Temp and Pressure Gauges

[axeman]

Been following this with interest so that I can make a sensible arrangement for my new 2.1 DJ that's slowly progressing. I have now been able to pick up a 0 - 150 degrees C oil temp guage and a 0 - 10bar oil pressure guage with corresponding double pole sender (markings on the hex show that the low OP idiot light will come on at 0.3 bar which seems right from what is written above).

For oil pressure the plan is to run a braided line from between the push rods between cylinders 3 & 4 up to the top of the engine then use a T piece to fit the VDO sender (thus providing info for the OP guage and low OP idiot light) and the high OP sender which will be relocated from its original position by the water pump pulley. (Actually looking much like axeman's set up on page 4 of this thread.)

This will then leave the oil temp sender to go where the high OP sender was originally and in a good flow of moving oil. I just need to find a sender of the right length to get into the flow without impeding it. The plan is to use a M10 x 1 sender and fit it into the reducer that the high OP sender would fit into. Do people think this would get far enough into the flow of oil? http://www.merlinmotorsport.co.uk/p6159 ... _info.html" onclick="window.open(this.href);return false; Or would it be better remove the reducer and just use an M16 x 1.5 sender (although I can't see that Merlin does one that size - which might give me that answer )

Any thoughts on this set up gratefully received - especially whether or not I have interpreted all the info abve correctly for a WBX.

Thanks,

Pete

thats exactly how i installed my oil temp gauge the first time in my oil wbx, with that m10x1.0 sender you have found, it was and is a good way of measuring the oil temp, but it will give you the temp in the sump of the engine which is going to to be cooler due to the volume of oil where the temp is being measured. on my present engine i have a sandwich plate which sits between the oil filter and the block where my sender is now located, very simular to the one that syncrosimon had in his oil cooler kit (separate thread and a very good read). this gives the a oil temp where the oil is actually working ie pumped through the crank and gives a higher temp.

neil

[Epiphone]

this is what I bought

VDO / Motometer Öldruckgeber 5 bar ohne WK/ Kontrollleuchte - Oil pressure sender 5 bar without control light
VDO Cockpit International Öldruckanzeige 5 Bar - Oil pressure gauge 5 bar

so they seem to match, sending the shop an email to confirm also.

[HarryMann]

I agree with Neil, that it certainly sounds a bit of a bridge too far (strange and unlikely)... though I suppose 5 bar at 5,000 rpm at 80°C just possible, which is not what you are saying.

before starting the engine shows just over 4 bar

Nah! that indicates a DC voltage offset error surely?

Neil is alos about right, typically at 80°C > 2 bar at 2000 pm

[PetenAli]

thats exactly how i installed my oil temp gauge the first time in my oil wbx, with that m10x1.0 sender you have found, it was and is a good way of measuring the oil temp, but it will give you the temp in the sump of the engine which is going to to be cooler due to the volume of oil where the temp is being measured. on my present engine i have a sandwich plate which sits between the oil filter and the block where my sender is now located, very simular to the one that syncrosimon had in his oil cooler kit (separate thread and a very good read). this gives the a oil temp where the oil is actually working ie pumped through the crank and gives a higher temp.

neil

Thanks Neil. Do you have an oil cooler as well? If so, where do you take the feed and return from? (I haven't checked out Syncrosimon's thread yet so it may be that all the answers are there).

Pete

[HarryMann]

Feed from the sandwich plate, there's an article on this somewhere

Anyway, Mocal is the normal make of oil cooler (reliable, no-chinese)

and ThinkAutomotive do the take-off plates, usually Type A here:-

http://www.thinkauto.com/takeoff.htm

Plate connections, pipes and cooler fittings have to match up, or best to not have to use adapters, many use (BSP) 3/8", 1/2" good, and occasional fools like me fit 3/4" (a bit on the large size for easy bends but will work, and give another 2.5 lites ish oil volume) 1/2" is probably optimal, that's what Brickworks kist use I believe.

[PetenAli]

Feed from the sandwich plate, there's an article on this somewhere

Anyway, Mocal is the normal make of oil cooler (reliable, no-chinese)

and ThinkAutomotive do the take-off plates, usually Type A here:-

http://www.thinkauto.com/takeoff.htm

Plate connections, pipes and cooler fittings have to match up, or best to not have to use adapters, many use (BSP) 3/8", 1/2" good, and occasional fools like me fit 3/4" (a bit on the large size for easy bends but will work, and give another 2.5 lites ish oil volume) 1/2" is probably optimal, that's what Brickworks kits use I believe.

Nice one Clive - thanks very much.

