HELP! Need a RADIATOR ASAP!!!

[Nash]

Can some one answer me this.

If the Radiator is used to pre-warm the Auto Transmission then how does it do that when the engine is cold ?

Does'nt the Radiator system use a thermostat that stops engine circulation when its cold ?

If that is the case how would hot engine water get back to the radiator to pre heat the Auto Transmission. ????

This has always puzzled me about this preheat claim...

 

[Kitty's VR4]

Craig, that was an assuption on my part, but I see your logic. Well I guess the technical Guru's of the forum will correctly answer this one....

 

[Kenneth]

Yes the thermostat does limit (usually doesn't stop all together to prevent thermal shock) the water flow when cold.

The thing is that the water temperature rises much faster than the oil temperature.

If you start your car and leave it idle for a couple of minutes, you can feel that the top radiator hose is hot, but the lower is cold. This is because the heat is entering the water and being transmitted out of the engine and heating the water in the radiator, but there is very little coolant flow through the system.

This allows the coolant to get up to temperature fairly quickly (I have always found the VR-4 gets coolant temps up very quickly) and will start warming your transmission oil.

Obviously from dead cold, you will get no benefit. You just can't warm something with no heat. It doesn't take long however, and if you treat your transmission like you should (and not rag it from cold) then it will get up to temperature (and therefore correct viscosity) much faster.
Usually it should also be able to hold the temperature down, however that doesn't appear to be the case.

Same goes for engine oil. It takes longer to get to running temperatures than the coolant. Just because the temperature needle is at its correct position doesn't mean the engine is going to be fully protected if you drive it hard.

If you have a oil cooler, you SHOULD run with thermostat, or use the coolant as a heat exchanger.

 

[Kenneth]

As clarification, my point is that the oil needs to be at the correct operating temperature to work as designed. Too cold and it doesn't protect as it should, too hot and the same.

Running the oil through the coolant heats it up faster than it would otherwise, and also absorbs a reasonable amount of excess heat.

It isn't un-common for high performance cars to use a similar system as a heat exchanger for their engine oil.
I personally wouldn't install a engine oil cooler without using a thermostat or heat exchanger. I wouldn't run an automatic transmission without one either, though perhaps they are a lot more tolerant... Then again, I wouldn't run an automatic transmission anyway... lol

 

[Kitty's VR4]

Thanks Kenneth,

So would you say it was of advantage, to get the Aluminium Radiator and modify to accommodate heat exchanger. i.e, my plan was to run 2x10mm OD looped pipes TIG'd back through the bottom tank of the radiator. My conclusion from your post would be that it should run in series with an oil cooler, in this order, A/T - Cooler - Radiator - A/T??

 

[Kenneth]

If your heat exchanger is sufficient at exchanging heat, you don't need a cooler.

You can buy heat exchangers which run in-line with your coolant. The are essentially a tube which you attach your coolant pipes too (like a hard pipe) which has a jacket around it which the oil circulates through to do the heat exchange.

 

[Kenneth]

This is the sort of thing I was thinking of: http://www.racerpartswholesale.com/category/Mocal_Heat_Exchangers

If you run the 40mm alloy radiator, there should be ample cooling available to absorb the extra from the transmission.

 

[Kitty's VR4]

Right. Looks like I'm guilty of overkill again, but to late, wish I would have asked earlier. Though I do live in semi-alpine climate with sub zero temps averaged on 30% of mornings year round, then on the other end of the spectrum we get temps into the 40's during summer.