IHADAV8.com - Turbo Buick Tech, and Nonsense

Tech Area => General Buick Tech => Topic started by: gordyzx9r on January 20 2012, 04:25:26 PM

Title: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on January 20 2012, 04:25:26 PM

I replaced my gauges with Stewart Warner gauges years ago...when I did that, the kit came with an oil pressure switch (sending unit?) that only had one prong for a wire as opposed to the stock ones with three prongs(?). 

Where can I find one of these one prong switches that will fit a turbo regal?

My oil pressure gauge is reading 15 PSI low, which made Bill real worried until he hooked up an under hood gauge.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: SuperSix on January 20 2012, 04:37:23 PM

All aftermarket only have one wire (Like my VDO) - the stock unit also functions as a switch for the fuel pump relay as well, hence the need for more wires.

I would assume you have to get the same model as the one you are replacing, or a current replacement that has the same range/output. Can you see a model #/etc on the old unit? Is your builder SURE his is accurate? The gauge may be the culprit too.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on January 20 2012, 07:42:10 PM

Quote from: SuperSix on January 20 2012, 04:37:23 PM

All aftermarket only have one wire (Like my VDO) - the stock unit also functions as a switch for the fuel pump relay as well, hence the need for more wires.

I would assume you have to get the same model as the one you are replacing, or a current replacement that has the same range/output. Can you see a model #/etc on the old unit? Is your builder SURE his is accurate? The gauge may be the culprit too.

Yeah, he's sure.  I'll have to wait to see it up close if I can get some numbers off of it.  He can't see anything.  I kept the instructions from gnxdash.com (Performance Instruments), but it doesn't give any details about the make or model of the switch in the kit.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on January 20 2012, 09:46:59 PM

all you have to do is buy the brand that matches the gauge...usuall y there is a difference between the one for a full sweep gauge and one for a 180 deg gauge...that is all you have to check

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on January 20 2012, 11:24:11 PM

Quote from: Steve Wood on January 20 2012, 09:46:59 PM

all you have to do is buy the brand that matches the gauge...usuall y there is a difference between the one for a full sweep gauge and one for a 180 deg gauge...that is all you have to check

Hate to be a pain, but what does that mean? The gauge manufacturer sells them?

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on January 20 2012, 11:32:55 PM

If autometer, or whatever, go to summit or whereever and look for the sender that matches the gauge you have.

they sell the senders independently as well as packaged with the gauges...

tell me the brand and if it is 180 degs or full sweep...I will find it for you

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on January 21 2012, 10:48:54 AM

Not sure what you mean by 180 degrees or full sweep.  I'm trying to post a picture of it but I keep getting the damn internal error here.  And File Den is down...

Here is a link to the photo on my google documents:

https://docs.google.com/open?id=0B1g22ACgB9mRMzQ0OWFiNWQtNDhlZS00Mjg2LTk1NzItYzUwM2FlNDM5Y2Ex (https://docs.google.com/open?id=0B1g22ACgB9mRMzQ0OWFiNWQtNDhlZS00Mjg2LTk1NzItYzUwM2FlNDM5Y2Ex)

(http://www.turbobuick.com/forums/attachments/general-turbo-buick-tech/152494d1327161456-oil-pressure-switch-sending-unit-only-one-prong-performance-instruments-dash-installed-260404-again.jpg)
(https://docs.google.com/open?id=0B1g22ACgB9mRMzQ0OWFiNWQtNDhlZS00Mjg2LTk1NzItYzUwM2FlNDM5Y2Ex)

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on January 21 2012, 11:09:39 AM

The tach is a full sweep ~270deg.
Your pressure gauge is 180 (or less)
Steve suggests the senders may be different betwixt the two.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: SuperSix on January 21 2012, 11:31:43 AM

Looks like a 90 degree.

http://www.summitracing.com/parts/SWW-279B-F/ (http://www.summitracing.com/parts/SWW-279B-F/)

http://www.summitracing.com/search/Brand/Stewart-Warner/Part-Type/Gauge-Sending-Units/?keyword=oil+pressure (http://www.summitracing.com/search/Brand/Stewart-Warner/Part-Type/Gauge-Sending-Units/?keyword=oil+pressure)

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on January 21 2012, 12:18:16 PM

it's what I call a 180 instead of a full sweep...autome ter calls them short sweep

But properly, the needle moves about 90 degs so I guess that is the right description.

