Valve lifter problem? (Oil pressure? Journals? Oil pump?)

(Sorry for this being so long, but I'm trying to tell everything so you can try to make the whole picture of the problem)
I have a Audi A6 1996 with 2.6L V6-engine, with hydraulic valve lifters.
The car has been driven for about 85k miles (<140k km)
One and a half week ago when I started the engine, there was loud clatter, like when the valves don't work ok, but this one was _loud_, believe me.
The oil change was due in near future, so I booked time from local repairshop for oil and filter change.
I don't know what oil's there have been before, but when I bought the car, I applied Mobil 1 0W-40 synthetic oil. I've only changed the oils once, before this week.
The repairman said that the valve lifters need to be changed, as the noise was too loud for normal operation.
So the valve lifters were changed, as well as the oil and filter.
And the noise didn't go away. Under the valve lifter gasket, there was lot of ... something (not dirt, but something), so we figured out to try engine flush and new oil change, if the something had clogged oil journals (the oil channels are called journals, aren't they?) from other V-branch. Also, when the gasket was removed, and the engine started, no oil came there, just few drips from somewhere. So it seemed that the clog in some journal stopped the oil from entering the valve lifters.
The flush seemed to do the trick, but when I had driven for few miles, the clatter returned. Next day, I drove the car back. At first, the clatter was there, but when I arrived at the repair facility, the engine was quiet.
They did the engine flush again, along with the oil and filter change. This time I drove around for 20 minutes nice and slowly, and engine seemed ok. Just when I entered a freeway, the clatter returned. When I headed back to the repair, the noise went away. I drove a little with higher rpm (~3000 rpm), and the clatter returned, and when I drove more carefully, it went away. For some moment, the clatter didn't return even with higher rpm, but then with one faster acceleration, the clatter returned ok.
So it seemed when the rpm's were raised more than average, the clatter came, and when driven slowly, it went away.
So what could be the problem?
I have been given thousands of hints, but not sure which one to try first.
One is the something in the engine, which might clog the journals again and again. Several flushs might do the job, or maybe some other methods?
Can the over-pressure valve at the oil pump be defekt, so that it starts to leak always when the rpm's are raised, thus negating the oil pressure raise when accelerating? I suppose the oil pumps themselves usually don't break down with this mileage, as well as they usually tend to work better with high rpm's. The oil pressure light never lits, but can I trust it?
Something wrong with the oil filter, or the interface between the engine and the filter?
The rotating rod (shaft? cam shaft?) which moves the valve lifters, is/are ok. What else should be checked before the engine is totally torn apart?
Hopefully someone has some ideas, any good advice would be appreciated.
-Tero
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ever replaced the Belt and Belt tensioner?? I suspect your problem lies either here or in the oil pump.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 27 Apr 2004, JP Roberts wrote:

Not sure about the tensioner, but the belt is changed 10k miles ago (~16k km).
Can it be the pump, if the other V-brach works (or at least seems to) correctly?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I had some noise at tilt, and some detonation under load at around 1950 rpm - on my 1.8T, and it all disappeared when I had the belt, tensioner and the V-branch pulleys replaced. Since your car has over 140 thousand km in the counter, you should already have had those replaced quite some time ago, so I'd suggest your doing this before any further attempts at replacing the pump.
Also, since it seems to be the case that the noise occurs under engine load - as you mentioned - this might indicate that there could possibly be a bad belt tooth causing detonation because of excessive timing advance at certain times when the bad belt tooth sent the wrong ignition timing. Because it's a six cyl. power loss might not be so noticeable as it would on a 4 cyl. engine.
My two cents,
JP Roberts

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 27 Apr 2004, JP Roberts wrote:

Hmm.. given my great knowledge about English, what you mean with V-branch pulleys? When I was talking about V-branch before, I meant the other half of my V-engine. I recall 1.8T is not V, but straight.
But if the belt is changed under 16 thousand km ago, I suppose it shouldn't be problem yet?

What indicates that it is not timing nor ignition problem, is that when they removed the valve lifter gasket, no oil came there when the engine was running.
So most probably the problem is somewhere in the oil flow chain, the pump, the filter, the journals etc... or maybe not :(
Any comments or suggestions are appreciated, since the real cause is still unknown. I just personally suspect the oil flow chain.
Thanks for comments,
-Tero
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Did they change tensioner and idlers, and possibly the water pump at that time? I have had the timing belt(s) changed on my 2.5tdi V6 recently, and I believe there were about four idlers and the tensioner that were replaced at the same time, plus the water pump as a precaution. The idlers alone were about EUR 550, and the waterpump about 80, IIRC.
I doubt that this is your problem though.

