Why does the oil pressure drops down?

I have a problem with the 1.8i engine of my karmann cabrio.

Sorry if I?m not using the right section of the forum, but I really need your help (I also read that a technical section is about to be created. Great!)

There it goes: when I put the engine to work the oil pressure seems to be ok, around 5 to 6bar (the car has an oil pressure gauge at the central console).

However, after a few minutes after putting it to work ? and this can vary between 15 to 30 minutes depending on ambient temperature ? the oil pressure drops down and the red light starts flashing whilst the gauge pointer rests to the left side, quite below 1bar!

I don?t drive the car in this condition and lately I avoided taking it out of the garage. But the summertime is coming!

I read some related topics in the forum but all of them seem to report electrical, dashboard and/or pressure sender problems. This seems to be different as the oil pressure is ok at the beginning and drops down as the engine heats. Apparently it has to do with the oil getting thinner with engine temperature but I don?t understand why and this is driving me crazy. The best reply I can get from the mechanic is that ?we must open the engine and see . . .? which is not very comfortable at all!

Any idea?

Don't know if this helps:

I'm running a DX series 1.8 cabriolet with the Bosch K-series fuel injection - original non-rebuilt engine with 114,000 miles on the clock.

Oil - Shell Helix-plus 10w-40

Oil pressure (warm engine) at idle is 2 bar / 1500 RPM 4 bar / 2000 RPM 5 bar - is about 1/2 bar when engine is running hot.

Try flushing with flushing oil and refilling with Shell Helix-plus 10w-40 to see if you get an improvement would be my first step.

M

rpvmoura said

I have a problem with the 1.8i engine of my karmann cabrio.

Sorry if I?m not using the right section of the forum, but I really need your help (I also read that a technical section is about to be created. Great!)

There it goes: when I put the engine to work the oil pressure seems to be ok, around 5 to 6bar (the car has an oil pressure gauge at the central console).

However, after a few minutes after putting it to work ? and this can vary between 15 to 30 minutes depending on ambient temperature ? the oil pressure drops down and the red light starts flashing whilst the gauge pointer rests to the left side, quite below 1bar!

I don?t drive the car in this condition and lately I avoided taking it out of the garage. But the summertime is coming!

I read some related topics in the forum but all of them seem to report electrical, dashboard and/or pressure sender problems. This seems to be different as the oil pressure is ok at the beginning and drops down as the engine heats. Apparently it has to do with the oil getting thinner with engine temperature but I don?t understand why and this is driving me crazy. The best reply I can get from the mechanic is that ?we must open the engine and see . . .? which is not very comfortable at all!

Any idea?

Really need to know engine mileage etc but sounds like worn shells,is there any noise from the engine at all?

Michael said

Don't know if this helps:

I'm running a DX series 1.8 cabriolet with the Bosch K-series fuel injection - original non-rebuilt engine with 114,000 miles on the clock.

Oil - Shell Helix-plus 10w-40

Oil pressure (warm engine) at idle is 2 bar / 1500 RPM 4 bar / 2000 RPM 5 bar - is about 1/2 bar when engine is running hot.

Try flushing with flushing oil and refilling with Shell Helix-plus 10w-40 to see if you get an improvement would be my first step.

M

Thanks Michael,

I use a synthetic Mobil 10W40 oil (don?t remember the name) and I?ve been told that I should use a mineral one. What do you think? Is the Helix Plus a mineral or a synthetic one?

I will check the oil pressure against your figures as soon as I get home in the evening. But I?m sure that at idle and after engine is hot (cooling fan on) the oil pressure is as low as yours, i.e., less than 1bar!? Is this ok? Thus, why does the red light flashes?

Pedro

the synthetic oil is proberly to thin flush and change the oil should be 15/40 i have put details on oil pressuire in another thread cant find it at the moment though

http://www.vwgolfmk1.org.uk/modules.php?name=Forums&file=viewtopic&t=33069

in this thread

collo16v said

rpvmoura said

Really need to know engine mileage etc but sounds like worn shells,is there any noise from the engine at all?

