Club 80-90 Forums

Hi All,

I drive a T25 westfalia with a 1.9 DH it is imported from the USA so a Vanagon.
I added an oil temp and pressure gauge to keep an eye on the engine and what I noticed during the
last holiday is that when I drive slow 70/80 km/h the oil temperature drops to +/- 80 degrees celcius or lower.
Before the temperature would go up to 90 and higher (110 degrees highway) depending on speed and outside temp but not
under the 90 degrees.

The water temp seems to be on the same spot as before. My first thought was that the waterthermostat doesn't
close anymore but then I should also see a drop in the water temperature or not?

But to come to a conclusion and to a question I would like to know if I'm right in thinking that the oil temp
should not go under the temp of the thermostat.

I used to have a DH, no oil gauges though. Ignorance was bliss I think sorry no ideas on temps.

You are right Not knowing is no worries

You don't say where you live outside temp makes a big difference.

Does this engine have the stock oil cooler?

Also you don't say if it was a quality gauge and sender or a cheap one and where the sender is fitted all these make a difference in my experience.

For the oil temp and pressure I use a VDO gauge and beloning sensors.

The engine doesn't have a oil cooler it is a 1.9 DH injection.

We where driving in Scotland near Applecross the outside temp was arround 18 degrees.
On our way back to the ferry in Newcastle we took the motorway, then the oil temp went
up to 100.

where is the VDO sendor?
Sump plug? if so probably just driving style and outside temperature
the crankcase is aluminium and will cool the sender so it probably always reads a bit lower than reality
the oil pressure relief valve location is even worse as oil does not flow there when hot it only flows cold when pressure is high if at all so you are not measuring real oil temps.

I have used a thermocouple down dipstick tube to compare gauge to real oil temps and you would be surprised how gauges are inaccurate due to location and artificial colling from case contact use them as a guide only.

itchyfeet wrote: I have used a thermocouple down dipstick tube to compare gauge to real oil temps and you would be surprised how gauges are inaccurate due to location and artificial colling from case contact use them as a guide only.

Not wanting to hijack but reading with interest as I'm debating fitting a oil cooler setup for longevity but thinking I should probably fit at least a pressure if not temperature gauge first. Dilemea is if temp senders are not always that reliable depening on location etc should I remain in ignorance and fit cooler anyway. The oil sandwich plates I've been looking at have ports availble for senders so would be logical to consider fitting as long as they do not foul anything but then its not really a before/after reading.

I use the values from the gauge not as a exact measurement but more to see if something changes.
I don't think the sensor are on the most ideal spot. I've have a sandwich plate between the engine and
oil filter. That is where I measure the pressure and temp.

I fitted the gauge about 1.5 years ago and the behaviour has been consequent the same untill two weeks
ago. A lower oil temp and as a result of that a higher oil pressure. I'm figuring out why the engine is cooler
than it was before and if I should do something about it.

A wiring fault with some added resistance perhaps?
Or thermostats fail open I'm told have you ever replaced it.?

ash1293 wrote:

itchyfeet wrote: I have used a thermocouple down dipstick tube to compare gauge to real oil temps and you would be surprised how gauges are inaccurate due to location and artificial colling from case contact use them as a guide only.

Not wanting to hijack

you just did
new threads are free on here

ash1293 wrote: Not wanting to hijack but reading with interest as I'm debating fitting a oil cooler setup for longevity but thinking I should probably fit at least a pressure if not temperature gauge first. Dilemea is if temp senders are not always that reliable depening on location etc should I remain in ignorance and fit cooler anyway. The oil sandwich plates I've been looking at have ports availble for senders so would be logical to consider fitting as long as they do not foul anything but then its not really a before/after reading.

In your new thread please state engine and age of vehicle IF it isn't already in your signature.

Is your sandwich plate like this?
https://www.ebay.co.uk/itm/Oil-Gauge-Fi ... 0005.m1851" onclick="window.open(this.href);return false;

I've have a sandwich plate between the engine and
oil filter.

Yes I use a sandwich plate like that. And a smaller oil (Saab 900 -> Mann 712/80 ) filter as the original is to large because of the exhaust pipe.

The thermostat is about 4 years old replaced it when I put in a new waterpump.

jacobh wrote:Yes I use a sandwich plate like that.

The thermostat is about 4 years old replaced it when I put in a new waterpump.

So not a thermostatic sandwich plate then? I believe that the thermostatic versions have a bypass so that the oil avoids the cooler matrix until the thermostat temperature is reached and the bypass closes. I have one of those in mine, and I'm pretty sure it only makes a difference during warm-up, and once the engine reaches operating temperature the bypass is closed all the time. But maybe not - maybe it's more like a water thermostat and is opening and closing all the time to regulate the temperature. In which case, if you do have a thermostatic sandwich plate, maybe the bypass has jammed closed.

CJH wrote:I have one of those in mine...

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