Engine heat rising rapidly FIXED

[chris-red]

I own a Speed Four so the same basic setup. I had a faulty rad cap, so if you are stuck it is worth changing was only £15 IIRC.

Make sure the cooling system is bled, an air lock could cause these symptons.
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Well, you know what they say. If you want to save the world, you have to push a few old ladies down the stairs.
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[Paris2]

I've bled the system to remove the thermostat, so will refill and make sure there's no air trapped.

I think changing rad cap is a good idea too, as it looks a bit old and shoddy.

[temeluchus]

[MCN]

You need to do an efficiency test on the cooling system.
Quite intensive task follows. Theoretically simple but interesting results.

You will need:

a thermometer at the thermostat/regulator housing. A glass one out of the chemists Not a baby one as they do not go high enough.
Try to sort of 'lag' them with rags and tape to prevent them losing the 'measured heat' but have the probe part touching metal to allow heat to conduct to the bulb/probe.
a thermometer at the top tank of the radiator.
a thermometer at the bottom tank of the radiator.

Run the engine and record the temp at 5 min intervals.

Do this until the fan switches on.

continue for another 4 or five readings.

You are trying to find out if the cooling system is cooling the engine effectively.

There should be a very slight drop between the regulator housing and the top tank. If your thermometer is sensitive and accurate enough you will see 1 degree C. Or more.
The main readings you are looking for are top and bottom tank.
The radiator should cool the coolant to be at least 10% cooler than the top tank. If so then the cooling system is good.
If you cannot see at least 10% drop from top to bottom then either the pump is no good or the radiator is blocked internally.

The last thing you should do is invest in taking the head off just yet.

You must be 100% certain of the head problem or you will do the work for nothing and meet the same problem after.

Mostly, head problems cause combustion gasses to blow into the coolant. It will displace the coolant if severe.

Is the water pump is easy to get to I would whip that off before pulling the rad off or the head.


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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[stevo as b4]

How certain is OP that they have no noticeable coolant loss? If almost certain there is so coolant loss, what does the coolant look like? I.e is it just a bit scummy but antifreeze coloured, or is it rusty brown or oily?

It's entirely possible for a radiator to leak externally, or alternatively for tubes inside to get blocked or damaged or collapse, as they are quite delicate things.

I agree with all the sound advice given so far in this thread, but before doing a cooling rate test across the rad, I think I would on my own bike just replace the expansion tank cap/radiator cap, and test or replace the stat too. If a new radiator wasn't daft money I'd probably be forking out for one, not a scientific way to solve a cooling problem, but it's three of the hardest working components in the cooling system, and radiators take a bloody pounding from road debris and any objects flung up hitting them etc.

When doing a coolant flush and re-fill, I think I'd get a water pump gasket too, so you can take the cover off and check both the impeller for damage/corrosion and the inlet and outlet ports to the pump body too.

I'd spin the engine over on the starter with no plugs in or the leads off, and check that the pump rotates too. The reason for this is from reading an article in CMM about a cooling problem on a staff members bike, which the drive to the pump was done via a jackshaft and 90degree bevel gear driving the pump shaft, which had failed.

I've also heard of people doing effectively a leak Down test on parts of the cooling system, where they pressurise the cooling system with air and monitor if and for how long it holds pressure for as a test.

I agree with not taking off a cylinder head until everything else has been eliminated, as head gaskets rarely just fail without one or more fairly obvious signs. There's a world full of people out there that have replaced head gaskets without ever fixing their engines cooling system fault, to find out there was nothing wrong with the head gasket in many cases.

[Paris2]

I am not certain there is no coolant loss, but the bike has been sat for a while with no noticeable leaks.
The coolant looks fine also on draining, not scummy or discoloured at all.

Following all of the advice so far this is my plan:
- Check the radiator for blockages, by seeing if water runs through from top to bottom.
- Refill the system and check the pump is working.
- Replace radiator cap (picking up a new one tomorrow).
If all above goes well then I will get the system filled and rigorously work out any air pockets.

Sound sensible?

If I am still not getting anywhere after this then I will have to take the bike to a mechanic. This is already pushing my comfort zone so doubt I will be digging much deeper in terms of removing radiator/head.
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Current Ride: Daytona 600

[Paris2]

Also want to thank everyone for the sound advice so far.
Very helpful, just what I expect from this forum
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Current Ride: Daytona 600

[Paris2]

Right so all has been done.

The bike seems to run cooler, but it still gets north of 110 degrees in traffic.
I did notice once stopping that the top of the radiator is ever so slightly cooler than the bottom, mean anything? I'm pretty sure there isn't any air in the system.
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Current Ride: Daytona 600

[chris-red]

[P.]

My Daytona 600 hit 115 but never went higher than that, it sharply fell afterwards too, went under 105 and hovered. It was warm however.

[Paris2]

It is exceptionally warm at the moment, so I'm taking that in to consideration.

I have seen 120 countless times though over the past few weeks, but never above that. And it does cool when I get moving over 20mph or so.

Maybe I should just remove the fairings
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Current Ride: Daytona 600

[Paris2]

FIXED

Worked out a few more air pockets in and around the pump. Did about 400 miles over the weekend, and didn't overheat once.
Hurrah
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Current Ride: Daytona 600