TDI oil pressure at the cylinder head

valois

Banned
Joined
Jan 11, 2000
The A3's mounted a low pressure switch at this location, I had a guage on it but decided to mount to a different location after installing the bypass, oil pressure was typically 40-50 psi cold, and around 10-15 psi at operating temps. Not the best location to monitor system oil pressure.
 

Dieselgeek

TDIClub Enthusiast, Vendor , w/Business number
Joined
Oct 3, 2000
Location
Golden, CO
TDI
2016 Golf TDI
Valois:

My lowly opinion is that at the head is where you measure oil pressure. You want to have a plausibility measure on your idiot light and it is more important to know how much oil pressure there is at the aluminum cam bearings. Your reported pressures are good.
What is your bypass?

jim
'90 Corrado TDI sans chip

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by valois:
The A3's mounted a low pressure switch at this location, I had a guage on it but decided to mount to a different location after installing the bypass, oil pressure was typically 40-50 psi cold, and around 10-15 psi at operating temps. Not the best location to monitor system oil pressure.<HR></BLOCKQUOTE>
 

GregR

Veteran Member
Joined
Nov 8, 1999
Location
Hillsboro, OH, USA 100+ miles
TDI
2014 Passat SE TDI, manual
valois,

The cylinder head location is where I was planning on mounting my pressure sender.

Did you move it to the dynamic pressure switch location on the oil filter mounting?

What kind of pressure readings did you get at the new location?

Thanks.

------------------
98 Jetta TDI, 86,000+ miles, Highest mpg 53.9

[This message has been edited by Tractor King (edited November 08, 2000).]
 

valois

Banned
Joined
Jan 11, 2000
Haven't got it reinstalled yet guys, I was planning on putting it at the outlet port of the Amsoil dual bypass filter, it should give me full system pressure there, as well as indicate a potential filter blockage. System pressure on these has to be above 29 psi when rpms are above 2000 or the high ppressure switch should trigger an alarm. I was not seeing nearly that much at the head. There is a unutilized port at the filter base on the A3's which used to be for the low pressure sender, they relocated this sender to the head, I guess the VW engineers agree with you Corrado, they wanted to monitor this point. It will be the lowest pressure point in the system aside from the sump itself. Karl tried the port at the filter cooler but indicated his probe was too long for the port.
 

Dieselgeek

TDIClub Enthusiast, Vendor , w/Business number
Joined
Oct 3, 2000
Location
Golden, CO
TDI
2016 Golf TDI
Hey:

Almost every VW Cabriolet and Audi 4000 on the planet has a VDO dual oil pressure sender in the head. It has a pole for the gauge and one for the idiot light. Not cheap new. Negates using any tees.

jim
'90 Corrado TDI-R Upsolute
 

Karl Roenick

Top Post Dawg
Joined
Sep 22, 1999
Location
Clifton Park, NY, US
i don't think you can use that with the new cars. i read of people trying-it would go off at startup. i think it was since they went to the single sensor and they have the delay built in.
 

GregR

Veteran Member
Joined
Nov 8, 1999
Location
Hillsboro, OH, USA 100+ miles
TDI
2014 Passat SE TDI, manual
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by valois:
Haven't got it reinstalled yet guys, I was planning on putting it at the outlet port of the Amsoil dual bypass filter, it should give me full system pressure there, as well as indicate a potential filter blockage. System pressure on these has to be above 29 psi when rpms are above 2000 or the high ppressure switch should trigger an alarm. I was not seeing nearly that much at the head. There is a unutilized port at the filter base on the A3's which used to be for the low pressure sender, they relocated this sender to the head, I guess the VW engineers agree with you Corrado, they wanted to monitor this point. It will be the lowest pressure point in the system aside from the sump itself. Karl tried the port at the filter cooler but indicated his probe was too long for the port.<HR></BLOCKQUOTE>


Thanks for the info.
I think I will put my pressure sender at the location on the cylinder head.
The setup for my bypass filter that I have planned wouldn't give me a good pressure reading at the outlet of the filter since it is being routed to the crankcase.


------------------
98 Jetta TDI, 86,000+ miles, Highest mpg 53.9
 

Brent Waldron

Well-known member
Joined
Sep 7, 2000
Location
Hoschton, Georgia USA
Thanks for the response. I was told that putting your oil pressure gauge at the top of the cylinder head will tell you that you have oil going to the cam. With no oil presssure to the cam results in failure that no one wants. By the way, I have a 1997 Passat. Not a new TDI.


1997 Passat: 140,000 miles
 

Dieselgeek

TDIClub Enthusiast, Vendor , w/Business number
Joined
Oct 3, 2000
Location
Golden, CO
TDI
2016 Golf TDI
I looked at a 2.0 engine in a '00 Jetta and there was a coolant line directly in front of the 5mm Allen plug at the end of the head. This is where the oil pressure sender should go. It's funny that VW has abandoned checking oil pressure at the head(though all 16v's/20v's/VR6's have the two senders at the filter housing). Maybe it wasn't a convenient install with that hard line in the way. Maybe it is insignificant. I just figured that you want to check oil pressure at the end of the pressure circuit to make sure all bearings are being force fed their due Texas Tea. I haven't had the opportunity to look at the new TDI to see if it has the same obstruction. If it doesn't, this is where the sender should go. I have some used dual senders from Cabriolets that would work great for this application. Many times, the dual sender's idiot light pole screws up and renders the sender useless since the oil pressure light is constantly activated. The oil pressure sender for the gauge itself is unaffected and thus makes the 'bad' sender perfect for a gauge-only application. I have one or two of these 'bad' senders.

jim
'90 Corrado with soul of a '98 Jetta TDI and one VERY loud oil pressure warning 'siren' that'l do for now.
 

valois

Banned
Joined
Jan 11, 2000
Gentlemen, your opinions are indeed persuasive, I will re-install the sender at the head, the points you made are well recieved and make sense. This time I will be using schedule 40 stainless on the fittings.
 

