remote oil cooler fan operation

[chateau la fete]

I live in the UK and have a 2332cc 48 ida type 1 motor, compression 8.9:1.
I have a 1.5 qt Berg deep sump, Melling oil pump, external oil filter and remote oil cooler with remote fan. I also use the standard oil cooler.
I use joe Gibbs HR1 15W50 oil and a VDO dip stick oil thermostat.
When the oil temp reads over 200 degrees, the fan still does not come on (all new parts including the oil thermoswitch, which is rated at 180 degrees and is fixed on the inlet side of the oil cooler)

I fill the oil to the lowest mark using a standard dipstick

I removed the thermoswitch for the fan (oil drained out of the thermostat switch hole as it should). I then heated up the thermostat switch to over 180 degrees and the fan came on and operated as it should, then the fan went off as the thermostat switch started to cool down - so all good there

I tested the oil dipstick thermometer in boiling water and it read exactly as it should on the oil temp gauge

When the car was over 200 degrees, the oil lines felt quite hot. The oil lines run from engine oil pump to remote filter, from remote filter to remote oil cooler, from remote oil cooler back to the engine. Remote oil cooler is mounted above axial L/H side

Any ideas why the fan is not operating when the thermostat reads over 200 degrees

[Martin S.]

Do you have an infrared temp tester to try? since the oil temp is the same as the block temp you can take a reading anywhere.
200 is not that hot (mine has read up to 250 on my VDO gauge with the plunger valve sender) so could it be your engine is not overheating?
I have a simple toggle switch on the dash and manually turn on the fan when needed which makes driving my bug more like flying an aircraft. 

[chateau la fete]

When I say over 200, I mean the fan doesn’t come on when it should (unless it cools through the filter!). The car gets to 230-250 quite quickly in most weathers (260 on hot days) and hovers around that weather on a long or short journey. It’s like the temp gauge is giving faults readings, but like I said I have tested it

[Martin S.]

To be clear, you have a VDO dip stick gauge. And the thermoswitch for the fan is mounted in the external line.
Even when the VDO reads 250, the thermoswitch does not switch on the fan even though it should at 200?

[chateau la fete]

Hi yes I have a VDO dipstick sender wired up to an oil temp gauge mounted in the dash. Even when the oil temp gauge reads up to 250 degrees the fan still does not come on. The switch for the fan (switch’s at 180 degrees) is mounted on the oil cooler in line with the oil line from the remote oil filter

[Martin S.]

The only thing I can think of is that the temp is different between the dipstick and the oil line.
Hopefully someone can think of a better answer!

[spoolin70]

Is it possible that thermostat sensor is sitting in a 'dead leg' point and although the oil flowing past/nearby is hot, the oil at the sensor point isn't moving so is a lower temp ?

Is the thermostat adjustable ? Can it be calibrated ?

How is it fixed to the inlet side of the cooler ? All the parts sound like they are working correctly so perhaps it's how they are fitted ?

We like pictures 

[chateau la fete]

The oil temp switch is the gold looking part

[modnrod]

If the white wire is an earth point, and if the oil cooler is rubber mounted, then you have no earth for the switch cct perhaps?

Looks nicely done btw.

[chateau la fete]

Hi it is an earth point and it measures very well to earth through the body of the cooler/bracket/screw.
All of the electrical side has been manually tested - all ok, just won’t switch on from the oil!

[alex d]

Are you running a thermostat for the oil line to the cooler? have you checked if that works?

Are you sure the fan thermostat is on the inlet and not the outlet of the cooler?

[chateau la fete]

No thermostat to the oil line cooler yet
The thermoswitch is on the inlet of the oil cooler

[Eddie DVK]

If the white wire is an earth point, and if the oil cooler is rubber mounted, then you have no earth for the switch cct perhaps?

My point also.
Rubber and earth don t work well together.

[chateau la fete]

Like I have said previously I have tested the earth and is good, have heated the thermoswitch up to temp and the fan switches on, which is good. If you notice from the picture, the earth wire grounds through bracket through to the body of the car (oil cooler bracket is mounted on metal standoff’s) - to earth.

[2332-64]

Maybe its the location of the thermoswitch and the oil cooling down slightly just enough by the time it reaches it, as its located near the gearbox?

On my previous 2332 I placed the thermoswitch very close to the oil pump outlet which then feed the oil out to the remote filter, then to a Mocal Oil Thermostat, to the remote cooler and back to the block.  

When warming up oil would circulate from the pump to the filter through the oil thermostat and then back to the block, once it reached a higher temp the mocal theromstat would open up and then the oil would flow through the remote oil cooler then back to the block and if it went past 180 degrees the thermoswitch would kick in and operate the fan -  Worked perfectly.

[chateau la fete]

Was the thermostat incorporated into the remote oil filter?
Did you have an in line thermoswitch and take it it was located after the oil thermostat?

[2332-64]

Was the thermostat incorporated into the remote oil filter?
Did you have an in line thermoswitch and take it it was located after the oil thermostat?

