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post #1 of 13 (permalink) Old 09-09-2013, 09:21 PM Thread Starter
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heat, fans and burping

Hey all,

Sorry I observe more than I post, but I have a question among the many who are experiencing some 'heat' this summer. I have noticed a slow increase of heat the last couple months and now it's to the point where I am starting to be concerned. It's nowhere near critical but it's hotter than I know it should be so I thought I would solicit some input.

Last year or so... 177 highway cruising, 190-197 on warm days/traffic
Last month or so... 190-195 highway cruising, 220's in traffic, 235 last week!

It's never gone over 235, even in its current state. I decided to replace the coolant with a 50/50 mix. Filled to specifications. Left the filler cap off to 'burp' the system and around 170's when the thermostat starts to open, i get a steady flow of coolant on the floor instead of seeing it 'flowing' through. Does this mean i might have a clogged up system? The old coolant wasn't chunky but it looked old. Also the bike doesn't seem like it has the power it used to... backfires a little bit on deceleration. I refreshed the PCIII map as a precaution. It won't overheat but like I said, just runs hotter than it has ever run, and I know something is 'off'.

Anything I should try first? I have read about the SPAL fans, engine ice, etc. but I don't want to cover up a problem with beefier fans or fluid because the RC has always run within range before. I'm no track rider, and I only have K&N filters and Yosh slip ons.


Thanks!

RuZZeLL
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post #2 of 13 (permalink) Old 09-10-2013, 01:26 AM
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When was the last time the coolant was changed (prior to this job)?

Did you rev the throttle to burp out pockets of air from the cooling system while refilling it? It might take a couple attempts to completely burp the system (multiple cold/hot engine cycles).

You could always try to "flush" out more of the old crud (you'll never remove 100% of the old stuff LOL) by running distilled water through the cooling system a couple more times.

Does your cooling fan(s) turn on at the appropriate temperature? What condition are the radiators in (are they gunked up/clear of debris)?

Are you consuming any coolant? Does the exhaust have that tell-tale "sweet" smell of radiator coolant coming from it?

It doesn't sound like you are technically overheating; I mean you're seeing those temps in traffic, during CA weather afterall. I'd probably try another drain/refill/burp and keep riding it while monitoring things...

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post #3 of 13 (permalink) Old 09-10-2013, 08:58 AM
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if you have an SP2 I'd be worried if you were doing 235 as the fans should kick on at 220.

As mentioned, you may wany to do a couple more flushes to be sure. Also, if the system was full, the expanding liquid will push out onto the floor. What I would do... Flush the system again and fill the overflow. let the bike heat up, then shut it off. The coolant should pull from the overflow as the engine cools. Do this several times. If the level in the overflow doesn't change, then you probably have a clog somewhere.
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post #4 of 13 (permalink) Old 09-10-2013, 11:04 AM Thread Starter
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Originally Posted by COBRA90GT View Post
When was the last time the coolant was changed (prior to this job)?

Did you rev the throttle to burp out pockets of air from the cooling system while refilling it? It might take a couple attempts to completely burp the system (multiple cold/hot engine cycles).

You could always try to "flush" out more of the old crud (you'll never remove 100% of the old stuff LOL) by running distilled water through the cooling system a couple more times.

Does your cooling fan(s) turn on at the appropriate temperature? What condition are the radiators in (are they gunked up/clear of debris)?

Are you consuming any coolant? Does the exhaust have that tell-tale "sweet" smell of radiator coolant coming from it?

It doesn't sound like you are technically overheating; I mean you're seeing those temps in traffic, during CA weather afterall. I'd probably try another drain/refill/burp and keep riding it while monitoring things...
Thank you for the reply!

Candidly, I only drained and refilled. I did the burp process only once and snapped the throttle per the instructions in the RVT service manual. The fluid was pretty old looking so I am going to guess 'never' on the last change because I am the second owner.

When I let the bike sit several days I do smell a bit of a watery, perhaps sweet smell from the exhaust... goes away quickly. It sounds like a true 'flush' is what i need, take the system apart and check hoses and run a little pressure through the radiators?

