Oil pressure issues on my b2 cq

andya · 01-08-21, 06:57 PM

Hi all. I've got an issue with the CQ. About 6 weeks ago I had the oil pressure light and buzzer coming on over 2200rpm and only when the engine was hot. I solved it by replacing the high oil pressure sender unit. Fast forward to last week, and I was travelling back from holidays having done 1000 miles of trouble free cruising and the buzzer and light came on again on the a303. I freewheeled off at a convenient slip road. Once I dropped below 2100rpm the buzzer and light went, but at idle, I had a flickering light. I decided not to continue at motorway speeds and went back home the back roads keeping my speed down.

Since then I've looked at both senders again. Their fine. I've changed the relay, that's made no difference. Any ideas? It's putting my spot at next week's AITP in jeopardy, so if anyone has any ideas let me know! I certainly wouldn't want to risk the journey up to Northamptonshire if it's not right

84CoupeGT · 01-08-21, 07:31 PM

I don't know too much about this, but just a thought... Has the oil been changed recently? Wrong grade of oil could possibly cause pressure issues... Or if it's due a change, filter or a valve somewhere could be clogged up?

tractor Dave · 01-08-21, 07:53 PM

Have you got an oil pressure test kit? Plug into the sender hole and test when warm.
They are cheap to buy if you haven't got one. I would lend you mine but postage back and forward would be more!

andya · 01-08-21, 07:55 PM

Quote:

Originally Posted by tractor Dave

Have you got an oil pressure test kit? Plug into the sender hole and test when warm.
They are cheap to buy if you haven't got one. I would lend you mine but postage back and forward would be more!

A mate is coming over to mine next Saturday with a pressure gauge kit. Just wondered if there's anything else I can check in the meantime

tractor Dave · 01-08-21, 08:02 PM

Quote:

Originally Posted by andya

A mate is coming over to mine next Saturday with a pressure gauge kit. Just wondered if there's anything else I can check in the meantime

Did you fit the correct pressure switch and was it a good make? Pressure test will confirm. Have you got the Aux gauges?

andya · 01-08-21, 08:08 PM

No on the aux gauges, but my friend does and has said he will bring them along. I did also think about the correct pressure switch (got it from gsf) - I've since brought one from eBays highland quattro seller - I'll try that tomorrow

andya · 01-08-21, 07:53 PM

I'm on the same oil. It's changed every year and I use genuine audi oil filters. What grade oil do you use on your GT?

It's worth noting that the light and buzzer only comes on when the engine is hot.

84CoupeGT · 01-08-21, 09:50 PM

Quote:

Originally Posted by andya

I'm on the same oil. It's changed every year and I use genuine audi oil filters. What grade oil do you use on your GT?

It's worth noting that the light and buzzer only comes on when the engine is hot.

From memory I put 15W/50 in, that's what it says in the owners manual, but I can't offer much feedback as I haven't driven it anywhere yet! Sounds highly unlikely it's the oil or a blockage then as you change every year.

Just in case you don't have the Haynes, other suggestions below...

4v6 · 02-08-21, 03:00 PM

If its not electrical id go for oil pressure relief valve, Ive seen these stick in the housing from time to time after they get a little scored or sludgy.
Easy to remove in situ just take out the oil temp switch on the pump and the valve, spring and a little oil should drop out, note the order and direction of the parts!!!
Polish the exterior of the valve plunger doodah with autosol or other metal polish and clean it thoroughly.
Refit then sit back and relax as the oil light comes on yet again..

steveb · 02-08-21, 08:03 PM

I have a vague memory of the oil pick up getting clogged and causing this problem

01-08-21, 08:08 PM	#6
andya Senior Member Classic Audi Club Member Join Date: Aug 2010 Location: Hampshire Posts: 1,149	No on the aux gauges, but my friend does and has said he will bring them along. I did also think about the correct pressure switch (got it from gsf) - I've since brought one from eBays highland quattro seller - I'll try that tomorrow __________________ 1985 Coupe Quattro 1986 Coupe 1.8 weber carb 1987 Coupe 2.2 GT

01-08-21, 07:53 PM	#7
andya Senior Member Classic Audi Club Member Join Date: Aug 2010 Location: Hampshire Posts: 1,149	I'm on the same oil. It's changed every year and I use genuine audi oil filters. What grade oil do you use on your GT? It's worth noting that the light and buzzer only comes on when the engine is hot. __________________ 1985 Coupe Quattro 1986 Coupe 1.8 weber carb 1987 Coupe 2.2 GT

02-08-21, 08:03 PM	#10
steveb Senior Member Classic Audi Club Member Join Date: Jul 2008 Location: West Berkshire Posts: 1,155	I have a vague memory of the oil pick up getting clogged and causing this problem __________________ [FONT] '76 Leyland Princess 2200 HLS '79 Scirocco storm '84 WR '89 coupe quattro '01 A2 1.4 TDI SE '14 A3 1.4 TFSI COD [/color][/size][/font]

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01-08-21, 07:31 PM	#2
84CoupeGT Grown up member Join Date: Nov 2020 Posts: 309	I don't know too much about this, but just a thought... Has the oil been changed recently? Wrong grade of oil could possibly cause pressure issues... Or if it's due a change, filter or a valve somewhere could be clogged up?

01-08-21, 07:53 PM	#3
tractor Dave Senior Member Classic Audi Club Member Join Date: Apr 2018 Location: Wales Posts: 1,174	Have you got an oil pressure test kit? Plug into the sender hole and test when warm. They are cheap to buy if you haven't got one. I would lend you mine but postage back and forward would be more!

02-08-21, 03:00 PM	#9
4v6 Ex Member Classic Audi Club Member Join Date: Dec 2007 Posts: 5,565	If its not electrical id go for oil pressure relief valve, Ive seen these stick in the housing from time to time after they get a little scored or sludgy. Easy to remove in situ just take out the oil temp switch on the pump and the valve, spring and a little oil should drop out, note the order and direction of the parts!!! Polish the exterior of the valve plunger doodah with autosol or other metal polish and clean it thoroughly. Refit then sit back and relax as the oil light comes on yet again..