Hi guys,
I've had an ongoing issue with a mechanic i took the car to just wondering if you guys could help clear some things up..

The engine is an a12 running the standard hitachi carb, extractors, points dizzy (replacing back to s2 this weekend), oversized rad (9ltr instead of the 4.5 ltr the car is a morris minor using the standard moggie radiator)

The idiot is still sticking to the story that my extractors and radiator are causing the engine to run cool. I spoke to the mechanic today. he told me that because the radiator is too big(this is a standard Morrie radiator) for the Datsun engine, as the engine is warming up the water passes into the radiator via the BOTTOM hose and mixes with the cold water in the radiator and then the cold water goes into the engine via the BOTTOM and the engine just cant get itself warmed up.

I asked him if he knew how a cooling system worked and told him that the radiator plays no part whatsover in the engine warm up process. I started to give him a physics lesson about the direction hot water goes but then i thought, whats the bloody point. There must be two passage ways in that bottom hose!!

This all before the thermostat opens of coarse.

he replaced the thermostat.. and in the end his "professional opinion" was to put some cardboard in front of the radiator?!

I'm just wondering how many of you are running extractors? any experiences with running too cold? any suggestions?

as he was saying oh they're not letting the manifold get hot enough and the water is just too much.. I again said to him "isn't that the thermostats job!"

yep my a12 has extractors and not only gets up to temp but got vary hot in summer

you can run too cool if the rad is too big and the water flow not quick enough or too quick.

its a fine line. some one will explain it better than me but cardboard infornt of the rad is a rough method to reduce airflow through the core. there for increasing the temps.

i have an opposite issue where with the L16 and s13 radiator, takes a while to heat up (so runs cold) then once it gets to temp, runs cool unless stuck in traffic, then heats up and doesnt cool down til moving again. even with 1 10 inch thermo fan so needs more cooling and possibly shrouding.

so yes it can happen and possibly the flow is too slow and too much coolant (9 lt is double the a series 4.5 lt) so by the time the coolant flows through the rad, slowly, it is cold cold

unfamilia, your problem is most likely the thermo fan. Because an S13 radiator is plenty big.

Extractors can't cause the engine to run cool.

thomen, is your engine running cool? I have always heard that a too big radiator will cause this. And if you have a 9 liter radiator when A12 stock is 4.5 liters, perhaps that is the problem. If your engine is running too cold, what do you have to lose by trying cardboard?

Try what DD says. The thermostat has a crack temperature below running temp. That flow may be sufficeint to keep it cold. Maybe try a hotter thermostat?

what water gauge are going off? the gauge might be a bit dodge too maybe. does it go up and down in temp or just stay cold?

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thats crap! if it was the case no outbord motors would ever get to operating temp(the ocean is as big a radiator as you can get) the thermostat is what controls rate of flow to the radiator and should not allow it to run cold if the appropriate temp rating is used.

remember that the biggest morris minor engine was a 1000cc and the datsun a-series was based on that design.

Yup most aftermarket thermostats are rubbish, just one of those parts you should always get genuine. ive had the same problem with new(aftermarket) themostats and stock cooling setup. change the stat to a new genuine one... problem solve.

anyone know the best place to find a genuine thermostat?

I agree with everyone here, I had a warming up problem with my car and it was definately the thermostat. Yeah I have been told to go genuine as well. The aftermarket one I have opens too late. If you want it genuine I guess the Nissan dealer would have one to suit.