Thermostat Replacement - 6th Gen VFR800 VTEC

Discussion in 'Mechanics Garage' started by elwray, Mar 17, 2010.

  1. elwray

    elwray New Member

    Country:
    United States
    Joined:
    Oct 22, 2009
    Messages:
    793
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Central NJ
    Map
    Here is some info on changing the thermostat on a 6th gen VTEC.

    On one of my last rides of last season, I noticed that my engine temperature wasn't rising past 150°F or so at idle, and would drop to 120-140° when cruising. Granted, ambient temperature at the time was approximately 35°F, but just idling it should have crept up much hotter. Regular operating temp for my bike when cruising was ~170-190°F. Clear indication of a stuck open thermostat.

    When the thermostat is working properly, it should be closed when the engine temperature is 0° to ~170°F. At this temperature, the thermostat is CLOSED preventing the flow of coolant to the radiators and allowing the engine to heat up. At ~170°F, the thermostat begins to OPEN and allows the cold coolant from the radiators to start circulating to the engine, cooling it, and sends the hot coolant to the radiators where it cools.

    If the thermostat sticks OPEN, the cold coolant circulates constantly, never allowing the bike to get up to temperature.

    This is outlined in the service manual starting on page 6-8. I'd say it's best to have the service manual open as well as this info with pictures to get this job done. Additionally, there are some steps with better picture coverage in Action's thermostat replacement thread found here:

    http://vfrworld.com/forums/mechanics-garage/11331-thermostst-replacement.html

    Between this thread, Action's walkthrough, and the service manual, this is a perfectly manageable operation for anyone who can turn a wrench -- amateurs included (I'm proof of that!). Just take your time, label where electrical connectors attach to, keep careful track of bolts, and don't get frustrated. And ask me any questions you may have an I will do my best to help!

    Step one:
    Remove the seat, and side fairings. Mind the plastic push-rivets! Unhook the battery.

    Step two:
    Drain the coolant. You can find the info for this on page 6-6 of the service manual.
    -Remove the drain bolts from the pump and engine block

    [​IMG]

    -Open the filler cap

    [​IMG]

    -Remove the overflow bottle

    [​IMG]

    -Prepare for a surprisingly long stream of coolant!

    [​IMG]

    [​IMG]

    Please dispose of this stray-cat kool aid properly!!

    Side note, old muffin tins make a great place to store and separate bolts/screws/fasteners/etc!

    Step 3
    Remove the fuel tank. Page 5-56 in the service manual. Remove the bolts by the handlebars, and prop the tank up. Remove the electrical connectors for the fuel pump. Remove the air vent hose and overflow hose. Remove the hinge bolts, and prop the tank upside down. Remove the fuel feed and fuel return hoses... I wasn't able to do this without making a huge mess :doh:. Maybe this would be a good time to add dry-flow quick disconnects for making this cleaner in the future...

    Step 4
    Remove the air box, velocity stacks, PAIR hoses, and assorted components. Take care with the electrical connectors. Mind the IAT sensor connection at the base of the airbox. This is pretty straightforward; just a bunch of screws and clamps and electrical connections.

    Step 5
    Now you should be looking at the throttle bodies. Remove the electrical connections

    [​IMG]

    You're going to want to remove the throttle cables from the throttle bodies.

    [​IMG]

    Step 6
    Now it's time to loosen the band clamps holding the insulator boots onto the throttle bodies. I don't have a great picture of this... but imagine this. The throttle body is sitting atop the cylinders. A rubber boot is slipped over the port on each cylinder, and the other side is slipped over the base of the throttle body. One clamp holds the boot to the cylinder, another holds it to the throttle body. These clamps are tightened and loosened with a phillips head screw.

    To get to the screws, you're going to need a long phillips head screwdriver. I wanted to replace the insulators with new ones, so I unscrewed both the throttle body (TB) side, and cylinder side so I could remove them entirely. If you don't want to do this, only loosen the upper TB side of the insulator.

    You get to the screws via this "hole" in the frame:

    [​IMG]

    Once the band clamp is loosened, there is nothing else holding in the throttle body to the engine -- but it likely won't come out without a fight! Don't pull by the fuel rails!! Try to pull it from the corners. If it still won't give up, try prying the boot away from the TB and spray WD-40 in there. Hair dryer may help.

    Once you get it to pop out, DON'T just pull. The fast idle wax unit is still connected. You'll need to loosen the worm clamps on this hose.

    [​IMG]

    Set the TB aside, and COVER THE INTAKE PORTS!!!

    Step 7
    Remove the thermostat from the housing!! Finally!! (keep in mind there is an o-ring in this housing. Replace if necessary)

    [​IMG]

    [​IMG]

    This is the old thermostat:

    [​IMG]

    Note the gap. This is what should be closed when cold. Coolant flows past this, thus preventing the bike from coming up to temperature.

    Step 8
    Put her back together!

    Okay, there are a few little things to note here. First, the insulator band clamps don't just get torqued down as tight as possible. You have to tighten them to a specific clearance -- in this case, 7mm +/- 1mm for the TB side. Give the insulators a good coating of oil to help the TB slip back into them.

