: replied 3 years ago.

Thanks.I only loose the reserve at higher rpms. Example: left the marina at 5:00 am and drove at 12/1300 rpm. Trolled most of the day at 850/900 rpm. Checked the reserve at 2:00 pm and it was level. returned 20 miles at 2200/2250 rpm, 1 hour. Checked the next day when engine was cool and reserve was empty but engine tank full????

You are very welcome Mike.

Normally that sounds like the coolant is being pushed from the system if you only lose coolant at high RPM's.

But if you do not see any coolant being pushed out, I would suspect its being consumed in one or more cylinders.

Let me know if you need more help.

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