Coolant location

[Keith Bachand]

Hello everyone!,

I just purchased a 1979 Trojan F26 that’s been modified as well as fitted with a 6BT Cummins attached to a Velvet drive transmission. It does run and seems to check out but does not have an hour meter.

My question is regarding coolant. It seems this motor doesn’t have a large coolant tank like most I see. If I open the cap on top of the wet exhaust housing there is indeed coolant in there (green colored) as well as some in the small overflow tank.

Raw seawater comes in and flows through the heat exchanger and out the exhaust. No aftercooler to cool the air as this seems to be a standard 6BT motor and not the BTA version.

Is it okay that this setup doesn’t have the large coolant reservoir that most seem to have?

Thanks in advance!

Topic

[Keith Bachand]

Tony Athens wrote:

I’ll mention one more thing.. The total lack of a coolant expansion tank goes against every Cummins engine requirements pertaining to proper closed coolant design requirements…………………….. Makes ZERO sense.

If this was my engine, I seriously consider upgrading your system.

Tony

Tony! Thanks for the response. As you mentioned the design makes no sense which is why I was a little confused as to what the deal was since every other 6BT marinized Cummins has a coolant expansion tank which mine doesn’t so its a little strange. I will definitely look into upgrading the system. I know its an older motor but would assume it has been rebuilt at one point or another so I would hate for it to fail due to cooling issues.

[Keith Bachand]

Corey Schmidt wrote:

That engine is an OLD engine but Tony mentioned that Cummins actually came out with an early 4B setup that way as well. It wont hurt anything but make sure you’ve always got enough coolant! If the coolant expands, it will hopefully go into the reservoir and then back into the engine!

Thank you so much for the response! I figure its definitely a pretty old motor but seems like it’s in decent health from what I can tell. I will bring some spare coolant and be sure I keep it on board just in case. It does appear the reservoir has coolant in it and will hopefully go back into the engine. I just wanted to be sure it wasn’t some jerry-rigged design but would make sense if it’s just a super old design.

Being this motor doesn’t have an hour meter – is there any way I can tell general health of this motor without going in for a full compression test and all of that?

The previous owner said it doesn’t burn oil, and from what I can tell it runs strong.

[Tony Athens]

I’ll mention one more thing.. The total lack of a coolant expansion tank goes against every Cummins engine requirements pertaining to proper closed coolant design requirements…………………….. Makes ZERO sense.

If this was my engine, I seriously consider upgrading your system.

Tony

1 user thanked author for this post.

Keith Bachand

[Corey Schmidt]

That engine is an OLD engine but Tony mentioned that Cummins actually came out with an early 4B setup that way as well. It wont hurt anything but make sure you’ve always got enough coolant! If the coolant expands, it will hopefully go into the reservoir and then back into the engine!

1 user thanked author for this post.

Keith Bachand

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