Thermostat Replacement

Discussion in 'Mechanics Garage' started by Action, Nov 4, 2007.

  1. stephanon2whls

    stephanon2whls New Member

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  2. Thereaper

    Thereaper New Member

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    Thermohell

    Ok My 2003 only Has 7400 miles on it and The thermostat is stuck open. I have fun working on my bike hell I built it from a frame and an engine However I dont want to do that again every year.
     
  3. donald branscom

    donald branscom New Member

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    Here is what SHOULD HAPPEN...
    The idiot that drew that part on a computer should be taken out to a shop and the motorcycle
    that is like the one he designed the water pump for should be there. Then that person should be made to change the water pump(yes..get their hands dirty!), then they should be made to go back and redesign the water pump placement.

    These young designers grow up with computer games and computers and never have to get their hands dirty. Then they just draw this stuff without thinking of the owners pocketbook or the mechanics troubles.

    I have seen so MANY poorly designed car and motorcycle parts in the last 10 years.
     
  4. danny_tb

    danny_tb New Member

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    I'm not sure if anyone has said what to do if your throttle body sticks to the inlet rubbers (even after loosening the screws - what a PITA that is!!!), but here's what I did when I needed to change my thermostat:

    * I got a piece of 1.5" x 0.75" timber...
    * Went to the left-hand side of the bike...
    * Put the wood under the lowest part of the throttle body casting (not things attached to it: the throttle body base-frame itself) I could find that was close to the rear head...
    * Levered the wood on the rear head cover/bolt...
    * Hit the piece of wood with a hammer to lever the throttle body up (I know... it isn't the most elegant of solutions, and my rear head cover isn't absolutely pristine, but most people wouldn't notice it, but my bike had about 90,000km and I suspect that the throttle body hadn't ever been removed... I had to get it off somehow)...
    * Lubricated the inlet rubbers before re-installation, and used the same piece of wood (see above, only this time straight up and down) as a "cushion" between the hammer and the throttle body (tapping carefully with the hammer) to get the throttle body back into position again (ie: seated in the rubbers properly). Note that I ONLY pushed/tapped down on solid throttle body housing parts, as close to the inlet rubbers as possible (ie: NOT on the fuel rail, etc).

    I hope that this helps others to replace their thermostats. Mods: please feel free to condense this if you see fit.


    Edit: I just saw a Honda Civic advertisement at the end of my post (it will probably be a different ad next time I look)... I can't think of a more boring car... Although I'm sure that the quality is probably great... Automated ads really do only grab the slightest of similarities for marketing purposes, don't they... :crazy:
     
  5. Metallican525

    Metallican525 New Member

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    Funny, I just did allmost the same damn thing with my girl last nite, I used one of my prybars instead, but it didn't mar the paint on the rear head one bit. Also, I put a rag over my TB before the wood to keep any small bits from falling into the bores. Good tip sir!!!
     
  6. Big_Jim59

    Big_Jim59 Well-Known Member

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    I have had my 5 gen VFR for a week and already know I am going to have to replace the T-stat. It was cold this past weekend and the bike never got above 153 while cruising.

    To answer the "why the thermostat?" question you have to understand how the system works. The water in the engine block is a closed loop system. The radiator is there to supply cool water when needed. It works like this, on start up the water circulates around the block and cylinders until the optimum temperature is reached. The thermostat opens at this point allowing hot water from the engine to pass to the radiator and, in turn, drawing cool water off the bottom of the radiator to replaced the hot water from the block. The thermostat will pulse keeping the water in the block at the correct temp. If the water in the radiator becomes too warm the thermo switch will turn the fan on and cool it down. This system allows the engine to run at a optimum temperature in a full range of environments from very cold, there the T-stat might open very rarely, to very warm climates where the flow of water from the radiator is almost constant. The T-stat and the thermo switch that controls the fan are very important in an efficient cooling system. This system allows the designers to make a smaller, more compact and effect radiator and keep the engine running at a temperature that is most conducive to efficient engine operation. In the old days (and I am talking teens and 20s) cooling systems were primitive with no water pump or thermostats using convection (hot water rises) to cool engines. Very large radiators were required with lots of boiling over.

