Need clarification on temp/pressure senders...

[ventureforth]

I'm getting ready to install my duostyling gauges and want to make sure I understand everything correctly.

Currently, my '82 1.6NA Rabbit has the following stock senders:

At the head-


The YELLOW arrows point to coolant temp senders, correct?  My Bentley only shows one sender at the coolant hose, but my Rabbit has two.  Is this correct?

The RED arrow is the stock oil pressure sender that's supposed to operate below 2000rpm, correct?

At the oil filter-



The BLUE arrow is the stock oil pressure sender that operates above 2000rpm, correct?

So, I have VDO temp sender 323-423 and VDO pressure sender 323-006.  I will replace the oil pressure sender at the head with the VDO pressure sender and the oil pressure sender at the oil filter with the VDO temp sender.  This will cause me to lose the idiot light functionality in the dash, but that's okay because I'll have a gauge warning me if pressure is too low.

So, is my plan of action correct?  Am I missing something?  I know the VDO pressure sender has a second contact for a warning light.  Should I hook up one or the other of the stock warning light wires to the VDO sender's additional contact?  I don't have an oil cooler on it, as you can see, so I think that means that I'm limited to just the installation points where the stock senders are currently located...correct?

Thanks.

[GEE-BEE]

I left everything  stock on mine as shown in your picture, added a oil psi/oil temp tee off the fitting at the top of the oil filter housing as shown in your pic's
Mcnallyelectronics.com

I have 780.00 in gauges from mcnally, blue back lit
aircraft quality , very accurate
egt/boost
oil temp/oil psi
water/volt

Drilled a hole for the water temp sender in the other coolant flange, coming from the pump ( front outlet )

New front with single temp outlet from dieselvw.com is a good buy  5.00
I picked up a new coolant hardline also for 10.00 while shopping

Mine is a aaz and had the plastic crap flanges

need a pic , email me at [email protected]

P.S. get some sprial conduit to finish your wiring and secure with rescue tape in black ( tape is silicone )

[ventureforth]

Thanks for the tips.

Just to be clear, I won't be doing anything to the coolant temp senders.  Those would remain stock.  It was more that I was wondering why there are two where the Bentley only mentions one...unless I missed something.

I was told using a T-fitting was not a great idea as it would effect flow too much and hurt accuracy/speed of reading.  Is this not  correct?  Is there any reason I shouldn't just replace the senders that are there with my two new senders and lose the idiot light in the process?  In other words, is there something besides the idiot light that gets effected by deleting those two oil senders and using my VDO senders?

[GEE-BEE]

One is for the glow plug temp sensor

I didnt want to remove  the oem , just enhance it

to each his own...

There is no problem with a T , only the quality of the material and senders used.

[Vincent Waldon]

There is no problem with a T

But no reason for one, either, in this case.    And, using a T is not recommended for temp sensors in any event... they work best when directly in a live flow.

The oil temp sensor will screw directly into the unused port (black circle) on the flange... the oil pressure sender can go into the existing oil pressure sensor port on the flange or on the head.  If you replace the one on the flange you can retain the switch on the head for your warning light... you'll need to ground the wire that used to go to the high pressure sensor to avoid false alarms.

One note however... there are long temp sensors and short temp sensors.  The long one will block oil flow if installed in the existing port... if you post a picture of the sensor you bought we should be able to help make sure that doesn't happen.

[ventureforth]

VDO 323-423 Temp Sender


VDO 360-006 Pressure Sender


Thanks for mentioning the black circle.  I had circled it to ask if it was a viable port, but then never actually asked.

I guess the next question would be, would it be worthwhile to keep the stock sender at the head and put both the new pressure and temp senders on the flange?  Though there have been mixed opinions (as one would expect, of course), the general consensus was that the best pressure reading would come from the head as it would be the lowest pressure reading in the system.  If the pressure is okay at the head, then it has to be okay before the head, whereas, in theory, the pressure could be okay (if just barely) at the flange but on the low side at the head.  Of course, if it was borderline enough at the flange, I guess it would be foolish to not take that as a bad sign.  And beyond that, either way you will be getting a baseline to work from.  If the flange is always at a particular bar/psi reading, and all of a sudden it is below that reading, there's your red flag.

