Thermostst Replacement

[Action]

My bike was taking a long time to warm up. I checked the rad.s and they were hot at about 150 degrees. I decided to replace the thermostat my self to save some $$$. I though I would post this to supplement what is in the service manual.

First I put a tarp under the bike to help catch any fluids.


The next step is to remove the tank. After you remove the two bolts at the front and rear you can turn it over and let it rest where the seat usually is. This will let you get at the hoses and wires underneath the tank. Place some towels under the tank so you don't scratch it. The banjo fitting takes an 8mm hex key. Note - gas will come out the lines you remove. I wasn't smart and still had a rather full tank.


After you're done with the tank remove the lower fairings and the air box.


Remove the screws around the edge of the air box, lift off the top, and take out the filter. Under the filter are the velocity stacks, take out the two screws on each one. On mine the taller ones were in back.


You'll have to remove the Map Sensor, TPS connection, and other wires and hose's attached to the air box. Don't forget the wire underneath.


With the Air Box removed you can see the throttle bodies.


The next thing to do is loosen the clamps at the base of each throttle body. Some people I talked to used a really long Phillips screwdriver. I found hooking three extensions together and using an 8mm socket on a small ratchet worked better. You have to go in through a cut-out in the left side of the frame, right where the coolant overflow bottle is. The manual says once the straps on the throttle body spacers are loose you can lift it off. Mine was still very much attached! I had to CAREFULLY pry it up using a big screwdriver and a small pry bar.

Drain the coolant and remover the two hoses going to the wax unit, its the cylinder in the center of the throttle body assembly (sorry no close up picture, was getting tired).

Once the throttle bodies are loose you have to remove the throttle cables. I took a close up picture so I could put it back the same way. The idle adjustment cable is also attached to the bottom of the throttle body and needs to be threaded up through the frame.



After the cables were removed I set it on the back side of the motor and started in on the thermostat housing. Remember to plug the intake holes in the block, you don't want to drop anything down there.



On mine all the hose clamps were facing the wrong direction so I had to pull off some extra hoses to get it loose.

This is what you are after.



Split the housing apart and you'll see the Thermostat. Mine was closed but after heating it up enough to open, it stayed open even after cooling to room temp.



I'll post more on the reinstall when the new thermo gets delivered.

Edit: All right, I got the new tstat after 2 tries from Service Honda. Reassembly is the reverse of everything above. Two things I screwed up - First after you reinstall the tstat housing and hoses, make sure you route the idle adjustment cable back where it belongs BEFORE you reinstall the throttle body's. It sucks to pull everything back apart when you notice your idle adjustment is missing. Second, make sure all you electrical connections are snapped together. It sucks even more to see the flashing FI light the first time you start it back up.

I would rate this job as fairly complex. A 7 - if 1 was putting air in the tires and 10 was taking out an engine. Probably a 5 once you've done it the first time.

Action

[Barrybullet]

Thanks,
I got up to removing the throttle bodies yesterday and could not budge them. I sprayed WD-40 around the stacks and still no movement. Where did you pry the bodies buy? I'm afraid to break them.
Barry

[squirrelman]

Great photos!
Soooooooooooooooo, did the replacement cure the problem???





because of different component placement, thermostat on my '86 VFR could easily be changed in under 10 minutes!! But that's progress, i guess.........

[Barrybullet]

I did not get the throttle bodies off yet to get to thr t-stat.

[Action]

I used a small pry bar. I placed a rag on the block and CAREFULLY pried them up. If i remember right, I pried against the outer edge of the throttle body right at each corner. It took a pretty good amount of force. You could also use a small hammer (to pry with - not hit anything with - lol). I also used a blow dyer to heat the spacers up some. I know they seem like they are welded on but they will come off. Good Luck!

Squirrelman - yup, runs great now. No issues with temp, either cold or hot.

Action

[Barrybullet]

Thanks for the input squirrelman. I was thinkiong about heating up the rubber boots too. I'm going to try your blow dryer technique.
Barry

[reg71]

yeah, great pix. funny thing is, I didn't even need to do this yet I found myself readin your whole how-to because it was done so well.

[prodigalbiker]

Same for me as for Reg71. Looks quite a job, more fiddly than really difficult (hope I don't have to do it one day though). I read the whole thing just because the images were so good and the description is even something I could follow. Well done!

[Action]

Thanks! I took lots of pictures cause I was worried about getting it all back together. Prodigalbiker, you're right it's more taking all the hoses and wires apart than anything really difficult.

Action

[derstuka]

Yeah, excellent write up Action! Thumbs up! Only thing missing is one or two hot babes around for our visual pleasure....

BTW, I keep wanting to call you "Action Jackson" (Carl Weathers).

