Coolant Temperature Issue

Choche · Jun 30, 2019

Finally got some time off work and decided to change the coolant on my Rocket Roadster. Never changed it before; anyway, plugged in DealerTool and turned on the bike to get a pattern of what the bike coolant temp readings are. By the way, the radiator is full along with the overflow bottle. Once the bike heated up, the fan came on; also, the temperature here is HOT (my truck swore it was 105 F). As I was monitoring the temperature in Dealertool, I noticed the fan never shut off. It was reading 106 C (about 223 F); left it on for a few more minutes, and the fan never shut off. I then plugged in my OBD reader to take the bike out and as soon as the bike gained some speed, the temperature started dropping. Riding the bike, the temperature was around 200 to 210 F.

There were no codes, overheating lights, overflow issues, or nothing like that; just feel that those temperatures are too high. I then went home since the coolant temperature does drop once the bike moves; I assume then the system should be working, although, maybe not efficiently.

Parked the bike outside this time (initially I had her on in my garage) and the same pattern was there. Temperature read up to 234 F; took her out for a quick spin and it drops about 10 - 15 degrees fairly quickly.

Again, no leaks, no lights, no codes, no overflow, but it just seems like the coolant temps are too high; anybody else seen this?

Also, I touch the hoses before the fan comes on and then after the fan and you can feel the temp difference; not sure if that's a good sign or not. Any info would be appreciated; I am changing the coolant but also going to boil some water and test out the thermostat. The service manual calls for about 190 F before it opens; 190 to 234 seems like a range too wide for me. Unless the reader is wrong since no lights came on.

Please advise.

mully95 · Jun 30, 2019

I don't know if this has anything to do with it but you might have air in the cooling system.

When I changed mine I removed a bolt out of the side of the engine. Once coolant was running out of the bolt hole I replace the bolt. This lets the air out of the system. The manual calls it a "bleed screw".

Choche · Jun 30, 2019

mully95 said:
I don't know if this has anything to do with it but you might have air in the cooling system.

When I changed mine I removed a bolt out of the side of the engine. Once coolant was running out of the bolt hole I replace the bolt. This lets the air out of the system. The manual calls it a "bleed screw".

Since I had not messed with it, I didn't think any air would be in the system but now that I remember, the dealer did replace the water pump a few years ago. At least that's what they said; didn't ever really trust them. I'll check it out though. Thanks.

Choche · Jul 1, 2019

mully95 said:
I don't know if this has anything to do with it but you might have air in the cooling system.

When I changed mine I removed a bolt out of the side of the engine. Once coolant was running out of the bolt hole I replace the bolt. This lets the air out of the system. The manual calls it a "bleed screw".

I removed the bleed screw and coolant surged out so that rules out the air bubble; I took it apart and removed the water pump and thermostat. The pump seems tight but I guess I'll still replace it. What I didn't like was the thermostat; boiled up some water to about 90 C and dropped it in. Let it sit and it seems to have taken too long to open. Let the water boil to about 106 C and it opened but not a great a deal; only about 5 or 6 mm; don't think that's normal. Turned off the flame and let the temperature drop to about 90 C, popped in the thermostat and it barely opens. I have to leave the flame running so the water temp rises and then it opens up a bit more. I feel uneasy over the whole thermostat issue.

Claviger · Jul 1, 2019

Good detective work

Coolant coming out of the bleed hole does not rule out an air bubble, my bike, in particular, will never bleed out all the air without a vacuum bleeder. A quick check is to let it get fully up to temp, to the point the fan comes on, then shut it off in a silent environment. Put your ear near the top of the motor and listen for a "dripping faucet". If you hear any water noises, it's a bubble (or a cracked head).

Thermostat and Radiator cap are good cheap parts swaps to see if it'll fix the problem, the KTM increased pressure cap I've linked elsewhere on the forums is cheap and usually on hand if you have a KTM dealer near you. The extra .4 BAR pressure has had only positive effects for my bike, no more hoses collapsing at sustained high RPM (5000-8000 through mountain roads), no more boilover upon shutdown as so many rockets have where they spit a few drops of fluid out that run down the engine just ahead of the oil tank etc.

As my first bike, my Daytona 955 scared the crap out of me when I first bought it. It would reach 118c-120c in stop and go traffic, no warning lights, all searches indicated that was normal temp for the bike, just at the upper end of the normal range. That was 9 years ago, haven't so much as swapped the cap or thermostat and it's still completely healthy (dynoed exactly what it was supposed to when new at a ripe old age of 17 years on).

Sitting idle in hot weather, with the fan on the rocket really doesn't cut temp too quickly, but it should slowly work it down from 100+ to 96 ish. It's a large heat load, a small fan, and it's meant to be moving.

When it's 70f outside, it takes about 15 miles for my coolant to reach 80c, and about 25 to hit 92-93, where it wont go beyond while I'm moving or much below once it's passed 90c. Even on hot days, it sits at 94-95 unless stuck in traffic. This anecdotally supports your evidence of a 90c cracking temp. I run water and water wetter only though, so my temps will inherently be a little lower than those running glycol based cooling systems.

