Blinking Oil Light / oil pressure question

vgr

Well-known member
Joined
Dec 23, 2011
Location
Phoenix
TDI
1998 Beetle 5spd
I started my car this morning in my driveway after it sat for 3 days and within 15 seconds of starting my oil light started blinking and beeping. I panicked and turned the car off. (I just assume if an oil light goes off its telling me "STOP")

I checked the motor and the undercarriage for oil spray and I didn't see any, nor is there any sign of leaking oil on my skidplate. The oil level is a little lower than it was a week ago when I checked it, but not significantly.

From my research here it seems like to properly diagnose this I need to do an oil pressure test. It sounds like this issue could just be the oil pressure sensor, however, it could also be an oil pressure problem which will cook the engine quick. (according to this thread). http://forums.tdiclub.com/showthread.php?t=334289

I live 3 hours from the nearest guru so taking it to a guru would mean a 3 hour tow, or a 3 hour drive, I'm not going to do the drive if I'm in question about this (hell I'm not going to do a 30 second drive). Is this something that with the right tools, I could accomplish myself? I did some searching and didn't find anything about how to do it, maybe I missed it?

My last thought is this, from talking with a friend who owned a tdi for several years, he said had this happen to him when the car would sit for several days in cold weather, and he would assume that the oil drained from the heads, and that it was never an issue for him. How plausible is this, as this is my exact situation.
 
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jettawreck

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Joined
Aug 2, 2004
Location
Northern Minnesota-55744
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2001 Jetta and 2003 Jetta
I have never had the oil light come on from sitting in the cold even for months. Oil pressure builds almost instantly, unless maybe you are using some 15w-40 dino stuff.
I did have a few randon scares when I had the 2000 Jetta TDI while cruising down the road. Shut off immediately and looked it over and when restarted, no more light/buzzer. Months or year later it would happen again. Bad sending unit/connection??
 

whitedog

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Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
The oil pressure switch is a single wire switch, so you can unplug it and touch it to ground to see if the flashing stops.

You should check to see what the oil pressure is though. The port thread is M10X1.0, but in a pinch you can use a 1/8 pipe thread adapter, but I don't know what it would do to the metric threads, so I don't recommend it.
 

vgr

Well-known member
Joined
Dec 23, 2011
Location
Phoenix
TDI
1998 Beetle 5spd
Jettawreck its quartz 15w40

Whitedog great information one question however what sort of tool do i use to test the oil, and would they sell it at advanced/napa (ive never done this sort of engine dianostics). I should note that i do have the full Bentley manual and vagcom cable
 

jettawreck

Top Post Dawg
Joined
Aug 2, 2004
Location
Northern Minnesota-55744
TDI
2001 Jetta and 2003 Jetta
Jettawreck its quartz 15w40

Whitedog great information one question however what sort of tool do i use to test the oil, and would they sell it at advanced/napa (ive never done this sort of engine dianostics). I should note that i do have the full Bentley manual and vagcom cable

Wrong oil. '98 TDI is 5w-40 full synthetic. Get that out of there.
 
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MrSafety

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Jun 27, 2010
Location
California... Novato... 25 Mi. N. of S.F.
TDI
2002 Jetta TDI/ALH/01M-'80 240D Mercedes/'81 Rabbit "Caddy"/'99 Lexus ES300
... my Oil Pressure "idiot light" came on too... !

"vgr",
Yes, my Oil Pressure "idiot warning light" came on recently and
I too shut down the engine out of the same concern as yours....
but in my case it was my 1.6L diesel powered Rabbit p/u that is my latest project vehicle !
After checking to make sure my recent oil/filter change was still showing on the dip-stick,
I checked the pressure sender unit/switch... and not being convinced it was OK,
I changed it out anyhow for ~$8.00 !
Well my light kept turning on intermittently... so I abandoned paying any attention
to the dash cluster oil pressure Idiot Light and installed an
audible "ding-dong" alarm and hooked it up to the new pressure sender switch...
so now it really gets my attention... and essentially my problem went away.
So in my case the problem was intermittent and somewhere in the dash cluster light warning system!
Now that I have a reliable audible warning system, my idiot light still periodically comes on!
So maybe you have the same kind of problem... in your dash cluster!??
But IF I were you and you can adapt and hook up
an analog pressure gauge for a while to monitor your oil pressure
and also keep your dash idiot light working,
I would use both and look at the gauge regularly and
definitely look at it any time the dash idiot light came on!
I now kind of like my "ding-dong" alarm...
for it definitely does a better job of alerting the driver than the lights ever did!
I might keep my "ding-dong" alarm... for recently it alerted me that
I was a mere 0.5 qts low in oil when it kept giving me a single "ding" whenever I made a sharp left turn!!!
I added the oil and no more "ding" !!
Regards,
Sam Ross
 