Cheers, Thomas
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

First mistake. Hydraulic lifters in overhead cam engines almost never fail. Noise from that area usually means an oil pressure problem. However from the garage's point of view they are relatively quick to change and a nice profit on the parts. You want to be asking for your money back as the symptoms stayed the same.

The diagnosis technique should be a no brainer. Fit an oil pressure gauge and see if the pressure is within specs at all rpms. The oil pressure warning light will only come on at a few psi (like 7 maybe) and is only there to tell you your engine has just expired. If the pressure is fine then at least the bottom end and pump are ok but maybe the oilway to the top end is blocked
The fact that your problem is intermittent and came on very suddenly points to a blockage either in the oil pickup pipe in the sump or in the feed to the head. Maybe bits of silicone sealant from the original assembly sqeezed into the sump and found their way into an oilway. If the oil pressure is down then first step is to remove the sump and check for a blocked pick up or other debris, a sticking oil pressure relief valve and the pump itself.
Also remember without us being able to hear the noise it may not be a lifter problem anyway. Something rattling against a cam belt cover perhaps or in the exhaust system. Anyway, it's all speculation until the oil pressure is checked. If the garage didn't do this as a first step then find someone else.
Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 28 Apr 2004, Dave Baker wrote:

I have to talk about this, now the first priority is to get the engine fixed. It costed around EUR400 (500$), so have to check the final costs to see if it's compensated anyhow.

The pressure has just been measured, and it's ok. So blockage is suspected at the moment, and most prob the engine will be opened someday in near future, to remove the blockage.

The problem is around the lifters, since no oil comes there when the lifter gasket was removed. The pressure is ok, and I (for now) hope that I don't have to change mechanic (again). In here, it's not that easy to find reliable repairshop, and this one has served me quite well on earlier occasions. Seems that they haven't encountered similar problem before, or at least I suspect, since they haven't yet pinpointed the cause for the problems.
Thanks for the comments,
-Tero
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Edited or Snipped

gauge and

warning light

you
bottom
I am with Dave Baker here................. What are the readings at the different rpm ranges WHEN this noise is experienced. Oil pressure might be excellent at idle, but what about at higher rpm levels, does it increase proportionately or actually drop down?
Ask your mechanic what the readings were/are so we can understand. And are there two or only one oil pressure switch/sending unit on your engine? I am wondering where he got the readings from and if he used a mechanical gauge or electronic.
I have seen oil pressure so high (at idle and first start) that it cause the lifters to pump up and the engine lost compression and stalled. Readings are needed to help make diagnosis. I have also fitted new oil pumps on engines with low oil pressure and the old lifter clatter noise vanished!! I usually work on 4/5 cylinder Audi/VW engines, so I am not too familar with the V6 nor the VR6 engines. :-( I have heard of oil passageways being clogged, possibly due to gaskets, and causing oil pressure problems. Again I am not sure on your engine though. Eyebrows are raised about your statement of finding debris inside of the engine.
later, dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 28 Apr 2004, dave AKA vwdoc1 wrote:

Have to ask about this from the mechanic. Hopefully he'd known what he'd done so far. I know that he said that the gauge pipe (or something) is too short to be wired to the cabin, so he hadn't actually driven around.
But, if he said he did the measurement when the sound was on, then the problem should have been seen also at low rpm, yes? As I think (with what?), I suppose if the sound can be heard at low rpm, something is blocking the oil from going to the lifters, so it it was pump problem at high rpm, the sound should go away when the pressure rises. So it's not pump problem, if my logic doesn't fail me.

