Knocking sound from head

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GT08
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Knocking sound from head

Post by GT08 »

Hi,

So there is a really concerning knocking sound from the engine of my Jetta. For reference it is a 2.0l 8v ADY with -+ 150 000km on. I put 90 000km on and it is an import engine so not to sure just an estimate.

The sound definitely comes from the head and sounds like a lifter has failed. A hard knocking sound that increases with rpm, but remains at idle very loudly.
I know sounds are difficult to explain over text, but I am at a loss of how to continue diagnosis.

The sound is definitely from between cylinder 1 and 2 and definitely from the head.

The sound started only when cold and after a week one day was there all the time. The power was not changed at all during this time, not that I was driving hard.

I did not have an oil pressure gauge before this so could not check that until the sound got a lot worse.

I replaced the oil pump and the lifters, as they are really old and that could help as preventative for the future.

After replacing the oil pump I checked the cold oil pressure. Between 6 and 7 bar cold at idle.

This was taken right after first start:

Image

Hot between 1.25 and 1.5 bar at idle
Hot between 5 and 6 bar @ 2000 rpm

The lifters all looked great with 1 of the lifters from cylinder 2 having the piston not firm like the other 7 lifters.

The old oil pump had some scoring on the inside where the gears were turning but no pitting are any real issues.

The oil pressure seems too high but not sure where to start to fix that. I read up on a lot of things that could have gone wrong.

If a valve spring has broken, would that not be very visible during the lifter change?

How should I proceed to diagnose? Should I remove the head and look for a failed valve? Should I do a compression test?

Not sure what to do, but the sound is horrendous and makes me not want to even do a comp test if needed.

Any input would be appreciated.
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Re: Knocking sound from head

Post by UDC »

When you replaced the oil pump did you check for any up and down play on the rods, could be a big end or main bearing........ did you find any metal filings in the sump
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Re: Knocking sound from head

Post by panic-mechanic »

If changing the lifter and oil pump did not make the noise go away I suggest you pull the sump again and look at the big ends. I suspect it ran a bearing.
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Re: Knocking sound from head

Post by GT08 »

UDC wrote: Tue Nov 06, 2018 11:11 pm When you replaced the oil pump did you check for any up and down play on the rods, could be a big end or main bearing........ did you find any metal filings in the sump
I did not check for any play, will check that. Not sure how but will check none the less. The oil in the sump was clean. No shavings or discoloring.
To check the play, I would start by removing the caps from the rods not the crank right?
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Re: Knocking sound from head

Post by GT08 »

panic-mechanic wrote: Wed Nov 07, 2018 6:34 am If changing the lifter and oil pump did not make the noise go away I suggest you pull the sump again and look at the big ends. I suspect it ran a bearing.
If the bearings are worn, I think I know what would have started the wear. Once up to temp about once a week during startup there is some kickback. I could never really figure out how to correct in the management.

This might have caused the bearings to take a knock when the kickback happens.

Thanks for the replies, will go and check for the play on the rods.

Can I replace the conrod bearings while in there? Or should the big end bearings also be replaced at the same time? (As I understand the big end bearings would need to be replaced on an engine stand).
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Re: Knocking sound from head

Post by panic-mechanic »

There are a huge amount of variables in your questions.
A run big end maybe so that it turns inside the rod and eat the crank up or it could have just marked the bearing and you can swop them out in place.
BUT you need to be able to put a micrometer on the crank to see that they are
a) in spec
b) not oval
so this is something that can't be answered without you having the caps off and the crank journals open.
remember rods and caps are a set and have to be marked for the pair and the direction it is fitted currently before you take them off.
Small end cannot be replaced / redone without opening the motor completely. IE full rebuild.
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Re: Knocking sound from head

Post by GT08 »

panic-mechanic wrote: Wed Nov 07, 2018 7:52 am There are a huge amount of variables in your questions.
A run big end maybe so that it turns inside the rod and eat the crank up or it could have just marked the bearing and you can swop them out in place.
BUT you need to be able to put a micrometer on the crank to see that they are
a) in spec
b) not oval
so this is something that can't be answered without you having the caps off and the crank journals open.
remember rods and caps are a set and have to be marked for the pair and the direction it is fitted currently before you take them off.
Small end cannot be replaced / redone without opening the motor completely. IE full rebuild.
Sorry for the confusion, I probably know just enough of the finer details of the crank and conrod details to get me in trouble.
On a previous engine (also an ADY) of a family member we replaced the pistons with the bearings connecting the rods but not the bearings in the caps that hold the crank in. Was thinking this would be the same case at worst.
Will drop the sump check for up and down play on the rods, if present will take it from there.

Thanks for the patients so far.
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Re: Knocking sound from head

Post by chucker02 »

A quick test you can do is while the car is running, remove the plug leads one by one and listen for any difference in the knocking noise. By removing the combustion created by the spark plug you remove the load on the cylinder. If the knocking noise gets softer when removing the plug lead you know which cylinder has a problem.
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Re: Knocking sound from head

Post by panic-mechanic »

The cap holding the rod on the crank is called a big end - thus big end bearings.
The other side of the connecting rod that the piston attaches to is called the small end.
The crank is held in the block with big caps and those are called Mains or main bearings.
without removing the crank or the head you can take the big end caps off and look at the bearing - you can even slip in a new set given that you know for sure that
a) the crank has not been eaten - ie no score marks and measures in spec and round using a micrometer
b) the bearing has not turned inside the cap and no blue marks or scoring is present on the inside of the conrod on on the crank journal
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Re: Knocking sound from head

