Oil pressure ?

[Alfan]

I have now been driving my Q4 the last 3 weeks and done 3.000km, only having a problem with a leak at the top of the fuel tank (which I hope is now fixed).

However, on my drive to visit family during Christmas, driving on the motorway at 110 - 140km/h, the oil pressure meter started dropping and fluctuating when increasing the speed from about 110km/h (3 bar) to 130km/h (2 bar or lower and fluctuating)! I don't experience that the engine is behaving/sounding badly, but last week there was more sound from the hydraulic valve lifters on the rear bank than usual.

I hope this is just the sensor acting up, since behaviour up to 110km/h seems to be normal. I made a video of it, which I will try and upload later.

Input is much appreciated!!

Link to video, hope it is possible to see the gauge behaviour:

https://www.dropbox.com/s/gjdhkjfilmkl8 ... 9.mp4?dl=0" onclick="window.open(this.href);return false;

[164EVER]

Watch your oil pressure when driving in curves, if it drops , probably the pressure is dropping because the bushings are used and need to be change for new ones.
Unless the shaft or the rods would break.
It means the engine is milaged.
Oil pump must be check and before all, change oil press sensor.

[alfa east]

It means the engine is milaged.

Well, if I read Alfan's subscript: "1994 Alfa Romeo 164 Q4 Proteo Rosso 515.000km" then yeah, you maybe on to something!

[wilco]

Hmm, when on idle the gauge says 0 and no lights comes on, probably it is the sensor.
but always a good idea to let it check at the workshop..
seeing the video, i suspect the sensor itself.
With that low pressure, you certainly will see the low pressure light go on in idle.

[Alfan]

Well, the valve chatter is on and off and now I added Wynn's 'Hydraulic valve lifter concentrate' to find out, if it changes/reduces the sound.

Within the next few weeks (if things don't change), I will replace oil and filter and replace the oil pressure sensor, as it might have gone faulty at the same time, by some coincidence.

[Alfan]

Time for an update. The oil pressure reading is still not good, but that must be the sender.

The valve chatter disappeared about a week ago and all seems to be normal, so I will wait a bit doing the oil change

[wilco]

good News but do a second opinion at the local garage and put a oil pressure gauge on it to make sure the Readings are okay

[AlfaWhiz]

Can be the sender, the technology is ancient, it looks like something from a tractor.

It is obvious, but make 100% sure you have enough oil in it.

[Alfan]

Engine still running good and no valve chatter, so the fluctuating pressure can only be the sender - I will find out when I replace it

And yes, I check the oil level regularly

[Alfan]

So I changed the oil, filter and pressure unit, but before that I ran Wynn's engine oil cleaner for 15 min at idle.

No valve chatter so far (300km) and the oil pressure gauge is stabilized. However, there is an offset on the pressure unit, I got, so when turning on ignition, it goes to '1'. I measure 58ohm on the new one and 325ohm on the old one at roughly the same temperature.

So right now things are back to normal, sort of

[164EVER]

Good news.
I had also to change the sender on my TD, and each time I restart old Bussos, I had three ALFA 6 in the past, I had to replace it.

[Alfan]

So after driving for a week after the oil change, the valve lifter sound is back. With the mileage I can't really be surprised.

However, when stuck in a motorway queue, all of a sudden the oil pressure went to max! Not what I expected and nothing else happened. It came back down when driving again, so either there is a problem with the gauge or a cable.

Something more to look into, when it is taken off the road after winter.

[wilco]

must be a wire problem. with a hot engine, there is no way the pressure wil get over 5 at idle.
Then, the valve clatter.. shouldn't be so much as they are hydraulic. only way they start clattering is they are all bad or else a low pressure..
but then.. I think its the wire or sensor that makes you scared hehehe