[plplplpl]

Back in ’20 I bit the bullet and bought the $45 OEM thermostat versus $12 Gates. The OEM has a different build quality from the generic thermostat and I didn’t want any issues.

Ok, as promised, I’d report back with my experience with the Aisin thermostat THH-017.
The installation was not without a hitch. Although after a trip to a local auto parts store for the correct gasket, the thermostat is working great. So my advice is, if you buy the Aisin thermostat, be sure and research the gasket needed for your vehicle.
I was sent this….
View attachment 160820
I needed this…..
View attachment 160821

Good to know, but dang, when I replaced my radiator in 2019 I think it was, I don't recall the Aisin being on Rockauto; otherwise, I would surely have gotten it, along with the hoses, instead of the Gates thermostat I went with.

So far, OK, but I shudder to think how much more my days are counted with the Gates and their declining quality in recent years.

Wow, I could have had an Aisin.

 

[Nail Grease]

Good to know, but dang, when I replaced my radiator in 2019 I think it was, I don't recall the Aisin being on Rockauto; otherwise, I would surely have gotten it, along with the hoses, instead of the Gates thermostat I went with.

So far, OK, but I shudder to think how much more my days are counted with the Gates and their declining quality in recent years.

Wow, I could have had an Aisin. View attachment 160957

Not to rub it in or anything but ya, there is obvious difference between OEM/Aisin versus Gates.

[Gates^]
A stuck thermostat will usually cause an engine code. Hopefully it would be detected before the hoses swell.

 

[DrD123]

I replaced the thermostat in the 05 we got this summer using the Aisin THH-017 as well - same experience with the gasket. I did this when I replaced the timing belt and had everything apart when I ran into the incorrect gasket issue. The original one was still in good shape, so I just transferred the old gasket over to the new thermostat and ran with it - seems to be doing just fine (no leaks).

 

[headknocker]

It's now June 2025 and Majestic Honda is currently charging a whopping $70 for the t-stat on the '05 Pilot....f that. I'd be willing to pay somewhere in the $40's for Honda OEM but I'm not willing to get raped for $70(plus s&h). Several months ago I was curious what they were charging for the rear stabilizer bar end links for my '98 CRV and I was astounded to see they were asking $110/each for them these days. I'll be going with the Aisin t-stat whenever I have to replace the current one. Thanks for the info, Nail Grease!

 

[Nail Grease]

So just to consolidate the experience into one post. If ordering Aisin THH-017, discard the gasket that comes in the box. Order Aisin THP-509 or equivalent.

 

[RonnieJ]

Or if you bought the Aisin thermostat in 2018 when you did your 2nd TB change, but were too lazy to replace it until it was weeping in 2023, the old part number had the correct gasket, and that thermostat was exactly the same as the OE thermostat, and was made in Japan as well.

 

[undivide]

ordered sometime last year but never got around to installing it. was going to hold off until maybe the next TB WP job.

 

[Nail Grease]

Or if you bought the Aisin thermostat in 2018 when you did your 2nd TB change, but were too lazy to replace it until it was weeping in 2023, the old part number had the correct gasket, and that thermostat was exactly the same as the OE thermostat, and was made in Japan as well.

View attachment 183759

While the thermostat is the correct one, My research on THH009 has no gasket included. 🤷🏻‍♂️

 

[Nail Grease]

View attachment 183760

ordered sometime last year but never got around to installing it. was going to hold off until maybe the next TB WP job.

So the correct gasket came in your box as pictured?

 

[RonnieJ]

So the correct gasket came in your box as pictured?

I am almost positive that it came with the gasket, as I don't see any "thermostat gasket" in any of my RA purchases for the Pilot.
And the gasket and thermostat looked exactly the same.
No issues when I replaced it.
I only commented as I didn't have issues, but was curious when I see the most current part number has changed, hence your PSA, that I didn't have issues with a 2018 part.

 

[Nail Grease]

I am almost positive that it came with the gasket, as I don't see any "thermostat gasket" in any of my RA purchases for the Pilot.
And the gasket and thermostat looked exactly the same.
No issues when I replaced it.
I only commented as I didn't have issues, but was curious when I see the most current part number has changed, hence your PSA, that I didn't have issues with a 2018 part.

Currently, RockAuto and Amazon photos show the wrong gasket for our vehicles, and that’s what I received when this thread was started.