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Topic: Thermostat issues part deux... (Read 712 times) previous topic - next topic

Thermostat issues part deux...

A late start this morning but away by 11:30am for an overnight at the Scooteney Reservoir... it closes for the season on October 9th.

I was feeling pretty cocky when we pulled onto I-90 behind a fairly new diesel pusher (with slides and everything) and they couldn't pull the hill east of the bridge across the lake but *I* could and I had to slow down.

So 15 miles down the road I scanned the gauges and water temp is 200F. It should be 180F. Up a hill in the slow lane and we're up to 225F. We *never* get to 225F on a cool (75F) day on this hill. So something is clearly up.

Pulled in to a big truck turn-around and add coolant (but we were really not down more than a quart) and head back towards home. I can keep temps under 200 by acting as a thermostat myself. Gauge reads 180F (normal) when idling but starts to climb under a little bit of a load. Boost pressure under 10 at all times. Increase speed (load) and temp climbs; back off and temp goes back down. But 60mph is too fast and way too fast if there is a hill.

This sounds like a classic "stuck" thermostat to me. Everything was fine just two weeks ago.

Fan belt ok... no leaks in radiator.

Second thermostat in two years if this is, indeed, the issue.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Thermostat issues part deux...

Reply #1 –
Yep, that's what it sounds like. Sometimes the thermostat in the hot water on the stove does not tell the tale. Cheap and easy to replace.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Thermostat issues part deux...

Reply #2 –
When I replaced my coolant in January, I couldn't believe all of the solids (silica, etc.) that came out of my cooling system.  I flushed it about 15 times before I felt that I'd gotten everything out that was going to come out.  It is easy to see how all of that crap could clog up a thermostat or a water pump. 

I'm very glad that I'm not using the old style coolant that needs additive anymore.  Just saying that if you don't know when it was last changed and its still the old style coolant, I'd flush it a lot and switch to the newer stuff. 
Robert
Build # 5304
1998 34' U270 Cummins 6CTA8.3

Re: Thermostat issues part deux...

Reply #3 –
Quote from: Pierce & Gaylie Stewart –
Yep, that's what it sounds like. Sometimes the thermostat in the hot water on the stove does not tell the tale. Cheap and easy to replace.
Usually, you would be right. However, on a U225 it is a 5 hour job. :(

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Thermostat issues part deux...

Reply #4 –
Quote from: rsihnhold –
When I replaced my coolant in January, I couldn't believe all of the solids (silica, etc.) that came out of my cooling system .... (snip)...  Just saying that if you don't know when it was last changed and its still the old style coolant, I'd flush it a lot and switch to the newer stuff.

Hmm... I have not given that much thought but it could be an issue. This is the second thermostat to act up in less than two years.

Where does one put the old coolant? Are there places that take it off your hands for you?

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Thermostat issues part deux...

Reply #5 –
I called my waste disposal/recycling center and was told to flush it down the sink.  Some areas may require you to dispose of it differently from what I've read. 
Robert
Build # 5304
1998 34' U270 Cummins 6CTA8.3

Re: Thermostat issues part deux...

Reply #6 –
Call your parts store like Autozone, NAPA, etc. Either they can take it or will know who can. Major infraction in our county to flush it or dump it.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Thermostat issues part deux...

Reply #7 –
I would never just dump coolant. Nasty stuff and not good for critters.

But since it appears that not all thermostats are equal (and the last one came from a Cummins authorized repair shop - at least they said they were) I am wondering if there are better and worse versions.

Are there?

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Thermostat issues part deux...

Reply #8 –
Ethylene Glycol and and Propylene Glycol are biodegradable. Also, it takes more than one thinks to kill something with Ethylene Glycol.
1998 U270 34'

Re: Thermostat issues part deux...

Reply #9 –
One advantage, really the only advantage from a functional standpoint, to the organic acid (OAT) based coolants is lack of toxicity and ease of disposal.  The glycol stuff is nasty and attractive to critters and the environment.
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Thermostat issues part deux...

Reply #10 –
What I'd really like to know is: Are there better thermostats and worse thermostats; or are they pretty much all the same. Or is there any way of quantifying it?

Since my thermostat - which is a major PITA to change - on the U225 died a year after replacing it (at exorbitant cost) I am wondering whether they used a crappy thermostat. I have had, in my lifetime, maybe three thermostats go bad and two of them went bad in my U225 in about 13 months. One might have been the original so that's probably an age thing. But the replacement, delivered by courier from (presumably) Cummins should have lasted much longer.

So... how would I go about identifying a "higher quality" thermostat?

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Thermostat issues part deux...

Reply #11 –
Craig,

Call a couple of well known overhaul shops that see a lot of your engine. Use their experience to help you make your decision. Another source might be a 5.9 forum. Got to be a lot of them out there with members that have had the same problem.

Keywords: 5.9, Cummins, thermostat, failure, source, replacement, etc.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Thermostat issues part deux...

Reply #12 –
Forums say use a genuine Cummins part; not NAPA.

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."

Re: Thermostat issues part deux...

Reply #13 –
Craig,

Our local logging company sells OEM Detroit and Cummins parts for far less than going to Cummins. They have a huge fleet, a greasy parts counter but good prices. They even order stuff for me at a discount. Detroit wanted $60 for a check valve while their price for the exact same part was $32.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Thermostat issues part deux...

Reply #14 –
Quote from: Pierce & Gaylie Stewart –
Our local logging company sells OEM Detroit and Cummins parts for far less than going to Cummins. They have a huge fleet, a greasy parts counter but good prices. They even order stuff for me at a discount. Detroit wanted $60 for a check valve while their price for the exact same part was $32.
Heck, I'd cheerfully pay $60 for one if I knew it would work for 20 years. I need to call FOT and find out if they used a different thermostat for RV applications. I suspect that might be an issue...

Craig
1993 U225 36' Unihome GV with PACBRAKE exhaust retarder, Banks Stinger and Solar Panels.
Toad: 1999 Jeep Wrangler 2-door soft-top.

"No one has ever had to evacuate a city because the solar panels broke."
 

Re: Thermostat issues part deux...

Reply #15 –
Some municipalities recommend dumping coolant down the (sewage) drain.  You have to search.  When I replaced our coolant we did not have that luxury so I took it to an advance auto.  There is a list of advance autos who take coolant, not all of them do on their website.  Also there is a nationwide website whose name I don't recall right now that lists disposal sites. 

The Advance auto had a 55 gallon drum.  We filled it up and had to leave 3 gallon jugs sitting beside the drum.  The looks you get.  I just say, sorry it's a big truck.