Club 80-90 Forums

Hi. I'll try to blend two topics together. So here are my problems with my AHU engine.

No 1. After the engine conversion I can hear the hydraulic follower lifters tapping on idle when the engine is warm. When doing the conversion I swapped the oil pump from my JX engine. I did not notice tapping on the donor car when it was running although I ran it very briefly before breaking. Two weeks ago I replaced all the lifters but the tapping remains. This got me thinking that the oil pump does not create enough pressure. So replacing the oil pump should solve the problem?

No 2. I bought myself on fleabay a cheap set of used VDO gauges off an audi. They came without senders so I bought a genuine used sender from another seller which did not state what audi model was it from, but stated that it was 0-5bar sender that I need. I installed the sender in the oil filter flange and wired the gauge. Now the readings I get are very strange to me. Cold engine started shows 5bar+ If revved the needle bends to the end of the scale. After two - three minutes the tapping begins and the gauge shows 3bar on idle but still goes out of scale when revved. And finally when the engine is fully warm the gauge shows 1bar on idle and about 5bar on 3000+rpm. So the gauge is working but I do not believe the readings are correct.
My thoughts on this problem are either the sender and the gauge do not mate or the sender is placed in the wrong place (I remember some audis had the sender in the cylinder head?) Later I'll try to look for the part numbers of the gauge and sender I have if it helps.

Sadly my mates at the garage do not have a mechanic oil pressure tester to test the actual pressure. What are your thoughts on these topics? Thanks

Donatas

Hi Donatas,

those readings seem pretty much right to me - however I would advise you taking the oil pressure reading at the cylinder head - you will lose some oil pressure before the head. You can put a t-piece for a remote reading and keep your low revs oil pressure sender there too - I did this. I would also advise you use the tdi pump with a JX pickup - this would give you the right oil pump for the engine.

The tapping you are talking about is annoying and I never completely got rid of it on mine - it drove me mad, but it was really hard to pin down. I used a stethoscope (or just long screwdriver) to try and pin down exactly where the noise was coming from. Bizarrely mine was really hard to pinpoint when near the engine - but it became very noticeable at the front of the van. It was suggested to me that the long water pipes were amplifying a noise somewhere in the cooling circuit but I'm not sure I buy that. I believe that mine was due to the engine being on an angle and that the lifters were allowing thinner, hotter oil to exit the followers quicker than they could pump up. The JX engines have solid lifters rather than hydraulic so perhaps that's something to do with it. You could try a slightly thicker oil perhaps - I used quantum 10w40 in mine rather than the platinum 5w40.

Sorry I can't give you a solution to the problem - I'm interested to hear what other wiser people suggest!

Ewen

According to Haynes you can use up to 20w - 50, I have used 15w - 40 in my 1Y.

I'm using 10w40 semi synthetic oil. My mate had a look at the oil pressure readings and he thinks it is definitely to low. He reckons that there should be almost no pressure in the cylinder head when the engine is hot and idle. I already drove more 10000 miles like that
I remember when putting the engine back together I had a look at both oil pumps and came to a conclusion that the pick ups were not interchangeable. That's why I've used the JX pump. The TDI pump now is long gone with the old JX. I guess I'll buy a new pump. The one brickwerks sell any good?

By the way the oil pressure sender has two terminals. One is for the gauge and another is the low pressure warning. 0.5 bar if I'm correct.
I'll measure the oil pressure in the cylinder head next time.

And finally where do I put the oil temp sender as now I have a gauge for that too?

Hi Donatas,

the warm idle figure is slightly low if reading from the oil filter housing - only way of really telling what the pressure is at the head is to read it there! I fitted an oil temp sensor on the sandwich plate for my front-mount oil cooler, but once again you'd be better off reading from the head as that's where the oil's done a lot of its work. I fitted something like this, and made a bracket for the oil pressure sensor on the bulkhead - seemed to work ok for me:



I'm not sure about the pickup pipe as I can't remember exactly what I did - I had the oil pump strainer get totally blocked and replaced the whole thing with a jx one as I was abroad and in a hurry to get it fixed before I got divorced. That gave me about 1.8 bar at hot idle but with a not very good gauge - it was really just a sanity check for me....

Good luck getting rid of the annoying tap!

Ewen