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KROWBAR

Active member
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Aug 30, 2010
Location
Orange County, NC, CSA
TDI
2003 NB
Don't use a 1/8 NPT in the port it will ruin it. M10X1.0 threads are not tapered but NPT threads are (i.e. crush fit). You are going into aluminum not steel. Not sure where the sender is on a Jetta but on an A4 beetle it's near the base where the oil filter is. You can put in a tee adapter and have the stock oil pressure sender as well as one for an oil pressure gauge. Takes away the guessing.
 

whitedog

Veteran Member
Joined
Jul 12, 2004
Location
Bend, Oregon
TDI
2004 Jetta that I fill by myself
Don't use a 1/8 NPT in the port it will ruin it. M10X1.0 threads are not tapered but NPT threads are (i.e. crush fit). You are going into aluminum not steel.
Absolutely agree, but sometimes a dogs gotta do what a dogs gotta do.
 

jerryfreak

Veteran Member
Joined
Feb 16, 2004
Location
Nor Cal
TDI
02 Jetta GLS sedan @295K, 99 Jetta sedan 275k,. 2015 tdi sedan, 105k
my 02 ALH has the light blinking occasionally


i thought it was random but it seems semi-reproducible. when coasting in 5th or 4th from highway speed when i go to turn off (only on my way to work, never on the way home under similar conditions.... so weird ?????)


should i get an M10 x 1 tee and throw a simple mechanical gauge in? whats an acceptable pressure for an ALH (200+K, blows a little smoke on cold start but is pretty solid otherwise
 

JB05

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Oct 20, 2005
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Il.USA
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Golf,2005,anthracite blue
I think the attached .5mm/22AWG wire can become fragile over time since it is located in a very hot environment. Mine was chewed in half from a squirrel and my first attempt to reconnect the wire did not work. I had to replace most of the wire. This kept the warning light off.
 

csstevej

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Aug 12, 2004
Location
north nj
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2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,glutton for punishment got another tdi 2001NB,another yellow tdi NB
Mine ended up being the low oil pressure sw being bad. First couple of time I freaked out,
Immediately pulled over and killed the engine and check the oil quantity. Each time good, started up car and all is well for days till it happened again.
Changed th LOP and all is fine.
 

jerryfreak

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Feb 16, 2004
Location
Nor Cal
TDI
02 Jetta GLS sedan @295K, 99 Jetta sedan 275k,. 2015 tdi sedan, 105k
I think the attached .5mm/22AWG wire can become fragile over time since it is located in a very hot environment. Mine was chewed in half from a squirrel and my first attempt to reconnect the wire did not work. I had to replace most of the wire. This kept the warning light off.
ill take another look. we have those freakin packrats here. one time one ate thru my fuel return line, what a mess. pretty sure they were responsible for my hvac electrical issues as well

can i test the sensor itself with a meter?

what would be normal signal level at oil pressure zero, idle, and say 1800 rpm
 

Nero Morg

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OR
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2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
It's more so a pressure switch not a pressure sensor. So it's either on or off. Oil pressure light comes on at 8-12psi of pressure. I don't know if it's a normally open or normally closed switch, but if you do a resistance test, you should get either 0.00ohms, or OL, depending on if the car is running.
 

jerryfreak

Veteran Member
Joined
Feb 16, 2004
Location
Nor Cal
TDI
02 Jetta GLS sedan @295K, 99 Jetta sedan 275k,. 2015 tdi sedan, 105k
so i put a tee in there, the oil sender wire did break on removal, but im not 100% sure that was the problem


cold start it was 60-70 psi at 2K, but once my car got to temperature on the coolant gauge it was barely north of 50. what concerns me, is i did a decel on the highway to simulate conditions where the light would previously come on, pressure dropped down to around 25 psi and pretty much stayed there. <20 on idle, maybe right above 25 at 2K


is it normal for oil temp/viscosity to lag coolant temp by that much? its a cheapo mechanical gauge im going to try to bleed the line to see if i can make it more responsive/accurate.


in this thread, bentley is quoted as saying pressure as low as 23psi is acceptable but i find that disconcerting


http://forums.tdiclub.com/showthread.php?t=355925
 

Nero Morg

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OR
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2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
Yeah that's completely normal. You should see some of the industrial 15l engines. Min spec oil pressure at idle is only 17psi, and those engines run for 1+mil miles.
 

WolfgangVW

Veteran Member
Joined
Oct 16, 2011
Location
Alberta, Canada
TDI
2003 Jetta TDI - Manual
OP sounds like you have the right oil,but maybe double check your manual. It should meet the VW 505.00 spec, that's what mine is anyway. You could also get away with 505.01 I think. I went into VW dealer once to get oil and they gave me 5w30 505.01, the guy said it's the upgraded spec for my car. I still however go with 5w40 505.00. Anyway as long as it meets the same spec listed in your manual.

At any rate sounds like a different issue. I've had the oil light blink etc a few times, but only when I've tried to start in extreme cold with no plug in and had to crank on it pretty good. Good luck!
 

