Hi, I have a 2015 skoda fabia mk3, 1.0L 60hp mpi engine, I changed my oil a few weeks back and when I changed it the engine began making a knocking noise, more recently it has started making a rattling on and off while at idle, after all I've tried I've run out of ideas, any ideas what it could be?

 

Fyi, Its got 156000km on it and I've owned it since April 2021, it had 151000km when I bought it.

 

Observations:

Doesn't feel like it's lost power.

Noise only happens when rpms are climbing, stops once rpms are held constant and nothing when they're dropping.

Noise stops above about 3k rpm.

Noise only happens when engine is warm and gets louder the warmer it gets.

Engine oil temp stays at 80-90 when warm

Runs like a clock when it's cold

 

What I've tried so far:

Originally put 5w30 oil in but recently changed it to 10w40 which didn't change the sound at all, no louder, no quieter.

Tried oil additive in with the 5w30 which changed nothing.

Tried premium fuel to check for pre-ignition

Pressed clutch in to confirm it's not gearbox noise.

Held rpms at 3-4k for a few minutes to check for collapsed lifters.

Just to confirm, are you say it has 156k-kms (97k-miles) on the clock?

 

Put in whatever weight of oil is specified in the Operator's Manual, go with better quality oil for better protection rather than additives, the correct Mobil 1 or correct Castrol Edge are good, go better if you want, plus not cheap oil filters at changes.

 

Are you sure it's not just a coincidence that the noise started after your oil change, are you sure the noise is actually from the engine.

 

You always want to keep the car battery in a good state of charge otherwise the computers can get awkward about running the car.

 

Have you checked with a scan tool to see what comes up.

 

Are the service items taken care of like air filter, spark plugs, (clean throttle control).

 

Any idea how the 151,000 km was done.

 

That's me out of ideas time for tea.

 

Yes, 156,000 kms

Put in castrol GTX ultra clean with the correct WV rating (502 00)

Noise is definitely coming from the engine, went around today asking mechanics to take a look, 3 of them said it sounded like bottom end bearings/ I'd need a new engine

Scan tool showed no codes

We checked air filter and spark plugs when we changed the oil, both were good

Bought the car from the city so I'd assume it was mostly city miles

 

It's sounding like a new engine for me anyway, will probably drive it till it ****s the bed and look for a new car in the meantime, still confused about how an oil change would have scrapped the bottom end tho

Depends on how big and open the city is  but I live in a large town and there can be a lot of stopping and slow moving traffic during the busy times.  A 1.0l is more like a city car engine size, I think it is the engine from the smaller Citigo so most people would perhaps go for that model in a city I'd have thought.  Of course a 1.0 is easier on insurance so perhaps a youngster had the car, or a bigger physical person or one that need a longer chassis to absorb the bumps more, bad back perhaps.

 

151,000 divided by say 6 years = 25km/year which is a lot for a city car, perhaps it was a group or family pool car, or they had a far off weekend retreat.

 

When you emptied out the first lot of oil from getting the car was it clean as if recently changed and/or with floating 'fillers' or bits?

 

If the oil was sludge-like or with 'fillers', same for oil filter, then perhaps cleaning them out of the engine has highlighted a problem, that was perhaps previously hidden.

 

If you're careful a large screwdriver or stick to your (protected) ear run along the underside of the engine might highlight the area of noise,

 

I'm not mechanical so don't know if those symptoms sound correct to what your 3 mechanics said but if they didn't see or examine the car it's just speculation on their part, sometimes embarrassingly simple things can make noises well beyond their significance.

 

Only as an example, I'm not saying it's the case for you, but I had a manifold gasket go and it sounded to me very mechanical, engine type noise, so after getting to the pub I took it easy going back home.  Basically a bit of paper type stuff upsetting the running of the engine but easily and cheaply sorted.  Years later the next manifold gasket blow sounded nothing like the previous but more like I expected it would.

 

Edited 20 July, 20214 yr by nta16

The car had sat for about 6 months before I bought it, the previous owner was a girl in around her 20's who had moved to live in another country and told her dad to sell her car, she wasn't the first owner of the car so maybe the owner before her did some higher mileage journeys, the car had an oil service sticker on the windshield when I bought it that said the next oil change was due for 161,000km or February 2021, I changed it at the start of July so a few months overdue but I don't think it would've affected much, the oil looked clean when It came out nevertheless and didn't have any debris/sludge, the mechanics all opened the bonnet and took a listen as I revved it, (they were all from different shops too), they all agreed it was something inside the engine and they'd need to take it apart to see what exactly, I can feel a vibration in the clutch pedal with each knock so I dont think it's a head gasket but rather some metal to metal contact inside the engine, it's strange though because I'd expect rod knock to get quieter with thicker oil but it hasnt

Just to add to that, it just clicked that the vibration I feel in the clutch would point to something knocking on the crankshaft, since the clutch is directly attached to it, it is a quite sharp vibration too, any ideas if it would be worth dropping the oil pan and checking for play in the rod bearings?

