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Topic: Thermostat source (Read 430 times) previous topic - next topic

Thermostat source

Planning on replacing my thermostat when I replace coolant. Cummins wants $75 for a new one, should I go with an aftermarket one, Napa couldn't find a cross reference on the part # but I found one online from Highway and Heavy Parts $17. Big difference, but I don't know if I should stray from OEM parts for something as important as a thermostat? Thoughts?
Michael & Roxene, Aussie the wonder dog & his daughter Luna the lunatic.
1993 Grand Villa Unihome 280 build #4203
36' 8.3 Cummins 300 hp- 2001 Chevrolet Tracker toad

Re: Thermostat source

Reply #1 –
I would go OEM, that's not a cheap engine.
1998 36 foot U270 Build No. 5328 WTFE, 900 watts solar, Victron controller, B2B, bat monitor, 600 AMPH lithium with 2018 Chevy Colorado toad, SKP #110239, Motorcade #17781, 2021 Escape 17B for when Coach is broken down and campsites are too small, retired and full-timer since Dec. 2020. Part of RV family since 1963.

Re: Thermostat source

Reply #2 –
Real McCoy thanks, I sent you a message concerning a previous post
Michael & Roxene, Aussie the wonder dog & his daughter Luna the lunatic.
1993 Grand Villa Unihome 280 build #4203
36' 8.3 Cummins 300 hp- 2001 Chevrolet Tracker toad

Re: Thermostat source

Reply #3 –
Quote from: mikerox –
Planning on replacing my thermostat when I replace coolant. Cummins wants $75 for a new one, should I go with an aftermarket one, Napa couldn't find a cross reference on the part # but I found one online from Highway and Heavy Parts $17. Big difference, but I don't know if I should stray from OEM parts for something as important as a thermostat? Thoughts?

Aftermarket thermostats can become a tricky situation especially for larger engines. In addition to the quality concerns there often design differences. The aftermarkets parts listing, cross references, are often based on the top body diameter, secondary disc if applicable, and temperature rating. Often the operating disc size or type are considered. This is real common problem in the RV gas engine world as almost all over the counter thermostats are actually the wrong disc design for the larger radiators and increased coolant flow that all those engines have compared to the vans and pickup truck. The other unknown is the operating characteristics of the stat. At what temp does it start to open and what is the difference in temp from opening start to full open? What is the response timing. What is the Hysteresis for it to begin closing. You may not see or notice the difference, but you may also get one that contributed to that spread where outside temps and load tend to have an effect on the running temp.  The engine that takes forever to warm up as the stat cracks open too early and then runs hotter than normal under heavy load as it doesn't open fully when needed. Changing a stat sometimes can became an experiment. Even with the OEM one. Sometimes there are also air bleed or bypass features that may be missing or may be there and not desired for the application.
My thought is that if you can easily change, you can go for the aftermarket. You do want to look at it carefully and consider where it came from. Compare it carefully with the one that comes out. As for the price difference, if Cummins is still supporting those older engines and providing even commodity parts, that needs some support. If we don't buy, at some point they won't provide.
Dennis Haynes
Bohemia NY
2008 Nimbus 342 SE Carlyle
Build #6475
Motorcade #19148

Re: Thermostat source

Reply #4 –
Go with the Cummins. It's cheap peace of mind. You won't regret it.
Mark & Bev
2001 U295 36' Slide
Cummins ISC 8.3 350HP
Build #5802
Jeep Wrangler Toad

Re: Thermostat source

Reply #5 –
I have only ever had one thermostat fail and it was a from Cummins and they usually fail open.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Thermostat source

Reply #6 –
Im confident what ever you replace it with wouldn't provide the service life yours has unfortunately. I would go Cummins OEM if I was replacing.

Re: Thermostat source

Reply #7 –
Quote from: Dennis H –
My thought is that if you can easily change, you can go for the aftermarket. Compare it carefully with the one that comes out. As for the price difference, if Cummins is still supporting those older engines and providing even commodity parts, that needs some support. If we don't buy, at some point they won't provide.
Everything here is exactly correct but I wanted to highlight the above .
Is it easy to change on the side of the road? How much coolant will you loose
Cost of replacement coolant.
Cost of tow?

Starting to make that overpriced part look cheap once you  include all the multipliers to its replacement.

Re: Thermostat source

Reply #8 –
I tried a cheap one from Amazon and it didn't work right, it wasn't long enough to seal at the lower end and block coolant flow. I ended up going to Cummins to get the right one. The part number had been updated multiple times with improvements since the original was built.
1991 U300 Side Aisle 6V92 Silver #3897
2004 U320 40' #6246