Club 80-90 Forums

Cobra88 wrote: You just need to think about high and low pressure areas.

Yep, that equates to airflow, and you will certainly aware that fluid dynamics is complicated. I am.

Cobra88 wrote: I also saw a fan to fit that cooler that Ash linked and a kenlowe type thermoswitch setup

I'm hardly going to disagree with that as I suggested it above

Cobra88 wrote: the problem with front mounting an oil cooler on the front of a T25 is pressure drop with lines that long
I would rather lose a little effectiveness and keep oil pressure.
(that's only a guess but I know from my work that long oil hose runs sap pressure quite effectively) (Aerospace)

That's a good point, and it'll be about both the pump flow and diameter of the hoses, but cooler oil will also be higher pressure oil

ash1293 wrote:
Bottom line is that by increasing the surface area exposed to air (or water in liquid oil oolers) you are incrasing the cooling capacity unless the air temperature is greater than the oil itself. While not as efficient as a radiator placed in direct airflow it should still have a significant measurable affect.

That's my point, you might as well have an efficient oil cooling system rather than an inefficient one, but the engineering is much more complex than area alone

By the way, you can tilt a radiator at an angle of up to about 15 degrees to the airflow without significantly affecting efficiency

Thanks 937carrera

and you will certainly aware that fluid dynamics is complicated.

My head hurts just thinking about it

The only time my engine oil gets strinking hot is when I'm over 65mph and the engine. is really working, I fail to see why a rear mounted oil rad would not do the job, most of the time its not needed which is why VW never fitted more than the small jobbie on the oil filter.

Syncro I understand could be really working at low speed but most vans are not.

itchyfeet wrote:So in conclusion don't believe oil temperature gauges , perhaps reasonably accurate if you have been driving consistently for at least 20 minuites.

Maybe just don't treat them as accurate instruments, but more of an indication of abnormal conditions.
You'll soon get to know what's normal for your gauge and sender location.
I'm thinking of putting an M14x1.5 to M10x1 adapter in my sump plug location and sticking a cheap gauge sender in there, yes it will read lower than true oil temp and not respond quickly due to the sump sinking heat but in your own words "who cares".

If I could get the blanking screw out of my oil pressure switch hole I'd put the sender there as- a: it's straight off the pump and b:-would be less prone to getting hit with a stone if I camp up a forestry track.
The plugged hole above the pressure switch looks like a possible place.

bigbadbob76 wrote: Maybe just don't treat them as accurate instruments, but more of an indication of abnormal conditions.
You'll soon get to know what's normal for your gauge and sender location.
I'm thinking of putting an M14x1.5 to M10x1 adapter in my sump plug location and sticking a cheap gauge sender in there, yes it will read lower than true oil temp and not respond quickly due to the sump sinking heat but in your own words "who cares".

I think you're right about using the gauge as an indicator of abnormal conditions. I have a sender in the sump plug location:



And I also have a Mocal thermostatic sandwich plate which directs my oil through a big front-mounted cooler.



The sandwich plate thermostat is set to 80 degrees, and my oil temperature gauge reads a steady 80 degrees ALL the time. Is that coincidence, i.e. a number of inaccuracies cancelling each other out by luck? Maybe, but I don't care - when it reads 80 on the gauge it means all is well.

As a nice side effect, I've noticed my water temperature needle is a lot more stable than it used to be - sits in the middle over the LED all the time - and I have the feeling that cooling the oil separately has taken a lot of the load off the water cooling circuit.

Oh, and I have an oil pressure gauge next to the oil temperature gauge, fed from the pushrod sender location, and as a consequence of the stable and moderate oil temperature the pressure is always nice and high.

CJH wrote: my oil temperature gauge reads a steady 80 degrees ALL the time.

even when cold?
summit wrong with it

I have read that 80 degrrees to too cold and does not allow moisture and nasties to burn off.
any comment on this?

CJH wrote:
And I also have a Mocal thermostatic sandwich plate which directs my oil through a big front-mounted cooler.