WolfgangVW

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Joined
Oct 16, 2011
Location
Alberta, Canada
TDI
2003 Jetta TDI - Manual
Hey sorry OP just realized in your avatar you have a '98 beetle. For some reason I thought i read 2002 Jetta. Ha sorry too much thread surfing lol. Anyway disregard my post if it's wrong, sorry about that. But still good luck!
 

Vince Waldon

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Apr 25, 2009
Location
Edmonton AB Canada
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2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
is it normal for oil temp/viscosity to lag coolant temp by that much? its a cheapo mechanical gauge im going to try to bleed the line to see if i can make it more responsive/accurate.


in this thread, bentley is quoted as saying pressure as low as 23psi is acceptable but i find that disconcerting
Yes, very normal for the oil temp to lag significantly behind the coolant temp, and thus the drop due to viscosity. Water has a much higher capacity to wick heat than oil.

The lag would be even more without the coolant/oil heat exchanger, which actually helps warm the oil up faster initially.

Your oil pressure is also pretty normal. "10 psi per 1000 RPM" was the guideline back in the Beetle days and in my mind it's as good a guideline as any. At the end of the day as long as there's some oil pressure you know that oil is circulating properly and doing its multiple jobs. More doesn't mean better in this case... maybe a bit more heat removal would be all.

As the engine wears and clearances increase what you'd expect to see is a gradual decrease in oil pressure at idle after a spirited drive on the highway... oil at its hottest and thinnest combined with low pump RPM... and that's when people often first notice the oil pressure light flickering on older vehicles. That would be 6-10 psi, and it sounds like you have twice that.

On old Beetles even *that* 6 psi was OK, according to the manual... as long as the light went out when you blipped the throttle. :)
 
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jerryfreak

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Feb 16, 2004
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Nor Cal
TDI
02 Jetta GLS sedan @295K, 99 Jetta sedan 275k,. 2015 tdi sedan, 105k
Yeah that's completely normal. You should see some of the industrial 15l engines. Min spec oil pressure at idle is only 17psi, and those engines run for 1+mil miles.

cheap gauge has poor resolution down there, so i guess as long as i have 50+ psi on cold start everything is good



just wondering why it would only come on at low rpms/ low pressure situations. does that indicate the gauge is faulty?


also whats the proper install for these non-tapered threads that bottom out. the tee came with one copper crush washer, but i kinda woulda needed another to do it right. i loaded the rest up with thread sealer and bottomed them out and all looks good for now
 

Nero Morg

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OR
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2014 A6 TDI, 2001 Jetta TDI, 2014 Passat TDI
Whenever I replace the sensors, uaualt due to engine swaps and differences in the harness, I just unthread the old sensor, snug the new one in, then a light pull to tighten it. Don't know what the torque spec is but I usually set it probably to 5-8ftlbs. No leaks yet.

It may be the spring in the sensor is worn out so it gives incorrect readings at idle. Hard to say. Are you able to check your oil pressure hot?
 

halocline

Veteran Member
Joined
Aug 13, 2009
Location
San Antonio
TDI
04 Jetta Wagon
just wondering why it would only come on at low rpms/ low pressure situations. does that indicate the gauge is faulty?

I'm not sure if I understand what you're asking, but the oil pressure is generated by a pump that is tied to engine speed. Higher engine RPMs mean that the pump is pumping faster, and producing much more oil pressure.



Regarding temperature, hot oil is thinner than cold oil, so it also produces less pressure. (More viscous liquid equals more pressure) That's one of the main reasons multi weight oil is used; as it gets hot, it retains viscosity. (Another is that it flows easily when cold)
 

jerryfreak

Veteran Member
Joined
Feb 16, 2004
Location
Nor Cal
TDI
02 Jetta GLS sedan @295K, 99 Jetta sedan 275k,. 2015 tdi sedan, 105k
seems like light is coming on again at low pressures when engine is hot


which tells me that the pressures are lower than they were when i posted this last year



at 285K miles, is that engine nearing its end? its time for a TB soon, i need to make some decisions.
 

Vince Waldon

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Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
SOP to answer that question would be to pull the oil pan and Plastigauge a couple bearings, both mains and rod.

IIRC there's a thread here somewhere where Frank06 has a specific main bearing he likes to use as the canary in the coal mine for the rest of them... I go for the thrust one if I only do one.

I've also been known to just do 'em all.. engines already apart and the bearings and TTY hardware are not that expensive. Depends on how attached you and the engine are.... I did NOT want to ever say goodby to my 1.8 German-made MK2 gasser in metallic teal green. :)
 

csstevej

Top Post Dawg
Joined
Aug 12, 2004
Location
north nj
TDI
2001 golf tdi 4 door auto now a manual, mine, 2000 golf 2 door M/T son's,daughters 98 NB non-TDI 2.0, 2003 TDI NB for next daughter, head repaired and on road,glutton for punishment got another tdi 2001NB,another yellow tdi NB
I’d redo the oil pressure with good gauges and see what I get.....
Where did you get the replacement low oil pressure switch?
I’m over 431,xxx miles on my car and it’s fine.
 
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