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Topic: Engine thermostat replacement on GV 8.3 (Read 564 times) previous topic - next topic

Engine thermostat replacement on GV 8.3

I'm getting ready to replace my coolant in my GV- 8.3 Cummins- I ordered a new thermostat to replace as well- this repair is new to me so I'm trying to educate myself as much as possible. I checked a few videos on YT to familiarize myself with the job- I noticed that most of the thermostats being replaced on YT videos have a seal around the larger housing ring, the new OEM one I ordered from Cummins does not have the o-ring. I have not opened up the thermostat on the coach yet- I wanted to make sure I had everything I needed first. I've checked for a gasket "kit" but not sure there is one. The 2 pictures are of my new thermostat- the one is of an example with an o-ring. Just wondered if anyone that has my same coach/engine can shed light on this. Thanks in advance. Michael
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: Engine thermostat replacement on GV 8.3

Reply #1 –
Mike,

Sorry I can't answer your question - I haven't changed our thermostat (or thermostats).  AFAIK our engine is still running the original factory equipment (whatever that is) without any apparent distress.  Knock wood.

If you haven't already, you might consider signing up at the Cummins QuickServe website.  It's free, and all you need is your engine ESN.  Doing so will allow you access to a nice parts catalog and other info that is specific to your individual engine.  Very handy for trying to answer questions about parts and part numbers.  Link below:

Cummins QuickServe Online

You can also reach the same parts listing by going to the Cummins Parts page and entering your ESN.

Genuine Cummins Parts

If you don't know your ESN, then here's where you find it.  Standing at the back end of coach, looking at the engine, there is a flat sheet metal cover on the "front" (nearest you) of the engine block.  The top edge of the cover is about 2" wide.  Look at the top edge, right below your A/C compressor mount, and you should find the black metal plate.  On the plate is your ESN (engine serial number).  Very important - write it down and keep it handy in the coach paperwork.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Engine thermostat replacement on GV 8.3

Reply #2 –
When I had a 8.3 Cummins it had 2 thermostats.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Engine thermostat replacement on GV 8.3

Reply #3 –
Quote from: oldguy –
When I had a 8.3 Cummins it had 2 thermostats.
The parts list on QuickServe for my C8.3 also shows two thermostats.  I just don't want to say that holds true for ALL 8.3 engines cuz I don't know that for sure.  The .pdf below is copied from the parts list for my engine.

That's why I want Mike to look up his ESN and see what it shows for his engine.



1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Engine thermostat replacement on GV 8.3

Reply #4 –
Chuck and Peter,
I was finally able to log into the Cummins site to check engine & parts diagrams and yes, I do also have the 2 thermostats. Knowing that now, I will need another thermostat and some gaskets. I had read some posts recommending changing the thermostat(s) when I do a coolant flush. I am considering going to the Final Charge coolant which means a conversion from the green coolant. We were planning a long trip to WA state from ATL and I was concerned with the summer temps. New, life events may change those plans so the coolant change might be put on hold. After more inspection and looking at the parts diagrams, the thermostat replacement is more involved than I first imagined. I don't have any overheating issues so I may just get some test strips right now and determine what filter is needed and change the coolant later. I am learning something new everyday and am grateful to the knowledge I gain on this forum. Always appreciative, Michael
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: Engine thermostat replacement on GV 8.3

Reply #5 –
Quote from: mikerox –
I don't have any overheating issues so I may just get some test strips right now and determine what filter is needed and change the coolant later.

Be aware that if you have a coolant that requires a filter with units of SCA in it now, if you switch to a different coolant, such as an extended life OAT, which does not require SCA, you will need to replace the filter with one having no additive (sometimes called a "blank" filter).

Brett can expand on this.

The reason we did a coolant system flush, clean, and refill plus new filter after we bought WildE is because the filter didn't match the coolant.  Sucked to have to do it (cost plus having to recycle all that coolant and flush) since it was a fairly recent coolant change, according to the records, but it was necessary in our minds.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Engine thermostat replacement on GV 8.3

Reply #6 –
My 97 C8.3 has a single thermostat. Quickserve and your serial number are your friends.
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: Engine thermostat replacement on GV 8.3

Reply #7 –
I think the single thermostat system will have different a different thermostat then the two system
thermostats.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Engine thermostat replacement on GV 8.3

Reply #8 –
Now would be the time to redo the coolant filter shutoff to the metal valve ,the plastic one is prone to breaking.
96 U270 BUILD 4810
85 380SL
Drummonds TN.

Re: Engine thermostat replacement on GV 8.3

Reply #9 –
Quote from: John44 –
Now would be the time to redo the coolant filter shutoff to the metal valve ,the plastic one is prone to breaking.
Link below to a thread discussing the troublesome plastic coolant filter shutoff valve.

C8.3 Water filter shut off valve broken
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Engine thermostat replacement on GV 8.3

Reply #10 –
I have found over the years that the coolant shut off valve is not worth the trouble. If you have the new filter right there, you don't lose very much coolant.
previous 1984 35 ft ORED 250 HP 3208 Cat       
previous 1998 40 ft U295 CAI 325 hp Cummins
previous 2003 40 Ft u320 build #6140 450 Cummins M11.                                                         
1999 Mazda Miata
Ron, Nancy, Tipper the cat, Max The dog
1997 U 270 36 ft build number 5174 8.3 Cummins