According to the SW site, this is the right sender   http://www.summitracing.com/parts/SWW-114875/ (http://www.summitracing.com/parts/SWW-114875/)

http://www.sw-performance.com/index80a3.html?page=details&p=114875 (http://www.sw-performance.com/index80a3.html?page=details&p=114875)

kinda strange because summit also shows a different number for the sw senders as well.  Need to check that other summit number and cross back, I guess

Autometer uses a different sender for a full sweep (270 deg) gauge than they do for the 90 deg and it costs a lot more.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on January 21 2012, 01:40:01 PM

Do I need to order thread adapter fittings for it as well?

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on January 21 2012, 01:45:44 PM

shouldn't it be the same as the one you took out?

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on January 21 2012, 02:03:58 PM

Quote from: Steve Wood on January 21 2012, 01:45:44 PM

shouldn't it be the same as the one you took out?

I guess we'll find out...the car is in another state, having it shipped there.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on January 21 2012, 03:09:39 PM

all the SW senders seem to be the same threads

only thing that I am confused on is any difference between these two

http://www.sw-performance.com/indexf351.html?page=details&p=279B-F (http://www.sw-performance.com/indexf351.html?page=details&p=279B-F)

and the one I listed above  http://www.sw-performance.com/indexf351.html?page=details&p=279B-F (http://www.sw-performance.com/indexf351.html?page=details&p=279B-F)

summit has them both...might be a question for SW if no one here sees a difference....

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on January 21 2012, 06:59:58 PM

Doesn't help they have two web sites:

That series is not shown here:
http://www.stewartwarner.com/Catalog/sdrpress.html (http://www.stewartwarner.com/Catalog/sdrpress.html)


both shown here:
http://www.sw-performance.com/products/SDRPressure.html (http://www.sw-performance.com/products/SDRPressure.html)

I don't see a difference so far

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on January 21 2012, 07:13:05 PM

yep, I could find no difference...a ll the pressure senders seem to be 240 ohm and the threads are the same...

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: SuperSix on January 21 2012, 07:19:57 PM

What about getting a PN off of the old unit?

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on January 22 2012, 10:22:13 AM

Quote from: daveismissing on January 21 2012, 06:59:58 PM

Doesn't help they have two web sites:

SW does aviation, automotive, and marine.  The problem I ran into a few years ago when my tachometer was failing (because of a intermittently failing after market ignition module) was that it was difficult to get tech support because they got rid of it and outsourced it to their vendors; and forgot to tell their vendors that they did that.  It was kinda funny, I was on the phone with a woman and she was trying to help me and said I needed to call SW tech support...I said I did and that they and their website listed her name, email, and phone number on their website to contact for tech support.  I finally got a lead sales manager, and he sent me two brand new 8K tachometers and a 10K tachometer for free plus put me into contact with one of their company engineers...wh o couldn't figure it out either. 

From what my builder says, there is no PN on the old unit.  I still have the instructions from Performance Instruments and it doesn't list the part in the inventory other than saying "new oil switch/sending unit". 

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on January 22 2012, 10:59:11 AM

as they seem to be spec'd the same, I see no reason either will not work....SW does not seem to have but one resistance range for their pressure gauges

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on February 03 2012, 08:45:37 AM

What kind of sealant should be put on the threads?  I thought I've read none, or to avoid anything teflon...

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: 1KWIKSIX on February 03 2012, 09:01:35 AM

Quote from: gordyzx9r on February 03 2012, 08:45:37 AM

What kind of sealant should be put on the threads?  I thought I've read none, or to avoid anything teflon...

 
I did not use any sealer on my brass VDO temp sensor or my VDO Oil pressure sensor.
 
With the one wire set up, the sensor needs to ground for them to work properly. If teflon or sealer is used, I read that they will not ground and will not give proper read out.
 
These are NPT (National Pipe Taper) threads, so they will seal themselves when tightened snugly.
 
I've had mine installed for several years now, no leaks!
 
dave

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: SuperSix on February 03 2012, 09:02:02 AM

You need SOME sealant - I used liquid teflon pipe sealant. a THIN smear in the threads.