Pete

[tencentlife]

thats exactly how i installed my oil temp gauge the first time in my oil wbx, with that m10x1.0 sender you have found, it was and is a good way of measuring the oil temp, but it will give you the temp in the sump of the engine which is going to to be cooler due to the volume of oil where the temp is being measured. on my present engine i have a sandwich plate which sits between the oil filter and the block where my sender is now located, very simular to the one that syncrosimon had in his oil cooler kit (separate thread and a very good read). this gives the a oil temp where the oil is actually working ie pumped through the crank and gives a higher temp.

neil

The location of the high OP switch is at the head of the main galley. This is after the oil has gone thru the pump and filter, so it will reflect heat added by the pump (not inconsiderable) and lost by the filter (negligible). It will read differently from sump temp. Sump temp is also as likely to be higher as lower, it depends on the rpm and flow rate at that moment, at high flow rates much more of the total oil volume will be dispersed throughout the engine while the oil that returns most quickly to the sump will be that thrown off the main and rod bearings, which will be the hottest oil seen anywhere in the engine (since bearing film shear is the principle cause of high oil temps), while the oil returning most slowly will be the much cooler oil that ran out to the rockers and bathed the rocker box and cooled some as it drained back to the sump thru the pushrod tubes. At low rpm and flow rates the bulk of the oil will be sitting in the sump and cooling.

The high OP switch location temp will be essentially the same as a sensor mounted in the sandwich plate post-external cooler, the difference being whatever heat is lost thru the filter which, as I said, will be negligible with a conventional can filter. That location will indicate more accurately than any other the working temp of the lubricant immediately before it flows the bearings.

The VDO M10 x 1.0 senders can be installed in the M16 x M10 steel reducer bushing but I find that to project the nose of the sender far enough that it is sampling the actual flow requires drilling out the bushing's first couple of M10 threads to allow the sender to be run in a bit further.

M16 x 1.5 senders are also made and I have used them in the past but since then dealers in the US don't carry that size. Availability in your area may be different.

Epiphone either has his gauge wired wrong or hasn't adequately grounded the sender. VDO gauges typically go to zero if the signal wire is grounded (the opposite of factory water temp and fuel gauge behavior) and run high with excessive resistance to ground on the signal wire. Try using a jumper wire from the sender body to a chassis ground, if the gauge now reads at zero with the key on then the sender isn't adequately grounded, if it doesn't then check how the gauge itself is wired.

[PetenAli]

Thanks very much for this info tencentlife. That's made a whole heap of things much clearer to an enthusiastic (but not very knowledgeable) amateur.

One other question if I may... am I right in recollecting that you also take your feed and return for oil cooler from a sandwich plate?

OOOPS! Quick E D I T - just seen your post on page 7 I now see that you use Mocal thermostatic take off plates.

Thanks.

[tencentlife]

Glad it helped clarify things.

I do need to revise this: "Sump temp is also as likely to be higher as lower..." which implies that it may be higher or lower than the measured galley temp. I should have said that the difference in sump temp from main galley temp will vary according to the factors I cited, but the pump will always add heat to the oil above sump temp.

Some of that heat may be removed by the built-in oil/water heat exchanger on vans so equipped if the post-pump oil temp is higher than water temp (but the amount the OWHX can remove is very limited because of the narrow temp differential). An external oil cooler setup can of course lower oil temp to below the initial sump temp.

Regardless, measuring oil temp at the main galley does show the "working" temp of the oil and hence will correlate consistently with oil pressure if you're also gauging that. It may not show the highest temp the oil ever reaches anywhere in the engine.

[PetenAli]

Thanks again tencent. You are so good at explaining stuff like this to non mechanical people like me. That's all clear now. There's some good stuff on the Samba from you about OP and OT that I've discovered today as well.

I am going for OP guage as well so there will be a recognisable correlation between the two

[Epiphone]

It seems to have got worse now no response from the gauge like before!

with the engine turned off and totally cold
12.4 volts going into the gauge and 6 volts coming out the connector where the cable for the sender would go but disconnected.
Nothing coming from the cable from the sender. The gauge show maxed out, totally on the right handsome.

Which the engine turned on and totally cold
13.1 volts going into the gauge and 6.3 coming out of the connector where the cable for the sender would go but disconnected.
3.8 volts coming from the cable the sender. The gauge shows maxed out again

Is it normal that once power is givin to the gauge (ignition) it maxes out. Is this normal?

[kevtherev]

what a palarva...
glad I fitted a Mechanical guage

[Epiphone]

I found a post on a Golf forum saying that they always go to the max when the sender is not connected.
http://www.clubgti.com/FORUM/showthread.php?t=129668

I also read on the Golf forum that from cold on a good engine can go over 5 bar. Seems its referred to as pegging the gauge!
http://forums.vwvortex.com/showthread.p ... g-questionBut not sure about a wbx

I went for a drive earlier and got it up to temperature, parked up then came back and turned the ignition on and it went to 2 bar. First normal looking pressure I've seen!

But when I start the engine it's going up to the top end again. I have installed a battery gauge as well and it's moving up slightly when the engine starts too.

For your viewing pleasure: https://vimeo.com/42861191

I was wondering, is it anything to do with the alternator kicking the voltage up on the on the system and then giving a false high reading on the gauge?

Just found this http://www.914world.com/bbs2/index.php? ... 0975&st=0&

[Epiphone]

Ah bugger it seems to be exactly this!

http://www.thesamba.com/vw/forum/viewtopic.php?t=240299

[HarryMann]

Ha! Was reading that good link last night and thinking.. uhuh, I wonder?