 

It only makes noise when it's warm so it would be difficult to drain the oil and drop to oil pan while it's still warm enough to have play

Sorry but if the mechanics looked and listened then I think you probably have your answer, something in the engine and possibly beyond economic repair (as they say).

 

Unless you've got a full and accurate service record of the car from new you won't know how well it's been looked after during different periods of its life.  Usually first owner gets it serviced for warranty period but after that often anything goes.  High mileage (km) journeys at a steady reasonable speed can be a lot less wearing on many parts and components than very low mileage.

 

I don't know if that engine and built at that time has a history of such faults at this age or mileage but it doesn't really matter as you have to deal with what you actually have.

 

Without a definitive answer as to what the problem actually is it's a gamble how long and/or well the engine will carry on so best to make sure the oil is warmed and drive it steadily without labouring it.  No dragstrip starts, too high or too low revs, overloading the car particularly up steep hills.

 

Your mission, should you chose to accept it, is to keep the engine going for as long as possible, report back in a year for your badge.  

Might be worth having a look, normally I'd say get the oil as hot as possible but that would be inducing too much strain here (remember I am NOT mechanical) but it might still be worth a look as you can clean up its bottom and get your magnifying glass out to look for signs of issues, or they may be glaringly obvious.  If you enjoying rolling on the ground covering yourself in oil, then why not, I've had enough of that over the hottest days of the year, and I've yet to top up the oil level so now we get a thunderstorm.

 

Ahahah ye, just baffles me as to how it made no noise before the oil change, then after the oil change I drove maybe 10 kms and it started knocking, perhaps the clean oil washed away some sludge that was cushioning the knock?, Anyways it's as you say, I'll either drive it till it blows up or try to trade it in to an unsuspecting garage if I find a replacement, whichever comes first, it's pretty hard to not rev high with such a small engine, it'll struggle to keep up with traffic haha

Find the oil pressure switch and disconnect it. Then take it for a short drive, check that you get a low pressure warning.

This is to see if the previous owner has somehow disabled the warning system to conceal an oil pressure problem.

Edited 20 July, 20214 yr by Wino

9 minutes ago, LightRobin said:

it'll struggle to keep up with traffic

Then let them keep up with you!  

 

The power band can be quite surprising, they're for eco driving so whilst you don't want to labour it you don't need high revs.  Go back to anticipating traffic and setting the gaps for more constant steady progress rather than the normal everyday jerky, lumpy, hit the pedals (rather than caress) that we all do.  Pretend your on the milk float in Father Ted or you're going for a world mpg mpk record or that petrol is at 2022 prices! 

Just a quick update, I got my hands dirty and took a look at the following:

 

Unplugged injectors to see if the knock changed at all, it appeared to quieten when I removed cylinder 1's injector and stay the same for the others

 

Took the spark plugs out, they had oil in the plug wells and on the threads but the tips were dry, it wasn't flooded with oil but almost enough to drip, possibly piston rings gone with piston slap making noise?

It doesn't burn oil as far as I can tell and there's no smoke from the exhaust

 

We also tried sticking a rod down each cylinder and the rotating the crank till the piston was going down, then tried pressing on it to see if there was play in the bearing allowing it to move, nothing moved as far as I can tell, also inspected the timing chain and pulleys, everything looked in good condition. One thing to note is that when we looked down the spark plugs holes with a flashlight there was a fairly thick black coating on the pistons, carbon presumably but not sure if it's normal so thought I'd mention, anyway I may order some stock size rod bearings and try to change them from under the oil pan, will update with how that goes if I do although if it needs new piston rings too it will be a waste of time

 

Ps. Noise appears to start at 65c oil temp and worsen as it gets warmer, perhaps we felt no play in the pistons because the engine had cooled too much (I warmed it up before taking things apart)

All beyond me.

 

I just try cleaning and lubricating, this won't solve your problem but might help.  Most people think  to service and maintain a new car but not as it gets older when it needs it more, most servicing and maintenance often just boils down to cleaning and lubricating but if there's been a build up of muck/crud/debris through subsequent lack of of servicing and maintenance then more vigorous cleaning and lubrication is often required.

 

For the engine it can be surprising what effect a thorough (hot) engine oil change (& filter) to clean fresh good quality oil can make plus a change of air filter, change or clean of plugs, clean of throttle body, MAF.

 

65c wouldn't be oil fully warmed, if the oil is old (or very old) and/or of poorer original quality then it'd be offering less protection and even lubrication.  Some think it's best to leave the muck in the engine to fill the gaps but it's also grinding things down more.  Anyway you've got to thoroughly clean the old oil away to see anything in the engine wear wise if you're taking the pan off.

 

I've got a feeling you can get some thinner oil additive to quieten things down rather than the thicker syrup like stuff some used to tip in in the olden days but there's only so much that will help.  It's a matter of balancing how much you want to do to keep the engine still going for how long.

