Oil Temperature Sender

Where is the sending unit mounted?   You really don't have a speedster - you have a replica so VW. 

Here's one for the plug in the oil strainer cover -

https://www.jbugs.com/product/V323055.html?rrec=true

and one for the oil pressure relief valve -

https://www.jbugs.com/product/V323064.html?rrec=true

Wolfgang,

You are always so helpful.

Will these centers work with my Brazilian gauge? The brand on the link seems different. We ordered a couple of different ones and they didn’t work.

I’ll take a photo of the old sensor that we reinstalled. Perhaps that will help.

Marshall

Lfepardo,

Wow. What a remarkably helpful reply. Thanks for taking the time to craft it.

Didn’t know about either parts supply house. Now they are on my favorites list.

Thanks again,

Marshall

OK.  Here are two photos of the "sender".  It appears to be a T arrangement.  A wire to the top and another to the bottom.  Is this unit accomplishing two things, e.g. pressure light and temperature?

Any idea, other than to remove the unit and look for numbers?  

Marshall

No photos attached and yes, remove the sender and look closely for numbers on it.

Greetings,

Here are two photos of my gauge set.  The gauge to the left is labled Cronomac Made in Brazil on the very bottom so I now know their make.  A couple of questions.

Are these still made and available or is this an older model no longer available?  Everything works nicely except except the oil temperature gauge.  I'm awaiting some more comments before pulling that T sender unit to look for ID part numbers.  I'm not even sure this is even the oil temperature sending unit.  Why two wires?  One a ground?  Why the T arrangement?

Marshall

So, Marshal,  in your last photo, which sender do you think is bad (top one or bottom one) and why  - what are the failing symptoms? 

@Marshall. I can’t comment on the gauge set make, but I do have a question or two that may help diagnose the problem.

- do you get any movement from the  oil temp needle when you power the car?  You should see something... though it may be minimal...  If not, you may want to pull the gauge ( a simple push from behind) and check/ clean all the connections. Something may have come loose/ or is dirty.  If the other elements in that gauge are working properly it’s probably not the ground.  Look for a bright green cable that matches the color of the cable on the sender wiring... that should be connected to your oil sender gauge mechanism.

Pictured in your last post you have the oil temp sending unit ( top of the T), and oil pressure switch ( bottom of the T).  

- The Oil Pressure Switch operates the oil pressure indicator bulb on the speedometer. The switch looks to be  the standard 10x1.0mm threaded one and operates at roughly 3 PSI. Meaning that if the oil pressure indicator light is on, your engine has less than 3 PSI of oil pressure at the switch

- the oil temp sending unit green cable should be run directly to your temp gauge. You should see the same colored green cable behind your gauge.  That’s the connection I would check.  I would also check for continuity between the oil sending usniy and the gauge.

- the T is commonly used on VS builds to run both of these senders.  

oil senders are simple mechanisms that don’t fail often... But they can fail.  There is a chance you have a loose/ dirty connection at the gauge or even at the sender ( corrosion can really mess with your wiring),  or your Chinese/ Brazilian  gauge has pooped out,   Check continuity and connections before buying a new sender. I can send you some how- to instructions to check continuity if you need help.

-  by the looks of it, you likely have the OEM VW  sender part #049 919 501 - oil temp sender, short - 10mm,  0-120c range used for mid-70s to mid-90s VW stuff.  And commonly used now for small aircooled engines. Also VDO version of this one installed in the car, part number 323-088. https://www.jbugs.com/product/V323088.html

i had a similar problem years back... it turned out I had a loose cable ( the first time).  Then, eventually the Chinese gauge failed... and I sent my gauges to Palo Alto Speedometer and VDO guts were installed replacing the cheap Chinese made ones.   

Hope this helps.

Gordon. 
Both photos are of the same sender.  This is the only sender on the motor that I can see. 

With the key on, I took the top wire off and grounded it to the fan housing. The oil temperature gauge pegged out. Based on that I assume that the gauge works and that the sender doesn’t?

Because there are two wires here, is this sender fulfilling more than one function? Is this one part or multiple parts?  

I haven’t worked up the courage to actually remove it yet to check for the part numbers you had mentioned earlier.

