Classic Audi Technical Mech/Tech Engine » 2.8 AAH Tappetts

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Old 04-12-13, 07:46 PM   #11
F6RTY
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Just a thought, if anyone knows these things, can an oil pump deliver good pressure but poor volume?

Sourcing an oil pump for this thing is going to be very difficult and very expensive so don't want to spend money when there's no need.

I've even spoken to Audi head-office about this whole problem and, unsurprisingly, were about as much use as a chocolate teapot.

Alan
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Old 05-12-13, 09:36 AM   #12
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I'd be dropping the sump and checking / cleaning the oil pump pick up
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Old 05-12-13, 10:24 AM   #13
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This sounds alot like the saga I've been through with my 2.0 5 cylinder. Bought the car with an intermittant bad tappet. Did the cambelt/waterpump etc and new tappets and the problem is worse! If I wasn't replacing the engine, I'd be doing what's been said and having the sump off to see if there's any crap in the pickup.

If the V6s are anything like the I5s the oil pressure sender is in the block. Presumably the oil meets this sender way before it gets to the head. So the pressure you see at the head(s) could be considerably lower that what the gauge is measuring in the block.
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Old 05-12-13, 02:05 PM   #14
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I would doubt that there's much in the way of crud in the sump and/or pick up pipe as the car has been religously serviced with the occasional flush too.

There wasn't a speck of muck in either the check-valves or pressure reliefs in the head.

I shall see what a gasket costs and just for peace of mind drop the sump and see what's what.

Alan
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Old 05-12-13, 06:40 PM   #15
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Hi
The picture of the engine centre v with cover off you are showing the check valves.......your pressure relief valves sit inside the cylinder head..........they are screwed into the cylinder head by the looks of it a multi splinded socket. Near the camshaft on end the head........remove rocker cover and splash plate to locate

The pressue relief valves limit oil pressure to cylinder head to 2.7 bar yhis prevents hydraulic tappets from keeping the valves open

The check valves prevent oil draining out of the oil bores and hydraulic tappets. ......this prevents repeat starting rattle of top end.


Hope this helps
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John
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Old 05-12-13, 06:55 PM   #16
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There is a oil pressure control valve. ....on the front of engine on the left side when looking from the front of car looks like it sits under the auxiliary ribbed tensioner.....

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John
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Old 06-12-13, 12:03 AM   #17
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Hi John. Yes, the pressure relief valves in each head were the first things that were changed as they're easy to get at.

Looking at the old ones, there seemed to be nothing wrong with them.

The odd thing is, if you start the engine cold and take the filler cap off, you can see the flow of oil albeit under the splash plate coming out of the valve.

Therefore on the one hand, with the valve leaking off one would assume that there is enough pressure in the oil gallery and the lifters should be pressurised.

But on the other, the lifters are 'ticking' which suggests insufficient pressure!

By bringing the revs up to 1200rpm the flow increases significantly and the lifters are quiet.

Alan
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Old 13-12-13, 11:51 AM   #18
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Car went in for some MOT work today, rear track rod and a CV boot. The front shocks were quite weak so a new set went on. Whilst there, they dropped the sump and checked the pick-up and it was all clean with next to no crud in the sump itself. The replacement oil was a 5w30 fully synthetic and although it still ticks a bit initially, it seems quieter when hot.

Alan
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Old 27-01-14, 02:49 PM   #19
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Well, this has still been ongoing! Took the car to an Audi specialist garage in Stonehouse, Glos. last week to see if they could shed any light on my predicament.

They hooked it up to a hand-held oil pressure gauge and the conclusion was that the oil pump was healthy and the pressure was seemingly very good.

Regarding the noise, it was not considered to be an hydraulic noise but more a mild case of piston slap, which is quite feasible I suppose.

Looking into how to quieten it down, I came across some stuff called Ametech engine restore.

Now, I'm always suspicious of these things and anything in the 'Snake Oil' category but I've given it a go as of last Saturday. The jury is still out as it will need time to see if it does what it states on the tin, but so far it's not too bad with a lot less noise.

I'll report back if it's any good.

Alan
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