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Discussion Starter #1 (Edited)
A friend (Dean M. of Elizabethtown) and I went for a ride on this Super weather Saturday. Clear and sunny skies, 88°F and zero winds. Beautiful. Riding through the PA, MD and WV country side. We had a very relaxing lunch in Harpers Ferry WV. Then we left the inn to gas up. I was on my 2002 ST4s and Dean on his ST2.

That's when it became interesting. The station was about four miles away. I made a left turn into the station and Dean was hitting his horn!!!

I parked next to the pump.

He yelled through his helmet: "Your brake is on fire!"

At this point I was off the bike pronto! Sure enough the real caliper had three inches of flame, green flame. I was able to blow it out and let it be to cool off. Certainly, no pumping of gas at this point. I didn't even know if I'd be able to get home, about 75 miles away.

We relaxed a bit and the rotor was cool enough to touch. I had it on the center stand. The rear wheel rotated smoothly and without drag. But, there'd be no drag at this point as the pads were down to the metal plates. Nothing left. I did feel like the bike had an anchor out for the four mile trip from our meal!

The brake pedal was useless. Zero pressure. There was fluid in the reservoir (fresh DoT4). But when I pushed the pedal a few times, fluid started to drip from the rear caliper.

So decision time. Go home on front brakes or not? I elected to GO!! But I made a solemn vow to Dean: "I'm not going to go over 85mph!!" And I didn't.

Did I miss the rear on the return trip? Yep, I'd have hit at least 115 mph with a P Turbo trying to show off!!

Anyway, my interesting trip wasn't over yet. On the way home there was an accident in MD on route 15 in Frederick. A tiny fender bender. Traffic was at a crawl for about 10 miles. Here is where the trip again grabbed my attention. Even with the Desmo Times Super Duper cooling set-up (Muzy fan blade and aux fan switch), my temp read-out began blinking!! What was the temp you ask? Try 248°F/120°C. I'm sure the blinking was its way of saying, 'sorry, but I cannot go higher!'

Anyway, soon enough the crawl was over, the temps cooled off and I adhered to my vow, keeping it under 85mph. Home without incident (sort of) and safe and sound. Great day Dean, and some work ahead: diagnose the rear caliper (I'm sure it'll need a rebuild at least or replacement), inspect rear rotor to ensure there are no cracks and.......

Have a good Sunday and go have your own 'Interesting Day" !! :smile2:

STeve
 

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Is it normal for this bike to not be able to stay within a safe operating temperature range? The only time I experienced overheating, which was on a CBR , was when the radiator had a hole in it, which resulted in a leaking head gasket.
 

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Ugh, I hate interesting days ...

My rear brake did something similar, but I noticed the drag and stopped before flames erupted. The caliper bore can develop a little ridge from rust/dirt that can cause it to hang up. Also, even a slight maladjustment of the push rod to the master can result in a little to much drag leading to heat leading to more drag, etc.

A reduced version of your overheating problem also happened. The overflow outlet nipple and hose to the radiator was plugged with goo. This caused the fluid level in the radiator to drop too low.

In both cases, there were milder warning signs before things got really bad. When something doesn't feel right, it usually isn't. Stop and investigate. Taking a corner at speed with the brake half-locked could easily make for an outright bad day.
 

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Discussion Starter #6
Is it normal for this bike to not be able to stay within a safe operating temperature range? The only time I experienced overheating, which was on a CBR , was when the radiator had a hole in it, which resulted in a leaking head gasket.
I certainly intend to check coolant level. I was surprised at temps. Nevertheless, the entire trip showed normal temps when moving. S
 

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Now we need fire retardant brake pads???

Lucky you caught that.

Those temps are crazy! As I'm sure you know, something is up. I've been in traffic like that several times and on pretty hot days. While the fan certainly kicks on, it has never gotten to the point where the display flashes! And yes, the display flashing is an indicator that you are beyond safe operating range. The opposite of the display flashing when the bike is cold. I have the OEM fan and no manual fan switch. I just let the bike do its thing.

If everything checks out otherwise, maybe the temp sensor for the display is faulty. There are two sensors. One for the ECU and one just for the display. Was the bike running OK with those temps?

Recently I've noticed my bike running hotter than normal. Yesterday I was out for a few hours and the the bike was in the 185 to 190 range while at a decent pace on back roads. Normally I see that when it is in the 90s for ambient temps. For yesterday's temps, mid 70s to maybe 80s, I should have been in the 175 to 180 range under the same conditions. I've also noted my radiator and oil cooler look like they could use a good cleaning. Probably due for a coolant flush too.
 

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Discussion Starter #8
..........

If everything checks out otherwise, maybe the temp sensor for the display is faulty. There are two sensors. One for the ECU and one just for the display. Was the bike running OK with those temps?
.......
Thanks Dan. Yes, after I verify full coolant level I intend to swap to a back-up and known good sensor. I did change them to Bosch a year or so ago. So I'm not really leaning in direction of a sensor failure. Nevertheless, it did read hot. BTW, my bike had the engine rebuild with hi compression Pistal pistons. Certainly developing more heat. And yes, it was running (and idling) very well well with that temp.