Dieselgeek

TDIClub Enthusiast, Vendor , w/Business number
Joined
Oct 3, 2000
Location
Golden, CO
TDI
2016 Golf TDI
Karl:

10-15 psi at idle is no problem to read at all on my VDO gauges. Your 40 psi is great for a loaded hydraulic lifter engine as read at the head. Idle speed oil pressure should be at least 7psi at the head. But 29 psi at 2000 rpm IS the most important since it predicts oil pressure at all other times. If you have less than 7psi at idle with the engine fully up to temperature, you might want to put a pump or bearings in your motor. All of my info comes from Techtonics Tuning.

As always, I could be wrong.
jim
'90 Corrado TDI

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Karl Roenick:
Isn't 10-15 psi hard to read on the normal narrow sweep electrical gauge?
I like seeing that ~40 psi normal right in the middle of my 80 psi gauge.
<HR></BLOCKQUOTE>
 

Karl Roenick

Top Post Dawg
Joined
Sep 22, 1999
Location
Clifton Park, NY, US
On my alh motor I am reading ~40 psi, warmed up, at 65 mph, off the oil filter flange (where the oem senses presure). The pressure never seems to go above ~75 psi because of the relief valve setting (72.5 ?). With the 80 psi gauge it's right smack dab in the middle at highway speed/warmed up. I don't know how much it's gonna drop when you read it at the head, but it could get hard to read.

Caveats: a: I don't have the opportunity to install a sender in your engines spot (what's the engine code anyways?)
b: I have old eyes. Well, an old body, generally.


PS: That place mentioned above to measure oil temp with the vdo 300 temp gauge and a an old vw vdo sender works great!
 

Dieselgeek

TDIClub Enthusiast, Vendor , w/Business number
Joined
Oct 3, 2000
Location
Golden, CO
TDI
2016 Golf TDI
Karl:

Your 40 psi at the filter will be perhaps 37 at the head. And I have an AHU '98 Jetta motor. Finally, an old and wise engine builder once told me that you always measure oil temperature as close to the main bearings as possible. Taking oil temp at the head (as I understand you are) is akin to taking a child's temp between his/her toes.

jim

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Karl Roenick:
On my alh motor I am reading ~40 psi, warmed up, at 65 mph, off the oil filter flange (where the oem senses presure). The pressure never seems to go above ~75 psi because of the relief valve setting (72.5 ?). With the 80 psi gauge it's right smack dab in the middle at highway speed/warmed up. I don't know how much it's gonna drop when you read it at the head, but it could get hard to read.

Caveats: a: I don't have the opportunity to install a sender in your engines spot (what's the engine code anyways?)
b: I have old eyes. Well, an old body, generally.


PS: That place mentioned above to measure oil temp with the vdo 300 temp gauge and a an old vw vdo sender works great!
<HR></BLOCKQUOTE>
 

Karl Roenick

Top Post Dawg
Joined
Sep 22, 1999
Location
Clifton Park, NY, US
Sometimes these threads get convoluted.
I'm taking the oil temp from a hole that was plugged on the oil filter flange. It is right next to the oil pressure tap. It works quite nice and is easy to install. I think the AHU's have this hole too.
 

Brent Waldron

Well-known member
Joined
Sep 7, 2000
Location
Hoschton, Georgia USA
Just to let some of you know, with my gauge installed at the cylinder head, it is reading about 15psi and is not hard to read at all. It can fall to what looks like 7-8 psi when in an extended idle but jumps back up when I take off.
 

weasel

Deactivated Member Account
Joined
Sep 12, 2000
TDI
None.
Karl:

Just how did you get that spare plug in the oil cooler jacket out
I wanted to use this for an oil temp gauge and I couldn't get the damned thing out !! I tried everything but a BFH.

------------------
Oo \/\/ oO
 

weasel

Deactivated Member Account
Joined
Sep 12, 2000
TDI
None.
Thanks, I'll give her a try again. Its kind of rusty and I thought it was a hex !! Oh well ... If I can get the damned thing out it will make a great place for my oil temp gauge. Much better than drilling a hole in the oil pan


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Oo \/\/ oO
 

weasel

Deactivated Member Account
Joined
Sep 12, 2000
TDI
None.
Its not a torx, it requires one of those ultra rare round bits
Guess I'll have to wip out the Dremel and cut a slot in it. You have any idea what the thread size is ??

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Oo \/\/ oO
 

weasel

Deactivated Member Account
Joined
Sep 12, 2000
TDI
None.
The vise grips won't grab, but maybe I'll try another day. If it is M10 on mine as well, I'll need an adapter before I do anything.

------------------
Oo \/\/ oO
 
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