So, if I understand correctly:

1. The advantage to putting both senders at the flange is that I at least keep the low pressure warning light in the dash for sub-2000rpm operation (assuming I ground the other, now unused, wire).

2. But if I'm okay with not having any warning light in the dash and just keeping an eye on the gauge, the advantage (as I understand it) of having the VDO pressure sender at the head is that I would be getting the lowest possible reading for the overall system, therefore providing a worst case scenario picture of the system.

3. Either way, I can retain one of the stock pressure senders by using the black circled port on the flange for the temp sender.

But is the sub-2000rpm sender absolutely and unarguably the better sender of the two to keep if you have to lose one?  In other words, is it better to have the sub-2000rpm warning vs. the 2000rpm+ warning?  I would imagine it would be, as it would account for the lowest possible pressure in the system and provide warning in a worst case scenario situation.

And is the additional warning light contact on the VDO pressure sender of any use?  Can it substitute for either of the stock senders and, therefore, maintain complete functionality of the dynamic pressure warning light system?

Here is part of  the item description for the VDO pressure sender:
 
"This sender has the dual terminals for the gauge and the factory oil light."

[theman53]

If it were me I would take out the under 2000 RPM ... usually when bad stuff happens it is closer to redline than idle. If it is at idle normally it will just seize up until it cools. If you lost oil pressure at 5,000 rpm the block is probably going to be a window for people to look through.

If you are only running the stock light and a gauge then the peice you are buying will run both. If you want to run more this is what I did.



You can see in the first what it is. In the second it is painted black and has the little brass piece in it. All it is is a piece of keystock that was drilled through and tapped so I could run the oil temp, oil pressure, and stock oil light. The piece on the filter flange is an air manifold. I drilled an tapped the filter flange for 1/4 pipe and put a nipple on it. All the american gauges seemed cheaper to me

[ventureforth]

So from the pictures I posted of the senders, is it possible to tell if they are of an appropriate length?

[theman53]

THe top brass one seems a little long but they look ok. Take it apart and see if it is like what you have???

[rabbitman]

323-423 looks pretty long.

I think the pressure sender in the head runs the idiot light and IIRC actuates at less than 10psi.

The pressure sender in the flange is for the warning buzzer, meaning if the pressure is lower than 28psi @ 2000rpm the buzzer will sound.

[Vincent Waldon]

Yup, I'd agree.... the temp sensor does look a bit long... here's the other style of factory oil temp sender and it's a quite a bit shorter:



I'll look up the part number for ya when I get home to my garage.

You could certainly try the longer one but would want to carefully check for oil pressure/flow issues.  You may also be able to see down the hole when you pull off the plug and determine if the length is a problem.

[ventureforth]

I guess I'll try to gauge it (no pun intended) when I look down the hole.  The thing is, that sender seems to be the only 300 degree temp sender I can find with an M10X1 thread.  eGauges, Summit, etc., only list VDO 323-423 as the M10X1 option.  Should I be looking elsewhere?

[R.O.R-2.0]

323-423 looks like a gasser oil temp sender.. or a gasser coolant temp sensor. gasser and diesel senders are probably the same pieces anyway. my diesel has a 16v oil high pressure switch in it and works fine.

[Vincent Waldon]

OK, found the part number:

1H0 919 563  

It's a M10x1 150C / 300F OEM short temp sensor found in 1995-2002 Rabbit Cabrios, 1989-1995 Corrados, 1996-2004 Eurovans, 1993-2001 Golfs and Jettas, 2001 Jetta Station Wagens, and 1992-1997 Passats according to ETKA

I'd forgotten that it has a spade lug terminal rather than the little dome that's used on earlier coolant temp sensors... I've updated the picture in my previous post.

Worldpac lists these for about 10 bucks Canadian.

[ventureforth]

Would it be that the longer one would be appropriate for a filter setup that had an oil cooler, as well.  I ask, because this is the sender that was specified by duostyling and with the vw motors specifically in mind.  Or is it a gas vs diesel thing?