help with oil light issues

[Tdiduck]

Whats up TDI heads!!! I have a 2003 golf 5spd with 275k miles on it....new to diesel engines but not cars anyway....any and all help will be appreciated I was driving the other day and the oil light came on. Pulled over checked the oil level and it was fine. no misfire, or rough idle or anything of the sort. Later in the day I had to start the car the oil light was on at all times when I had to move it (I turned off asap) later in the day. Got the car home replaced the oil pressure sensor and that only seemed to have been a small fix because the light went away when the car is idling, so I thought the issue was fixed took the car for a drive down my street....I was wrong the light comes on when I am going over 15-20mph and 1500-2000 rpm....so I did an oil change flushed it with motor medic motor flush figured there was sludge build up. while I was performing the flush it said to run the engine for 5 minutes at no point did the light come on and she purred as usual. Poured some new oil after doing the flush, it has a new oil pressure sensor thought I was in the clear went down the street AND still get that oil light but only after I hit 15-20mph and above 1500rpm.

I've done some research on what the culprit could be but im really stumped and the possibilities that I have read range from a lose dipstick tube (which it did have one from a mk4 1.8T :/ stupid amazon... but the fit was snug and did not notice any leaks or anything just a slight difference in angle of the tube) leaking rear main seal, bad oil pump, possible bad turbo (not to sure on this one... first turbo car...has decent boost and pull doesnt not feel sluggish) or bad bearings? OR it could be something else. I dont know where to start so i would really appreciate your help...... and im pretty mechanically inclined just dont have the funds to be playing wacka mole right now replacing parts trying to figute out what could be wrong.

 

[Vince Waldon]

The sensor is ignored below about 2000 RPM, so that's why you're not seeing any issues when the car is idling.

First step IMHO would be to get/borrow an oil pressure gauge and find out what actual pressure you have... low oil pressure is death to the turbo, the bearings, etc, and you should probably not run the engine a second longer than you need to. An oil-starved engine will run just fine, right up until the second a bearing seizes.

Zero oil pressure will tell you one thing, low oil pressure another.

It could be two bad pressure sensors in a row.. .but the odds aren't in your favour.

 

[BobnOH]

Bad crankshaft and/or connecting rod bearings. But you do want to rule out everything else first. Do as Vince recommends. Check the oil filter, could be upside down or damaged cap seal, rare, but was a recent thread on this. If you see oil up on the camshaft, the pump is working.
Good news is the bearings can be inspected and replaced on the car.

 

[Tdiduck]

waiting on the oil pressure gauge to arrive so I can check the oil pressure. Also ordered the correct dipstick tube(dorman 917-305) to install, bought a new oil filter to make sure it goes in properly its a wix 57210 it does not have any writing for the orientation...how to I know what side is up? one side has a big opening with rib like inside. The other side seems be the same size hole but covered in plastic and about a 1" in the hole gets smaller.

When you say cap do you mean the oil filter cap?

vince- this is the OPS that I purchased from O'reilly. they have 6 listed so idk if it could be that I got the wrong one....
URO Parts Oil Pressure Switch - 038919081

Will inform you guys of the results from the pressure test when I do it later today if the part gets here at a decent time

 

[Genesis]

The filter goes in with the plastic collar (which comes up about halfway) DOWN. It should have "top" written on the top.

The filter cap has a post that goes down the middle; there is an O-ring on that (which should come with the new filter; there are two, one on the cap and one much smaller one on the stick.) It should be replaced when the filter is changed.

Check the filter cap and make sure (1) the stick is there that goes to the bottom and (2) it has the O-ring on it. If both are true then DO NOT run the engine until you can put a pressure GAUGE on the sender port and see what's there. If its near-zero you're in serious trouble given how much you have run it already.

As others have noted the oil pressure switch is ignored until you get to about 2000 RPM. This is IMHO bad design but it is what it is.

 

[JB05]

I had to change the sensor wire which had become fragile due to its location in a hot environment. No more oil light.

 

[Tdiduck]

Just did the oil pressure test the car's reading is 15-18 psi.

 

[Vince Waldon]

At what RPM? Oil fully hot (10-15 minutes of spirited driving) ?

Good news that it's not 0!

 

[BobnOH]

We know it only monitors at certain RPMs. Only spec I could find is 25psi @2K. Guessing that's with a warmed up engine, but it may not matter.

 

[Vince Waldon]

Yup, "25 psi, 2000 RPM, engine fully warm (rad fans have cycled at least once" is the only official spec.

(EDIT 2.5 bar (36 psi) is in fact the factory number, as correctly pointed out below.)

The rest is in the eye of the beholder I guess.

For me, 15-18 psi with a hot engine at idle would sound OK. 15-18 psi at 3000 RPM with a cold engine would not.

 

[dieseldonato]

General rule of thumb 10psi per 1k rpm.

 

[JackvasDeferens]

The Bentley says "It is possible for the oil pressure warning system to be functioning properly and still give an occasional indication of a malfunction." Checking oil pressure: warm the engine and when the radiator fan has cycled at least once accelerate the engine to 2000 rpm. The oil temperature (not the coolant temperature) need to be at least 176F. The reading should be 2.5 bar (36 psi) minimum.
I bought a used 2001 Jetta 5-speed and I experienced my oil light going off (that horrible beep) soon after I bought the car (oil light didn't come on at all until I changed the oil to 5w-40). I parked it and did everything you are doing (replacing oil pressure switch, tracing wires, etc.).
When I checked the oil pressure, it was about 10 at 2000 rpm. I pulled the pan, and sure enough the oil pump's bolts had backed out https://forums.tdiclub.com/index.php?media/oil_pump_bolt-jpg.153456/full.
Replaced the oil pump, installed a oil pressure gauge and oil temp gauge, and drove on. Apparently the damage was already done. 75k miles later... spun bearing https://forums.tdiclub.com/index.php?media/pxl_20210421_213923909-jpg.153457/full
Not trying to scare you, but you need to make sure the oil pressure you are observing is with the engine oil at 176 or so.
The junkyard engine I replaced this one with registers about 32 psi at 2000 rpm with the oil at 180F or so. I'm taking the same approach as @dieseldonato and going with the 10 psi for every 1000 rpm.

