subachad

Hi,

I am in the process of installing a Koyo in my 2008 Rx8 and earlier today I found out that the upper coolant hose is different between the earlier and later 2004 Model years. Luckily I had my hose and they happen to have a 2006 getting a new engine. It looks like the hose and the thermostat housing have changed. I wasn't able to find out all the other changes and hope someone here might know.

Why the change?
What parts changed?

From what I can tell, the thermostat housing comes out at an angle instead of straight and the coolant tank is also different though it doesn't look any different from what's on my car.

Here is what the thermostat housing looks like on my 2004.




In separate but related news, I think I see why some people overheat with the Koyo in traffic. It doesn't have tighter fins than the radiator its replacing but it does have a gap all the way around the fan shroud. My shop camera is not very good but you can see the gap and the different foam options I was testing.





The information I was finding on the Koyo seemed a bit off from what I'm experiencing. I'll post up a review once I can actually drive the car again. The coolant line is a week out, so it won't be until after that.

9krpmrx8

iTrader: (46)

I just checked the garage and the Tstat housing I have from an 06' engine is identical to the 04' one I have. Same for the coolant reservoir, what changes are you talking about exactly?

nycgps

iTrader: (1)

the coolant tank did had a design changed around 2004-2005, it's a really tiny change and it doesn't change the fact that it sucks ***** and requires frequent change (every couple of yrs), the change was you can swap the sensor out and install it to a tank only new tank.

As for the thermostat thing, I think I know what you mean, you can only see it in Really early cars (I have seen a lot of 2003 rx8). as far as I know they change the angle (if my memory is okie) slightly so the hose fits better all around thats all.

As for Koyo, I gotta say early adopters had issues most likely because they never bothered to remove/install the foam around(or just grab new ones at home depot, cheap), so the car overheats left & right cuz the air is going around the radiator, not thru it.

subachad

9x - That nipple that doesn't have a hose, came out at a 45 degree angle on an 06 I saw at the dealership. The "updated" coolant hose comes in at a 45 degree angle instead of a 90 degree angle. The parts diagram shows the older design.




The part number I'm referring to is 15-381A in the parts diagram.

Here is a newer design I pulled from a site. The part number is 15-381D

subachad

So I cut a standard water line so I could run a little test. It looks like either one might work, it just routes around the battery tray different. It's possible the battery tray has changed as well. I haven't tried cross referencing the parts. Does anyone have a similar picture to the two I have here? I want to see if the tray is different and how you are running the coolant line. It's entirely possible I could have saved a week of downtime by simply using the updated hose.

Here is the stock hose in position which has the same bends as the parts diagram.




Now here is a straight hose that uses similar bends to the updated cooling hose. Notice to make it work I drop down in between the two left battery tray mounts. It doesn't handle the bends too well, but I imagine if it was a shaped hose, it would actually be OK.