Club 80-90 Forums

bigbadbob76 wrote:That looks better Paul.
Following with interest.

yes indeed

I found my low cost 'elcheapo' tacho and oil pressure gauge was reasonably good but the oil temp gauges were not great.

You get what you pay for and I'd dig deeper for better gauges in future.

I still think the position is important and doubt the oil relief valve is a good place there will be too much thermal lag in reading real oil temperature

think of it like the petrol gauge ...only accurate on the flat...

The oil temperature gauge is only accurate with steady driving style for a considerable duration

itchyfeet wrote:The oil temperature gauge is only accurate with steady driving style for a considerable duration

So to check your oil pressure at 80*C you need to drive steadily for a while and then let it cool to 80*C then read your pressure gauge.

Well I used a thermocouple
the lag is there when cooling down also ( driving slow after a motorway run) on my van too because I have an oil cooler

much easier for oil pressure testing with a thermocouple
gauge is for driving

fair enough.

Going back a few pages.... can you tell me what diameter this hole saw is?



Cheers.
BBB.

Page 23 it was

Dia 40mm then filled out to be a tight fit so no seal needed, tube is dia 42mm ish

original one here updated with size

http://forum.club8090.co.uk/viewtopic.p ... 0#p8209161" onclick="window.open(this.href);return false;

and the lagging measurements of elcheapo gauge here

http://forum.club8090.co.uk/viewtopic.p ... 5#p8217944" onclick="window.open(this.href);return false;

Cheers Paul, I have a 40mm hole saw.

bigbadbob76 wrote:Cheers Paul, I have a 40mm hole saw.

Whatever you do don't cut up.a good oil filler tube they are £££££££

plenty of broken ones around

Don't worry, I cut up my old rusty one with it's pinholes.
I just drilled the cap out of my tower and left the central bit.
Then cut a notch in the filler tube to fit over the central bit.
Nice snug fit once I beveled the end of the filler tube to guide it in.
I'm not replacing my filler tube, at least not yet until I see the benefits of an oil temp gauge,
but I wanted a cap on the tower to check for mayo regularly.

Could you use a paxolin insulating spacer between your plate and the sump to reduce the heat sinking effect of the case on your sender? Might help your lag.


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bigbadbob76 wrote:Could you use a paxolin insulating spacer between your plate and the sump to reduce the heat sinking effect of the case on your sender? Might help your lag.

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perhaps, it has a gasket which is insulating already I think some of the lag is just the senser/sensor design becuse the VDO is much better

I get mayo on the tin top in winter and some moisture in summer.
lower seals is weeping slightly maybe

bigbadbob76 wrote: Then cut a notch in the filler tube to fit over the central bit.

I made a hole so the tube can't push out or work it's way out , copper pipe stops it twisting when you remove cap.

P1090657 by Paul_Barr, on Flickr

I have some 5mm paxolin and can easily make and send you a spacer if you want to try it.
Would need another gasket and longer studs or the existing ones screwed out my 6mm or so.

Thanks for the offer Bob but I'm nervous of using anything that could degrade and allow my oil to flow out
I once lost my sump plug because some thoughtful person suggested I use a fibre washer and it didn't last.

Had a look and it appears to be a paper laminate not clear if its suitable for oil, I realise most gaskets are paper but not that thick, would it hold a torque on the nuts?

I'm going to see how it behaves on the road then I may revisit an insulator later

Or you could try it first

Good point on the degradation and dumping out your oil.
Paxolin and Tufnol are both rated at 90*C continuous and 120*C occasionally.
I'd like to think there would be wiggle room there to cover the manufacturers ass but long term it may degrade at 100*C + continuous.
I might just try it first.

I think you are trying to solve a problem that maybe cannot be solved.

Here's a link to the Porsche 911 approach for '77 to '98, the temperature sender (though they call it sensor ) is simply screwed into the case with a metal sealing washer. The 911 had a combined oil temperature and pressure gauge fitted from introduction in 1964, so over 30 years experience with this design. 911 is
dry sumped so this is measuring oil temp in one of the galleries.

https://www.design911.co.uk/fu/prod3398 ... 964---993/

While I'm posting this, just for a bit of fun is a picture of the oil filler as fitted to the fastback version of the VW 412 and Porsche 914. Oil filler on top of the crankcase breather.

937carrera wrote:I think you are trying to solve a problem that maybe cannot be solved.

I think I have solved my problem already, not sure what problem you think I'm trying to solve?

I found a place to mount the sender/sensor in the sump oil where VW IMO whould have measured oil temp, and anm getting a reasonable accuracy this is what I was trying to achieve.

I found that cheapo temp guages are crap and you have to buy a better one.

I found that there will be some temperture lag in almost any guage becuse the sender/sensor is a chunk of metal and probably attached to the case and that has to heat up / cool down and it often does it slower than the oil heats up / coolls down ( depending upon driving style)

I found that when driving slow the oil temp stays quite low and consistant but as soon as you drive it hard it raises rapidly.

yes a sump plug sender would work but not for me as it's really not suited to a WBX and the connector poking out the bottom is subject to damage, it has to be removed each oil change.

A oil pressure relief mounted sender/sensor is not accurtate as it's not in the sump oil ( no oil flow when hot)

Mounting a sender/sensor in an oil gallery will likely show a higher temperture but that won't help me to see if my engine is within VW spec.