Post by GT08 »

panic-mechanic wrote: Thu Nov 08, 2018 9:23 am The cap holding the rod on the crank is called a big end - thus big end bearings.
The other side of the connecting rod that the piston attaches to is called the small end.
The crank is held in the block with big caps and those are called Mains or main bearings.
without removing the crank or the head you can take the big end caps off and look at the bearing - you can even slip in a new set given that you know for sure that
a) the crank has not been eaten - ie no score marks and measures in spec and round using a micrometer
b) the bearing has not turned inside the cap and no blue marks or scoring is present on the inside of the conrod on on the crank journal
Thanks for the explanation. That is definitely where I went wrong. I did not know of the Main bearings name. Before making this post I wanted to remove the head and inspect the pistons from the top. That would have been a lot more work than removing the sump. Although I fear the outcome of the sound is going to end with only one outcome, a very expensive fix.

One more question if I may. The oil pressure to what I have read seems too high and the threads on the internet of other people suggest that the sound may well be lifter that is over pressure and to hard for idle thus causing the knocking sound. Any thoughts? Or am I just confusing things again?
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Re: Knocking sound from head

Post by panic-mechanic »

No. That oil pressur will not cause any issues in as far a noises go.
On vw's when the oil pressure gets too high the lifter will pump up and leave the valves standing slightly open. At that stage there is no compresion and the engine stops running. So usually results in no noise at all as you cannot start it.
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Re: Knocking sound from head

Post by GT08 »

Thanks for all the replies and advice. The car has been fixed and the sound is gone.

TL;DR the car has been fixed by a mechanic. The lifters were bled and reinstalled.

So I dropped the sump and looked for up and down play on the rods, there was none that I could find.
I removed the big end bearing caps and inspected the bearings. All looked really good for the amount of km on the engine.
The bearings for piston nr 4 had a small score mark that just about catches your finger nail, but no real marks of disress.

On further inspection of the cam shaft I found this on cylinder 2:

Image

Not sure what made this mark but that might be what caused the lifters to fail in the first place.

Not knowing what to do more, we booked the car in at a local mechanic that I know really well and trust.

They removed the lifters and soaked them in oil overnight. They then installed them again and all was well.
I also soaked the lifter upside down in the same oil used in the engine on the initial install. I don't know if the oil they used was thinner or they manually bled the lifters.

I have read up on the forum that it is debated heavily if this is needed but in this case either it helped or I just somehow messed up the install.

Anyway, all is well now. The cost was a lot less than I expected. I will be driving the Jetta daily from next week to see how it goes.

Thanks again for all the advice and putting up with my lack of knowledge.
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Re: Knocking sound from head

Post by Masendaco »

panic-mechanic wrote:No. That oil pressur will not cause any issues in as far a noises go.
On vw's when the oil pressure gets too high the lifter will pump up and leave the valves standing slightly open. At that stage there is no compresion and the engine stops running. So usually results in no noise at all as you cannot start it.
@panic-mechanic

Why would your oil pressure be to high?

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Re: Knocking sound from head

Post by panic-mechanic »

Pump pressure relief valve fails.
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Re: Knocking sound from head

Post by Masendaco »

panic-mechanic wrote:Pump pressure relief valve fails.
OK. Taught it might be vicocity related or to high pressure from the oil pump. Not sure how that would happen though.

Where is this valve located?

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Re: Knocking sound from head

Post by Masendaco »

panic-mechanic wrote:If changing the lifter and oil pump did not make the noise go away I suggest you pull the sump again and look at the big ends. I suspect it ran a bearing.
Could this start as a light clucking sound in the engine?


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Re: Knocking sound from head

Post by Masendaco »

panic-mechanic wrote:No. That oil pressur will not cause any issues in as far a noises go.
On vw's when the oil pressure gets too high the lifter will pump up and leave the valves standing slightly open. At that stage there is no compresion and the engine stops running. So usually results in no noise at all as you cannot start it.
And would not fire? As the motor does not run and give signal to the ecu that it does?

Or would it just stutter and not start, maybe bend valves if interference?

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Re: Knocking sound from head

Post by panic-mechanic »

Relief valve sits in the pump body. Usually no noises. No of course it still gives a signal to the ecu but because the valves are open , no compression, no run. I have not seen damage from interference but that will depend engine to engine and how close the valves are to touching. But it will have to be a high comp very modded motor where less than a mm of valve open wil cause interference.
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Golf 2.0 2e engine has a knocking sound

Post by Ugen10906 »

Hi Guys. I need some advise with this issue, I redid my complete motor Started it up and was sounding perfect. Took the car for a drive at the time had a set of 40 sideiez on and the second cylinder wasn't getting fuel so it idled rough running on 3 cylinders. I put in petrol/injector cleaner in the tank and took it for a long drive hoping it will clear. The car had power till 3000rpm then was very sluggish. I pushed it to about 5000rmp then its started making a knocking sound and cylinder 2 still wasn't getting fuel. Removed the sidez and put a standard carb the car starts well and idles good but as soon as I press the accelerator I can hear the knocking sound the oil buzzer comes on and stays on after driving the car still has no power after 3000rpm.
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Re: Knocking sound from head

Post by Donavan »

oil pump failure and by sound of it you already have some bearing damage
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Re: Knocking sound from head

Post by Ashwin00001 »

I got a golf 4 1.8 20v car runs well when it heats the car starts to knock the oil light comes on then goes off and then on again but the still runs well
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Re: Knocking sound from head

Post by Ashwin00001 »

I changed oil checked oil pump still when cold its quit drive for +- 50km then it starts
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