[Rangerscott]

You wouldnt happen to know the dimensions of the thermostat would ya?


I like to find one at a auto store and just make one fit rather than pay $30 for a t-stat.


Also what is the rated temp on the vfr stat?

[squirrelman]

the thermo-unit is of standard dimensions...take the OLD one into autozone with you, and find the OLDEST man to help you....

temp setting is 190 degrees F. ..... i think

i remember that it's from early-'90s Honda Civic...i think....

[Rangerscott]

Ok. I just would rather find one without taking mine out. LOL


Part searching these days is such a hassle. If its not in a computer then it doesnt exist. Nimrods. Haha

[Action]

Rangerscott, I'll look at home tonight but I don't think I kept the old one. The T-stat should start to open 176-183 F (80-84C) and be fully open at 203 F (103C).

[Rangerscott]

Got the honda civic t-stat to fit.

[Mudddawg]

Originally Posted by Rangerscott

Got the honda civic t-stat to fit.

So how does the civic one work? I called 6 shops and no one has a factory on in stock.. Looooseeeerrrrssssss.

[eddievalleytrailer]

Originally Posted by Action

Rangerscott, I'll look at home tonight but I don't think I kept the old one. The T-stat should start to open 176-183 F (80-84C) and be fully open at 203 F (203C).

If you ever apply for a job at Clymer, put me down as a reference. You'll do a better job than a lot of their writers and photographers.

[derstuka]

Damn Action, looks like I am gonna have to follow in your foot steps. My bike is taking too long to warm up as well. Man, what a pisser this thing is to get at. Have to take apart half the bike....oh, and thanks to you excellent write up, it will be much easier...even though my bike is a 5th gen. My hat is off to you sir!

[Rangerscott]

Originally Posted by Mudddawg

So how does the civic one work? I called 6 shops and no one has a factory on in stock.. Looooseeeerrrrssssss.

It works and thats all I want out of it.


The wax shaft is about twice the size of the stocker so I'm hoping that means it'll last longer than an oem.


Working on an how-to. Its simple as cutting pie as long as you dont mind using a dremel.

[snowparang]

can anyone advise what are the possible ill effects of removing the T-stat completely?

I mean, why is there a need to reduce the flow of coolant? The more cooling the better, so I thought the valve should always be fully opened.

[chesthing]

You don't want to do that - it will run rich and idle high for way too long. I can't believe what a huge pita Honda made this job!

[Rangerscott]

Originally Posted by snowparang

can anyone advise what are the possible ill effects of removing the T-stat completely?

I mean, why is there a need to reduce the flow of coolant? The more cooling the better, so I thought the valve should always be fully opened.

You need restriction for

1. For the engine to warm up as fast as possible. The longer it takes, the longer it runs rich and damage can occur running an engine too cold.

2. Restriction helps keep the coolant in the rads for a period of time so it can be cooled off. If there is just non-restricted flow the coolant will just fly through the rads and barely get cooled off. Thats why your bike will run super hot in the city, but is still able to keep cool on the highway. Also you'll notice it takes longer for the bike to cool down.

[cowboy]

Thanks for a great job!!! I needed one as well, and was nervous when I got the air box off. Together Sam Adams and myself pulled it through. Thanks again for the pics and description. People like yall make the internet AWESOME and the dealership broke. Thanks again!

[Action]

Originally Posted by cowboy

Thanks for a great job!!! I needed one as well, and was nervous when I got the air box off. Together Sam Adams and myself pulled it through. Thanks again for the pics and description. People like yall make the internet AWESOME and the dealership broke. Thanks again!

Glad the write-up helped. I feel the same way, it's better when you can at least see what you are getting in to.

Action

[hondawolf]

Great write-up! Thanks again. I noticed mine is running as low as 145 degrees on the freeway at night, when it's in the 40's. Didn't realize they had it stuffed down in the middle, that sucks. Your write-up makes it look easy, though time consuming. Thanks again, guess I'll have something to do this weekend after all.

[drewl]

Thanks for the reference, Action. Just in time.

[drewl]

It is done. Thanks for the warning on the throttle body. That part sucked.
Good write up. Saved me from having to do it.

[Action]

Drewl - Glad you got her done. I know its a pain. I bled both brakes and the clutch today, not fun either.

Action

[jetblack]

That is the cleanest garage I've ever seen.

[Joey_Dude]

I replaced the thermostat as just preventative maintenance and I have to add one thing to watch out for is putting the throttle bodies back properly. If you don't push them in all the way down the rest of the parts won't fit. Maybe it was just me but just pushing down wouldn't cut it. I ended up getting a 4x4 wood block and lying it on the throttle body and pounding on the wood block with a hammer so it'd go down.