Loud rattling / tapping noise above 2000 rpm

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JogiahMk4
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Car Make: VW
Car Model: Mk4 GTi (110kw)

Loud rattling / tapping noise above 2000 rpm

Post by JogiahMk4 »

My 1.8 T agu is making a very ,very loud rattling noise when I rev the engine past 2000 rpm , I recently rebuilt the engine, new valve stem seals , rings , mains , big ends , turbo recondition, new oil and water pump as well . I can't tell where the sound is coming from , i removed the auxiliary belt system and unfortunately the sound was still there after. I Don't think its bearing knock as it doesn't occur at idle or anything less than exactly 200RPM , and the sound doesn't appear at all after 2nd gear .I popped the valve cover off and the cams or the caps don't have any scoring on them .

Any ideas ? Also as a side note the low oil pressure light briefly flashed once before the noise started , it just flashed once and went off
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dcmk4
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Re: Loud rattling / tapping noise above 2000 rpm

Post by dcmk4 »

How is the tension on the chain tensioner between the cams? It could be losing pressure resulting in noises.
'14 Golf Mk7 GTI
THANAS STG/// ECU&DSG
Littco L380x
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JogiahMk4
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Car Model: Mk4 GTi (110kw)

Re: Loud rattling / tapping noise above 2000 rpm

Post by JogiahMk4 »

Thanks for the reply , I did check the tension on the chain , it seemed to he fine , there wasn't any slack and I didn't notice any scoring on the chain ot anywhere else from the chain but I'll take off the valve cover again to double check. Any other signs to look out for for a failing cam chain tensioner ?
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dcmk4
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Re: Loud rattling / tapping noise above 2000 rpm

Post by dcmk4 »

If it seems to be holding pressure when the car is off and you checked, it should be fine.
The mention of the oil pressure warning and that noise seemed to tie in together if there's a pressure loss the chain will of course lose tension
'14 Golf Mk7 GTI
THANAS STG/// ECU&DSG
Littco L380x
All the ponies
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JogiahMk4
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Registered for: 3 years 3 months
Car Make: VW
Car Model: Mk4 GTi (110kw)

Re: Loud rattling / tapping noise above 2000 rpm

Post by JogiahMk4 »

I think the car picked up a bearing knock on cylinder 2 , unplugged the injector on cylinder 2 and the noise goes away sadly . Could be that the engineer didn't cut the crank correctly
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dcmk4
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Re: Loud rattling / tapping noise above 2000 rpm

Post by dcmk4 »

It could be that the bearings were not sized correctly or an oil supply issue to that one..
'14 Golf Mk7 GTI
THANAS STG/// ECU&DSG
Littco L380x
All the ponies
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JogiahMk4
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Posts: 42
Registered for: 3 years 3 months
Car Make: VW
Car Model: Mk4 GTi (110kw)

Re: Loud rattling / tapping noise above 2000 rpm

Post by JogiahMk4 »

dcmk4 wrote: Wed May 26, 2021 4:14 pm It could be that the bearings were not sized correctly or an oil supply issue to that one..
I went with king racing bearings so I doubt it's that and I never had a problem with oil pressure until this noise started ,but I'll be pulling the crank tommorow and seeing what happens
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