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

Ever replaced the Belt and Belt tensioner?? I suspect your problem lies either here or in the oil pump.

"Tero Patana" escribió en el mensaje news: snipped-for-privacy@paju.oulu.fi...

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?

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

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

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

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.

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

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

Actually not at all uncommon with Audis. I have had a couple of Audis with hydraulic lifters that started ticking at lower rpms shortly after I bought the car and started using Mobil 1. I have only replaced the lifters on one car though, which was really bad. I have also seen/heard other Audis with *really* noisy lifters.

They have also started to leak at the front crank seal shortly after switching to Mobil 1, which is why I now always replace the seal when replacing the timing belt(s). Very cheap to do while replacing the belt, very expensive to do when everything is in place.

Thomas

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

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

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.

You drove the car 85K miles and only changed the oil once?

Um, I seriously hope that you bought this car used and have only had it a couple thousand miles. I wouldn't leave *any* oil in an engine longer than 10K miles, and I tend to change my own vehicles at 3-5K.

In any case, in response to your question, I'd be interested to know actual oil pressure as measured at various places around the engine. I dunno if you've got a sludge problem or actual engine wear, but I'd be betting on one or the other.

nate

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

The gauge had too short something, so it couldn't be fitted inside the car, thus it wasn't driven around. The noise was there when the measurements were done.

I'm slowly thinking about new cars, it's just the car tax in this happy land that is something un-heard of.

Just glanced few prices, for example Chrysler Sebring Sedan with 2.7L V6 engine with automatic transmission, starting from 42k$, with better features 45k$, and the convertible (2.7L w/ automatic) is from 63k$.

Take that! In addition to outrageous income tax (moderate salary gives around 30% tax, _high_ salary from 50 to over 60%), who can afford new cars here? Sometimes I wish I worked in better country...

Still, I hope the mechanic can found the real cause, or if he doesn't, hopefully someone here can give the exact clue on what to check. Good tips here for now, have to talk with the mechanic if some of them should be checked.

-Tero

It says:" 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."

So I guess that could be read as if I don't know what oils the previous owner(s) did use, but when I bought the car, I (almost) immediately changed the oils.

Yes, I have driven now with this car almost exactly 10k miles, with these oils 6-7k, as I said in the post, the oil change was due in near future. The Mobil 1 recommends around here something like 6-7k change interval. I also change filter every time when the oil is changed.

I try to get that information. Could someone tell what is "sludge", since my English-inHead-dictionary doesn't recognize that word, and my Webster is at work. Engine wear shouldn't be the issues, since it looks to be in good condition (AFAIK), if you don't look at the debris inside the engine.

-Tero

I think that what you are calling "debris" is what I'm thinking of as "sludge." Catchall word for that black goo and/or hard crusty stuff found inside an engine's oil system when something hasn't been right with it.

nate

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

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.

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.

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