Engine noise

[ChrisGadd]

Hi,

After having my car off the road for the best part of 3-4 yrs I have finally started the engine only to discover that there is a loud metallic knocking related to the speed of the engine. The exhaust is off the car and I have replaced the engine oil, filter and sump plug.

So far :-
1) Checked oil pressure on tick over and it's at 25 which seems a little low?
2) Checked valve clearance and all seems ok.
3) Taken the plugs out and turned the engine over with the starter motor and still knocking noise.
4) Removed the alternator and water pump drive belt and turned the engine over and still knocking noise.
5) Done a compression test and cylinders 1,2,3,4 at 140 cylinder 5 is 120 and 6 is 150. (This was done with the engine cold as I don't want to damage the engine any further.)
6) Partially removed the dipstick still no difference.

I can't really hear where exactly the noise is coming from but thought about dropping the sump and having a look if there is anything obviously wrong. So the question is have I missed anything to try before embarking on dropping the sump? and has anyone removed their sump in situ

Oh and it's an S3 2.9

[ChrisGadd]

Griffinr said:

Is it a heavy knock or loud tapety knock? Could it be that you have hydraulic tappets and one of them has drained down and not primed.

Difficult one to answer but it is definitely a loud knock. It's a late S3 but as I understand it it's difficult to know if it's hydraulic tappets or not.

[ChrisGadd]

GreenV8S said:

Seems unlikely that a bearing would choose to fail suddenly while the engine was laid up. Even if it started up with zero oil pressure it wouldn't immediately destroy a bearing. The idea of a follower that has drained and not pumped back up seems far more credible to me. I'd be tempted to turn the engine over slowly by hand and see whether there is any play ion the big/little ends, take the rocker covers off and see whether all the rocker arms are gapped about right.

Hi peter, I've already had the rocker covers off and checked the tappets which only needed a slight adjustment, although I may be tempted to take the right hand cover off again and re-check cylinder No 5 given the lack of compression. I suppose the next thing to do is remove the cylinder head and see if there is anything showing.

[ChrisGadd]

phillpot said:

Before taking anything apart I'd be inclined to try and find an "expert ear", or two, to have a listen

Good idea Mike, I'll see if I can upload some footage of the engine sound.



lot of talk of tappets and valve clearances, do you know for sure if you have solid or hydraulic lifters? Did you adjust any of them more than a slight amount?

From what I can remember it was only slight adjustments, as for hydraulic or solid lifters I believe the only way to tell is by taking the heads off ?

Logic would say if you've done nothing major to the engine there should be nothing major wrong if it was working ok before?

My thoughts exactly and I certainly don't want to disturb what has been so far a very reliable engine.

ChrisGadd said:

The exhaust is off the car

Surprised you could hear anything!

I can hear the knocking when cranking the engine over on the starter motor and plugs out.

[ChrisGadd]

Alan461 said:

Have the plugs been out or plenum off while it's been laid up?
Something could have fallen into one of the pots and be fouling at tdc

Hi Alan,

Plugs have only just been removed to try and work out what the knocking is so I doubt anything has dropped into one of the pots. I think the next thing to do is check the engine number to see if it does have hydraulic tappets.

[ChrisGadd]

Hi folks, here's an update on my knocking issue. I have looked at the Engine Numbers and it suggests from the previous posts on here that I may have an engine with hydraulic lifters. So that may explain the knocking noise if one of the lifters isn't getting the supply of oil needed.


Two things that spring to mind :-

1) When I adjusted the tappet clearance they were set to solid lifter settings not hydraulic as the hydraulic lifters are as I understand it pre-loaded so should have no gap ?

2) If I do have hydraulic lifters then if they are set to the solid lifters clearance then the valves will not open as far as they should and reduce the engine performance?

Is there any information about how to correctly set the pre-load on the lifters ? and if I set these and it's not got hydraulic lifters what damage will it do ?

Thoughts please

[ChrisGadd]

White S3 said:

Have you managed to locate the rough area that the noise is coming from? After a 2yr period off the road my water pump had failed but didn't show until shortly after MoT. After replacing it with hindsight there was a quiet metallic knocking before the steam train effect every time it came up to temp.

On examination, the failed water pump had about 2mm of play in the bearing and in my hands I could generate a metal on metal "dink" sound. Opening it up, serious corrosion and I had drained the coolant system before taking the body off. New pump was silent off and on the car, so if emanating front lower half of engine block check the play in the pully block.

