Replacing the thermostat
 

I just bought the Mugen thermostat and fan switch in preparation for 2 track days in a couple of weeks.

I'm hearing that the thermostat install is a PITA!

Has anyone done this and can offer any hints on how to get it done?

I searched in the DIY sticky and found 1 guy from Germany that did it but it was mostly just a couple of pictures.

ANY help would be most appreciated!

drain the coolant first. Don't bother taking off the lower radiator hose. snake your hands in from the bottom, get a small socket and take off the bolts to the thermostat housing. make sure the rubber gasket seals.

Good bright light, do it from underneath on jackstands. Once under the car it's easy.

I just changed my thermostat 2 weeks ago. It was easy. The hardest thing to change on our coolant system is the upper radiator hose. (with intake manifold still installed). The thermostat is pretty straight forward. Just be sure to put the pin at the top, or 12 o'clock position - just like the factory service manual shows.


I was having cooling system issues, and given the age of everything I decided to change the thermostat, rad cap, reservoir cap and hose swivel, fan temp switch, oil cooler seal and of course new type 2 coolant. Runs and cools like new.

ttt

Doing this tomorrow night so any more words of wisdom would definitely help!

do it from under the car... lots of light ... dont remove the hose itself just the outlet.. its rather easy.. just a 10mm and an extention does wonders

I'm helping NH_s2k_Guy do this tomorrow night. Thanks for the advice guys. We'll be doing it on a mid-rise scissor lift so access from the bottom is the way we will go.

NH_s2k_Guy since your car will be hot I'm pretty sure that means once we get the car on the lift you will be taking me out for dinner before we get started ;)

Sounds like a plan!

Also going for a beer run!!

UNDER the car, trust me.

Just pull the two bolts. No need to even remove the hose from thermo housing.

Best advice is BLEEDING. Search. Don't drive the car until the heater blows very hot air.

Completed the thermostat and fan switch install last night.

Did it from underneath the car, there is 1 bolt on the thermostat housing that was not the easiest to get to, but, with a 10mm
socket and a small extension, we were able to get it out. Be careful when pulling the thermostat, even after draining the radiator
there is still lots of coolant that comes out.

The fan switch is super easy after you get all the plastic removed from underneath the car. Used a 24mm deep socket.

After a couple of rounds of running the car and bleeding, we weren't getting much heat from the vents in the car...we ended up revving the car
a couple of times and that caused things to flow better and got heat within 30 seconds.

Took about 90 minutes not including the time for the coolant to cool down enough to drain it. That time did include the refilling and bleeding process.

Thanks to everyone for their insight, it really helped!

I see the OP's car is an AP2 and if I remember right the AP2's thermostat is a lot easier to reach. Do you recommend doing it from underneath for AP1's as well? I've been contemplating taking the intake manifold off to change it but if it's easier to go underneath then I will.

Ap1 and ap2 are the same as far as thermostat access. Doing the thermo from underneath the car is a piece of cake.

Thoughts on the various aftermarket thermostat options or no thermostat at all for a primarily track driven car?

While changing the oil tonight I looked under the car you're right, getting to the thermostat from underneath will be a piece of cake. The question is how to get to the upper hose when changing the hose? I'm planning to change the hoses and thermostat all at the same time soon but I can't even see where the upper hose ends on the AP1. How do you recommend getting it off?

You have to do it by feel, it's a little easier if you take off the tensioner and alternator, as you'll be able to see a bit better. But you gotta feel your way under, sliding off the hose clamp is tricky but doable, then just yank it out. Putting it in is equally tricky.