Hi and thanks,

I'm pleased to give you all the information you need! Please ask me

The engine have less than 80.000km and the engine sounds like music. It starts like a clock even after long periods off, it doesn't lose any oil and the colour of it is alloways clean amber (not burnt black). It seems that as the oil gets thinner it escapes through any "damn small stupid hole" to elsewhere inside the engine I can't figure out. Can it be any oil pump damage or malfunction due to the long periods the car is off running?

Pedro

sorry matie typo

"Oil pressure (warm engine) at idle is 2 bar / 1500 RPM 4 bar / 2000 RPM 5 bar - is about 1/2 bar when engine is running hot"

should read "is about 1/2 bar lower when engine is running hot"

Michael said

sorry matie typo

"Oil pressure (warm engine) at idle is 2 bar / 1500 RPM 4 bar / 2000 RPM 5 bar - is about 1/2 bar when engine is running hot"

should read "is about 1/2 bar lower when engine is running hot"

Ok! And about the oil, do you use a synthetic or a mineral one? What is you experiece?

Pedro

Shell Helix-plus 10w-40 is synthetic

Your Mobil oil is equivalent - good oil

Come on guys, I need your help  . . .

who votes for:

• worn shells
• pressure sender(s)
• oil pump is damageg
• unapropriate oil and/or brand

Please don't make me agree with the mechanic and let him open the engine without having the diagnostic.

Happy Easter!

Your oil pressure is held up by two things. Oil pump and shells. Ok agree that you are using too thin an oil, VW engines were never that refined to run fully synthetic anyway although a lot of people use it. I would firstly change to a good quality 15/40, change the oil filter to an OE VAG or equivilant and see if this makes any difference. There could also be other factors, partially blocked gallery etc although these would show up from the start. How does the engine sound?

Mines on 170,000 miles and here's my readings for the oil pressure

When cold 5 bar, when warm (but not hot) 4.5 bar when driving and 2.5 bar at idle,  when thraping it long distance down the motorway 3.5 - 4.0 bar and if I then go to idle the pressure drops to 1 bar….it's been like that for 3 years and no rattling from the engine at all.  All those pressure readings were with the oil sold by VW (forgot the name of it)

I put a cheap oil in early last year, just to give the engine a flush before a proper service and went to Santa Pod in it, the oil pressure was 5 bar cold, but when she got hot it didn't even manage 2.5 bar when motorway driving  8O ……so try changing the oil for a good brand, before you take the engine in for open heart surgery.

yep - all of the above.  Would also look at changing the pressure sender - might be the oil prssure is fine - just that the instruments are receiving the wrong data.

with only 80 clicks on the clock, running like a watch and burning nice and clean I'd be loath to pull it apart.

M

before you do anything including opening the engine up,i would borrow a mechanical oil pressure gauge and check the actual readings and go from there  :wink:
Bert

I would do an oil/filter change first, using the correct grade Mineral oil (not synthetic) and replace the oil presure sensors while ur there. Then go from there. Cheap and easy

Wow!

Thank you Cero, GAMMIGOLFGTI, Michael, Bert and Jay666.

Now I've got good advise and enough stuff to help me finding out what is realy happening (before opening the engine).

Besides, I fell less concerned as my engine beaves much like GAMMIGOLFGTI's one!

I'll start to buy a mineral oil from a local VW dealer, change the oil filter and see what happens. Then I will change the pressure senders and I will try to chek pressure directly from tha block with a gauge.

I will let you know the results

Thanks again.

Pedro

i used mobil1 5w40 in an old gti i had, regular oil and filter changes and had no problems at all with her. all depends on the condition of the engine, as far as i'm concerned.
 i'd be surprised if the oil is the problem. worth a try though. best bet, is to follow berts advise, to be sure.