Marshall

I can't see an oil temp sender getting very accurate readings  OUT of the real flow of oil.  Sump plate, oil cooler relief plug or oil pressure valve spring "bolt" would give a better reading

@Marshall posted:

Both photos are of the same sender.  

With the key on, I took the top wire off and grounded it to the fan housing. The oil temperature gauge pegged out. B

Because there are two wires here, is this sender fulfilling more than one function? Is this one part or multiple parts?  

 

Marshall,

Your photo appears to show two senders on a tee. Since the top one is for the temperature gauge, the bottom is most likely for the oil pressure light. With the key on but the engine not running, the oil light should be on. Disconnect the bottom wire, the oil light should go out. 

Do you have an multimeter? If so, measure the resistance in ohms between the top sender's lug and sender body, with the engine cold the wire disconnected. Go take a nice long drive, then measure the resistance again with the engine hot. Report the values and we'll have some idea if the sender is working. Also check the resistance between the sender body and the engine block itself. It should be a couple of ohms at most. If it's high or open the sender isn't grounded, this could cause the gauge to read low all the time.   

Eric

One could be for the oil pressure light and the other for the oil pressure gauge.  Look at the sump area/bottom of engine for another sender.

Wolfgang,

The car is going to the shop early next month and I'll have them look for another sender or even a plugged sender location on the bottom of the sump then.

An interesting thing happened yesterday.  I've been driving about 40 miles a day up the parkways on the Maryland and VA sides of the Potomac.  On returning home yesterday, I noticed that the needle on my temperature gauge had moved off 0.  The gauge is not marked with marks or numbers so no actual temperature is discernible.  The very end of the needle can swing into a small red zone.

The needle had swung maybe 1/2 inch out of a possible 2-1/2 inch swing. 

Any idea what an "acceptable" needle location on a gauge as this might be?  Anywhere not in the red zone.  Stop the car if needle goes half way to red.  

Any thoughts?

Marshall 

I just double checked the link Lfpardo send me on the temp sender and the company says this sender reads up to 250F.

What is a normal temperature for my 1641 cc motor to run?

Is it smart to assume that the red portion of my gauge is 250F and I can prorate needle location back to 0 to approximate oil temperature?

Marshall, assume NOTHING. Oil temp should ideally run between 180-200F, as that is the temp that moisture and acids/impurities are "burned" off.

If it doesn't get hot enough, it's probably worse than too hot. Wear is greatly increased with not-hot-enough oil.

Once you get the sender working, get yourself an instant-read thermometer, and take readings at various temps via the instant-read touching the oil sender. Then you'll get an indication of what temps the gauge is indicating.

Marshall, first - what Danny said. Assume nothing.

There's little quality control in these replica gauges, so every one is different. And where the sender is mounted on the engine will make a difference in how the gauge reads.

That said, I made up this diagram a few years back when this subject came up. With no 'scale' marked on my gauge, I've taken to interpreting the readings about like this, after driving the car for a few years and measuring the oil temp with a thermometer in the dipstick hole.

And, after watching others post photos of their gauges, this seems roughly in line with what most folks are seeing, too.

PS: I have a manually controlled fan on my external oil cooler, thus the reference to 'turn fan on'.

Cheers!

X2 what dannyP says.  Assume nothing.  the Chinese/ Brazilian gauges are a crap shoot.  A good thermometer is highly recommended to help you decode where the needle is/ the temp your engine is running at.

unless you put senders in better locations and install a proper temp gauge under your dash, Most of us use either of the below items for safe measure (unless someone like Palo Alto Speedometer has replaced the cheap guts for VDO guts in your gauge, and matched / calibrated the needle to a vdo sender).

1) oil temp Warning light dip stick: https://www.thesamba.com/vw/cl...etail.php?id=2180658

http://www.savemybug.com/index.htm

2) dip stick thermometer: https://vwparts.aircooled.net/.../thermo-dipstick.htm

I had my gauges updated by Palo Alto a Speedometer in 2015 w/ VDO guts, and on road trips Or really hot days I still use either 1) or 2) above for safe measures.

Welcome to the madness.