Hydraulic lifters/Tappets & Engine Flush

**TDi_B5** · 23-02-2009,08:43 PM

Right,

I'm desperate to get to the bottom of this noise from my TDI 110 AFN. I've started other posts about it, and after reading many others, the ticking/clicking/clacking noise seems to be a hydraulic lifter/tappet issue. It isn't audible at idle, although the smallest amount of throttle makes it sound. This noise hasn't gradually appeared, one day (when I picked the car up from the garage after a cambelt change) it was there, not a peep before. Took it back to the garage, they reckoned it was the tappets but said it will be fine. Its a horrible noise, quite noticable and very annoying with the windows down, sounds like an old tractor. I changed the oil and filter 1.5k ago and I'm now thinking of doing an engine flush with something like 'forte' and replacing the filter again in the hope that it will dissolve/clear any blockages in the tappets. There seems to be a whole engine flush debate going on and people are either for or against. I can see good points on either side of the arguement, but am still unsure where to stand. The car has a full service history, but this doesn't necessarily mean the inside of the engine going to be spotless, especially after 184,000 miles. It just seems daft to ignore a noise like this and pin it down to old age and high mileage, I hate the idea that i could be damaging the engine.

So, any suggestions? Engine flush, oil and filter change? Visual inspection of tappets? (wouldn't want to attempt this myself as I wouldn't know what I'm looking for..) I'm located in Southampton, Hampshire just off the M3, is anyone local that could lend an ear/accompany me on a test drive to hear the noise?? I would really appreciate some feedback, comments, suggestion, anything!!

Thanks in advance.

**snapdragon** · 23-02-2009,08:53 PM

The trouble with hydraullic tappets is that IF they are blocked, you can't just add something to the oil and hope to unblock them as there is no flow of oil through them to carry the solvent through even if they are not blocked, as they are pressurised by oil, they don't have it flowing through to any extent and not at all if blocked.
It's not as though they are actually immersed in oil and can be left to soak, like say an aerosol nozzle left to soak in acetone.

**TDi_B5** · 23-02-2009,09:43 PM

Ok, so if we assume they are infact blocked, I take it the only way so unblock them would be to remove them and clean them? Which Sounds like hell of job for an amateur mechanic!? I can understand your point that adding something to the oil may not reach the blockage, but surely an engine 'flush' that has detergents would stand a better chance? The tappets can't be completely blocked can they? If we assume that there is at least some flow through them, would the flush not work?

**martin1810** · 23-02-2009,10:12 PM

Are you sure it is the tappets. Is the timing correct. Seems odd that a belt change should suddenly lead to blocked tappets.

**snapdragon** · 23-02-2009,10:16 PM

The hydrallic tappet:
http://www.youtube.com/watch?v=lorANZ1Tptw
The oil stays in there and is pressurised to act as a hydraulically adjustable shim to spread the two halves of the lifter apart and thus take up the lash.
The oil won't flow through it or into it, the oil will just pressurise whatever is already in there. There little harm in trying though. Generally, they need replacing.

What you can see on the video is the tappet starts empty and that is when many cars rattle at startup and then fills with yellow oil and you will see this 'lock' the two halves together hydraulically.
Yours may be plugged up inside so that they are stuck or the oil cannot flow through the tiny inlet.

The unit on the video is probably around actual size of an average hydraulic adjuster, but quite a bit longer.

**mato** · 23-02-2009,10:43 PM

Sounds like diesel knock to me mate, id get that timing checked by a reputable diesel shop or indy. After that id get the injectors checked out, might need new nozzles.

I changed my cam belt recently with out the aid of the special locking pins. It was a bit of a bugger, had to line evey thing up about 3 times before i got belt on correctly. Its very easy to get the pump a tooth out.

**TDi_B5** · 24-02-2009,11:41 AM

Some great replies guys, thanks. The timing has been suggested before, the only reason I didn't go further with this is because the car runs spot on, just as it has always done. (and the fact that the cambelt & waterpump were changed by a vw specialist, so I assumed they knew their stuff) I often use injector cleaner in with the fuel too, and its only just gone through the MOT and ofcourse, the emissions test too. (I was half expecting a comment from the MOT tester saying the engine was making a ticking noise)

Is there a way of testing the timing without stripping parts of the engine down? I can't afford a garage bill and if I were to take the car to a diesel specialist for example, would they be able to tell if the timing was out without any costly labour? There are a few diesel specialists in Southampton, but their websites seem to suggest that they deal mainly with fuel pumps and injectors.

Thanks again.

**TDi_B5** · 27-04-2009,10:28 AM

Hi guys, I'm going to revive this post again as I still haven't got to the bottom of this issue yet. Recently had the car put on vag com which suggested that my timing was retarded on the pump (timing was 34-38 on the graph). I've just got back from the garage that did the cambelt change and although the timing a little bit out is out, he said it was within an acceptable margin and the horrible noise is infact the hydraulic tappets. He was happy that it wasn't diesel knock, he said if it was it would have been a lower pitch noise. After reading this post again, I also don't think its an injector issue as I often use injector cleaner and have done since owning the car.

So I'm now back to square one. What confuses me the most is that the noise started as soon as I drove away from the garage after the cambelt change, he said it was coincidence, could the new belt simply be putting more strain on the tappets thus making the noise? And, all the tappet posts I've read state that they make the most noise at idle? Mine don't, can't hear mine at idle unless I give it some throttle, the noise is only there when the engine is under load.

My potential plan of action now, starting at the cheap end is to do an engine flush using forte and change the oil despite advice given in this post. If no joy comes from that, I shall then look into changing the tappets, does anyone have any advice on that, is it a hard job? Why would these tappets go? I know its done 185k, but its got a FSH and I change the oil every 6k, it has wanted for nothing. Getting quite frustrated now, its been almost 7 months since this began and i'm planning to drive to Germany in the summer so need the old girl to be in tip top shape.

If anyone has any pearls of wisdom for me, please, please let me know!

**cazyp** · 27-04-2009,10:42 AM

I still find it strange that it happened 'at' the cambelt change. New cambelt should put no extra pressure on anything - just keep everything running in sync together.

You could try listening to the engine - cover off - hold a long screwdriver to the cam cover and put your ear on the wooden handle - acts like a stethoscope. (Unless you are a Doctor or happen to have a stethoscope which is even better!)
Move it about and see if you can hear where the noise is coming from inside. (Careful not to get your tie/hair/caftan/long beards etc caught in a running engine..

.)

Then get down near the radiator and see if the noise seems to be coming from around the area of the cam belt/aux belts and pulleys. I wonder if everything has been tightened up properly down there?

**TDi_B5** · 27-04-2009,10:48 AM

I find it strange too, but after 2 trips back to the garage and 2 seperate technicians going over it I feel like a bit of prat taking it back. Its a reputable garage so I would think everything was tightened. The engine cover lives in the boot nowadays. The noise is coming from the top end of the engine, not from the cam/aux belt area. I have a stethoscope, although I doubt I'd hear anything except the engine in general, surely?!

P.S - I assume the oil pressure is fine, when I remove the oil filler cap there is plenty of oil in the rocker area.