    [​IMG]

    NorcalBoy suggested that I make a "feeler gauge" out of something flexible. I used a piece of thin scrap metal.

    [​IMG]

    Once you get that set, it's time to start putting the rest back together. First connect the throttle cables.

    Note that there are two connectors that are interchangeable -- the IAT sensor and the Bypass control solenoid valve. I originally had these switched, and that threw an IAT sensor FI blink code. Drove me NUTS trying to figure it out. Meatloaf was kind enough to send me a spare IAT sensor to troubleshoot. Thanks for that!

    This is the IAT sensor plug.

    [​IMG]

    This gray connector is for the bypass control solenoid valve.

    [​IMG]

    Refer to this page in the service manual for vacuum hose routing:

    [​IMG]

    The installation of the rest of the parts should be pretty easy. DON'T FORGET TO FILL THE COOLANT UP!

    Please let me know if you have any input or suggestions, or things I missed. Hope this helps!
     
    Last edited: Mar 18, 2010
  2. Scubalong

    Scubalong Official Greeter?

    Country:
    United States
    Joined:
    Mar 11, 2008
    Messages:
    9,239
    Likes Received:
    25
    Trophy Points:
    93
    Location:
    O.C Suck
    Thanks for the info. Great write up
     
  3. TOE CUTTER

    TOE CUTTER Mullet Man

    Country:
    United States
    Joined:
    Nov 30, 2008
    Messages:
    6,731
    Likes Received:
    85
    Trophy Points:
    78
    Location:
    Sacramento
    Map
    A very fine write up! You must give it a time rating in beers.....I give it a 2-3 beer time table.
     
  4. elwray

    elwray New Member

    Country:
    United States
    Joined:
    Oct 22, 2009
    Messages:
    793
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Central NJ
    Map
    Keep in mind, I have never worked on a fuel injected motorcycle before, let alone a V4 which aren't known for being amateur-mechanic friendly. But here are my ratings:

    The actual removal of parts down to the throttle body is a 2-3 beer job. Pretty straightforward, just have to be gentle.

    If your throttle body had never been removed for the last 18,000 miles and the bike was stored outside with no cover, as I suspect mine was, the actual throttle body removal is a 6-pack.

    Reinstall is 2-3 beers. Or, if you're like me and you took the whole insulator off and put the band clamps on backwards, and only realized it once you got the TB seated and couldn't tighten them, that's another 2 beers. :doh:

    Then, trouble shooting the 9-blink IAT sensor FI code. That was getting me up into quarter keg territory. But once I figured it out, I needed another 2-3 beers to celebrate. :party2:
     
  5. 02 VFR Rider

    02 VFR Rider New Member

    Joined:
    Jan 29, 2009
    Messages:
    2,286
    Likes Received:
    2
    Trophy Points:
    0
    great write up Dr. Ray
     
  6. Booyah

    Booyah New Member

    Country:
    United States
    Joined:
    Mar 2, 2010
    Messages:
    68
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Brandon, Manitoba, Canada
    Map
    Should have left the 'stuck open' thermostat in and called it a performance mod. :cool:

    I wonder how many people would have asked where they could get a/an 'open thermostat'?

    All jokes aside... awesome write up. The more step by step maintenance stuff I can find the better. Thank you good sir.:thumb:
     
  7. elwray

    elwray New Member

    Country:
    United States
    Joined:
    Oct 22, 2009
    Messages:
    793
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Central NJ
    Map
    You're very welcome -- a lot of people on this site have helped me out since I got my VFR, so I want to try and help others.

    If anything in my post isn't clear or needs further detail, please let me know and I'll do my best to make it better!
     
  8. Junyr

    Junyr New Member

    Joined:
    Apr 28, 2009
    Messages:
    265
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Des Moines, Iowa, United States
    Map
    Aside from the thermostat, O-ring, and coolant is there any other consumables or required (maybe highly suggested) parts that need to be replaced?

    It's lookign like I have this job coming up and when I order my thermostat I'm going to go ahead and get the O-ring you mention. Just wanted to get everythign elise I needed.
     
  9. Pliskin

    Pliskin New Member

    Country:
    United States
    Joined:
    Jun 3, 2008
    Messages:
    3,699
    Likes Received:
    0
    Trophy Points:
    36
    Location:
    Morris County, New Jersey
    Map
    Are you sure that's coolant and not the result of too many green beers on St. Paddy's Day?

    J/K, nice write up.
     
  10. elwray

    elwray New Member

    Country:
    United States
    Joined:
    Oct 22, 2009
    Messages:
    793
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Central NJ
    Map
    Updated original post, added link to Action's thermostat replacement thread. Action included many pictures as well, some show these steps better than my pictures and service manual clips.

    If you can swing it in the budget, maybe replace the rubber insulator boots while you're at it. Mine were very weathered, probably from being left out in the elements by the PO, and were slightly warped by the time I got them off. The last thing you want is to get it all back together again with the old boots and not have it seat or seal correctly.