Choche · Jul 1, 2019

Claviger said:
Good detective work

Coolant coming out of the bleed hole does not rule out an air bubble, my bike, in particular, will never bleed out all the air without a vacuum bleeder. A quick check is to let it get fully up to temp, to the point the fan comes on, then shut it off in a silent environment. Put your ear near the top of the motor and listen for a "dripping faucet". If you hear any water noises, it's a bubble (or a cracked head).

Thermostat and Radiator cap are good cheap parts swaps to see if it'll fix the problem, the KTM increased pressure cap I've linked elsewhere on the forums is cheap and usually on hand if you have a KTM dealer near you. The extra .4 BAR pressure has had only positive effects for my bike, no more hoses collapsing at sustained high RPM (5000-8000 through mountain roads), no more boilover upon shutdown as so many rockets have where they spit a few drops of fluid out that run down the engine just ahead of the oil tank etc.

As my first bike, my Daytona 955 scared the crap out of me when I first bought it. It would reach 118c-120c in stop and go traffic, no warning lights, all searches indicated that was normal temp for the bike, just at the upper end of the normal range. That was 9 years ago, haven't so much as swapped the cap or thermostat and it's still completely healthy (dynoed exactly what it was supposed to when new at a ripe old age of 17 years on).

Sitting idle in hot weather, with the fan on the rocket really doesn't cut temp too quickly, but it should slowly work it down from 100+ to 96 ish. It's a large heat load, a small fan, and it's meant to be moving.

When it's 70f outside, it takes about 15 miles for my coolant to reach 80c, and about 25 to hit 92-93, where it wont go beyond while I'm moving or much below once it's passed 90c. Even on hot days, it sits at 94-95 unless stuck in traffic. This anecdotally supports your evidence of a 90c cracking temp. I run water and water wetter only though, so my temps will inherently be a little lower than those running glycol based cooling systems.

Thanks for the advice; 120c, that is scary. What caused me to go on this hunt is that in the past, the fan would cycle on and off which I would assume the coolant system was working normally. This past time, the fan never shut off; that's when I put on my Sherlock Holmes cap. I, though, should have replaced the coolant sooner; never had since I bought it new and should have. I don't know if that eventually led to less efficient coolant system; anyway, I still ordered the pump since it had a drop or two of coolant underneath (I do let it sit too much), thermostat, hoses, and the thermostat housing o-ring. I also ran some distilled water through the radiator but it came out absolutely clean.

On another note, the coolant that came out does look darker than the new one; I'm guessing it does deteriorate with time. I also ordered the clutch cover gasket; was thinking of peeking in and take a look at the detent spring or it may just be an excuse to take a look inside the beast.

On another note, I can't fathom the idea of your bike making 265+ horses? One day, I took off from my house in second gear; as I was making the turn, I swear I just slightly twisted the throttle and it quickly slipped and went sideways; released the throttle to gain control quickly and this is with a stock engine. Imagine over 260 horsepower???????

I used to have a Chrysler 300 sedan with a 2.7; I think it was rated at about 170 horsepower Imagine that.

Claviger · Jul 1, 2019

Best of luck, I'm sure you'll be temp stable after what you're doing. Essentially its an all new cooling system, or will be once you've finished!!

barbagris · Jul 1, 2019

One tiny bit of advice.

When you refill - The bike NEEDS to be vertical (not on the side stand) - this is in the manual.
What is also important, though NOT in the manual is that the engine is higher at the front than at the rear. i.e. Front wheel in the air.

All this helps keep bubbles at bay. Also recommended (by one of the original R3 Gurus) is DEI Radiator Relief. I use this and find it helps both in the warming up and cooling down phases.

ime - R3's do NOT like sitting still. When I visit the UK - in the time it takes to clear customs the cooling system is already WELL hot. Even with strong cool sea breezes the wash off the radiator raises the air temps hitting the intake by as much as 25°C.

IF you decide to replace the hoses - and especially if you move to SAMCO - make sure you follow the hose clamping instructions. If you don't you'll be chasing drips and leaks for days.

I have a vacuum bleeder now too. Will it ever get used?

Choche · Jul 2, 2019

Claviger said:
Best of luck, I'm sure you'll be temp stable after what you're doing. Essentially its an all new cooling system, or will be once you've finished!!

Thanks.

Choche · Jul 2, 2019

barbagris said:
One tiny bit of advice.

When you refill - The bike NEEDS to be vertical (not on the side stand) - this is in the manual.
What is also important, though NOT in the manual is that the engine is higher at the front than at the rear. i.e. Front wheel in the air.

All this helps keep bubbles at bay. Also recommended (by one of the original R3 Gurus) is DEI Radiator Relief. I use this and find it helps both in the warming up and cooling down phases.

ime - R3's do NOT like sitting still. When I visit the UK - in the time it takes to clear customs the cooling system is already WELL hot. Even with strong cool sea breezes the wash off the radiator raises the air temps hitting the intake by as much as 25°C.

IF you decide to replace the hoses - and especially if you move to SAMCO - make sure you follow the hose clamping instructions. If you don't you'll be chasing drips and leaks for days.

I have a vacuum bleeder now too. Will it ever get used?

Thanks for the advice; I bought the Black Widow motorcycle jack along with the JBQ bracket. I always set her up straight when working on her; it just seems to make things on the left side more accessible; or I'm just getting old -- lol
.
DEI relief, will give it a try. Thanks again.

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