Anyone tried an inline thermostat?

Jay ne Ohio · **Joined:** Sun Dec 12, 2010 5:49 pm **Posts:** 216

My thermostat is failing in my 05 (105,000 miles) and I see that I will not be able to get on kapalczynski's list for the upgraded 192 degree thermostat. So I had an idea and did a quick search. I found an inline housing that uses a standard chevy thermostat. Has anyone tried adding an inline thermostat to the upper radiator hose? They are available from Summit Racing for $69.99, so the price is less than OEM and I can put a 192 degree in there to get the engine a little warmer. Simply slice a chunk out of the upper radiator hose and slide this baby in without touching the OEM. Would there be any problem with having two thermostats? The OEM will obviously open first, but the inline would keep the water from flowing to the radiator until it reached 192. Here is a link to the inline at Summit:

http://www.summitracing.com/parts/MEZ-WN0072/

Any thoughts?

bhc04 · **Posted:** Wed Mar 02, 2011 9:53 pm

This is really a great idea, I like it. Don't see why it won't work. Looking foward to someone's post on this that may have more mechanical experience.

BlackLibertyCRD · **Posted:** Wed Mar 02, 2011 9:56 pm

I don't know how reliable it will be and if you do this I would think you should gut the old thermostat housing.

racertracer · **Posted:** Wed Mar 02, 2011 11:48 pm

I know that a previous post on this same subject exists, but good luck finding it, I tried.

nursecosmo · **Posted:** Thu Mar 03, 2011 8:25 pm

What a coincidence, I have been seriously considering this option for a few days now. I have a new thermostat on back order from my local dealer and a couple of days ago was looking at the one from summit. I brought this subject up a couple of years ago but it kind of got poo-pooed viewtopic.php?f=5&t=45881&p=503634&hilit=thermostat#p503634 .

The only reason that I haven't already done it is because I was led to believe that the engine would be adversely affected because all those screwy recirculating outlets on the OE thermostat would not be able to do their thing and some part of the block would overheat. Well, I was discussing this with a friend who owns a carpet cleaning business with a fleet of truck mounted units, and made an interesting discovery. He has several Nissan and Hino trucks which have a very similarly complicated, one piece, non serviceable thermostat. However, his trucks use engine coolant to preheat the water holding tanks and have an external, in-line thermostat which looks something like an egg. It raises the coolant temp to 190F and causes no adverse effects to the diesel truck engines. He doesn't know who supplies the "Eggs" but they would be too big anyway. I might just call the dealer tomorrow and tell them to forget about the back ordered unit and get started on the rest of the repairs.

Joe Romas · **Posted:** Thu Mar 03, 2011 8:35 pm

I think the subject was touched on in Mark's thermostat thread. I kind of recall our thermostat's internal workings could prevent this from working properly. You may want to read up on all 30 some pages for an answer why it might not work.

flman · **Posted:** Thu Mar 03, 2011 10:04 pm

Here is a long thread on it, I was considering doing it myself when the need arises.

http://www.greendieselengineering.com/f ... st/69.page

Tested

http://www.greendieselengineering.com/f ... 9.page#675

kapalczynski · **Posted:** Tue Mar 08, 2011 3:30 am

This has been discussed in other threads. On the factory design there is a dual purpose, the lower port gets blocked off as the thermostat opens. If you introduce a second thermostat to the system, they will open at different times and the bypass section can be blocked off before the in-line is open. This can allows no circulation through the radiator or the bypass section when the factory thermostat is open adn the second in-line is closed. There is also the possability the water pump could over pressure certain sections of the system since no coolant is actually flowing. Also, since the second thermostat would be so far away from teh engine and there is no flow it would take alot of time for the coolant next to the inline thermostat to get warm enough to open the in-line thermostat. This could cause the engine to get too hot during the warm up cycle. Once the engine is up to operating temperature and coolant is flowing by the in-line thermostat it would probably function normally. On the factory design, the bypass is always circulating coolant through the thermostat housing so as it warms up it opens the passage to the radiator and closes the bypass.

This was actually discussed before the thermostat modification began and is the reason we decided to go ahead with the modification.

- Mark

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

I wander if this may work for me since mine isn't working at all. Mine isn't even working partially. I can start the jeep and let it idle from here to eternity and the guage doesn't raise above the first bar and never past the 1/4 mark no matter how much I drive it. The "disc" thermostat can be drilled with a small bit to allow some antifreeze to circulate till it gets warm enough to open.

Joe Romas · **Posted:** Tue Mar 08, 2011 6:23 pm

TennesseeCRD wrote:

I wander if this may work for me since mine isn't working at all. Mine isn't even working partially. I can start the jeep and let it idle from here to eternity and the guage doesn't raise above the first bar and never past the 1/4 mark no matter how much I drive it. The "disc" thermostat can be drilled with a small bit to allow some antifreeze to circulate till it gets warm enough to open.

Carefully read what Mark wrote above. Your thermostat is open to the radiator so it's bypass is closed. If you put an inline one on it will block the flow to the radiator and the coolant will have no place to go and there will be excess pressure that might have bad results :dead:

nursecosmo · **Posted:** Tue Mar 08, 2011 9:10 pm

However, since there seems to be only one person on the planet who has ever put an in-line thermostat in, (Dave on the GDE forum and he has reported no problems) nobody can really say that this mod will do any damage to the engine. Do we have an impeller water pump? If so, overpressure is unlikely, especially if the in-line unit has some kind of pass through or pressure relief feature. I am getting a new thermostat put in next Wednesday but I am giving serious consideration to just installing the in-line one anyway.

warp2diesel · **Posted:** Tue Mar 08, 2011 10:02 pm

Modern thermostats with the bypass feature allow more HP in a smaller engine with out doing damage. WE have 168HP stock to 200HP+ with some of the tunes and other mods, not a 35HP tractor engine. I would not try an inline thermostat unless it was the recirculation type like BMW used on the 2002. :2cents:

Anyone tried an inline thermostat?

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