Hi

I have a  Polo 1999 1.4 CL 8V 6N (APQ Engine 60HP) and the oil pressure warning light comes on if revving above idle and is sounding very 'tappetty'!

I have changed the oil pressure switch and have found quite a lot of sludge in the engine, have flushed the engine oil, replaced filter and cleaned strainer.

No improvement - it points towards the oil pump but would like to know if this could still be an oi sludge problem blocking the oil ways around the cylinder head.

 

Is there a simple test to determine whether this is an oil pump or oil way blockage - or at least a low cost option to proceed with first? I'm almost at the point of writing the car off if Oil pump job which is a shame as been a loyal runner for years.

 

Thanks for your advice

It is quite possible that the use of flushing oil has freed off some sludge that would have otherwise stayed more or less harmlessly inside the crankcase.

Suggest that you change the oil and filter again and see if there is any improvement.

Removing the sump in order to clean the pick-up strainer, is possibly the worst part of changing the oil pump, so you now know what that involves.

The only sure way to check the oil pressure, is to fit a pressure gauge - You could do this either as a 'test gauge' or fit one permanently in the car, if you did the latter, you would also need a 'T' piece in order to be able to use the gauge AND the existing pressure switch.

You can buy a gauge and all the parts that you will need, if you download the catalogue from www.vehicleproducts.co.uk

 

Lack of oil pressure with increase in engine speed above idling, generally indicates a blocked pick-up strainer. I am just wondering if some sludge freed when flushing, has again blocked the strainer - Was there ANY improvement after you first cleaned it?

I am never very trusting of aftermarket sensors, this includes things like the oil pressure switch - Was the new one a genuine VW part?

 

Regards

Hi

There was no improvement after cleaning the strainer and the pressure was low before the flush - that was the reason for the flush, oil warning light and buzzer and I found lots of muck in the rocker cover (under oil filler cap). Engine also sounds like tappets are noisy - but was thinking this is due to lack of oil and not damage.

The Strainer was completely full of sludge - so I'm thinking it must be like that in other places and could be restricting flow to the top of the engine.

 

I would like to use a 'super flush' to really attack the sludge - I did hear of someone using diesel oil for a few minutes which was quite successful??

 

To invest too much more isn't really worth it - new Oil Pump is half the car value and I'm not 100% convinced it is faulty

 

Thanks

 

 

 

get some one to terra clean it, then check the oil pressure, also if you wip the sump take no 4 con rod cap off and check the bearings.

 

oil pressure is only made by the clearance within the bearings not within the oil pump, oil pumps only create flow.

Hi

Thanks for your help - Terraclean sounds great but expensive - but perhaps lower cost than a double flush

Here are some more clues -

Ran the engine for 15 minutes and things began to quieten down as everything warmed up.

I put a pressure gauge in place of the pressure sensor and that reads 4 Bar going up to 5 Bar at 2500 rpm. there is now nice clean oil at the top of the engine which drains down without resistance, the engine is now running much quieter. HOWEVER - at idle the oil pressure warning light is out but when you rev the engine there are 3 audible beeps and the light comes on - after another 20 seconds or so at idle the light goes out - if you rev it again the same alarm comes on and this continues.

Have talked to a a couple of people about this and all are confused how the pressure can be fine on the gauge but not on the sensor. By the way it has had 2 new sensors now as well in case the new one I bought was also faulty.

Anything else I can try??

forgot to say the 2 replacement sensors were both NOT VW genuine parts - perhaps something I should try next.

Could anyone confirm if the AQP engine only has a single pressure switch (low pressure) 0.15 to 0.35 bar? Because I am measuring 3.5 to 5 bar at the same position as the sensor at 2500 rpm??

 

Edited 22 November, 20169 yr by LOZZA

Problem solved - wrong replacement oil pressure switch (twice) - for the 1.4 APQ 4 cyl 60 hp engine, there are several shown by most parts suppliers. However some are normally closed and some are normally open. So by installing a normally closed switch as soon as the engine reached 2000 revs the panel behind the speedo decided that the switch must have switched due to low pressure but it was simply in its normal state. It seems that most illustrated parts catalogs show that this engine has a normally closed switch - IT DOESN'T they are wrong. It took a call to a specialist parts supplier to give the correct specification.

Useful tip - if you have to replace your pressure switch consider measuring continuity between the terminal and the body to see if it is normally closed or normally open at least to give you a clue. Also consider measuring the continuity between the end of the cable and earth - this should be the same as the switch in normal state.

 

So there was a real problem in that the oil strainer was blocked and the old switch did its job - once cleaned it should have been ok but in being extra cautious and replacing the switch as well (with the wrong one as advised by most suppliers) it appeared that we still had the problem - very frustrating that even with an engine number the suppliers get it wrong!!