VFR 5th Generation Thermostat Replacement

Discussion in '5th Generation 1998-2001' started by Big_Jim59, May 2, 2015.

  1. Big_Jim59

    Big_Jim59 Member

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    For all of you 5th Gen owners this is for you. Sooner or later you will have to replace a sticking or stuck thermostat. It’s just inevitable. This is how I did it.

    1) First I pulled the gas tank. A word of caution here. I thought I had it empty enough. I didn’t. Run the tank almost dry before you start. It will save a lot of hassle and your work space will not be nearly as explosive as mine.

    2) Remove the fairing lowers. You will end up with a bike that looks like this. (Your color my vary.)
    1-fairing-off.jpg

    3) Remove the air cleaner top. The screws around the back are hidden so use your longest phillips head screw driver. I have some mechanical fingers that enable me to access these screws and not drop them down the frame.
    2-air-filter-top.jpg 3-air-filter.jpg

    4) Remove the four velocity stacks. They are held on with two phillips head screws each.
    6-stacks-off.jpg

    5) Now comes the fun part. I didn’t get a lot of pictures of this because it’s impossible for the most part. All the connections are under the air box and I was pretty busy trying to remember where it all went. I marked a lot of the vacuum lines and connectors with labeled tape just to make sure I knew where they all went.

    6) On the left side as you are sitting on the bike disconnect the white electrical connector and the two breather pipes. Don’t worry about getting them back on. You can’t but you will do it anyway.
    7-under-left.jpg

    7) At the front disconnect the big breather hose and the small vacuum hose for the PAR system.

    8) On the right side disconnect the gray electrical connector and a lower vacuum hose that once again is impossible to get to. (I actually replaced this line with one that was a half inch longer and still had hell getting it back on. I just though you should know.)
    8-under-right.jpg

    9) At the back of the air box pull the vacuum line and another gray connector. (This one is easy to get to.)
    10) Pull the wires to the coils remembering which one goes where. Pull the spark plug wires and lift the air box off the throttle bodies.
    4-colis.jpg

    11) Drain the coolant. I prefer to use the bottom most hose. Then i reconnect it so I don't forget.
    5-drain-rad.jpg

    12) Disconnect the overflow water tank and drain it. (it’s just easier when it is empty)

    13) Let the water tank hang because you need to get into the space behind it to access the throttle body boot clamps.

    14) If you have a long phillips head screw driver it’s not long enough for this job. I had to use a couple of extensions and a 3/8” drive phillips head socket. I was working blind most of the time. I could see the back side of the clamp screw so I had to position the driver in the front by feel. By the time I got it back together I was getting pretty good at the game. (I sucks in a major way while you are doing it.) I have no pictures of this because you can't see what you are doing anyway. The best I can do is to tell you that you will know what I am talking about when you get in there. It can be done.
    9-tool.jpg

    15) Once I had the clamps loosened off I pried the top of each boot and gave it a shot of light oil.

    16) Like other before me I used a pry bar (a very long and big flat blade screw driver) and a block of wood to pop the throttle bodies up and out of their boots. I pried firmly but gently on the mounting screws at the back of the TB. The oil helped and the back came up first and easy and I just pulled up to remove the front.

    17) I just lifted the throttle bodies up without detaching anything else. I figure the less I do the better. This exposed the thermostat housing and related hoses. I used a bit of bailing wire to pull the TBs up and out of the way. You can gain enough access to get the thermostat housing out and that's what you want.
    10-Thermo-at-last.jpg

    18) Remove the small hoses from the top of the housing. Loosen the hose clamps for the three bigger hoses. Remove the big hose the passes through the frame to the radiator and be sure to catch the water on your pants and foot.

    19) Pull the thermostat housing off along with the remaining hoses.
    11-thermo-out.jpg

    20) Remove the two 8mm bolts and open the thermostat housing.
    12-stuck-open.jpg

    21) Pull the offending thermostat and replace it and the rubber seal.