 

[Genesis]

IMHO at "working" RPMs/load ~30+psi is a reasonable minimum. Under that you're asking for trouble and it usually does arrive.

 

[Tdiduck]

Vince it was at idle I did not drive the car at all there were times were I would rev it up to 13-1500, but nothing further than that. The engine was running for about ten minutes again I did not want to run it more than was needed to check the pressure.

Genesis the new oil filter came with the new o rings and they were replaced and the oil filter can only go in one way. I'm trying to upload a picture from my camera but can't seem to figure out how.

JB05 I can try to test for continuity with my multimeter.

jackvasdeferen So with how long the light has been on and the motor running im hoping not to much damage has been done, it just sucks that the test was not done properly by me so I might have to do it again.

I was thinking of replacing the rear main seal as it is leaking from that area as well. Decided to clean the engine bay just incase I had to do a tear down as to not get as dirty. Noticed some oil where the tranny and motor meet by the dogbone mount. But at this point what would you guys recommend as the next course of action? I'd like to keep the car but my major concern are damaged internals.

A) Take oil pan off and check oil pump and see if bolts have backed out. or pick up tube is bent or broken.
if this is done should the bearings be checked and since I'm here might as well check the cylinder walls? and or what else should be checked?

B) Remove the transmission and replace the rear main seal and test again?

C) Check the turbo line see if that could be something as well?

D) Anything else that I have missed that could be a culprit?

 

[dieseldonato]

Unless the rear main is leaking bad enough to let all the oil leak out to a very low level it won't cause low oil pressure. Things like oil pump wear, bearing wear, any clearances opening up too far, oil.pressure regulator staying open or broken, pick up tube cracked etc.

 

[Tdiduck]

Dieseldonato So option A seems like the best course of action to take?

 

[dieseldonato]

Yeah, basically check the easy stuff first then go from there.

 

[Vince Waldon]

Before tearing anything apart I'd suggest doing the pressure test again, at the specified temperature and RPM. You know you have *some* oil pressure, so the test is safe to run.

If it's OK then you know you have an electrical problem, no need to remove the oil pan etc.

 

[JackvasDeferens]

I agree with @Vince Waldon . If you have ~30 psi at 2k with oil at ~180F, there's some other culprit causing that damnable oil light and it's insistent beeping.

 

[Tdiduck]

yeah I belive someone on here said it could be a bad wire.....I imagine just from location of the wire alone being so close to the engine and the age of wires that it could also be an issue. Also found this thread Blinking Oil Light / oil pressure question | TDIClub Forums what if i do something like Mrsafety does (post #8)

 

[Tdiduck]

So i drove the car to the store to warm it up and do the pressure test and guess what the oil light did not come on.... the one thing that I did was change the dipstick tube.....
Votex - Engine Oil Dipstick Tube is Compatible with 1998-2006 Volkswagen Beetle-Golf-Jetta 1.9L TDI Diesel - Part Number 038-103-663
Is the tube I purchased I'll admit it was my 2nd tube the 1st one cracked when I was installing it, well when I got the second one made sure I watched some videos so I was positive I would know how do it how hard can it be to install a dipstick tube right......low and behold the 2nd one broke IN THE SAME SPOT!!! I said F@ck it put some epoxy around the bottom called it good for right now don't want to get a 3rd one just to break it....I was just pushing straight down like everyone says in the videos and yeah no luck...maybe those wheathies gave me that extra but not likely. Anyway...now I will take it for a drive check the oil pressure and after that hope my internals were not damaged by this conundrum.

 

[Vince Waldon]

Yeah they are all after-market now and, in my experience, break if you look at 'em sideways. I always buy 'em in pairs, just cause.

 

[Tdiduck]

serioulsy tho!! the first one was my bad used a mallet because I didn't have my wheatie's that morning so I wasn't pushing hard enough haha but i guess ill have to try again... i was thinking what if I boil some water as to "soften" the plastic up and then try it? or does anyone have a better idea?

 

[dieseldonato]

Yes, heat it up a bit. I used my wife's hair dryer, worked great, but didn't go over well with the mrs....

 

[mittzlepick]

I have a piece of heater hose holing my tube together and went a week without with a broken tube no codes. Several times without a cap no codes.

 

[Tdiduck]

Hey guys figured I would give you an update on the car....so the car runs no issues or lights. decided that I would go for a test drive took the car on a 3hr drive to see if it was ok (went camping) the car ran like a champ!! never turned off or anything I was stoked. On the way back it same thing was running great! when I got into that SF traffic came up to a light and the car just shut itself off, no lights no warnings nothing.....tried to turn it over right away nothing light turned green had to throw on the hazards after about a minute the car turned back on. Half a mile later same thing happened. In the span of about 2-3 miles it happened 3-4 times. as soon as i got out of the city and on the freeway its like nothing happened.

 

[csstevej]

When it died and you went to start it…. Does the GP light come on for a sec. If not then it’s the 109 relay that will give you the symptoms your seeing.

 

[Tdiduck]

yeah the GP light comes on

 

[Zak99b5]

Just a wag--crank speed sensor.

 

[Tdiduck]

if it was a crank speed sensor the CEL would come on would it not?