As a nice side effect, I've noticed my water temperature needle is a lot more stable than it used to be - sits in the middle over the LED all the time - and I have the feeling that cooling the oil separately has taken a lot of the load off the water cooling circuit.

I didn't know what you had done, honest, I agree on the oil circuit reducing load on the water circuit too. Proper job.

itchyfeet wrote:I have read that 80 degrrees to too cold and does not allow moisture and nasties to burn off.
any comment on this?

I'm no expert on this, but I have read that it doesn't need to be at 100 degrees to 'boil' off any moisture - 80 degrees will promote fairly rapid evaporation. Imagine, say, a baking tray held at 80 degrees with a film of water on top - how long would it take for the water to evaporate? I read a nice post somewhere by someone who explained the physics - probably won't be able to find it again though.

Anyway, who says it's at 80 degrees throughout the engine - I thought that's what this thread was exploring/explaining. 80 degrees on my gauge MAY mean that it's close to 80 degrees at the sump sender, but what temperature is it at elsewhere in the engine?

itchyfeet wrote:I have read that 80 degrrees to too cold and does not allow moisture and nasties to burn off.
any comment on this?

He's talking oil temp, water temp is higher as he said the gauge is bang in the centre. Separate thermostats achieve whatever you want.

CJH wrote:I read a nice post somewhere by someone who explained the physics - probably won't be able to find it again though.

Found it!

937carrera wrote:

itchyfeet wrote:I have read that 80 degrrees to too cold and does not allow moisture and nasties to burn off.
any comment on this?

He's talking oil temp, water temp is higher as he said the gauge is bang in the centre. Separate thermostats achieve whatever you want.

yes I know
80degrees oil temp is lower than the boiling point of water so condensation in your sump does not boil off

itchyfeet wrote: yes I know
80degrees oil temp is lower than the boiling point of water so condensation in your sump does not boil off

Doesn't need to boil off - just needs to evaporate. Posts 4 and 5 on page 2 of the thread I linked.

CJH wrote:I think you're right about using the gauge as an indicator of abnormal conditions. I have a sender in the sump plug location......
And I also have a Mocal thermostatic sandwich plate

Now you've got me thinking a sender sandwich plate (rather than a cooler sandwich plate) would be a good place to put my BOD pressure switch (mines blanked off ) and oil temp sender.
less heat sinking and the oil is being circulated through there by the pump.

CJH wrote:

bigbadbob76 wrote: Maybe just don't treat them as accurate instruments, but more of an indication of abnormal conditions.
You'll soon get to know what's normal for your gauge and sender location.
I'm thinking of putting an M14x1.5 to M10x1 adapter in my sump plug location and sticking a cheap gauge sender in there, yes it will read lower than true oil temp and not respond quickly due to the sump sinking heat but in your own words "who cares".

I think you're right about using the gauge as an indicator of abnormal conditions. I have a sender in the sump plug location:



And I also have a Mocal thermostatic sandwich plate which directs my oil through a big front-mounted cooler.



The sandwich plate thermostat is set to 80 degrees, and my oil temperature gauge reads a steady 80 degrees ALL the time. Is that coincidence, i.e. a number of inaccuracies cancelling each other out by luck? Maybe, but I don't care - when it reads 80 on the gauge it means all is well.

As a nice side effect, I've noticed my water temperature needle is a lot more stable than it used to be - sits in the middle over the LED all the time - and I have the feeling that cooling the oil separately has taken a lot of the load off the water cooling circuit.

Oh, and I have an oil pressure gauge next to the oil temperature gauge, fed from the pushrod sender location, and as a consequence of the stable and moderate oil temperature the pressure is always nice and high.

Do you have standard oil pump and what size pipes to the front rad, I have noticed that my oil pressure fluctuates with the oil cooler in the passenger side vent bottom ( some journeys better than others)it would be nice to make the efficiency more stable by moving to the front