    22) Reinstall the newly assembled thermostat housing. This can be tricky because the hose spigots are too wide to start. It was made complicated by the fact that I replaced the hoses. They are different with the front hose having a slight bend. Like everything else the thermostat housing was difficult to reinstall. If there was a trick to it i didn't know it.

    23) At this point I refilled the radiator with coolant. If I have any leaks I want to know before I go through the hell of installing the TBs.

    24) Reassemble in the reverse order. Make sure you get everything plugged in and all the vacuum hoses put in the right places. The vacuum hose on the right side was the worst. I used some hemostats I had in my special tools drawer to grab the vacuum hose and install it because my fingers just didn't fit. As I stated before, I replaced the OEM vacuum line with one that was a half inch longer and it was still very difficult to get install. For the rest of the hoses it is next to impossible to get them on but do it anyway because there is such satisfaction in doing a job well.

    The biggest issue is have a long enough phillips head screw driver to reach the TB boot clamps. You will need this before you start.

    By the way, the project was worth it. On start up it warms quickly to around 175. Then the thermostat opens and it brings it down a bit and then it stays around that point. It's just wonderful. I anticipate being able to ride without fixating on the temperature readout.
     
    Last edited: May 3, 2015
  2. Scubalong

    Scubalong Official Greeter?

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    Thanks for sharing Jim
    That is hell of a job just to replace ...:jaw:
     
  3. Big_Jim59

    Big_Jim59 Member

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    It took two bike projects including the VTR rebuild to finally get up the courage to tackle this thermostat!
     
  4. nookiaz

    nookiaz New Member

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    Amazing job! I'll probably need 1 week & Santa's helpers to do this!
     
  5. ridervfr

    ridervfr Member

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    I think its a "suckie" job on most of the v-fours, saw some magna-toids of yore that looked easy as the t-stat was hanging off the right side of the engine. Make sure the hose bands are tight, I am more than familar with having to go back in there and tighten a band or two, don't ask. :mech: its an important thing to change, my 91 was stu ck open, and the 93 was done just as pm.

    Nice write up with the pictures! I have phillips head screwdrivers that you could reach china with btw :loco: Cheers
     
  6. Terry Smith

    Terry Smith Member

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    Good Job Jim!

    Because of doing this before, I own a 2-foot long phillips head screwdriver but have no toolbox long enough to keep it in!
     
  7. Big_Jim59

    Big_Jim59 Member

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    That's exactly what I was thinking. If I had a phillips head screwdrive long enough to do the job I would have to drill a hole in the side of my tool box and let it stick out! The biggest problem with using the 3/8 drive phillips head socket was it tended to come apart when I would withdraw all the extensions and the socket. More than once I had to fish around in there with a magnet on a stick. The VTR (Superhawk) has socket head carb boot clamps which are easily reached with a 1/4" drive, a few extensions and a 8mm socket.
     
  8. ridervfr

    ridervfr Member

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    I learned a new word from a coworker, its "ratchet" means rigging something. Extensions and sockets coming undone or getting stuck somewhere could drive a man over the edge :pound: :frusty: glad it was a happy ending. You can always get a bigger tool box too.
     
  9. Big_Jim59

    Big_Jim59 Member

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    A very long phillips head screw driver in on my shopping list but it might be like a number of tool in my box, a one trick pony. Does anyone else have tool that were used for something and they are never used again?

    I used to work at a place called Malibu Grand Prix. I was the shop foreman there and we ran Sachs wankel rotary. The rear of the engine had a cover that had to be removed for a number of maintenance tasks. I had a Snap-On palm ratchet and a long reach 6mm allen socket. I used that everyday as long as I was there. It's still in my box but it doesn't get much use.
     
  10. ridervfr

    ridervfr Member

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    Funny those palm ratchets, have seen them and thought about "them" for 30 seconds but passed. I have one of those Hazet 1/4 drive ratchet handles that turns one of your 1/4 extensions into a ratcheting t-handle, just snap-on your favourite socket and go to town, (no shameless advertising or puns intended.) We all have stuff that we bought thinking that we would make more use out of them. I have some ratchet wrenches that sit on the shelf next to some books, wtf? He who dies with the most tools wins :mech: Cheers
     
  11. Big_Jim59

    Big_Jim59 Member

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    I have a 1/2" drive stud puller. I saw it on the Snap-On truck and thought that was the coolest too I had ever seen. I was doing a lot of work in those days on BSA singles and BMW air heads both of which have studs. Later I did some air cooled VW builds and they have studs. Till this day, I have never have used that tool! You just don't have to pull studs.
     
