Rising Oil Pressure.

[springs 0]

Hi Guys.

 

I've had a search around but couldn't find many answers to my question.

 

I've got a 1.6 gti and once the car is up to temp and car's been driven, when you stop the car either at traffic lights etc the oil pressure (top left gauge) will start raising and the red light and stop light will turn on. If you rev the engine the gauge will drop down but raise if you let off the throttle. I topped up the oil when i got the car and it did make it a little better but obviously no cure.

 

Any ideas?

[giveitsomebar 0]

surely if the gauge is raising its going towards the max mark not the red light side?? these cars are prone to have fault oil sender units might be worth replacing that first and then if its still the same then start looking into bottom end / oil pump

Edited June 4, 2010 by giveitsomebar

[springs 0]

Which sensor is it? i noticed there is one on the sump but i'm guessing that's a oil level sensor?

[rescue dude 0]

Which sensor is it? i noticed there is one on the sump but i'm guessing that's a oil level sensor?

 

 

Thats the oil temperature.

 

You need one of the two on the front of the block. Can't remember which one.

 

One does the gauge and the other the low pressure warning if I remember correctly.

[springs 0]

Ah cool.. Thanks. Ill have a read through the haynes and see what i can find regarding them

[rescue dude 0]

The pressure sender is the right one, the one on the left is the 'Stop' light sender.

[Miles 331 1 Cars]

Sounds like some wires are on worng, The oil pressure guage with too much pressure just stops working until the pressure comes down again as I have this in my Gentry, Only the stop warning light's bring the STOP light on

[McDude 33]

Sounds like some wires are on worng, The oil pressure guage with too much pressure just stops working until the pressure comes down again as I have this in my Gentry, Only the stop warning light's bring the STOP light on

Also the behaviour of the guage sounds wierd too. At idle the oil pressure should drop (needle to the right) and then go back up (needle to the left) with revs. It should settle at a point and not move once engine is revving.

[giveitsomebar 0]

i have a group a oil spring in mine and it reads off the scale and the stop light doesnt come on either? thats why i asked if it was going towards the red.

[springs 0]

I think what i will do to make it a bit easier to understand is once the car is back together ill grab a quick video of it and hopefully will show you more clearly what I'm going on about.

[CosKev 16]

Also the behaviour of the guage sounds wierd too. At idle the oil pressure should drop (needle to the right) and then go back up (needle to the left) with revs. It should settle at a point and not move once engine is revving.

 

Thats the wrong way round ain't it?????

 

Lower pressure or eng not running the needle goes to the left.

 

Start the eng/rev it and needle rises to the right

[springs 0]

I've managed to get some sort of video of the problem. Car was idling for a few mins before this was taken. although you can't see if on the video the needle starts in the middle and slowly starts going towards the left. What you don't see is that eventually the red light will come on and so will the stop light.

 

In the video at about 40 secs I blip the throttle and the needle rises and then slowly comes back down towards the left again.

 

[MrG 3]

I'm with CosKev, rises to the right drops away to the left.

 

so judging by your description (as the vid doesn't tell you much) is you start to lose pressure? But when you rev it, it increases.

 

so does it drop to zero and the light come on when its idling? Or does it do that when you're driving?

[McDude 33]

Ignore my input - I got the needle behaviour the wrong way round.

 

Sorry.

 

Please continue...

[springs 0]

it only does it when at idle. If I'm driving its fine but when i stop at traffic lights etc is when it drops.

[shalmaneser 26]

it only does it when at idle. If I'm driving its fine but when i stop at traffic lights etc is when it drops.

 

That's completely normal behaviour, although your pressure overall does look a little low perhaps. when hot and at idle my car is about in the middle of the gauge. anything more than about 2K revs and it's topped out - as far as it can go to the right.

 

You've got nothing to worry about here, although it may be worth putting in some slightly thicker oil next oil change?

 

The oil pump is directly connected to the crank, so oil pressure is to an extent a function of crank speed.

[pug_ham 244 3 Cars]

As said, thats looks fairly normal behaviour albeit a little on the low side but what mileage has your engine done because even though they are generally strong engines they can still suffer if not fed decent oil previously.

 

I think you have a possible sender or wiring issue, maybe both combined to give you you guages levels.

 

Graham.

[powermandan 0]

if you have a low idle speed you can get this problem.

[Anthony 1,003]

You seem to be a bit confused in your earlier posts - the oil pressure gauge is 0 on the far left (ie the red light) and 8 bar on the right right. The needle moves further right as the oil pressure increases.

 

As said above, the gauge behaviour is normal - cold oil is thicker and gives higher pressure than hot, thin oil (hence the gauge is higher when started from cold compared to after a few miles) and since the oil pump is driven from the crank, oil pressure will increase as the revs climb (upto the point where it achieves max pressure, when it will remain constant until the revs decrease)

 

However, what is not normal and cause for concern is the oil pressure dropping so low at idle that the STOP light is coming on. When this happens, roughly what speed is the engine idling at and how high is the oil temperature? With a GTi-6 oil pump setup and the idle speed governed by the ICV, it shouldn't really ever drop low enough for the light to come on.

 

At 4000rpm, how high does the oil pressure gauge read? Should be something nearing 3/4 on the gauge with a GTi-6 engine, but given that the gauges are far from perfect at the best of times, so long as it's above halfway I wouldn't worry too much.

[springs 0]

I think the oil in the car is 10w40 but needs an oil change soon anyway. Mileage on the car is about 146K

 

Not 100% accurate on this but I think the car idles at less than 900 rpm. Will check tonight about the idle.

 

The concerning part is the stop light coming on. Never good in most situations.

Edited June 7, 2010 by springs

[Anthony 1,003]

Has it still got the GTi-6 engine fitted, or is it an 8v again now?

[springs 0]

This is a 1.6 8v.

 

The Gti-6 is in another shell although no longer alive

[Anthony 1,003]

Ah right, ignore a few of my comments above then.

 

The oil pressure will probably only get to about 1/2 - 2/3 on the gauge at 4000rpm+, and it's entirely plausable that the idle could dip low enough to make the STOP light come on if it's not setup/running right. Set it so that it idles around 1000rpm hot (turn the idle speed screw on the throttle body anti-clockwise to increase idle speed) and see if that improves matters.

 

Also, double check that the 22mm crank pulley bolt is tight, as if this comes loose it will cause the oil pressure to be lower than expected and behave in odd ways. This particular quirk was fixed on GTi-6's, hence not mentioning it earlier.

[springs 0]

Will check those 2 things over when I get home and see where it goes from there.

 

Thanks for the Info.

[GLPoomobile 958]

Not 100% accurate on this but I think the car idles at less than 900 rpm. Will check tonight about the idle.

 

I've never had any of my GTIs set that low. Always set them to about 1000rpm hot idle. I say "about 1000rpm" because with Jetronic being as crap as it is when old and worn, it's often difficult to set it dead on and have it maintain that speed for ever more. I can't even imagine having a Jetronic equipped GTI idling steadily at sub 900rpm without stalling fairly regulalry!