S4 - Overheating, Cause found, I think

[Teatime-S4]

Hi Peeps,
S4 has been overheating for ages; some long runs it would be OK but gradually got worse and worse. Symptoms LHS of radiator and Hoses very hot, RHS (cap side) stone cold, suspected Airlock, Pump, Thermostat, tried lots of Burping flushing etc and finally lashed out £130 for new thermostat - all no change. Finally today took the radiator off yet again and played with it in the sink, I am now convinced that the baffle in the LHS, that should be there to make the water go fully "round" the radiator has broken and the water is taking the easiest path straight through from top to bottom, bypassing the finned tubes completely. Will probably try and have repaired (a mate has recommended GMX Radiators). I will let you know how I get on, but thought you all might like to know as I have seen these sympoms posted before. Hopefully it is a rare fault.

Good Riding,
Teatime

[PDS]

thanks for posting, hopefully i wont ever have any need for this bit of knowledge, but worth noting as a potential/possible issue. what year is the bike and what sort of mileage has it covered out of interest.

cheers

[Dookbob]

£130 for a thermostat, jeez, there has got to be an alternative for that.

[Rockhopper]

There is, test the old one first!

[Teatime-S4]

Just got the Radiator back from GMX Radiators, they cut open the radiator and said that the baffle was in place and there was nothing wrong with it. They said that there is a gap deliberately left in the baffle that allows some flow from top inlet to bottom outlet, why is not known. Anybody out there know?

So now I am another £80 down and still no further forward. Incidentally I did test the old thermostat in a saucepan of boiling water where it worked ok, before (after more overheating) spending £130 on a new one (it is in a moulded plastic housing specific to Ducati hence the high price) although things often test OK, a one off cycle in a saucepan may not be the same as repeated cycling under both pressure and temperature.

Having twice checked that the water pump is OK the only thing that seems to be left now is a head leak, advice welcome.

best regards
Teatime

[Rally]

Have you tried seeing if it blows bubbles in the top of the radiator or the expansion bottle when the engine runs? That would indicate head gasket. You can sometimes smell exhaust gases in the water as well if the gasket has gone. How about pumping up the system to working pressure to see if it leaks air as well.

[Capo]

What is the condition of the oil?

[Teatime-S4]

Hi Rally and Capo,
Thanks for the responses, I haven't seen any bubbles with the Rad Cap off, or any in the Expansion tank (at least not until the coolant starts boiling!!!) no oil in the coolant or water in the engine Oil. However whereas it used to take at least 20 to 30 miles before it overheated the problem is getting worst so I shall certainly do all those checks again. I have also had the water pump cover off and checked the condition of the impeller and that it goes round when the engine is turned over. Will do the sniff check too, not heard that one before.

Thanks again
Teatime

[desmo]

There are quite a lot of checks you can do to try & pin down the problem.

1. fit an independant gauge to check the true temperature of the coolant

2. use a infa-red temp reader on the radiator core to check for even temperature, any cold spots will indicate a blockage in the core (available from Maplins at a reasonable cost)

3. weigh the radiator & compare the weight to a new one or a known good one, a heavy radiator will indicate a lot of sludge build up in the core.

4. get / borrow a C02 sniffer, this device fits in the top of the radiator & the litmus paper or fluid depending on device type changes colour if it detects CO2 (I.E a headgasket leaking or cracked head)

5. Temporarily remove the thermosat & see if it still overheats?

6. remove the radiator cap (cold engine) start up & give it a few revs, the coolant should drop a few cms in the neck indicating that you have a flow, as you return to idle the coolant should rise to it's original position, if it overflows badly this could indicate that it is pressurising (headgasket failure or cracked head)

7. check for any kinked / trapped or collapsed hoses.

[Capo]

I suspect a blockage in the core. Try connecting a garden hose to the bottom connection, flush back to the RH header with the cap off, then put cap on and flush to the open top connection.

[gary tompkins]

Are the fans working properly?

[Loosehead]

I Had the same with my S4, tested another rad, and the rad was the issue it seems it was fouled, bought a replacement, be warned it aint a cheap buy, but problems gone.....

I spent a load of time messing around with this, testing thermostat, sensors running the rad through etc drove me nuts.

[jerry]

Always use non silicant coolant in S4 .

[Teatime-S4]

Still same problems with my S4, however just read a thread on Ducatisti of similar problems - LHS (inlet and outlet side) of radiator red hot, RHS (radiator cap side) stone cold. I am more convinced than ever that I did find the fault when mucking about with the radiator in the sink. Where I could see water flowing easily straight from inlet to outlet without going round the core/matrix. (I could also satisfy myself that the matrix/core was not blocked by feeding water in from the radiator cap side and it appearing at inlet/outlet) I am not convinced there should be any gap here as I allowed myself to be convinced there should be, by the GMX radiator repair guy. He said it was identical to another Ducati radiator he had, same gap in the baffle plate. Then I asked myself what would a Radiator repair guy be doing with a Ducati Radiator if some other owner hadn't sent it to them because it was faulty too?

No evidence of any other fault, just no flow through radiator, but top and bottom hoses always hot. Will be ringing GMX tomorrow for another chat and Moto Rapido who the thread says have seen this fault in 4 or 5 bikes now.

baffled of Bournemouth (aka Teatime)

[Stafford]

If you knew the fluid capacity of the radiator pouring in that measured amount would show any short fall in capacity. Just a thought.

[Teatime-S4]

Yes, finally fixed, it was the radiator, I have just bought a second hand one for £200, a new one is, wait for it, £969 plus VAT presumably. First ride out I knew all was well as the rad was hot all over and the outlet significantly cooler than the inlet as it should be. (plus no signs of the fans coming on). Regular readers of this page will recall that the cap side of the faulty rad was always cold and the inlet and outlet side, both rad and pipes, uniformly hot.

I tested the new radiator and it has a bypass from inlet to outlet the same as mine had, so this is not a fault, they are indeed all like that, (apologies to GMX radiators, although I do feel they should have flow tested the rad and identified the real fault).

So the thin tubes that pass through the cooling matrix are obviously blocked in some way. Either by crud, source uknown as there are no signs of sludge/deposits elsewhere in the cooling system. Or maybe they have collapsed when the engine cools down.

The new rad does not fit well and is the wrong colour, so I am still going to try and fix the old one somehow. (I tried using some flushing on it no change).

Seems typically my luck that I have finally got the bike fixed in October.

Best regs to all Ducati Riders (and the others) from Teatime