1.8t suddenly making loud tapping noise

as title, the car has suddenly started making a loud distinct tapping noise, this noise is related to engine speed, it taps faster as you increase the revs.

the car is running mobil 1 esp 5w-30 oil

i've just fitted an ECS Tuning shallow sump and have done a small amount of driving with it on. i fitted the shorter pickup pipe that came with the sump. today i drove 35 mile in the car with no problems. then an hour later i drove 3 miles across town and at the end of the journey a loud tapping noise suddenly started coming from the engine.

The car is a mk2 scirocco which has recently been converted to a 1.8t, the car is still in the 'ironing out' phase. i haven't had the engine apart at all. the engine's done about 110k miles.

Currently the oil level is up to the dipstick mark as you'd expect.

I'm thinking the problem could be:
- Screwed hydraulic lifter
- pickup pipe blocked by excess sump sealant (although the pickup pipe was clear when i put the sump on)

With the shallow sump you'd think you'd need a little more oil, but as the oil is up to level I wouldn't think there's oil starvation.

There isn't an oil pressure warning light on the dash, assuming that part is working!

What else could cause sudden loud tapping?

 

pickup pipe blocked by excess sump sealant or pick up pipe problem ..come lose

oil pressure warning light only comes on with little or no pressure ...Get an oil pressure gauge on it ...and don't drive it
Only you know how much sealer you used ...Volkswagen stuff I hope ..very little needed ...If it doubt pull it off and check/redo it

 

Step 1 oil pressure gauge

 

Agree with the sealer both quality of VW stuff (White is spec for Turbos) and quanlty thing as you have only just done a change that could effect it

if you do have oil pressure gauge there should be a point in the head to measure. The OEM sensor is right next to the oil filter and if your on 1.8t clocks warning only triggers after 2K and high value PSI!

 

Are u running vvt? As the tensioners can go resulting in a loud tapping noise which sounds like engine about to go bang , thats what happened to my mk4 20vt, might not be that but it will give u another area to check

 

no I'm on mk2 golf clocks.

thought it could be cam tensioner but I've taken the rocker cover off and the chain seems tight. in comparison to videos on YouTube where can tensioners have gone, my noise is less like a diesel and is a more discrete 'klack'. just uploading a video.

took the sump off and the pickup was fine. (was using dirko sealant btw!)

had a visual inspection of the lifters too, they all seem to be in contact with the cams when I rotate the engine by hand.. think I could do with getting a feeler gauge between the cams and lifters tho..

do you think my next step is taking out the cams to inspect/replace the lifters/inspect further for damage?

with my ear against a lot screwdriver I did notice more of the sound coming from the middle/base of the engine though which is confusing.

 

Here's a video of the noise.

[video=youtube;-ylRs4sdY0o]https://www.youtube.com/watch?v=-ylRs4sdY0o[/video]

 

Do a compression test to see if it shows a problem with a specific cylinder.

 

what Turbo are you running?

if its a stock k03 or k03s ignore me but if its a hybrid or k04 and you are on stock rods it might be a bent rod I had a very similar noise and for me it was a bent rod which made the piston on that cylinder run lower in the bore and hit the oil squirter under the piston making a god awful noise.

good luck with finding the issue

 

damn that doesn't sound good! I'm only on a little KO3 so hopefully rodney is ok!

I need to do a compression test and report back.

 

Sounds very mechanical!

 

Have you had the plugs out yet? I had had kind of sound on my last 1.8t. The end of a plug burnt off and was on top of a cylinder, it ended up bending a valve as it got stuck as one opened.

 

You can check for bent rod by measuring piston height with a long screwdriver down the spark plug hole as a quick diagnostic

 

Doesn't sound good! Compression test as stated! Think I'd pull the sump off and check bottoms of Pistons for damage

 

Today's [cold] compression test results (4 tests for each cylinder):

Cylinder 1 - 165 psi
Cylinder 2 - 147 psi
Cylinder 3 - 172 psi
Cylinder 4 - 145 psi

The bentley manual specifies for a new engine that compression be between 145 and 200 psi, with no more that 44psi difference between cylinders. The wear limit is around 100psi, so the engine seems to be fine there.

To check for a worn ring I added a little oil to each cylinder and tested again:

Cylinder 1 - 200 psi
Cylinder 2 - 205 psi
Cylinder 3 - 230 psi
Cylinder 4 - 225 psi

(amount of oil wasn't exact however)

So if I'm right, this test indicates that the noise isn't related to pistons/rods, and I need to probe further!?

 

Checked the plugs, they're all ok.

 

Just a thought... I could be totally wrong but have you checked the chain tensioner (I think its to the oil pump) on the N/S of the engine under the rocker cover? wondered if the chain was ratting?!?!

 

This is the same noise I have in my Corrado I have just bought. Please let me know if you find the problem mate. I have had all the lifters out and rebuilt them which didn't change the noise.

 

did a hot compression test.. here's the figures

c1 150
c2 120 (130 with oil)
c3 150
c4 130 (170 with oil)

tried a feeler gauge under the lifters, no clearance between them and the cams so all good there.

i'm going to take off the head this week and inspect further. tbh i might just strip and rebuild the thing..

have you checked your big end bearings b20wht?