Dave receives many question on engine heating issues but asking questions there is no coolant loss.
The first answer I ask is when was the last time engine temperature regulator replaced and the sticking of what is called jiggle pin some temperature regulator. It is recommended to replace the
engine temperature regulator every 2 years. Ran across heating problems same nature with our
Red engines ( Cummins ) that are the same vintage as our Caterpillar engines. Going deep into
technical information with a ongoing problem, this is what Dave has found in technical bulletin in
Cummins ISL 400 and several models affected. Technical Service bulletin May of 2004 as follows.
Coolant level Sensor Durability Concerns.to inform dealers and distributor network that an on
going issue 2 an 3 pin Coolant Level sensors and extended life coolant has been identified in the field.
Corrosion and coating of the coolant level sensor probes causes low coolant level fault codes. If an
engine records low coolant level fault codes and uses extended life coolant the above is the most
likely cause. Extended life coolants use complex chemistry to combat corrosion. One characteristic
of the chemistry uses the voltage potential as the pointer to the problem areas in the coolant system
and attempts to insulate one of The contributors. The coolant would than perceive the voltage
differential between the coolant level sensor probes as ongoing corrosion and attempt to insulate
one of the pins. When the chemical imbalance occurs , the coated pin drives the ECM signal voltage
up, causing low coolant level faults. The coating can be visually observed on the sensor probe, and
resembles oxidation and or black soot. The chemical characteristics of the extended life coolant can cause corrosion and coating of the coolant sensor probes. In closing many engines came with the
Green Coolant and have at some point changed over to life time Coolant. Again this affects both
2-pin and 3-pin Level sensors. Dave Atherton Retired Cat Mechanic