The stock replacement OEM pressure sender I just installed had some on the threads from the factory..

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 03 2012, 09:30:48 AM

liquid teflon is the usual suggestion from the manufacturer

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on February 03 2012, 11:11:54 AM

I think the teflon is more about getting it back out again....
:)

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: SuperSix on February 03 2012, 11:39:59 AM

I don't think so. It's to create a more seal-able surface on the fittings. Fills in/seals small imperfections in the threads, fittings, etc.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Charlief1 on February 03 2012, 12:15:07 PM

Quote from: SuperSix on February 03 2012, 11:39:59 AM

I don't think so. It's to create a more seal-able surface on the fittings. Fills in/seals small imperfections in the threads, fittings, etc.

Mark's right here. The only other way to get a perfect fit is to lap the parts in and it''s much easier to use a sealant of some sort. A lot less messy as well. :D

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on February 03 2012, 12:24:44 PM

We have water pumps that we fire up and prime each spring. the steel plugs we pull always seal
-sealant or not. But you sure are pissed in the spring  if you didn't get some tape on the plug
 the last time in the fall.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: gordyzx9r on February 03 2012, 02:57:28 PM

For some reason the gauge reads worse than it did before with the old sending unit.  Other than getting a new gauge, is there a way to isolate the problem?  The oil pressure reads fine when using a mechanical gauge under the hood but it's way off with the electrical gauge.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on February 03 2012, 06:47:20 PM

IF the mfg published a resistance vs pressure chart you could put known resistors in place of the sender and check the gauge, or measure the resistance of the sender at various pressures.
I've not seen one tho.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 03 2012, 07:48:15 PM

Damn...SW gives you the min resistance and the max resistance with appropriate temps as well as stating to use Teflon liquid so the  single terminal sensor will ground properly.


The GM manual gives you the resistance and temperatures as well.


You need to get out more!

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on February 03 2012, 08:43:34 PM

And you really believe the response is linear?
 :)

He didn't tell us where it was off did he?



edit: I forgot the high value was defined too, so yes I defer to my elder and superior.
(zap's elder and superior? -rings a bell)


One could test at those resistance values at least.

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 04 2012, 12:17:21 AM

depends if you believe the factory or not...aftermar ket seems to believe it is linear, but I will leave it to you to argue with them


actually, I have to look to be sure the factory one is linear...I think I plotted it out once, but, that was a long time ago.


I have never seen an electric gauge that was other than kinda close

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 04 2012, 12:28:55 AM

Pressure Resistance (Nominal) Limits

0 psi (0 Kps)240 Ohm229.0-242.5

Full Rating33.5 Ohm27.0-43.0

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 04 2012, 12:29:50 AM

Of course, with limits like this, how would one know if it was linear, kinda linear, sorta linear, or sometimes, maybe linear

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 04 2012, 12:51:26 AM

Oh yeah, just dawned on me that I was thinking of the factory temp sender which is another kettle of fish entirely so I guess I will defer to Zap to answer about the pressure gauge sender having nothing to go on but what SW publishes :icon_lol:

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on February 04 2012, 09:32:11 AM

Quote from: Steve Wood on February 04 2012, 12:17:21 AM

...I think I plotted it out once, but, that was a long time ago.

I'm impressed,... again. :)

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 04 2012, 09:39:04 AM

I have a curious mind, but that was the temp sensor and it works differently from pressure


I have too many cars doing laps in my head

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: daveismissing on February 04 2012, 09:41:44 AM

Quote from: Steve Wood on February 04 2012, 12:28:55 AM

Pressure Resistance (Nominal) Limits

0 psi (0 Kps)240 Ohm229.0-242.5

Full Rating33.5 Ohm27.0-43.0

Looks like the mfg greatest concern is that the gauge zeros so they don't get returned as defective upon install.

A series resistor would make it read lower, shunting to make it read higher would be a pita.
 

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Steve Wood on February 04 2012, 10:41:31 AM

using a mechanical gauge would be the real solution

Title: Re: Oil Pressure Switch/Sending Unit with only one prong?
Post by: Top Speed on February 04 2012, 11:53:16 AM

I prefer mechanical gauges for oil pressure and water temp.