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Onan 35EK thermostat question...


First, the particulars: Model is 35EK, serial # is A970627734, the Spec is 86116D, running on nat...

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Old 11-26-2013, 11:46 AM
farokh farokh is offline
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Default Onan 35EK thermostat question...

First, the particulars: Model is 35EK, serial # is A970627734, the Spec is 86116D, running on nat gas.

When I ran the genset a couple of days ago to exercise it, the temp gauge didn't go over about 135 degrees (air temp was about 40). I ran it for about 2 hours with a 4KW load. I would think that the running temperature would be higher and I was figuring that I need to replace the thermostat. I know that car thermostats usually run 180-190 degrees, and I wanted to be sure that was the correct range for the genet.

Thanks!
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Old 11-26-2013, 12:27 PM
JerryLee JerryLee is offline
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Default Re: 35EK thermostat question...

The experts will be along shortly but I think this engine is no different that a typical auto engine of the same era so a 180-195 thermostat should be good for this engine. You might as well refill with new anti-freeze and check the radiator cap and take a close look at the coolant recovery hose and tank if it has one.

I have no special knowledge of this generator so listen to the experts before you listen to me.
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Old 11-26-2013, 12:27 PM
Motorhead Motorhead is offline
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Default Re: 35EK thermostat question...

Seeing that the engine is a Ford 300 6cyl, I would want it to be running at at least 170-180 at all times. 135 is too cold to keep moisture build up inside of the engine burned off. You could buy a new thermostat at an auto parts store for a '97 Ford 300 6 cyl. The auto parts may say that a 195-210 is stock but you usually have a choice. My preference would be a 180 degree. Make sure your cooling system coolant is kept up to date. Don't use the green stuff. Use a diesel truck coolant. Lasts much longer and protects better longer.
The FORD 300 6 cylinder, in my opinion, is one of the BEST designed and bullet proof 6 cylinders ever built! I know.... I drove a bunch of them in my 30 years at UPS! If anyone can "TORTURE TEST" anything.... It's UPS!
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Old 11-26-2013, 01:47 PM
farokh farokh is offline
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Default Re: 35EK thermostat question...

Yes, I figured I would change the coolant and flush the cooling system while I was changing the thermostat. Can I use any coolant or do I need something with specific additives?

This unit doesn't have a coolant recovery tank, although I'm debating adding one to make it easier to check the level.

Anyone have a particular favorite brand for the thermostat?

Thanks!
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Old 11-26-2013, 01:55 PM
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Default Re: 35EK thermostat question...

It is just a standard truck engine. So 180/190 would be just fine. The only thing Onan did was put on the sensors and change the fan drive.
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Old 11-26-2013, 02:10 PM
Dave Edmonds Dave Edmonds is offline
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Smile Re: 35EK thermostat question...

When I purchased my 1989-vintage 20ES, I noticed that the temp gauge did not move at all. Found out that the temp sensor was bad, replaced it, gauge didn't go up much at all. Found out that the thermostat had been removed from the engine. Original trouble was that the radiator was stopped up on the outside, allowing almost no airflow through the radiator. Some brilliant serviceman removed the thermostat to keep the thing from overheating, not bothering to diagnose the real problem. After permanently installing it, I noticed that the only air exiting the radiator was in the middle, nothing was coming out anywhere else. Removed the radiator and took it to the radiator shop; they cleaned it out inside and out. Put in proper thermostat, reinstalled radiator with new anti-freeze, VIOLA! - proper engine temp and performance!
Dave Edmonds
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Old 11-26-2013, 04:17 PM
Motorhead Motorhead is offline
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Default Re: 35EK thermostat question...

Stant is a good thermostat. Just stay away from any of the Chinese crap. A coolant recovery tank is a good idea for that unit. Make sure you have the proper type of cap for the recovery tank.
Here is a link on DELO extended life coolant: http://www.deloperformance.com/produ...tifreezes.aspx

I would drain, flush radiator and block, change thermostat and install new coolant and distilled or real low mineral content water. (Bottled jugs from the grocery store). If the gauge is faulty, your best bet is a NON-electric, mechanical gauge like a Stewart Warner.
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Old 11-26-2013, 06:07 PM
Gunny Gunny is offline
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Default Re: 35EK thermostat question...

I'd flush the cooling system and install an new thermostat. 190 degree would be my choice although the ones on either side would be OK.

Use extended life coolant, buy premixed, no water needed. Just be sure the old is all the way out/gone.

Cascade dish washing detergent makes an excellent cooling system cleaner, just be sure you run it long enough to dissolve it and let it do its job, then get it all out.

Do NOT use distilled water in a cooling system. OK for batteries or a steam iron but not cooling systems.
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Old 11-26-2013, 06:53 PM
Motorhead Motorhead is offline
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Default Re: 35EK thermostat question...

