Does anyone know what the functional differences are between the factory Mitsubishi thermostat for the Evo 8 (part # MN143463) and the Evo 9 (part # MD363571)?

Do these two OEM Evo thermostats have different opening temperatures or significantly different diaphragm designs that might affect flow characteristics when fully open?

If anyone has access to both parts to look at them side by side, it would helpful just to know if they look different or not.

I'm curious because the cost of the OEM Evo 9 thermostat @ $59 is double the cost of the Evo 8 thermostat ($29).

Also, I know that the Evo 8/9 thermostats should be interchangeable, at least in terms of mechanical fitment, because the lower-temp Mishimoto thermostat is just one part number (MMTS-EVO-01) for "Evo 7/8/9, 2001-2007" applications:

http://www.mishimoto.com/mitsubishi-...mostat-01.html

Thanks in advance for the help!

 

Anyone?

 

I would like to know too...

 

different stat and thermostat housing and water pump steel steel pipe on evo 8 , it doesnt have a bypass outlet on the bottom of the stat housing so then the stat is different (shorter) as it doesnt the spring and steel plate that seal the bypass when eng reaches operating temp.


evo 8 stat

http://www.meek.com.au/index.php?_a=...product_id=829


evo 9 stat

http://www.google.ie/imgres?imgurl=h...Q9QEwBg&dur=29

 

Awesome, thanks very much for the info/links todd6027!

So, the Evo9 thermostat housing having an bypass outlet: what does that mean in terms of the Evo9 system cooling performance, as opposed to the Evo8's which lacks this thermostat bypass feature?

Also, vaguely related: based on the factory service manual available at http://www.evoscan.com/vehicle-manuals, these are the specs/testing parameters for the Evo9 thermostat:

OPENING TEMP: 80 C ± 1.5 C (176 F ± 3 F)
FULL-OPENING TEMP: 93 C (199 F)
AMOUNT OF VALVE LIFT: 9.5 mm (0.37") or more



Also, here are the two thermostat images, side by side... makes it easier to compare / see the difference, and this picture will stay up here on evom even if meek.com.au takes their images down:

 

By the way just to add for our future reference;

The the Evo 7 and 9 shares the same OEM thermostat with part # MD363571, while the 8 is unique and uses part # MN143463.

 

So I need a evo thermostat. I have a evo 9 thermostat housing, but need to change out my RALLIART low temp thermostat. I have no heat!

No one seemed to answer egbeater's question and mine as well. What is the difference?

"So, the Evo9 thermostat housing having an bypass outlet: what does that mean in terms of the Evo9 system cooling performance, as opposed to the Evo8's which lacks this thermostat bypass feature?"

I was going to get at the part's store, but can't figure it out online.

Thanks!

 

interested in why the difference??

 

The question was answered....was answered by todd6027.

The thermostat housings are different, as well as the water pipe. For what ever reason, mitsubishi decided to revert back to the Evo 7 water cooling setup for the Evo 9.

As for actual results to cooling performance difference compared to the Evo 8....probably SFA! In other words, you'll never probably ever find out.

The official statement for the change at Evo 9 was: "As a measure to deal with the increased engine output, a bottom by-pass type has been used, resulting in more effective cooling water temperature control."

 

Todd6027 only stated the image differences not to why?

Does that mean you can only use a 9 thermostat in a evo 9 housing and the same for the evo 8 housing?

That seams wierd cause Mishimoto/RALLIART/Cosworth only sells one part # , if that was the case then Mishimoto would have 2 part numbers?

 

You cannot use an OEM Evo 7 or 9 thermostat (they are the same) in an Evo 8 housing. You might be able to fit an Evo 8 thermostat in an Evo 7/9 housing, but that is not the thermostat designed for that housing.

Seems weird, or seems like sacrificing how the OEM intended the cooling system to work so that an aftermarket company(s) can make easy money by making one product, ie, because it "fits"?

As for Ralliart, they do not make one part number. I'm very familiar with the Ralliart part numbers for the 71 degree thermostat for the Evo 7 and 8, and the 76 degree thermostat for the Evo 9, and they all have different part numbers.

 

Thanks for the reply!

At the present time I have a evo 8 RALLIART thermostat in my evo 9 housing. I did not know that they were different thermostat until it got cold and I have absolutely no heat. I am at a loss of wanting to spend another $55 + shipping and have to order it ): .

Sounds like I will be selling my RALLIART thermostat as well ):

 

Glad I read this thread and wish I would have done some research. Ordered a thermostat for Evo 9 that I never ended up using. Didn't think the 8's or 9's were any different anyway.

Still have it and I'm selling it to a buddy who has an 8, turns out I was sold an 8 at the 9 price. Sucks for me, but good for him so he can keep his car on the road and for $30 cheaper.

 

Thanks for the comment, but I see the physical difference for each thermostat, but still don't know if they are interchangeable like the evo 8 water pump?

So I guess I will be ordering a Beck/Arnley evo 9 thermostat soon!

 

Status update:
So I ordered the Beck/Arnley evo 9 thermostat because I couldn't get myself to pay $55 for oem one and it cost me $6.

My temperature gauge went higher than it was before with the RALLIART thermostat, but still no heat! I ran across a post on an evo facebook group that evo 8 HAVAC temperature control cable and gears are a bad design and Mitsu released a new design. My knob was stuck on cold, thus no heat.

So flipping manually until I order the new gears and cable; see youtube video:

Thanks!