Maybe today or tomorrow. BTW, which is the display sensor? Front or back one? I guess I could pull the connector until I get the right one.

thanks

Steve
 

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...BTW, which is the display sensor? Front or back one? I guess I could pull the connector until I get the right one.

thanks

Steve
Vert cyl feeds the ECU (which controls the fan relay). H cyl. feeds UR readout. Sounds like the readout is probably correct, and maybe the ECU one is askew, and not turning the fan on at the correct temp.

Reason I say this is because when I changed out my ST2 sensors, I did the readout one 1st. I saw the temp go all the way to 248F and flash, and the fan never came on...

Then I changed out the Vert. cyl. one and all wasa well after that.

You could always try verifying with an optical pyrometer had a HF. Don't 4 get UR free flashlight!
 

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Discussion Starter #11 (Edited)
Update re rear brake caliper: took it off and fully apart. Parts (piston and bore) look good. This caliper has two halves held together by two bolts. Pistons came out with a finger grab. Seals totally shot based on age and tremendous heat.

Good side is it is totally rebuild-able. Bad side is no one offers Brembo seal kits for this P34 (34mm piston) rear caliper. Liability issues is their song. Yoyodyne used to take calls. No more and they don't reference Brembo on their website.

I'll keep looking. I could get a set of parts from UK or other places in Europe, but not here. And they are not OE Brembo seals. Not a confidence builder.

STeve
 

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Brakes are over-rated. :0

Seriously though,,, Ducati put's Rear brakes on their bikes, for the 1st 10yrs they're useless, then they spontaneously combust!?! ffs...

Now that's an engineering accomplishment.
 

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Discussion Starter #14
Update rear brake melt-down and display very high temp.

Rear Brake: I installed a new caliper and MC. Straightforward. PITA bleeding as caliper isn't much higher vs master and hard to get air to migrate to the caliper bleeder. I did crack the brake line at the MC a few times and all is well now. BTW, the caliper came with new pads: BONUS!! and unexpected.

High temp read-out: The bike ran very well with the high numbers on the display. I suspected the temp sensors. I reviewed the common parts sticky and ordered the Bosch sensors from Amazon. Approx $15 each. Great!! Removed the fairing and pulled the old and installed the new. The coolant level was within spec with the 'over flow bottle' at the min level. But still of no real concern. Radiator was full and fan worked fine. The sensors were the OE Jager, only 15 years old. The HZ cylinder sensor (display) showed evidence of leaking internally into the electrical plug connection. I suspect the sensor was shot and I'm 99% sure it was a non-event as far as over heat goes.

So, since I have the fairing off, I'll change the coolant as I cannot remember the last time it was done. Not a biggie as the PITA task is fairing removal!!

I'll probably do it tomorrow, let it idle a bit to try to get it up to temp and to get the air out and the system to draw from the bottle. Don't really know of any better technique.

STeve
 
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If you didn't already know, the trick to adding coolant on these bikes is to do it on the side stand. Add slowly. You'll have less of an issue with needing to burp air later. The water union with the hose coming off the water pump at the rear cylinder, "almost" high point in the system, has a bleed screw you can remove when adding coolant to help in letting air escape. I think both cylinder water unions have the screw, but the vertical one would really be the only one with a purpose.
 
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Discussion Starter #16 (Edited)
Well, all was going very well. The rear caliper and rear master cylinder went into place and I was able to fully and properly bleed the system. I was able to ensure the actuator rod was about 1 to 1 and 1/2 mm prior to contact.

As far as the replacement of the temperature sensors, that went very well. And then I tackled the coolant change out. I was able to drain the coolant by unclipping the lower radiator hose and I also open the bleeder attached to the point where the vertical cylinder hose attaches to the motor. Additionally I might point out it best to also remove the drain plug from the water pump. It is very obvious as it protrudes from the face of the water pump. Quite a bit came out from there. I added coolant, ran it and let it cool off. All good and no leaks.

I buttoned up the left side and all went well I then tackled the right side fairing and was getting things straightened out and then all of a sudden there was water dripping from somewhere near the Overflow bottle. I removed the right side fairing and low and behold it was dripping from the Overflow bottle connection hose to the radiator. I tried tightening up the clip thinking I may have overlooked that step but no. As soon as I snugged up the clip the Overflow bottle nipple on the radiator neck gave way and it parted from the radiator itself. Good thing my wife wasn't around she would have heard me. And who knows what after that. In any event I saw a radiator on eBay and ordered it. I know I will have to remove it. I don't know if such is repairable, it's probably not worth the effort based on what the cost of a used replacement is. Never the less I have no idea as to the history involved with a used part such as a radiator. Who knows maybe it has a crack. Probably my luck. Steve
 

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Discussion Starter #17 (Edited)
I have no idea what caused it. When I drained the Overflow bottle I remove the connecting hose from the end where the hose connects to the bottle and not where it ended up breaking. Oh well, better in the garage than on a long trip.
 

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Discussion Starter #18
BTW, a new one from Omaha is $900.
 
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