Gunny, Why not distilled water?
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Old 11-26-2013, 08:39 PM
Lawdawg Lawdawg is offline
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Default Re: 35EK thermostat question...

Quote:
Originally Posted by Gunny View Post
I'd flush the cooling system and install an new thermostat. 190 degree would be my choice although the ones on either side would be OK.

Use extended life coolant, buy premixed, no water needed. Just be sure the old is all the way out/gone.

Cascade dish washing detergent makes an excellent cooling system cleaner, just be sure you run it long enough to dissolve it and let it do its job, then get it all out.

Do NOT use distilled water in a cooling system. OK for batteries or a steam iron but not cooling systems.
Gunny
My 2004 F350 Diesel Manual and the Ford Shop all say to use Distilled Water for the Cooling System and the Batts.they say the Minerals in Tap water cause Electrolysis in the Cooling System with all of the Dissimilar metals in the system . Doug.

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Gunny
My 2004 F350 Diesel Manual and the Ford Shop all say to use Distilled Water for the Cooling System and the Batts.they say the Minerals in Tap water cause Electrolysis in the Cooling System with all of the Dissimilar metals in the system . Doug.
Ps got 202000+ on it so far.
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Old 11-26-2013, 08:42 PM
Gunny Gunny is offline
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Default Re: 35EK thermostat question...

Distilled water leeches minerals. Will go looking for a publication that addresses this tomorrow at work, just saw it a week or so ago.

De ionized water is best to use. If you look at the labels on pre mixed antifreeze, they usually indicate thats what is use there.
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Old 11-26-2013, 09:54 PM
farokh farokh is offline
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Default Re: 35EK thermostat question...

I guess I'll play it safe and replace with pre-mix 50/50 coolant
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Old 11-27-2013, 08:05 PM
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Default Re: 35EK thermostat question...

OK.

Distilled or de-ionized water are pretty much interchangeable for use in batteries or cooling systems.

Had a long chat with the head cooling systems guru in Austria this morning and was enlightened.

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Old 11-27-2013, 09:09 PM
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Default Re: Onan 35EK thermostat question...

No problem Gunny. I had read about water that is completely mineral free that it is aggressive towards anything that it can leach minerals back from. So I too questioned "Distilled" water in cooling systems and wondered if it would be aggressive inside an engine cooling system. I read up in a Mercedes Benz Factory Shop manual and they recommended "Conditioned" water. Must be some special German thing but I was thinking Conditioned water as De-Ionized water.
I have a sink R-O unit and when I do a cooling system coolant re-mix, I use it for my water source.
One VERY interesting that I read in the same Mercedes manual was that they recommended using CITRIC Acid crystals mixed in water to tun as a safe cooling system flush. I tried it and it works wonderful. Works better than any flush that I have ever used and I am very cautious to use any commercial brand of radiator flush as it usually took out the water pump seal. Citric acid is very gentle on water pump seals.
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Old 11-27-2013, 09:33 PM
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Default Re: Onan 35EK thermostat question...

In a pinch you can also use BEER. Sounds odd but it does work.
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Old 11-27-2013, 10:07 PM
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Default Re: Onan 35EK thermostat question...

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In a pinch you can also use BEER. Sounds odd but it does work.
Said like a TRUE Texan! I think that in Texas, "Everything goes better with BEER!"
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Old 11-28-2013, 08:36 AM
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Default Re: Onan 35EK thermostat question...

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Originally Posted by Billy J Shafer View Post
In a pinch you can also use BEER. Sounds odd but it does work.
Dude!

Thats alcohol abuse. If all I had to flush a radiator was beer, I'd drink it and............well...........
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Old 11-28-2013, 08:48 AM
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Default Re: Onan 35EK thermostat question...

Quote:
Originally Posted by Billy J Shafer View Post
In a pinch you can also use BEER. Sounds odd but it does work.
He forgot to tell you only if it is flat .
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Old 11-28-2013, 10:01 AM
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Default Re: Onan 35EK thermostat question...

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He forgot to tell you only if it is flat .
Kpack
I tried using Flat Beer bought a Case of Heineken ran over it with my truck until it was flat tried opening the cans and nothing was in them. what was wrong? I think Gunny has a better idea. just want to be careful when opening the Cooling system after the flush if it is still under pressure. Little Woman would not let me back in the house until I showered with the Hose in the yard for a Looooong time. Doug.
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Old 11-28-2013, 11:08 AM
Leon N. Leon N. is offline
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Default Re: Onan 35EK thermostat question...

If it were me, I would add a coolant overflow recovery tank. That way you do not get air entrained into the system. Air causes oxidation which shortens the life of the cooling system. A happy Thanksgiving day to all.

Leon
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