Diesel Engine Started Tapping/rattling

[pjwpjw]

Weve got a mk2 1.9tdi Galaxy 02 plate, and we just drove from Preston-ish to Glasgow in it. Motorway all the way, sat between 80 and 90 all the way.

 

When i slowed down to 40 off the M8 i noticed the engine was tapping like hell, certainly more than normal. Its loudest between about 1500 and 2000 revs, and is there on idle. It rises with the engine speed, but wierdly it disappears when you take your foot off the throttle and the engine speed is returning to idle.

 

Once at idle speed it is there, and pretty loud. More like a noisy tappet but a bloody loud one!

 

Just wondered if anyone else has experienced it, and if its time to think about getting a new head on it. Ive just serviced it using the correct oil about 2 months ago, VAGCOM scan comes up with nothing. Not underpowered, no smoke, no oil leaks etc etc.

 

Any ideas?

[Phil]

last time i experienced the same symptoms, it turned out to be the alternator bearings, try taking off your aux belts and then see if the noise has disappeared?...

doing this will rule out quite a lot of things....

 

HTH

 

Phil

[pjwpjw]

last time i experienced the same symptoms, it turned out to be the alternator bearings, try taking off your aux belts and then see if the noise has disappeared?...

doing this will rule out quite a lot of things....

 

HTH

 

Phil

 

thanks mate ill give it a go tomorrow. its raining tonight so ill try and get into the bay in a bit more detail soon as possible.

[ggobin]

Hi. I had the same issue last week

 

Replaced the alternator clutch pulley and tensioner. All good now.

 

Like phil said test and see how you get on.

[pjwpjw]

Hi. I had the same issue last week

 

Replaced the alternator clutch pulley and tensioner. All good now.

 

Like phil said test and see how you get on.

 

Thanks, ill have a good look at the tensioner. I have only just replaced the pulley the other week as the clutch in it went. Praying for the tensioner lol, dont want to be having the head off it if i can help it.

[pjwpjw]

Ok, just been out, definitely the top end. You can feel it through the rocker cover. Feels like no2 but cant be sure.

 

Whats the commonest thing that can cause a noisy tappet/follower? Ive only just drained the oil out but im tempted to change it again with a flush.

[sparky Paul]

Could be a sticky/worn hydraulic tappet?

 

IIRC the camshaft is directly over the valves on these, so no followers to go bad... on the other hand, it means the camshaft has to come out to get to the hydraulic tappets.

[pjwpjw]

Could be a sticky/worn hydraulic tappet?

 

IIRC the camshaft is directly over the valves on these, so no followers to go bad... on the other hand, it means the camshaft has to come out to get to the hydraulic tappets.

 

I thought tappets were the same thing as followers? Im not scared of taking stuff to bits i just want to be sure im making a difference.

[sparky Paul]

Although the term 'followers' is sometimes used to refer to tappet inserts, 'cam followers' are more accurately the roller bearing part of the rocker arms found on some OHC engines with offset cam/valve arrangements.

 

The cam lobes on your engine push directly onto the hydraulic tappet insert, which is a cartridge which fits into the head casting, sitting between each valve stem and the camshaft.

[pjwpjw]

Although the term 'followers' is sometimes used to refer to tappet inserts, 'cam followers' are more accurately the roller bearing part of the rocker arms found on some OHC engines with offset cam/valve arrangements.

 

The cam lobes on your engine push directly onto the hydraulic tappet insert, which is a cartridge which fits into the head casting, sitting between each valve stem and the camshaft.

 

ahh right cool, i just wanted to get my terminology right so people know what im on about lol

 

Ive taken the rocker cover off (back two bolts are a swine) and with the aid of a towel collecting oil started it with the cover off. Seems that its actually coming from the right hand side (around no4) but i just cant seem to narrow it down as its pretty loud. if i put my hand on each rocker arm in sequence they all feel pretty similar. Nothing that obvious unfortunately.

 

No scoring on anything, nothing looks knackered. Engines all nice and clean inside.

 

If i turn the engine over by hand from the crank pulley should i be able to see if any of the followers are sticking?