 

So it's been a while but thought Id update anyway, I took the oil pan off yesterday and the bottom end looked immaculate, couldn't have been cleaner, nevertheless I replaced the rod bearings since everything was already apart, engine sounds exactly the same as before so that rules out bearings, plus I've driven about another 3000km since last update and the sound hasn't gotten any worse so I'm really confused now. The accessory belt has start to squeek when the engine is cold but goes away when warm, not sure if it's related and possibly the belt tensioner is making noise? It baffles me that it only happens when the engine is warm, surely a tensioner would make noise regardless. But anyway, anyone got any ideas what else it could be?

With the belt it could be resistance from whatever it drives, or is driven by, or the belt itself which might be more effected by being warmed.

 

Could try running the engine with the belt off to see what noises disappear(?), perhaps the rattle.

 

Are you sure your knocking noise is from the engine and not elsewhere, nothing silly like you've moved something whilst doing the oil change, or the engine mounts, or left something (or tool) somewhere it shouldn't be.  10 miles after oil change I'd thought was just a coincidence but I'm very often wrong.

 

Is your scan tool able to go deep enough to pick up enough info, if it runs well when cold but not after then you really need a scan tool that can record live running data when the engine is running at problem time.

 

Perhaps a sound recording of the knocking noise might help.

 

Knocking noise is definitely from the engine, best I can tell is it's coming from the timing belt side of the engine, not far enough over to be the engine mounts but in that general area. The scan tool I have is just one of those basic Bluetooth ones that just show codes so can't check live data, I'm working all day today but will try run it without the belt tomorrow, tried to take a video of it rq, https://youtube.com/shorts/Jlxf2Q3i1f4?feature=share let me know if you hear it, it's the best I can do for now since I'm at work

Yes I can definitely hear something not sure about knocking as such, bonnet up next time to hear more, I can hear two or three noises.  I'm not sure it's a internal engine noise - but others would know much more and hear more than me.

 

Have you done other servicing work on the engine (one of the least important things on a vehicle) like replaced air filter, spark plugs, etc.?

 

Also have you tried looking for a vacuum leak or hose/connector off, spraying carb cleaner or such like around the manifold with engine warmed and running?

 

ETA: Tested coils individually, wiggled any and all other wires/cables you can get your protected fingers on when engine is still cold.

 

Cleaned the MAF and throttle body?  Checked water and exhaust sensors? - The computers can throw all sorts of strange wobbles and if you have more than one issue combining their effects the wobbles could be more and stranger.

 

You really need someone who knows what they're talking about, which ain't me and someone with a good VW scan tool there's only four marked on this map if it's still current and the person still wants to help out. - https://tinyurl.com/yn6mmtyk

 

Edited 19 August, 20214 yr by nta16
ETA:

I've inspected the air filter and spark plugs and they both looked fine so I don't think that they're the culprit, the sound is much louder in person and barely comes across on the video, best I can describe it is it's a metallic tinny knock, almost as if you were to tap a screwdriver on a piece of sheet metal, I will do some further poking around tomorrow and will try to get a better video of it

Fyi some of the sounds you were hearing could have been other cars since I filmed it in a busy parking lot

Just watched the video back, all those sounds were from my car actually

Did you clean the air filter and filter box whilst you were there, I've seen people just look at the top of the filter.

 

Sucking or blowing gaskets can make funny noises.

 

The sounds I was thinking of were probably from your car but I don't know how high you were revving it.

 

2 minutes ago, LightRobin said:

Just watched the video back, all those sounds were from my car actually

You're a mind reader, I hadn't yet typed that in my reply !  

 

Also I had a look at the repair manual and the alternator belt has no tensioner and doesn't run around any pulleys, just the alternator to the crank pulley so I doubt it's related

And yes I took the filter out of the box, it looked like it had been changed recently

Did you try swapping the coils and plugs over sides of engine, if the sound is around 1 & 2 end swap them with 3 & 4 see if sound moves ends or stays where it is..  And if the sound moves end swap only one back to it's original position and see what happens, and when the music stops grab a seat.

 

If the plugs haven't been changed for a while or you don't  for the effort and cost I'd just put a good set of new plugs in anyway, can make a surprising difference even if the old plugs are OK they can be long passed their best or optimum.  I loathe farting about with cars I like reliability, well as much as I can get with old British cars that have many modern made **** poor parts for them, and loads of rubbish rubber parts  I imagine some crap modern made parts go on to modern vehicles now too, not worth counterfeiting them like they used to just sell them cheap legally.

 

14 minutes ago, LightRobin said:

Also I had a look at the repair manual and the alternator belt has no tensioner and doesn't run around any pulleys, just the alternator to the crank pulley so I doubt it's related

Easy to take off and try though as that might have been one of the sounds I heard - or it might just be it's usual noise at that age.

 

Battery (almost always driver's fault) and charging system faults are one of the main causes of breakdowns for roadside repair companies.  A poor battery will put strain on alternator and a poor alternator will put additional strain on the battery.  Not much point sorting one item like the knocking  to very soon be let down by another, the alternator very probably (famous last words) won't be the cause of the knocking but if you're going to be using the car at night and/or in the winter you don't want to get caught out like most do.  Prevention is better than wet, cold miserable roadside recovery. 

 

Edited 19 August, 20214 yr by nta16