    Does anyone have a part number for that Civic replacement T-stat?
     
  7. Durk

    Durk New Member

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    My tstat is ok and I've seen around 155-165 crusing in mid 50s temps. If it was stuck open you'd be seeing a long time for it to warm up, if it warmed up at all. Nothing wrong with some PM but you may not notice any difference.
    Glad you are enjoying your 5th gen, I picked mine up in June and I've been all smiles ever since.
     
  8. Big_Jim59

    Big_Jim59 Well-Known Member

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    If I am running a 190 T-stat, the bike should warm to 190 or at least in the 180s while riding and stay there. Running consistently cooler is a sign of a stuck T-stat. I had to do this work on my VF500F when I first got it and once it was put right I never had any problems with over heating or fan issues. The Honda cars never seem to have this problem but the bikes all do. Go figure. In any case it is a good excuse to do the PMs and replace old vacuum hoses. It is a 12 year old bike after all.
     
  9. 510 vfr

    510 vfr New Member

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    Hi Action, I know this thermostat replacement took place a couple years ago. I'm about to start to tear mine down and do it this weekend. I just have a quick question. Did you notice your bike running rich with the smell of gas and poor fuel mileage? Mines is a 02 my bike isn't getting hotter than 170 degress but I can smell gas strong out my exhaust and my MPG is crap. Thank you
     
  10. nearfreezing

    nearfreezing New Member

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    Great write-up, thanks for doing it! Just replaced the thermostat/O-ring, fast idle wax unit, and coolant with the help of this thread on my 6th gen with 14k mi. I got to do the whole tear down again after I buttoned everything together, started the engine, and found a slow coolant leak. Tightening up all the hose clamps seemed to solve the problem.

    I purchased a 20" #2 screwdriver from Home Depot for $10, which was essential to loosening the throttle body clamps. Prying with the handle of a hammer on the four corners of the throttle body and the head cover dislodged the throttle body from the insulators. I applied motor oil to the throttle body side of the insulators to ease installation and future ( :mad: ) disassembly. The key to reinstalling the throttle bodies into the insulators is having a good technique... I found first inserting the rearmost points of the rear throttle bodies worked well to get the right alignment.

    The VFR warms up quickly now, and the coolant temperature stays consistently above ~175F. The cold idle is still low (1200rpm) and a little rough, so maybe the fast idle wax unit wasn't the problem.
     
  11. TNRabbit

    TNRabbit New Member

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    So none of this talented bunch have ever figure out a way to this without removing the TB? Hard to believe~
     
  12. drewl

    drewl Well-Known Member

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    The housing is located between the two heads in the middle of the V inside the frame. It is blocked on all sides by immoveable objects except as described here.
    I have done mine twice and found no short cuts.
     
  13. Alaskan

    Alaskan Well-Known Member

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    Have you? Love to hear/see it if you have!



    .
     
  14. Metallican525

    Metallican525 New Member

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    You don't have to "remove" the throttle bodies, just elevate them about six inches. No fuel line disconnection needed, might wanna release the idle adjustment cable from its perch outside for a little more slack but you can leave it connected to the TB's.
     
  15. Brocko

    Brocko New Member

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    Replaced T-stat on 2002 a couple of months ago

    The 2002 bike I just acquired had a sticky T-stat too, with only 8500kms on it. This is probably one of the reasons the previous owner(s) got rid of it. Honda probably charges the better part of a grand for the job. I did the replacement myself and was kinda shocked when I got down below the airbox. Honda really didn't do their homework on this one. Unfortunately I didn't see this write up until now. Fortunately everything went realy well. I took about 6-8 hours (first and only time I hope). Just want to reinforce a couple of pointers made by the original author.

