# Cam chain tensioner oil pressure



## ttr gr (Jun 1, 2006)

Good afternoon!!!

After hearing a rattling noise from the top of the engine for a second after starting the engine and after reading a similar case i have come to the point of believing that it is propably a cam chain tensioner problem.I will start by changing the oil to MOTUL E-TECH 8100 but i would also like to know which part of the engine is responsible for the oil pressure of the cam chain tensioner when the car is switched off.Is it a remote part that can be changed without getting into the big trouble of the cam chain tensioner replacement???
Anxiously awaiting of advice!!!!


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## Hosken Racing (Sep 8, 2005)

Is this on a TT?
If it is a TT, It doesn't have a Cam chain. Its an easy mistake to make. 
Quite a common rattle on start up comes from the hydraulic lifters when they are a bit worn and they take a bit of time to fill with oil. Different oil can make a difference.
Regards,
Mark


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## John-H (Jul 13, 2005)

Well it does and it doesn't. Certailly the cams are first driven by a long rubber cam belt driven from the crank sprocket but this belt only drives the exhaust cam shaft. The inlet cam shaft is driven by a short chain from the exhaust cam shaft at the other end of the engine.

There is an oil damped belt tensioner/damper which if worn can rattle - more at idle but also at certain other rosonant frequencies at certain engine speeds. This has its own captive oil and is not pressurised by engine sump oil.

The chain tensioner is under oil pressure from the oil pump. If this rattles it's more likely to rattle at idle and when hot when the oil pressure is lowest. Sometimes the tensioner can leak excessively and cause low head pressure, which causes the cam followers to collapse and rattle - again mainly at idle when hot.

There is a non return valve in the cylinder head but it's purpose is to stop the oil draining back into the block when the engine is stopped, so that when the engine is started, oil pressure is established quickly without having to pump out air first. When the engine is stationary there is no oil pressure in the head as any pressure would escape out of the bearings immediately.

If you experience cam follower rattle at hot idle it can be caused by this leaking tensioner but can also be caused by a worn oil pump or other engine bearings etc. Diagnosis would entail checking the oil pump pressure at hot idle - if it's good; the pump, main bearings and big ends are fine and it's more likely to be a problem at the top of the engine - possibly the tensioner.


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## ttr gr (Jun 1, 2006)

Oops! I forgot to mention that it is a 225 Quattro TTR of 2001 with 55000KM.Is the MOTUL 8100 the right oil or should i choose a thicker oil since i live in Greece where temperatures are definately higher than the average central european ones? I hope that it will get better by an oil change
Thank you!!!!


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## boyo-phil (Sep 5, 2006)

ive just had my cam chain tensioner replaced and had a new chain as well as well as a new cam belt and water pump as the cam belt had to be taken off anyhow, i had a rattle ontop of the engine after starting the car up it sounded as though it was a rattle from a exhaust heat shield, it cost me in the region of Â£600 from a specialist, there could also ne a problem with a one way valve that pumps the oil to the hydraulic tensioner so im told, a garage will check this first as its the cheaper and more common problem as the valve falls out of place apparently..


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## John-H (Jul 13, 2005)

The second number in the SAE rating denotes the viscosity at 100 deg C. The larger the number the thicker the oil. As your oil is more likely to reach a higher temperature in Greece a higher number is better as with the Motul.

I've been looking for the non return valve in Bentley but can't find it. I can see the one on the V6 - it fits between the block and head like most engines I've come across. Sorry that's not much help.


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## Chip_iTT (Nov 14, 2003)

John-H said:


> The second number in the SAE rating denotes the viscosity at 100 deg C. The larger the number the thicker the oil. As your oil is more likely to reach a higher temperature in Greece a higher number is better as with the Motul.
> 
> I've been looking for the non return valve in Bentley but can't find it. I can see the one on the V6 - it fits between the block and head like most engines I've come across. Sorry that's not much help.


Isnt it on the oil-filter housing? I could be wrong, thats from memory, but recall looking at this b4.


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## John-H (Jul 13, 2005)

Ah, yes found it - thanks Irving  It screws into the back face of the oil filter bracket to 8 Nm torque PN: 8N-Y-090 000 Â£7.10 +VAT


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## gt russell (Nov 27, 2005)

HI John , 
How do you check the oil pump pressure ?