  12. Big_Jim59

    Big_Jim59 Member

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    After putting a few good miles on the VFR in +90 degree weather I have found that 1) The engine warms quicker with the new t-stat. 2) It holds a pretty steady temperature, when underway, at around 185. 3)Sitting in traffic is warms to 224 before the fan kicks on.

    This, high end temperature is just drives me nuts. Should I install a new cooling fan thermo switch or a manual toggle switch?
     
  13. Terry Smith

    Terry Smith Member

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    The fan switch should do it's thing at 208-216F according to the shop manual, so you could fit a new one ( I think they're about $50) but you could just as easily bridge a manual toggle around the existing switch.
     
  14. spridget

    spridget New Member

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    I'm in the middle of tackling this job as I type. I have made it as far as loosening the TB clamps. I purchased an extra long philips screwdriver before I started. I paused when I couldn't get the TB assm to pull off the heads. I'll try some penetrating oil on the boots and more (gentle) prying.

    I did not remove the tank. I removed the two bolts at the front and the two at the rear on the hinge. The bike is on the center stand. I placed a small work table next to the bike and sat the tank on the table. It's still about 1/2 full. Otherwise, no issues so far. I've been careful to take my time with the vacuum hoses to prevent tearing hoses or breaking fittings.

    My '99 has only 8000 miles on it. I noticed the temps were running around 150F on cool days, and only 165F on warm days. This job is a freaking nightmare when compared to nearly every other thermostat job. While the fairings are off, I went ahead and replaced the regulator / rectifier with a Rick's unit and installed a pair of new horns (the electrical connector broke off the old horn, which did not appear to be stock).

    Thanks for the write-up!
     
  15. jjones

    jjones New Member

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    Great write up. Just ordering the parts as mine is stuck open, it is now freezing here (1c last ride!) the temp just sat around 60c :(

    I have the screwdriver sorted and the bit that I am not looking forward to is reattaching the vacuum hoses :(
     
  16. Big_Jim59

    Big_Jim59 Member

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    It is not fun. I have some long surgical clamps that really helped.
     
  17. OZ VFR

    OZ VFR Member

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    I just ordered a new thermostat this morning.
    I've noticed it seems to not close fully, or open fully.
    I have a bit more room, as I don't have pair valves, or coils.
    But it's still going to be a nightmare.
    Planning to get my injectors cleaned while I'm there, I think removing the TB's once in anyones life should be enough.
     
    Last edited: Nov 23, 2015
  18. Knight

    Knight New Member

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    Can anyone expound on why thermostats fail? I have been unable to find good information on this, particularly for these bikes.

    Does it affect the thermostat to sit for long periods? Does drying out this thermostat from sitting affect it negatively?

    AKA is there any way to preserve a thermostat for longer, or is it just age, use, and duty cycle that kills it?
     
  19. RVFR

    RVFR Member

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    Nice write up, but this makes me go Eooo.... doesn't look all, that much fun. more a case of the fall out from getting into it. broken clips, lost parts and the dreaded where the H did that go. you know... I'm not sure with the history of the 5th I have just when and where this will bite me. Oh joy, knock on wood it doesn't come sooner, it can come way later as far as I'm concerned. I have other goodies to attend too first. .. but yea nice write up thanks FWIW I have the the 2' screwdriver all ready. and yes it has it's own special place to be put.
     
  20. Big_Jim59

    Big_Jim59 Member

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    My feeling is most automotive type thermostats are a high volume low quality production item. Fortunately, when they fail, they are designed (so I understand it) to fail open. I have had experience with failed t-stats that failed closed and that blew hoses off. My feeling is the design is ancient but adequate for the job and no one makes a quality t-stat.
     
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