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Discussion Starter #1
Driving home from work last night down the dual carriageway and the oil pressure starts to creep up. I'm doing about 70 because traffic is quite heavy, so not exactly thrashing it, and keeping a constant speed. It's usually up around 4.5 - 5 bar cruising like this, but within a couple of miles it had crept up to almost 8 bar on the gauge :eek:

I slowed down to 55mph and it dropped back down to 5 bar and stayed there. Hmmm. What could cause this I wonder, dodgy gauge/sender maybe? Why would oil pressure shoot up like that. Car was driving perfectly, no sign of trouble other than the reading.

This morning I checked the oil, it was on the low side, but I don't see how that explains a rise in oil pressure? It was fine on the journey this morning. Any ideas peeps?
 

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What was the water temp doing? Any chance the water / oil HX was overcooling the oil? Is there a pressure limiting valve in the system somewhere? If there is, maybe it's sticking?
 

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Have you just changed to fully synthetic? Sometimes doing so releases crud which may cause a partial blockage.

Phil
 

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Hi,

the sender units usually give up first...I would go for that.

Could also be a shortcut in the wiring.

Last reason could be a jammed overpressure valve.

grtz

amir
 

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BW Try cleaning the terminal on the sender and also making sure that it`s a tight fit ;) :D

If still no better then change the sender :rolleyes:
 
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Cheers guys. I haven't changed oil grade, I'm running Magnatec semi-synth. It hasn't done it again....yet :)
 

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I'd guess a chaffed wire earthing somewhere like the block. It won't be your engine. :)
 

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Hi Peeps,

I had a similar thing happen to me yesterday...

Cold start up is about 4.5/5 bar... rarely at around 3.5 when a temperature...

Anyway.. at about 80mph one minute it's @ 4bar next under 8... if the senders shot surely the gauge wouldn't either? Slowed to do 50... yes 50 and it eventually came down... (I'm talking !!!!!! again... I'm going home!)

Then this morning, on start up she coughing, spluttering, missing... I left her to warm up for a bit and seemed ok upon return... (guess she needs a service soon eh!)

BW - what sorted it for you... oil top up?
 

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I hate doing this - the voice of doom really bugs me...

BUT, have a scout around for signs of a leaking head gasket :( with it being your oil pressure going up, it would be a water -> oil leak, so would show up as mayo on your oil filler cap. With hotter weather, your cooling system is under increased strain, so might show up a problem. Was your water temp as normal - i.e. no more than 90degC?

I hope it is just a dodgy sender, but just to be sure... you might catch a problem before it happens...
 
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umesh - sorry mate, the problem just went away - I think it was just a dodgy sender moment. It hasn't happened since (that I've noticed). Oils has been changed since also.
 

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NO RICH' don't say THAT!

will check the oil...

but yeah the engine temp was around 90c. . . the pressure was loopy :eek:

Hmm will have to check the sender isn't loose also I s'pose - anyone got a location diagram?
 

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umesh said:
NO RICH' don't say THAT!

will check the oil...

but yeah the engine temp was around 90c. . . the pressure was loopy :eek:

Hmm will have to check the sender isn't loose also I s'pose - anyone got a location diagram?
:rolleyes: It's number 2 in the top part of the diagram :rolleyes:
 

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I don't know, but as it's on the back of the engine under the inlet manifold I suspect it's not that easy to get at........... :rolleyes:
 
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Discussion Starter #15
Yes it is easy. There is plenty of room to get your hand/arm in there. It is yellow coloured (or the plug is, can't remember) and it's behind cylinder number 4 (on the 8v anyway).
 
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