    The best price I found for them was at hdlparts.com (them and directlineparts.com are sponsors of a VTX forum I frequent, they've usually got great prices):
    $9.84 each, part number 16211-MCW-D00 (need 4)

    I probably should have replaced the band clamps too but they looked decent. I think I may have bent one or two trying to get the TB to let go:
    $2.50 each, part number 16217-MCW-000 (TB side, need 4) and 16218-MCW-000 (cylinder side, need 4). This probably isn't as important as the boots were -- mine were very hard and brittle feeling.

    Make sure you either have a [very] long phillips head screwdriver, or can put a phillips head bit onto a socket extension. It's tight in there, so a 1/4" extension would probably be easier. A universal joint might make things easier, too. This is probably better than the screwdriver actually, but it's not really a big deal either way. Either one will get the job done.

    The flexible thin metal feeler gauges were invaluable. Trying to do that with an actual feeler gauge would have been impossible.

    Other than that, you should be fine with just standard issue toolbox tools (sockets, allen wrenches, screwdrivers, etc).

    Good luck, post up questions if you run into any!
     
  11. elwray

    elwray New Member

    Country:
    United States
    Joined:
    Oct 22, 2009
    Messages:
    793
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Central NJ
    Map
    Hmmmmmm LOL I wasn't supposed to pour the beer into the antifreeze?? No wonder my bike was throwing the FI blink code for "have to pee!!" :lol:
     
  12. drewl

    drewl Insider

    Country:
    United States
    Joined:
    Nov 13, 2007
    Messages:
    5,760
    Likes Received:
    6
    Trophy Points:
    83
    Location:
    Virginia Beach, Va
    Map
    The throttle bodies are a pain in the ass, with a capital ASS to get off. It is almost impossible when they are cold. Also keep in mind that that cold aluminum is brittle, so don't try to pry the throttle body frame with anything.
    It takes time and patience to get them out. Relax, you'll thank me later.

    Great write up. Well done.
     
  13. elwray

    elwray New Member

    Country:
    United States
    Joined:
    Oct 22, 2009
    Messages:
    793
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Central NJ
    Map
    +1

    I was doing this in the garage when it was <35°F... borderline nightmare getting them off. Hair dryer helped! Just take your time and get them out without breaking anything... it'll be much cheaper and quicker in the long run!
     
  14. Joey_Dude

    Joey_Dude Member

    Country:
    United States
    Joined:
    Oct 28, 2007
    Messages:
    1,956
    Likes Received:
    13
    Trophy Points:
    53
    Location:
    North Georgia
    Map
    +1 nice and thorough writeup! A tip on the fuel tank what you can do is get a pillow or something soft and flip the gas tank on it like so:

    [​IMG]

    Then you disconnect the gas lines, this method allows you to keep it clean and gas tank scratch free.
     
  15. elwray

    elwray New Member

    Country:
    United States
    Joined:
    Oct 22, 2009
    Messages:
    793
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Central NJ
    Map
    Great tip! If I had this tip when I was doing the job, I probably wouldn't be looking for a sticker to put on my tank right now! ;)
     
  16. dizzy

    dizzy New Member

    Joined:
    Apr 6, 2008
    Messages:
    527
    Likes Received:
    1
    Trophy Points:
    0
    Location:
    MN
    Map
    Careful doing that...don't stretch those fuel lines any more than necessary. They can break.
     
  17. TOE CUTTER

    TOE CUTTER Mullet Man

    Country:
    United States
    Joined:
    Nov 30, 2008
    Messages:
    6,731
    Likes Received:
    85
    Trophy Points:
    78
    Location:
    Sacramento
    Map
    Brute force

    Drewl has over stated the difficulty of this repair. Checked the factory manual and beer and a hammer are the only tools required for the repair.:boozer::smash:
     
  18. vfourbear

    vfourbear New Member

    Country:
    United States
    Joined:
    Jul 14, 2008
    Messages:
    2,519
    Likes Received:
    0
    Trophy Points:
    36
    Location:
    Louisville, KY - Under my tinfoil hat
    Map
    Nice job elwray.
     
  19. C_Noll

    C_Noll New Member

    Joined:
    Apr 26, 2012
    Messages:
    1
    Likes Received:
    0
    Trophy Points:
    0
    I just want to say thank you for the write up. I bought a 98 VFR800 last week and two days later had the thermo go bad. Just finished replacing it (what a PITA!!) haha, but thank you, I used your write up as my step by step guide.
     
  20. Da Rooster

    Da Rooster New Member

    Joined:
    Nov 27, 2013
    Messages:
    3
    Likes Received:
    0
    Trophy Points:
    0
    Holy smokes...

    I thought I was going to get in and out in a couple hours. This looks major. Sheesh Honda - thanks for making a bike that already runs hot a NIGHTMARE to work on. I only hope that it all goes back together smooth... Why couldn't they have put it down by the water pump or something?!?
     
Related Topics

Share This Page