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Engine Specific Info and Questions => IDI Engine => Topic started by: TonyTDTruck on April 22, 2012, 07:19:08 pm

Title: Oil sending unit Question
Post by: TonyTDTruck on April 22, 2012, 07:19:08 pm
In these pictures you can see blank holes for sending units. Anybody have p/n for these?
And what is the unit at the back of the head for? I have seen these used for head temp in the past for gas motors.
On the oil flange, there is an extra slot for a oil pressure gauge it looks like. Does it matter what spot for oil pressure gauge?
Thanks

(http://i44.tinypic.com/2en21bc.jpg)
(http://i42.tinypic.com/30sgaqc.jpg)
Title: Re: Oil sending unit Question
Post by: libbydiesel on April 22, 2012, 08:09:04 pm
From Mk2 onward the various VWs have been fitted with the dynamic oil pressure warning system which has two senders, one which registers oil pressure at idle and one above 2,000 rpms. 
Title: Re: Oil sending unit Question
Post by: jb86 on April 22, 2012, 09:18:29 pm
Use a blue sender in the end of cylinder head - that registers about 3psi and turns off the solid red light that you see when you turn the key on
The flange uses either a white - 1.8 bar for n/a or 1.4 bar for turbo engine
I accidentally put white one in my brand new turbo engine and the light would flash and buzz when I hit the highway
German Autoparts has these
Jon
Title: Re: Oil sending unit Question
Post by: bajacalal on April 22, 2012, 10:23:15 pm
IMO the head is a more reliable source for engine oil pressure readings, it's further from the pump, put the sending unit there. Yes, the VW system took readings at 2 places to run the warning light and the high-pressure sensor (on the filter flange) is RPM specific and only is used over 2000 rpm. It's a horrible example of over-engineering a problem that would have easily been solved by fitting the cars with a proper oil gauge.

The threads are 10x1.0 mm if you can't find a VW specific block-off plug.
Title: Re: Oil sending unit Question
Post by: libbydiesel on April 23, 2012, 09:55:42 am
Personally I prefer the dynamic oil pressure warning system over a gauge.  Having a buzzer go off with low oil pressure at cruise is a really good idea.  A gauge is only useful when someone is looking at it.
Title: Re: Oil sending unit Question
Post by: TonyTDTruck on April 23, 2012, 10:02:55 am
Thanks for all the help. My first VW car was a 71 Beetle. I ran out of oil and after that lesson I put a gauge and idiot light in it. At the time my light wasn't working. Idiot doesn't begin to describe it.
I think I'll do the same this time. It's great to have a buzzer go off at cruise too.
Today, cars wake you up when you fall asleep at the wheel. Who would have thunk it.
This AAZ is going in a Transporter that had a 1.6TD in it originally. I don't think it had a warning system with buzzer. When I bought it, it came with a 2.1L water boxer and now I'm converting it back to diesel.
Title: Re: Oil sending unit Question
Post by: Rising on April 25, 2012, 01:27:29 pm
Personally I prefer the dynamic oil pressure warning system over a gauge.  Having a buzzer go off with low oil pressure at cruise is a really good idea.  A gauge is only useful when someone is looking at it.

According to vince waldon's site:
http://vincewaldon.com/index.php?option=com_content&task=view&id=40&Itemid=28

"- a flashing light and buzzer are a function of the high-pressure sensor on the filter flange.

- the car only looks at the high pressure sensor when the car is over 2000 RPM. "

So the buzzer doesn't even go off if you have low pressure... which is why my car is confusing to me.

From Mk2 onward the various VWs have been fitted with the dynamic oil pressure warning system which has two senders, one which registers oil pressure at idle and one above 2,000 rpms. 

Are you sure this is mk2's only? I have a two sensor system and my car is an 84... Just wondering is it not a dynamic system? Just buzzing and sound for both high and low on 84s?
Title: Re: Oil sending unit Question
Post by: ToddA1 on April 25, 2012, 04:17:28 pm
VDO makes a dual post sender that I usually use.  Keeps the warning light and it's only about $25.

-Todd
Title: Re: Oil sending unit Question
Post by: libbydiesel on April 25, 2012, 05:06:31 pm
Personally I prefer the dynamic oil pressure warning system over a gauge.  Having a buzzer go off with low oil pressure at cruise is a really good idea.  A gauge is only useful when someone is looking at it.

According to vince waldon's site:
http://vincewaldon.com/index.php?option=com_content&task=view&id=40&Itemid=28

"- a flashing light and buzzer are a function of the high-pressure sensor on the filter flange.

- the car only looks at the high pressure sensor when the car is over 2000 RPM. "

So the buzzer doesn't even go off if you have low pressure... which is why my car is confusing to me.

From Mk2 onward the various VWs have been fitted with the dynamic oil pressure warning system which has two senders, one which registers oil pressure at idle and one above 2,000 rpms. 

Are you sure this is mk2's only? I have a two sensor system and my car is an 84... Just wondering is it not a dynamic system? Just buzzing and sound for both high and low on 84s?

Oil pressure increases with engine speed.  Because of that, the oil pressure is higher when cruising than it is at idle.  Because most catastrophic failures occur when under power rather than idling, VW decided that it was a good idea to warn the vehicle operator when the oil pressure dropped too low when driving rather than just when idling.  The "high pressure" sender does not buzz to indicate that the pressure is too high, it gives the warning when oil pressure is too low when the rpms are above 2,000 rpms.

As far as my comment about mk2s, I used that generally rather than specifically.  You would have to look at your specific model to see when they transitioned to the dynamic system. 
Title: Re: Oil sending unit Question
Post by: theman53 on April 25, 2012, 05:41:24 pm
http://vincewaldon.com/index.php?option=com_content&task=view&id=40&Itemid=28
Title: Re: Re: Re: Oil sending unit Question
Post by: Rising on April 25, 2012, 06:50:25 pm
Personally I prefer the dynamic oil pressure warning system over a gauge.  Having a buzzer go off with low oil pressure at cruise is a really good idea.  A gauge is only useful when someone is looking at it.

According to vince waldon's site:
http://vincewaldon.com/index.php?option=com_content&task=view&id=40&Itemid=28

"- a flashing light and buzzer are a function of the high-pressure sensor on the filter flange.

- the car only looks at the high pressure sensor when the car is over 2000 RPM. "

So the buzzer doesn't even go off if you have low pressure... which is why my car is confusing to me.

Quote

Oil pressure increases with engine speed.  Because of that, the oil pressure is higher when cruising than it is at idle.  Because most catastrophic failures occur when under power rather than idling, VW decided that it was a good idea to warn the vehicle operator when the oil pressure dropped too low when driving rather than just when idling.  The "high pressure" sender does not buzz to indicate that the pressure is too high, it gives the warning when oil pressure is too low when the rpms are above 2,000 rpms.

As far as my comment about mk2s, I used that generally rather than specifically.  You would have to look at your specific model to see when they transitioned to the dynamic system. 

That makes about a thousand times more sense. I was very confused about why VW was apparently out of their minds when they designed this system.

I was just thinking fuzzy. Thanks for the clarification!
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