Over cooling

Has any one bought a new radiator for a series and how did it perform. I bought one (aluminium) not 3 core and it is over cooling. Runs a little warmer with a drilled thermostat. In essence the problem is that temp goes up to near red but water is so cold in return it will not let thermostat open as it seems too cold on one side and boiling on the other. When it does open top of rad is hot but rest is stone cold and cycle repeats. With thermostat drilled whole rad warms evenly and engine runs just below normal/ just above cold depending outside temp. Thermostat opens at at around 74 degrees in pan and tested with laser thermometer.

Have you tried this experiment with a working water pump as well?

Yes new pump, X 4 thermostats, with heater matrix attached, bypassed, frost, sunshine, dog in the garden, cat on the fence. Only circulates if radiator totally blocked off with a piece of carpet or thermostat drilled. I can only conclude new rad is over cooling and affecting thermostat. I have not been able to get another 3 core rad . I was wondering has anyone else come across this? Thanks for reading the post though.

Mine is aluminium and works bang on. I have taken the original fan off the waterpump though. Just use an electric one when stood in traffic if he goes over 60.
Thats not the block temp but the water temp as I have a digital readout from the top hose.

Good idea might try it without the fan.Thanks for that. I will do the swivels next and then revisit this.

Not got an airlock have you? I know trapped air in the system will cause the symptoms you describe, freezing cold bottom hose and hot at the top

I don,t think so I have filled it from rad, heater matrix, head and always get the same thing which is why I was thinking over efficient cooling affecting thermostat from below. I have filled it on ramps at angle and tried it without heater matrix plumbed in. This is a second engine as I thought the original 3 bearing one might have had problems and put new head gasket on that one in an attempt to cure it before replacing with 5 bearing one.

Additional note if it was an airlock why does drilled thermostat cure problem of circulation?

Just a thought, but you did flush the block when you changed the rad, didnt you?

Block flushed, more than once both ways and heater matrix all ran clean. It really has got me stumped except for maybe an over efficient rad. Electric fan does sound like a consideration.

Dunno really. Too efficient a radiator seems the least likely to me and doesn't even explain it properly but an electric fan won't hurt and if it cures the problem, I suppose that's good.

SpringDon said:

Dunno really. Too efficient a radiator seems the least likely to me and doesn't even explain it properly but an electric fan won't hurt and if it cures the problem, I suppose that's good.

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As above. Aside from anything else the stat is designed to operate with once side far colder than the other else it'd never open after starting up.

I'm confused about 'drilling' the stat. They all have a small hole to allow seep through and prevent a cold coolant trap.

Well I figured if water was not getting through enlarge hole on thermostat to allow flow. This worked and now radiator warm across whole panel and temp running at just above cold. Gets warmer if I block off rad. Goes back t o cold rad overly hot slightly pressurised top pipe with non drilled stat. No leaks in system and no over heat or pressure with drilled thermostat just runs below temp. I think remove fan fit normal stat and see how I go, then maybe go electric fan if all working as it should.

The problem has to be the stat. An over efficient rad won't stop a stat from working, by drilling it you're effectively removing it.

It has to be something basic. A duff batch of stats, fitting the wrong way around or something.

Has there been some sort of modification to the stat housing or pipework?

Just ran it now with warmer weather got up to normal and sat there. That is still with a drilled stat mind you. Interested In dodgy batch of stats could I be that unlucky on the fourth one. Got em from main dealer not landrover made but branded and not Brit part. Radiator 47 degrees top 37 bottom engine block 57 to 60 all over bottom hose warm and a heater that gives warm air. No smoke steam pressure and flow in the rad.

Seems reasonable. Some people used to use radiator muffs in winter on diesel because they ran too cold.

Used to use a rad muff on my one ten before I sold it. Can't get one for this except for stupid money. Will I think investigate rad muff before anything else. Thanks for all replies.

Not very technical said:

Used to use a rad muff on my one ten before I sold it. Can't get one for this except for stupid money. Will I think investigate rad muff before anything else. Thanks for all replies.

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£30 ish on fleabay if ya don't fancy using a fertiliser sack

Fertiliser bag would do me, have used a tool roll from pound land In the past. Cheers.

I use a section of plastic card tight against the lower half of the rad in winter,held in place by another springy bit of plastic. More effective than the standard rad muff on the grill as air just passes under and around it.