Changing Cummins 6BTA 5.9 Thermostat

[jreekree]

Going to put SBMar 160 thermostats in my 6BTA 5.9s. Should I drain the coolant from the expansion tank before taking out old thermostat. Since the thermostat is lower than tank I’m wondering if I’m going to have a mess when I take the thermostat housing off or f fluid is mostly trapped and static in engine.
Forewarned, you know.

 

[bayview]

Why 160? The engines will run better at slow speed with hotter stats and above the opening temp it won't make any difference.

My Cs need to be drained but not sure about your Bs.

Good time to change coolant and coolant filters.

 

[jreekree]

Good question. Been reading Tony’s posts n Seaboard Marine site about BTA engines and it makes sense to run a bit cooler when running the engines at the upper end of their HP ratings. Cummins infact puts 160 thermostats in their newer engines. I do know that heat can cook an engine pretty quickly and get costly.
I just had to remove both turbos so I just replaced all fluids. Hateto dump too much out for this project, but for me I can’t see a reason not to lower the temp a bit.
I do know on airplane engines we try to keep the oil temp above 180 -190 to boil moisture out of the oil that’s a byproduct of combustion, but can't find any harm in running the BTA’s a bit cooler. I’ll try to post a link to the explanation if I can.
Thx

 

[jreekree]

Choosing 160 or 180 thermostat.

Hope this link works.

https://www.sbmar.com/articles/choosing-the-160f-or-180f-thermostat-for-your-cummins-6bta/

 

[kapnd]

The answer lies in how you typically operate the boat.
If you like to cover ground fast, and frequently use the upper third of your rpm range, the 160 thermostat is what you’ll want.
If you spend most of your cruising time at displacement speeds, the OEM thermostat is suitable.

 

[Jeff F]

You have to drain the coolant. Most of it, anyway.

Why do you think you need to change them? I get Tony's argument for lower in a high load use case. Near as I can tell it's to give you a little more time to throttle back in case of a cooling system failure when combined with a soft alarm. But there are lots of other good defences against that, like cooling water flow alarms.

I put a 185 themostat in my 6bta because I typically just idle along and wanted a hot motor for that. At high throttle I keep a close eye on temps, and have an alarm that gets my attention. I checked the OEM reco at the time. 160 seems really low to me.

But if you're typically running hard, no harm.

 

[firehoser75]

Jerry,
Jeff F has it right. You will need to drain most of the coolant to replace the thermostat, but if you drain into a large, clean bucket, could you not reuse it?
I just preventively changed my thermostat, but I just replaced with what was there (185) as I often run at 1300 rpm.
From what I can gather from Tony's info on this, is if you run regularly at 2200 rpm (or thereabouts) you will benefit from the 160 thermostat, otherwise, stay with the 185.

 

[C lectric]

On most engines, at least part of the heat exchanger is above the thermostat so you need to partially drain the system or you will have coolant all over the place.

No need to discard the drainings though if the stuff was newly installed. Use a clean bucket to drain it into and put it back in when you are done with the thermostats.
I have done this several times over the years. I use a 5 gal bucket for which I kept the lid .