[sparky Paul]

I'm not too familiar with the VW diesel engines, but I believe the rocker assemblies drive the injectors. The eight valves are directly under the camshaft, and the tappets/lifters are driven directly by the camshaft lobes.

 

Unfortunately, this can be difficult to diagnose tappet problems without removal of the camshaft and tappets, as the tappets rely on engine oil pressure to maintain the adjustment, although a stuck lifter my be obvious by a large clearance between the lobe and tappet when the valve is closed. Once the oil has drained from the tappets, you should be able to feel the spring if you push each tappet down.

 

Don't know if this might help with diagnosis...

 

http://www.myturbodi...lace-vw-tdi.htm

Edited August 13, 2011 by sparky Paul

[pjwpjw]

Thanks mate, thats really really good info - ill give it a good inspection tomorrow and hopefully ill get good light and no rain!

 

Ill post my findings soon as i can. I predict i wont be able to find anything and might have to resort to a garage to diagnose it :)

[tbag]

Thanks mate, thats really really good info - ill give it a good inspection tomorrow and hopefully ill get good light and no rain!

 

Ill post my findings soon as i can. I predict i wont be able to find anything and might have to resort to a garage to diagnose it :)

Hi,i have had this noise, not unlike a hammer hitting a anvil and a was told to run the engine above 3000 rpm for maybe ten minutes or so to get rid of any air that might be trapped in one of the tappets. so off i went up the bypass in ist gear for 5 miles, ok it sounds daft but it worked. i was just about to go on my hols as well, so stripping it down was not an option. t bag

[pjwpjw]

To be honest thats the speed i was at engine wise when it started - i was pulling about 3krpm on the motorway. Worth a go though i suppose, going to go out this afternoon and inspect the cam lobes and followers in detail. If i can ill put some photos up but theres not a lot to see tbh.

[pjwpjw]

Driving it today, when using engine braking the knock disappears.

 

Could it be the 'reverse torque' of the engine braking stopping the knock?

 

Any ideas what it could be from this?

 

 

 

 

 

I intend to remove the camshaft on thursday.

[seatkid]

my guess is injector or worn injector cam/follower Edited August 15, 2011 by seatkid

[pjwpjw]

my guess is injector or worn injector cam/follower

 

How would i know if its an injector? Surely the engine would run rough and/or vagcom scan would flag it up? Is there a way to test?

[pjwpjw]

Sussed it. Feel like a bit of a pleb for not noticing it the first time i had the rocker cover off, but its a proper 'jeeezus' moment.

 

I decided to check all the torques on the bolts to ensure nothing had come loose. That was when i noticed that one of the four bolts holding one of the injector rocker rails on wasnt there!

 

Then panic set in - if it wasnt there.. where the feck was it. Out of sheer and blinding luck, i felt right down into all the oil ways and nooks in the head and found it, and managed to get it out with a circular magnet attached to some strimmer wire (didnt want more metal flying about in the engine).

 

One lucky escape.

 

Thing is, looking under the head of the bolt i found its flush. The bolt left in the engine is sat about 2mm into the hole where it sits. So i started fishing again and found nothing more after an hour. So i took the oil filter off, and again came up with nothing.

 

I intend to get the other three bolts off and see if the head of the bolt matches up to the rest of it. If not, ive got about 2mm of metal kicking about in the engine somewhere and its sump off time soon as it stops raining. Im aware these are stretch bolts and have to be replaced each time, so im *hoping* that it does match up once i get to it.

 

Four new bolts on order from VW cost

[sparky Paul]

At least you found something before something nasty happened, it could all have gone horribly wrong had the other bolt snapped too.

 

The bolt shank left in the head will be loose and could have wound itself in with the vibration. Once you take the rocker off and extract the bit, check it against the length of a new bolt, as you suggest.

Edited August 16, 2011 by sparky Paul

[pjwpjw]

Yep, was loose and had wound itself in. Took it out by removing all the other 3 bolts that were still torqued up and matched it with the head, no more metal wandering about in the engine ;)

 

All sorted now, was a bit rattly on startup due to no oil in the top end but soon sorted itself out. Thanks to all who replied.

[sparky Paul]

Good to hear a happy ending.;)