Use Auto Rad in Manual Car as Engine Oil Cooler

[MeFB]

I'm thinking about plumbing-up the transmission oil cooler section of an auto radiator as an engine oil cooler on a manual car

What I'm planning to do is simply plumb the outlet of my external oil filter to the inlet of the oil cooler and then from the outlet of the oil cooler back to the normal return point for the external filters (via the existing tapped hole in the block beneath the breather tube).

I think there would be very little pressure in the system as the return is really just gravity feeding back to the sump.

Does anybody see any glaring mistakes in my cunning plan?

[Mick]

but why

[MeFB]

but why

I'm planning what I want to do for my hottie grey motor (which will benefit from a little extra cooling).

[Harv]

It'll work, but the cooling effect will be interesting.

The grey bypass filters are desined to take just a dribble of oil flow, in order to prevent starving the bearings. Because the flow is so low, the heat transfer will be a little ordinary (contrary to popular belief, the higher the circulating flow rate, the higher the heat transfer). You will get some cooling, but nothing huge (about as much as a good finned sump).

To get better benefit, the flow needs to increase... maybe by converting the grey to full flow cooling . Would need to be a little careful, as the oil pump deadhead (40psi) is higher than the radiator operating pressure (7psi). An aftermarket cooler (with a higher design pressure) would probably be safer.

Cheers,
Harv

[Mick]

i don't really see any benefit to it as the cooling in the bottom of the radiator only consists of a tube that runs in and out of the bottom tank, may even have a negative effect, if you want to cool the oil you would be better off with a propper oil cooler, trans oil runs alot hotter than engine oil

[MeFB]

trans oil runs alot hotter than engine oil

Thanks Mick. That's something that I hadn't really thought about

So I guess the consensus is that it would work, but not really be very effective.

I'll give it some more thought.

[Craig Allardyce]

G'day Alan,
your modification has some merit. I have worked on heavy diesel engines for some years now whereby engine oil cooling utilising the engines cooling system has been the norm. As stated with the bypass filter arrangement you'd probably have little effect if any in cooling the oil due to lack of flow and volume.
In my opinion you would have to convert the lube system to full flow and have the lube oil passed thru the oil cooler under full lube pressure to achieve any proper amount of heat transfer.
I'd be a bit reluctant to do this for all the engineering and calcs that you would have to do to ensure proper and sufficient oil flow to the engine after modification. One scary point of using the radiator is you may burst the oil cooler in the radiator considering the difference in transmission cooling & lube pressures, and engine lube pressures. A gut full of oil in your cooling system will be big trouble. Whats worse is if you manage to get coolant in your engine oil it can be destructive to engine bearings in a very short amount of time.
There is one bonus though to running the oil through a coolant heat exchanger, and that is you will achieve getting the lube oil to its operating temp in a shorter amount of time.
If your really fixed on oil cooling then I would go to changing the lube system to full flow. Then I would plumb in an oil cooler sandwich adapter with the external oil filter. However with all this I would definitley be making sure that my lube flow rate and pressure would be sufficient for the engine. It may see the need for a higher volume oil pump as well. This may have a flow on effect with extra load on the distributor drive gear, oil pump drive tang, fibre timing gear, etc etc. I think you get my drift of the flow on effect...pardon the pun
Anyway I hope this helps somewhat with your quest. I look forward to seeing what you work out doing.
Cheers

[MeFB]

I'm with Mick - I don't see that this will be of any useful purpose on a grey motor unless you were driving at 130km/h at 40 degrees every day

No, wouldn't be doing that, but having the Judson rattling away under the bonnet will be adding a little heat because of the increased compression. I guess a bigger radiator would probably do a better job, but I'm just chucking ideas around at the moment.

[rosco]

Ok, I can throw a little bit of weight to Craig's post.... NO! don't - you won't gain much.

I didn't run the auto piping through the radiator trick.... but went almost in a totally different direction.

I have a Frantz external by-pass filter fitted to my old bus. The unit I used was the Frantz filter with cooling fins - much like you see on an air-cooled engine. It has about 12 fins around the filter body housing which are press fitted.
Usually, these are fitted as an additional oil filter to the auto trans... I decided this would also be good for oil cooling and filtration to my grey engine.

Initially, when the grey was still in the vehicle - I fitted this Frantz and cut out three holes in the radiator baffle to provide cooling.
I can categorically state that it made not one jot of difference to cooling the oil in the engine... the by-pass filter simply does not afford sufficient volume to make any significant difference..... yes, the oil filter body gets hot - but stays hot at all times - regardless of engine speed...... the very little amount of oil passing through the ports from the engine will not afford appropriate cooling....
We must consider that normally, in a full flow spin on filter - the entire contents of the oil pan pass through the filter about 3 - 7 times per minute... this, I'm confident would make a difference to oil temperature if a suitable exchanger were fitted... but in a by-pass application..... almost zilch...

You must also consider that there is a detrimental effect on cooling oil..... that is - over-cooling.....

When your engine is first started, the oil is quite thick.... it takes some time before the engine reaches operating temperature and also the oil....... if you are running trips where the engine barely reaches operating temperature - the oil will not heat sufficiently to evaporate the distilled pollutants from it......

If you do decide to somehow incorporate a full flow system...... at any time the oil has not reached operating temperature - the oil will most likely "by-pass" the filtration system.... this occurs because the oil to far too thick to pass through the filter element.... and the "by-pass" valve opens - re-circulating unfiltered oil through the system.....
You might just exaserpate this by the inclusion of a full flow system with a cooler......

Back to Craig - he'll have a lot more on this, now that I've given the topic some further aspects....

frats,
Rosco

[Craig Allardyce]

No not really Roscoe, your spot on.
I probably should of mentioned oil cooler bypass valves that are used to prevent rupturing the oil cooler when the oil is to heavy when cold.
Over cooling with an air cooled cooler could be a problem, and I guess if it were worth all the trouble you could engineer in a thermatic bypass valve. Over cooling isn't usually an issue with jacket water cooled engine oil coolers/heat exchangers as the minimum temp the oil will get down to will be engine jacket water temp.

[MeFB]

OK, thanks guys. I'll take your advice and not do it

[Mick]

if yor looking at more comp cooling the water is more of an issue than cooling the oil this in turn will cool the oil, there's also something far more technical than i could try to help with but oils are also designed to run at certain min temps aswell