Coolant coming from Heat Exchanger

The importance of an effective pre-heat system



As the UK is recovering from weather which saw some areas experiencing their coldest ever day in March, we’ve been attending an engine which has its own temperature issues.

During some routine servicing of the engine, our engineer, Will, was informed of “black coolant”, which had recently been changed.

We knew that this particular engine has had problems with the pre-heaters in the past, so that’s where we started our investigation.

Now, the engine is operated as a back-up, so it does not run regularly, nor for a significant amount of time.

And when it does run, because of the application, it goes straight to full load.

These operating conditions, along with the fact it is in a harsh environment, makes the need for an effective pre-heat system vital.

Having looked back at the pre-heat system, we could see the black coolant was a result of a burnt-out pre-heat element.

Looking further into the root cause, they were burning out because the system was not circulating the heated water fully. Not only was it ineffective, but the heated water was collecting around the element and burning it out.

As a comparison, the second heater (fitted on the A bank) was working fine.

Coolant coming from Heat Exchanger

The difference was the location.

The picture on the left shows the coolant coming from the bottom of the heat exchanger before feeding back into the block. The picture on the right shows the B bank heater which uses coolant from the block, before returning it to the block, with little difference in heights.

There are various systems available, and with a pumped unit, better circulation can be achieved.

It’s not for the first time we have carried out a routine service and the site engineers have been able to call upon our engineers’ expertise and I guess this little story demonstrates the advantages of having an experienced diesel engineer supporting your servicing.

Please get in contact if you’d like more information on effective pre-heat systems, or if you’d like an engineer to attend your engines to help solve any on-going problems.


If you’re after a trustworthy engine specialist with an excellent track record for your job, email us or call +44 (0)1206 673101.

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