The fans snap to attention right at 220-222 degrees and sometimes cool down to 210 and then the temp creeps back up, or, if I'm on it hard it will creep up to 230-235 but NEVER beyond 235. So the system is working, it seems, just not as much as I want these days. I had one of those solid 177-185 degree bikes until the last month or so!



Thanks again! Any more info you may have is always appreciated.

-RuZZeLL
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post #5 of 13 (permalink) Old 09-10-2013, 11:11 AM
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You never answered the SP1/SP2 question ... it makes a difference.

Based on what you have observed, you seem to have a restriction in the cooling system. Since you saw nasty coolant, that would support the restriction theory, a thorough reverse flush should be your first job. Remove the hoses and reverse flush both radiators and see what comes out. Refill, burp and try again.
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post #6 of 13 (permalink) Old 09-10-2013, 11:12 AM
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I just answered this same question yesterday. It's a cut and paste, but appropriate.
Also, make sure your bike is leaned over on it's kickstand when you burp the cooling system.

Quote:
I have an idea. Start by doing a complete coolant flush. There's no engine drain bolt, so you need to dismount both radiators to empty all the flushing water out. Call me nutty, but when I first did it, I ran 2 flush cycles with about 4 gallons of distilled water.
After that I removed all the hoses, cleaned them up where they fit over the various nipples and connectors, removed the overflow tank and thoroughly cleaned it out, and made sure there was a good flow between the radiator overflow nipple and the hose that routes to the overflow bottle. I replaced the thermostat too.
Then I refilled it with Engine Ice. I've since changed that out too, and now I just run the cheaper Dex-Cool. It's safe for our all aluminum radiator systems, I researched it.

If you do that, and properly burp the cooling system, I think you may find that your bike won't go much higher than 220F degrees.
I would definitely incorporate the manual switch mod so you can kick the fans on when you feel like it. If done correctly, (it's real easy) it won't interfere with the normal operation of the ECU kicking the fan on in case you forget.

I wish I could tell you how to do the switch, it's different for my SP1 and I don't remember the details for how to do it on the SP2.
A lot of folks here have done it, so someone will offer help soon I bet...

Then if you still aren't happy with the running temps, go to SPAL mod.
Just my 0.00000000002 cents worth...
https://www.rc51forums.com/forums/showthread.php?t=26114

John, 2000 RC51 #000100

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post #7 of 13 (permalink) Old 09-10-2013, 12:02 PM Thread Starter
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You never answered the SP1/SP2 question ... it makes a difference.

Based on what you have observed, you seem to have a restriction in the cooling system. Since you saw nasty coolant, that would support the restriction theory, a thorough reverse flush should be your first job. Remove the hoses and reverse flush both radiators and see what comes out. Refill, burp and try again.
Sorry, missed that one! I have a 2005 SP2, 28k mi
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post #8 of 13 (permalink) Old 09-10-2013, 12:04 PM Thread Starter
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Originally Posted by jondog9 View Post
I just answered this same question yesterday. It's a cut and paste, but appropriate.
Also, make sure your bike is leaned over on it's kickstand when you burp the cooling system.



https://www.rc51forums.com/forums/showthread.php?t=26114
Oh crap. [slaps forehead]

I had it on the rear stand I think because I thought it would drain better from the right side. Dangit. This matters, huh....

Frack.

-R
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post #9 of 13 (permalink) Old 09-10-2013, 12:08 PM
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Since it is an SP2, with 2 fans, you should not see much over 225, much less 235.

Flush, burp and report back.
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post #10 of 13 (permalink) Old 09-10-2013, 12:40 PM
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Oh crap. [slaps forehead]

I had it on the rear stand I think because I thought it would drain better from the right side. Dangit. This matters, huh....

Frack.

-R
I know huh?
The manual brought this little step to my attention. This way the rad cap is the highest point in the system, since your chasing air bubbles...

Works like a charm for me.

John, 2000 RC51 #000100

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