    Siphon the gas tank dry. (A buddy of mine lit up a gas tank during removal when he bent over and a pocket screwdriver fell out of his shirt pocket and sparked as it hit the concrete floor with the spilled gas! Definitely not cool for him. )

    Make sure to cover up the intakes once the throttle body is off.

    Put some grease on the rubber connectors before popping the throttle body back on. You'll here a nice 'klok' sound when the t-body snaps properly back into place.

    Make sure to snap all the electrical connectors firmly together.

    Get all the hoses firmly back in the right places.

    Careful routing the hoses and wires so as not to pinch any on reassembly.

    I changed the o-ring gasket as well as the thermostat. No point in putting it all back together to find out it leaks.

    Now it warms up fast and temp stays constant at about 80 C on the highway.
     
  16. BOIKE333

    BOIKE333 New Member

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    Anybody have a part number? I can't find it at the auto store?
     
  17. NormK

    NormK New Member

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    Well does anybody have a Honda Civic thermostat part number or model year for an 86 750
     
  18. NormK

    NormK New Member

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    Ok so does anybody know if it is a 52mm diameter thermostat
     
  19. H3nry

    H3nry Member

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    Replaced thermostat today on my 2001. I propped the tank up and bungied the airbox bottom to it, so the coils and hoses at the back of the airbox could stay attached. Loosened the throttle body assembly and held it up and to the left side with another bungie cord, so there were a minimum of hoses and wires detached. There were plenty, nonetheless.

    Notes: heating the carb bases was a big help getting the throttle bodies off. Until heated, they just would not let go.
    Local Honda shop wants $50 and 3 weeks to order a t'stat. O'Reily's Auto Supply has a Murray 3848 thermostat which works fine.
    The 3848 is 44mm flange OD same as Honda, but does not have the bottom valve plate. Since that plate is only open during warm up to let a bit of water bypass the closed t'stat and circulate around the T'stat so it is at engine temp, I took the plate off the old unit and placed it in the bottom of the housing with its spring to hold it shut. It has enough holes in it to warm up the 'stat in winter. Checked it out today cold start, high speed cruise, twisties, and slow traffic. Works great. For the first time since I bought it, the bike acts like it has a proper cooling system. Oh, the Murray 'stat cost $5 + sales tax. It fits various Chevy, Buick, and Suzuki cars.
    A bit of RTV on each hose spigot and throttle body makes things slide together easily and with luck will let them come apart in future if this ever needs to be done again. Hope not - it's a royal PITA.

    Yesterday I installed LED headlights from Cycle Gear. Bought on sale a while back. So far, so good. Brighter, and the low beams stay on with high beams, so there's less difference when switching beams. My main concern is the little fans built into the heat sinks. Will they stand up to vibration etc.? Will the LEDs stay cool enough to work after the fans crap out? Time will tell.

    Day before yesterday I took the fan off and turned it around so it blows outward. It needs a couple of spacers and longer top mounting bolts. The bottom mount is left hanging. Some aluminum duct tape sealed the gap between the original fan shroud and the radiator. I left a gap in the tape at the bottom so grasshoppers and rocks could fall out. Now the fan doesn't fight airflow when the bike is moving.
     
  20. H3nry

    H3nry Member

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    To identify a thermostat which fits the 5th gen and probably others, it is 44mm / 1.73in. dia at the flange and 82C / 180F temperature rating. Autozone lists a Valucraft 3848 ($3.99) which fits the same list of cars as the Murray 3848. Ask for a thermostat for a 1995 Chevy C2500 pickup or a 2001 Suzuki Swift. It also fits several hundred others, so your store probably has them in stock.

    I doubt it was really necessary to put the bottom plate from the old 'stat into the housing. It partially blocks a radiator bypass designed to heat the 'stat at cold start. I doubt the bypass even fully open diverts enough coolant from the radiators to make any difference, but I'm in Texas. Cold weather isn't my main concern, it's hot here. The side mounted radiators don't cool as well as front mounted ones, so I left the bypass partially closed.
     
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