Thermostat housing removal

[safetyguy]

I searched but I couldn't find an answer. Everyone talks about doing this but no one has described an easy way to do it.

 

After taking off all the plastic fairing pieces and radiator grill cover, it looks to me like you have to loosen the radiator to get at the thermostat housing. There has to be an easier way.

 

When my VR sits overnight (and it is getting colder at night), I have a leak from the O-ring on the thermostat housing. While I am in there doing that, I will replace the thermostat (NAPA substitute) and all the other O rings that I could get from a Yamaha dealer. The only two I couldn't get (and they are the same) are for the elbow fitting (# 21 on the Yamaha Water Pump Part drawing) -- is there a commercially available substitute that anyone knows of?

 

Last question on this subject, are all the hoses standard sizes? I'd like to replace all the front ones at the same time I take out the thermostat housing.

[skydoc_17]

Hey Mike,

This is one of the more "Nasty" jobs on a VR that must be done from time to time. I have attached a few pics so we can talk about it. In the first pic called side view, this is pretty much what you get to see after you have removed the side cover and Rad. side grill. (Keep in mind that on this bike the outer fairing has been removed.) Removing the 4 bolts that hold the Rad. in place has worked the best for me. It allows you to rock the Rad. away from the frame and gives you access to the top Rad. hose and the thermostat housing as you can see in the pic called Rad. View. The thermostat housing is actually located behind the inner fairing and there is not a lot of room to work in there. See pic called Up View. The hoses are formed, and can only be purchased at Yamaha for the best fit. They are still available but are not cheap. I have replaced a few Rad. drain plug hoses at my "little shop by the creek" due to leakage but have had to replace VERY FEW of the larger main hoses except for damage due to a crash. I DO install new hose clamps to as many hoses as I can get to because that appears to be where the leakage occurs. Unless you have one that is actually leaking, I would say that you would be OK to reuse them. YOU are the final judge on that call. In the final pic called WP Tube, if this is the tube you are speaking of I have ordered and received these o'rings just last month from Southwest Moto:

 

21

http://www.yamahasportsplaza.com/common/images/icoPartSuper.gif Loading...

SKU: 93210-27194-00 O-RING

2

$5.54

http://www.yamahasportsplaza.com/modules/oemparts/images/partsadd.gif

 

Just click "ADD TO CART" and you are there ready to buy. ( I have dealer software in my computer that allows me to find any part for the Yamaha Ventures, I am sharing that feature with you.)

If you really want to bullet proof the coolant system, replace the drain plug hose and add the Rad. drain upgrade to your VR listed in the classifieds:

 

http://www.venturerider.org/classifieds/showproduct.php?product=1724

 

This is the other pesky place that leaks during temp. changes and if you ring the Phillips head screw off trying to replace the drain screw then you will be replacing the entire assembly.

Hope this helps, If you have any questions, or need parts, let me know.

Earl

Edited September 12, 2009 by skydoc_17

[frankd]

I've done this job twice this year (on 2 different bikes!!) and it's not too bad....

 

I drain the cooling system by pulling the bolt under the water pump (19MM wrench). After a bit open the radiator cap (you have to wait because the coolant resevior tank will drain out the top of the radiator and make a mess if you don't wait). If you haven't drained the cooling system for a bit, then maybe you want to remove the plates that cover the cylinder drain plugs and remove them. The plates are the ones on the side of each cylinder held in by 1 philllips screw. Then I remove the small plastic piece that joins the fairing lowers (in front of the motor). Of course, on Mk II bikes you'd remove the plastic that you pull to change the oil filter (cowcatcher). Remove the 4 radiator bolts so you can move it forward and up. I'm not certain you have to, but I pull the right front cylinder exhaust pipe to make room to get to the thermostat housing. Loosen the hose clamps and remove the hose on the thermostat and the bottom connection of the small hose in the center of the engine. That way when you pull the thermostat mounting screws and remove the tube that the one bolt holds in, you can just swing it out of the way. Pull the 90 degree tube out of the engine and see if you can slide it out of the thermostat. If you can't easily get it to slide out, just turn it about 90 degrees and it'll slide out with the thermostat.

 

Remove the 2 screws that hold the thermostat in (phillips head on Mk1, Allen head on Mk II) and remove the thermostat. When I did my brother's bike (my old 83), I used O rings I bought at Ace Hardware for the 90 degree tube. Just take them with you and match them up as close as possible--a little smaller diameter will be fine, they'll just stretch a little. The O ring from the thermostat housing looked like it was a square rubber piece on both bikes. It starts out a regular O ring, but flattens out with time. The O ring for the thermostat housing is only about 3/32" diameter. Put everything back together, replace the drain plug, fill up radiator with coolant, turn the thermostat bypass valve to bypass, start the bike, fill the radiator again and after a couple of minutes, turn the thermostat bypass valve to the original posiiton. Then re-fill the expansion tank.

 

I did my bike just before I left for PIP. I'd put about 100 miles on it before we left and I had no leaks. The first night out, it leaked quite a bit. The rest of the trip it was much better, but a couple of times it did drip. I've got to pull it apart again and see what's wrong. I suspect I'll find some crud built up where the O ring sits. I would make sure that the housing halves are clean before I put it back together. I'll probably try a Scotch abrasive pad to clean mine.

[safetyguy]

Thanks to both of you for some good pointers. This is the kind of useful information that we all can use.

 

I think that I will acquire some additional parts and tackle this job in the next week or so.

[yamadawg]

I went through exactly what you are describing with my '83 and my '88. I found that the thermostat cover becomes distorted, possibly from the heat since it is right behind the exhaust pipe, and leaks even with a new o-ring, even an oversized one. The thing would only leak when cool. My suggestion is that you save yourself some grief from doing the job twice and get the thermostat cover and replace it as you are at it. It is reasonably priced, surprisingly well under $20, for Yama parts. The part number and description for the '88 is

 

26H-12413-00-00

COVER, THERMOSTAT

 

 

 

I seem to remember that I just loosened up the radiator and pulled it away enough to get in there and removed the exhaust pipe. After I figured that the clamp must be totally removed from the exhaust pipe at the collector and got the pipe off there was plenty of room. Then it was a breeze.

 

Good Luck!