Radiator cool spots

[Lewy]

I've had a good trawl through the posts but need a bit more advice. My rad is warm at the top and very noticably cooler to cool at the bottom after a normal run. The hose out of the bottom of the rad is cool , top hose is hot. Is this normal and where is the 'core' that people have mentioned to feel cool spots for?

I'm seeing Allan in Plymouth on Tuesday for at very least a long overdue coolant change and maybe a flush. He has talked about the sludge build up and the narrow bore of the radiator and mentioned a bigger and more substantail radiator he has fitted - dual core? Woner if people have noticed a much bigger difference after a rad change. My temp under normal conditions is fine but big hills can push the mason alarm gauge up and my TM2 up too. What is apparent is that although I can see the water temp gauge going down and reacting as the stat opnes, once the higher temps have been reached on a run, the engine seems to stay in this hotter region and is quicker to get hot on the next hill or incline. Which leads me to believe the water is getting round the engine, but at a reduced rate that makes it harder to cope when the engine has more demand placed on it. Also still pretty sure the fan sensor is not working too which probably does not help, so I've been putting air con on to get fans operating.

Any thoughts?

[haydn callow]

Well,,,your going to the right place....have a chat with Alan whilst your with him....his advice will be as good as it gets.

[mikeonb4c]

I've had a good trawl through the posts but need a bit more advice. My rad is warm at the top and very noticably cooler to cool at the bottom after a normal run. The hose out of the bottom of the rad is cool , top hose is hot. Is this normal and where is the 'core' that people have mentioned to feel cool spots for?

I'm seeing Allan in Plymouth on Tuesday for at very least a long overdue coolant change and maybe a flush. He has talked about the sludge build up and the narrow bore of the radiator and mentioned a bigger and more substantail radiator he has fitted - dual core? Woner if people have noticed a much bigger difference after a rad change. My temp under normal conditions is fine but big hills can push the mason alarm gauge up and my TM2 up too. What is apparent is that although I can see the water temp gauge going down and reacting as the stat opnes, once the higher temps have been reached on a run, the engine seems to stay in this hotter region and is quicker to get hot on the next hill or incline. Which leads me to believe the water is getting round the engine, but at a reduced rate that makes it harder to cope when the engine has more demand placed on it. Also still pretty sure the fan sensor is not working too which probably does not help, so I've been putting air con on to get fans operating.

Any thoughts?

I think you are on the right (logic) track but see what Allans say. I'm very interested in the issue of inadequate engine cooling and thermal build up. Can't help but feel that a new radiator can only do good, and it would be interesting to see if the rad fan sensors are doing their job and/or what the cooling effect would be if you had over-ride switch for them (though that isn't a real solution if the rad - or thermostat - aren't doing their job properly)

[Lewy]

Yep will see what Allan says and will feedback if there is anything interesting to say.

Mike - As for the over-ride switch -I'd have one but was put off by ECU-gate thread. Doesn't putting the air-con on activate the fans in the same way as an over-ride switch would?

[mikeonb4c]

Mike - As for the over-ride switch -I'd have one but was put off by ECU-gate thread. Doesn't putting the air-con on activate the fans in the same way as an over-ride switch would?

I'm not sure. I know they come on if the aircon as 'on' when ignition key turned to 'on' but I'd imagined that was a 'quirk' and that they went off when engine actually started. If they don't, it may simply be because the aircon works the engine harder and thus the designers think a fan (or both fans - the Bongo has two) should be permanently on.

I can't advise on the ECU risk. I fitted a supply direct from hte battery via fuse and switch to my scavenger fan and have had no trouble. I think it was infact agreed that the ECU doesn't use 12v whereas of course the fan does. This suggests to me the circuits are not connected and that the ECU used a relay to switch a 12v supply to the fan, but doesnt go near the 12v supply itself. Unless the ECU decides to switch the fan on (which I don't think it ever has yet, so hard to test!) I don't see anyway my new supply could feed back into any part of the ECU circuit (switch or power side). I would imagine a similar situation exists with the rad fans, although they are more likely to experience switching on by the ECU so you are more likely to find out if my theory is flawed (ouch!). But I felt adventurous with my Bongo so.......you have to decide how you feel!

The main point has to be though that fitting over-ride switches to rad. fans to get things right is to dodge around the central issue i.e. why is the cooling system not doing its job properly. I think it has to be either:

1) Thermostat not opening / closing properly
2) Radiator (or other part of system) obstructing flow
3) Radiator tubes caked so heat trasfer impaired (links with (2) above)
4) Rad fan sensors not doing their job and kicking fans on when needed
5) Something else generating excessive heat (lets not go there - unlikely anyway )

Good luck - keep us posted

[Lewy]

I'm not sure. I know they come on if the aircon as 'on' when ignition key turned to 'on' but I'd imagined that was a 'quirk' and that they went off when engine actually started. If they don't, it may simply be because the aircon works the engine harder and thus the designers think a fan (or both fans - the Bongo has two) should be permanently on.

I checked today - the fans do come on and go off with the aircon compressor - I think at the slower speed.

Off to Allans tomorrow - probably for a new rad - perhaps one of his heavy duty ones???

[mikeonb4c]

I'm not sure. I know they come on if the aircon as 'on' when ignition key turned to 'on' but I'd imagined that was a 'quirk' and that they went off when engine actually started. If they don't, it may simply be because the aircon works the engine harder and thus the designers think a fan (or both fans - the Bongo has two) should be permanently on.

I checked today - the fans do come on with the aircon compressor, then go off and then quick in again - I think at the slower speed.

Off to Allans tomorrow - probably for a new rad - perhaps one of his heavy duty ones???

Well if Allan's can't sort it......I'll eat my hat

Good luck getting it sorted