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## Wak (May 6, 2002)

gt russell said:


> HI John ,
> How do you check the oil pump pressure ?


Dont think its possible (In VAGCOM) other than there is a low pressure switch to give you a warning if its below a threshold at idle and under higher revs.

Trouble is I believe pressure type of damage can occur before these thresholds are reached.

The Audi procedure involves them fitting an oil pressure gauge to the filter housing and measuring its actual pressure.

I have fitted an additional oil pressure gauge on the dash to be able to keep an eye on whats happening and is the only way if you want to keep tabs on it regularly.

Once you get used to typical idle pressure and typical pressure at say 2000 revs a gauge gives you some peace of mind to monitor this potentially damaging characteristic.


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## John-H (Jul 13, 2005)

Hi Russell,

You're not having problems are you? Hope not. Anyway, in answer to your question - having looked up the specs in Bentley:

* Attain 80 deg C. oil temperature (radiator fans cut in at least once)
* Unscrew oil pressure switch from oil filter bracket and screw in pressure gauge

- The Audi gauge allows you to screw the switch into the gauge at the same time so you can check the switch too. You could do this with a T adapter. You also need to rig up a circuit (lamp, multimeter etc) to the switch.

* Start the engine and observe both the oil pressure and when the switch operates (which may be during cranking).

- Switch operation pressure = 1.2 to 1.6 bar (17.5 to 23.3 psi)
- Oil pressure at idle = 1.0 bar (14.56 psi)
- Oil pressure at 3,000 rpm = 3.5 to 4.5 bar ( 51 to 65.5 psi)

If the specifications are not obtained first replace the pressure relief valve in the filter bracket then the oil pump.

That's what the manual says. I'd also add that after the oil pump is changed and if that still doesn't improve the pressure, you might have excess mains or big end bearing clearance.

Other things to watch out for are oil strainer pickup pipe blockage or air leak. Also, the pressure relief valve could have worn the casing bore. The filter may also be blocked or collapsed.

The switch pressure is high compared to older engines (where the lamp is directly wired to the switch) that usually operate at 2.5psi or so. It's more akin to what we used to put into rally cars to give advanced warning of oil pressure failure. It must be ignored at idle :wink:


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## ttr gr (Jun 1, 2006)

Thank you all for your help!!!
Is this non return valve easy to access? Is it at the external of the engine or do i have to take off a cover or something? Finally,are all engine part numbers the same throughout europe or could they differ from country to country?
THank you very much!!!!


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## John-H (Jul 13, 2005)

The oil filter is at the front middle of the engine. You can access the oil filter by reaching up with the engine under cover off but to get the filter bracket off may require access from above with the dipstick cover and it's bracket assembly underneath removed.

You'd better check the dealer for the part number of the valve as there seems to be more than one part number but they cover AJQ, APX, APP, ARY, BAM, AUQ, AUM engines.

Gasket - PN: 06A 115 441 J @ Â£5.40 +VAT
Valve F 8N-Y-090 000 - PN: 077 103 175 B @ Â£7.10 +VAT
or Valve F 8N-Y-090 001 - PN: 06A 103 175 @ Â£7.10 +VAT

The item in question is iten 6 and you'll need a new gasket item 5.


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## gt russell (Nov 27, 2005)

hi thanks for the info John and Wak 
I have heard for only a couple of times a tappety noise near the oil filler cap after the engine has been idoling for about a minute. It does go away after a while so Im not to concerned at the moment. I was wondering if the oil pump could be replaced from the outside like some ford engines or is it a sump off engine out job ? costing about 1 million dealer pounds :lol:


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## John-H (Jul 13, 2005)

It's sump off Russell but you can unlink it from the chain drive without side dissassembly.


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## Cheekos (May 19, 2012)

John-H said:


> It's sump off Russell but you can unlink it from the chain drive without side dissassembly.


I had a loud tapping noise When in slow moving traffic, or when I had driven the car, turned off then restarted when warm, never from cold, I checked the sump strainer, no problem there, changed te chain and tensioner today and fixed the problem, also fixed the exhaust heat sheild rattle noise when You accelerate!


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