The thermoswitch was inline and was placed next to the oil pump outlet as this is where the oil is at it hottest.  The oil line then went to a remote filter, from the filter it went to a remote Mocal thermostat. When the oil was cool the thermostat is closed so it would just loop the oil back into the block. Once the oil temp heated up the thermostat opened up and the oil then went to the remote mocal oil cooler, back to the thermostat then to the block. The difference between the thermostat opening and the thermoswitch operating was around 15 degrees, so the thermostat was always opened flow before the switch activated to turn the fan on. IIRC the thermostat was 165 degrees F and the switch was 180 degrees F.

I would recommend fitting a thermostat before the remote cooler, as pumping high pressured cold thick oil into a remote oil cooler can cause them to swell and split....   ask me how I know  

[Martin S.]

I don't have a thermostat at all on mine so far so good. I do watch the oil pressure gauge when starting it even on the coldest days close to freezing and see the pressure spike up to 70 lbs. or so but I don't think that's enough to cause any damage. Probably the fact that I run 5W40 synthoil keeps that oil flowing even when cold. Using 15W or 20W you are at higher risk when cold.
My turbo motor runs real hot always and I see the temp needle starting to move only a few minutes into a drive.

[chateau la fete]

Thanks for that, I will have a think, as this was my next step 👍

[Jim Ratto]

When I say over 200, I mean the fan doesn’t come on when it should (unless it cools through the filter!). The car gets to 230-250 quite quickly in most weathers (260 on hot days) and hovers around that weather on a long or short journey. It’s like the temp gauge is giving faults readings, but like I said I have tested it

Sorry this isn't helping diagnose your switch/power issue, but your oil temp seems to indicate you have a cooling or an engine problem. The oil system you are running shouldn't allow the oil temperature to run that high.
I would say I would suspect how accurate your instrument and sender are, but like you said, you've tested them.
I run a similar oil system:
20W50 oil
30mm modified OE Schadeck pump
Berg non-relief cover
Baldwin B253 spin on
Setrab cooler
Stock VW doghouse with orig 181 fan housing/cylinder covers, -031B OE fan, cooler has foam and metal frame at M6 studs
Santana power pulley
Engine is just under 9.0:1, ignition advance is 35' total.
My oil temperature on 100F day, after extended freeway driving (low and high speed- [traffic]) does not show above 180F on my VDO instrument.

I would try to nail down why your engine is seeing 260F oil temps. Good luck,

Jim

[Martin S.]

That temp popped out for me as well. My engine has an excuse as it has an under the decklid turbo (pizza oven) blasting 500 deg heat.

[chateau la fete]

I have been thinking a long the lines of tuning, which is pretty much ok, but still wonder why the fan doesn’t switch on?!
The other route I was thinking was oil pump, but seem to have good pressure and the car runs good!

I run a Mallory unilite with electronic ignition, a Mallory CDI. Advance is set at 10  static and 20 on the curve

[Martin S.]

I find that when bugs overheat, they lose some power and feel overall sluggish. If you touch the dipstick, it almost burns your hand. As long as you don't feel the power dropping and the engine runs crisp, it probably is not overheating.

[Jim Ratto]

I have been thinking a long the lines of tuning, which is pretty much ok, but still wonder why the fan doesn’t switch on?!
The other route I was thinking was oil pump, but seem to have good pressure and the car runs good!

I run a Mallory unilite with electronic ignition, a Mallory CDI. Advance is set at 10  static and 20 on the curve

Do you have a roast beef thermometer (used to check done-ness of a roast). If so, go drive your car until it registers 200F or whatever on instrument. Slide thermometer down dipstick tube and take a reading.
Another way I check to see if an engine has been running too hot is to look at rocker chambers. If the engine's been overheating, you'll find the rocker chambers in heads will be gold-ish colored or worse, bronze.
Magnesium engine cases tend not to like oil temps of 220F or higher for long.


Good luck

Jim

[chateau la fete]

I put the VDO sender thermostat in a cup of boiling water and the gauge read as it should. Over the next few days I will try an infa red thermometer at different points of the engine/oil lines/filter/cooler, etc

[chateau la fete]

Jim - what type of sender do you use, where do you mount it?

[Martin S.]

I'd be curious too about the different options for senders/ locations.
What is the most important is the case temp itself. The oil can withstand plenty of heat, especially synthetic, although if it's overheating the oil can look and smell "burnt" as well.
But you don't want too much heat in the actual case itself, which is the same as the bearings. And the heat kills the bearings.

The heads are cooled separately and differently in a bug, which is a different subject. 

[Jim Ratto]

Jim - what type of sender do you use, where do you mount it?

I have the VDO "tee" at stock oil pressure switch takeoff. I have used this one since 1990. I like the sender that replaces the bypass plug too.

[chateau la fete]

I borrowed an infra red thermometer, took the car for a good run, the auto meter temp gauge read just over 240 degrees  and the fan did not come on. Took the dipstick sender out and touched it, very warm, but not excessive. I then measured the following temps with the thermometer:
Heads: 240 degrees
Oil filter: 170 degrees
Block: 175 degrees
Kept the car running (ticking over) to get warmer and after a few minutes the fan kicked in!! All the readings had then gone up about 10 degrees. Turned the car off and after a couple of minutes the fan switched off - working exactly as intended!!
So looks like after a certain temp, the sender/gauge goes way out of calibration - so the bin it is!!

[Martin S.]