I try to remember to ask these at next talk.
Thanks for comments,
-Tero
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
edited

Lifters will demand more oil pressure at higher rpms (they are doing more work then). So the oil pressure needs to be checked at different rpm levels since it could be fine at low rpms, but not at high rpms. Please post the results! thanks. later, dave
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'm about to call the mechanic for update on my engine. First I need estimation from someone outsider, for how much it takes to open and change the other cover isolating device (what you call it?), if the other cover has already been opened and the isolating thingy been changed.
Since all the common things have been already removed, I suppose it shouldn't be that much extra work, but the mechanic estimated quite surprisingly amount of labour for changing both, instead of one.
I'm about to get that information, but it wouldn't hurt if here someone who has changed the thing in V-engine, told how much he estimates the labour from professional mechanic.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I'm coming in at the end of this. There's a pressure relief valve in both heads. Twice I have seen a problem with them. One fell out, it was laying under the valve cover when I removed it. The other simply stuck wide open, no pressure to the top of the engine, all the oil blew out the valve. Both were a pretty cheap repair. Good luck.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ok, hopefully this is my final post around this issue.
I got the car back yesterday. The mechanic had opened the cover (gasket?) of the non-oiled V-branch. The cover insulating-thingy (you haven't yet told me the correct term for that part) has these holes in it, and then there's this quite narrow bridge combining two of the holes. The mechanic had found clog in that narrow bridge, and after replacing the thingy the engine has been running perfectly. The clog was this black debris which gathers in the engine if you don't rev enough from time to time.
So it seems, that now the engine is fine. I drove the car around somewhat yesterday, and today to work, and I surely hope the failure doesn't come back. One thing to notify, since the lifters have been changed, the engine is more quiet than most of new cars I've driven. At traffic lights, with neutral-gear on, I had to turn off all things including A/C+fan, and still it was hard to hear if the engine was running or not.
As a pre-empitve strike, I suppose I should have the other V-branch cover opened and the isolating-thingy replaced. I've been told that they should be changed every 100k miles, and most of the cars around here are driven at least 200k, many even 300-400k, so there's still plenty of changes in the future to come.
I did ask about the oil pressure during the test, the mechanic said that the pressure was around 5 bar (~73 psi) at high rpm. I guess this is ok (or good?) result?
Finally I can continue enjoying driving nice car, and listening sound from Bose-system. I've have had a little bad luck with previous cars, I hope I can now rely on this car.
Thanks for everyone for comments, good to know that if there's going to be any problems, I know at least one place where to look for expert tips.
BR, Tero
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Please explain where the "insulating-thingy" is located and how it looks. Is it the rubber or cork seal that sits between the cylinder head and the valve cover? That is a gasket ("packning" in swedish).
Cheers, Thomas
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 4 May 2004, Thomas Tornblom wrote:

I suppose it's that cork seal between the cylinders and the gasket.
To make sure: It's about 30 cm x 12 cm (12inc x 4.5 inc), about 1 mm thick (or 2), has three big holes for cylinders, and many smaller holes for other channels, oil as a one (or more). I know what it is called in Finnish, but that doesn't help you that much. I suppose direct conversion from the Finnish word would become "Gasket insulator".
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tero Patana wrote:

"Cylinder head gasket" or simply "head gasket" in American English :-)
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That sounds like a head gasket. It's the thing that sits between the cylinder head and the engine block and seals the combustion gasses, coolant, oil.
like this:
http://parts.overnightautoparts.com/parts/online_catalog/wizard.jsp?year 98&make=AU&model-Q-001&category=A&part=Cylinder+Head+Gasket
Thomas
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The HEAD gasket was "clogged"????????
Now THATS different. --
writes: | > > Ok, hopefully this is my final post around this issue. | > > | > > I got the car back yesterday. The mechanic had opened the cover (gasket?) | > > of the non-oiled V-branch. The cover insulating-thingy (you haven't yet | > > told me the correct term for that part) has these holes in it, and then | > | > Please explain where the "insulating-thingy" is located and how it | > looks. Is it the rubber or cork seal that sits between the cylinder | > head and the valve cover? That is a gasket ("packning" in swedish). | > | | I suppose it's that cork seal between the cylinders and the gasket. | | To make sure: It's about 30 cm x 12 cm (12inc x 4.5 inc), about 1 mm thick | (or 2), has three big holes for cylinders, and many smaller holes for | other channels, oil as a one (or more). I know what it is called in | Finnish, but that doesn't help you that much. I suppose direct conversion | from the Finnish word would become "Gasket insulator".
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Measured under what conditions? Just in the garage at tickover? If the noise is intermittent then the oil pressure may be too. You need a gauge in the car to be able to see what happens when the noise starts. Given the cost of garage labour time and parts costs for trying random parts substitution at the owners expense it would make sense to have a gauge mounted temporarily inside the car, drive it for a bit and see what happens.
Dave Baker - Puma Race Engines (www.pumaracing.co.uk) I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.