Hi sorry for the long delay in responding but I've been otherwise occupied, it can't be the water pump or alternator because I removed the drive belt to eliminate the possibility of these being the problem. It must be mechanical and not related to any ancillaries because I can still hear the noise when the plugs have been removed and the engine is cranked over with the starter motor. My guess is a valve that is sticking or a block in the hydraulic lifter. As said before the tappets look to me to be adjusted as though they are solid lifters and not the hydraulic lifters that this engine has.Does anyone have any advise on how to set the lifters and clear any blockages?

[ChrisGadd]

Top Gear TVR said:

has the sump taken a clowt from a poorly placed jack / stand or similar?

Not that I'm aware of, I think I'll have to get someone else to crank the engine over and lie under the engine to see if the noise is coming from the sump.

[ChrisGadd]

The Beaver King said:

On a scale of 1 - 10, 1 being whisper quiet and 10 being 'Holy crap, she's gonna blow!', how loud is the knocking?

I have a theory based on my own experience, but the knock would need to be pretty loud (7-10 range).

I'd say a 5 - 6 but do enlighten me on your theory it could be something I need to consider

[ChrisGadd]

HvdWeerden said:

Search function !

http://www.pistonheads.com/gassing/topic.asp?t=376...

Thanks Han most useful

[ChrisGadd]

Latest update .... I have now discovered the source of the banging noise. After asking my lovely assistant to crank over the engine whilst laying under the car it was obvious straight away that the crank was catching the sump so whilst jacking the front of the engine up to get the gearbox back in I must have buckled/dented the sump

So next questions are ...

Is there anything I can do to the sump without removing it to try and straighten it?

Can the sump be easily removed without removing the engine from the car and any tips help would be much appreciated.

[ChrisGadd]

Boosted LS1 said:

I think it'll be a rod catching at the shallow front part of the sump?

Certainly what I suspect as well having listened to the hollow sound and by placing my hand underneath. Also it only catches the sump in one place when rotating the engine. So I suppose I could work out roughly where the crank is catching?

Edited by ChrisGadd on Monday 13th June 14:10

Edited by ChrisGadd on Monday 13th June 14:11

[ChrisGadd]

Thanks for all the good suggestions, I've purchased one of These I'm hoping that it will be man enough to do the job. If not then a slide hammer will be the next option.

[ChrisGadd]

Plan of action whilst waiting for the dent puller is to find out which bit of the crank is catching the sump. So plan is to remove the spark plugs and turn the engine until I can hear the knock and then get a thin piece of wire and see which cylinder is a BDC. At least this way I will know which part of the sump needs attention.

[ChrisGadd]

I think if it gets to the point of fixing a nut to the underside of the sump I'll use something like JB weld

[ChrisGadd]

So after a busy weekend doing house stuff I've managed to have a go with the dent puller and trying to glue a M12 nut underneath to use a slide hammer and I have to admit defeat. It's soooo annoying because the crank is only just catching the sump. The car is on ramps and isn't road worthy so can't take it to a local garage and I don't have a welder or the skills to tack a nut onto the sump. So does anybody out there live close enough to give me a hand ?

[ChrisGadd]

Mobile welder coming tonight fingers crossed it's going to work.

[ChrisGadd]

Latest update, mobile welder arrived and was a top bloke with loads of experience. Ten minutes later and a M12 nut tacked onto the dent in the sump (which was almost unnoticeable) and one knock with the slide hammer and hey presto all well again. I'm leaving the nut on the sump because it lowers the center of gravity and will aid cornering One big lesson learned ... be extra careful when jacking the car. Thanks to all the help and suggestions it helped me get there in the end

[ChrisGadd]

greymrj said:

But do tell all, did he do it with oil in or out? Was there any fuss at all?

No fuss and decided that oil left in was a better option to try and disperse the heat, no fuss but I'm glad I got a professional in to do the welding because the sump isn't that thick.

Do you realise that the next guy who buys your car is going to be on to this forum in years to come asking what is supposed to be attached to the screwed thread on the bottom of the sump

I can't see myself selling the car it's such a joy to work on and the support given on this site is second to none

[ChrisGadd]

Scoobimax said:

Great news Chris - so you joining us on the barn farm run on Saturday?

Fraid not Max the old gal is still being tarted up, now concentrating on the engine bay and electrics