WBX

[itchyfeet]

Driving on the motorway at 70mph today ( its hot ouside 25 degC) it pretty much sits here, this is a DG with oil cooler you have to wonder what temp it would be without one?

oil temp motorway by Paul_Barr, on Flickr

[937carrera]

What was the water temperature like (on the gauge, I know you don't have a readout)

Oil pressure still looks reasonably good, but lower than your last M-way pic when the oil was cooler.

[itchyfeet]

What was the water temperature like (on the gauge, I know you don't have a readout)

Oil pressure still looks reasonably good, but lower than your last M-way pic when the oil was cooler.

bob on the middle of gauge as usual

[937carrera]

That's what I thought you would say. That would seem to indicate that none of the additional heat energy in the oil is being transferred to the water. Does that make sense to you.

Alternatively is the water temperature gauge not a true measuring instrument but were they already one of the new fangled gauges (smart but dumbed down) that reassures the driver by sticking in the middle provided that the water temperature is within a given operating range.

[itchyfeet]

That's what I thought you would say. That would seem to indicate that none of the additional heat energy in the oil is being transferred to the water. Does that make sense to you.

dunno but I'm going to find out by putting a tap in the oil cooler feed
I suspect the temp will be higher

[937carrera]

It probably will, so what will that indicate ?

I remember a discussion I had with a QC manager about 20 years ago in the chemical industry. Through that I learnt just how important agreement of test methods was for QC work. Same for measuring engine parameters.

You mentioned earlier in the thread that VW had a temperature spec for the oil. Did you ever find out where / how that was measured ?

I had a read around last night trying to find the answer to that question (unsuccessful) and came across these pages.

http://www.ratwell.com/technical/VDOGauges.html

https://www.thesamba.com/vw/forum/viewt ... ?p=8182929

I know these are for air cooled type 4 engines, but the guts are the still very similar to the WBX. Interesting (at least to me) that the Porsche 914/4 had the oil temp sender as standard, which the VW 411/412 didn't. The WBX doesn't have the same plate though does it.

[itchyfeet]

You mentioned earlier in the thread that VW had a temperature spec for the oil. Did you ever find out where / how that was measured ?
.

no, I'm sure somebody would have answered that question by now if it were anything other than obvious which to me is poke a thermocouple down the filler tube or more likely dipstick because most cars don't have a filler tube that leads to the sump.

[itchyfeet]

Continuing on the theme of measuring temperatures ( just because I'm interested) I fitted a thermocouple down the dipstick tube and sealed it with tape and a cable tie, I then drove down the motorway and around town to see what the gauge did compared to a more accurate and quick changing thermocouple which I call real oil temp.

P1100413 by Paul_Barr, on Flickr


What happened as I drove was the real oil temp rose much higher than the gauge and much quicker, these are the black numbers, as it got to about 100-105 the gauge had caught up, this was about 20 mins on fast roads / motoray but not over 60, I wanted to give the gauge a chance to catch up. I assume this is because the engine takes time to get up to temperature and the sensor being thermally connected also has the same thermal delay.

After that I hit 70 and the gauge and real temp were reasonably accurate, I hit traffic before I could go past 115 but looking at the picture it's possible.

After I hit traffic and then got off the real oil temperature fell much quicker than the gauge ( this DG WBX has a standard VW oil cooler), this is the red number 95, while it traffic the oil temp stayed around 95-100 and the gauge caught up, but after passing the traffic and driving hard again the real oil temp quickly rose past the gauge and that's the red 105

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

Who know what happens in winter that's another experiment as is my DJ.


oil temp motorway gauge vs thermocouple by Paul_Barr, on Flickr

[bigbadbob76]

Hmmm...
so when VW spec the oil pressure as >2 bar @ 2kRPM @ 80*C is that coolant temp or oil temp? and measured where?

[itchyfeet]

Hmmm...
so when VW spec the oil pressure as >2 bar @ 2kRPM @ 80*C is that coolant temp or oil temp? and measured where?

oil temperature.

good point about where to measure as they were never fitted with oil temp gauges, I assume sump oil temperature becuse thats all a VW technician could do, I use a thermocouple down the dipstick tube

[Cobra88]

Hi Itchy

I'm guessing your on the Water warmer/cooler thingy not a proper Mocal type jobbie ?

Rick

PS: scratch that I just read std WBX Cooler

[itchyfeet]

Hi Itchy

I'm guessing your on the Water warmer/cooler thingy not a proper Mocal type jobbie ?

Rick

Correct i'm struggling to justify over 400 quid plus labour to fit.

[Cobra88]

Make a kit up from Ebay using a Mocal cooler.

I have just made up a kit for my auto box for £56 (not mocal cooler)

[itchyfeet]

I don't know anything about oil coolers od what to buy.

[Cobra88]

Hi Itchy

Depends if you want it front mounted or under your Van

I'm going under mine to one side but out of line with the wheels.
Mocal 19 row cooler
Mocal sandwich plate with 80 degree thermostat
then a trip to your local pirtek for
2x AN 10 push fit 90 deg Unions for Cooler end
2x AN10 Push Fit Straight Unions for Oil filter end
2m of AN10 Push fit oil hose (prob about 6-7m if you front mount).

Cobble up a pair of mounts for the cooler or buy a Mocal mount or ebay copy.

If you get stuck fitting it just shout as it's not hard at all.

I wouldn't think much more than £200 ish

Rick