Sqeak/rattle on startup tdi90

cheechy

A2OC Donor
In the last few weeks the car has developed a clear rattle on startup. I assumed the noise combo which includes a squeaking like noise was related to the aux belt so that was changed last week.

This morning after sitting a few days in wet and cold the noise is back (and it comes back only after sitting a few days in these conditions)

The timing belt and oil chain were changed oct 2018 for info.

Noise disappears within a couple of minutes but the reason for ask is to ensure its not a symptom of something serious approaching that I'm currently unable to diagnose.

I did ask wom to look into this last week when I was down but given they couldn't recreate after I'd driven the car down to them they changed the v belt and tried another couple of things to no avail it seems.

Suggestions welcome what to look at :)
 
Goid shout i'll try and capture next time it happens...will need to leave car sitting a few days.
 
Hydraulic tappet? From Wikipedia: https://en.wikipedia.org/wiki/Hydraulic_tappet

"There are a number of potential problems with hydraulic lifters. Frequently, the valvetrain will rattle loudly on startup due to oil draining from the lifters when the vehicle is parked. This is not considered a significant issue provided the noise disappears within a couple of minutes; typically it usually lasts only a second or two. A rattle that does not go away can indicate a blocked oil feed, or that one or more of the lifters has collapsed due to wear and is no longer opening its valve fully. The affected lifter should be replaced in the latter situation. "

"Generally, hydraulic tappets are more sensitive to engine oil quality and frequency of oil changes, as carbon sludge and residues may easily lock up the tappets or block oil channels, making the clearance setting ineffective. This has negative impact, especially on the engine camshaft and valves due to excessive wear if the clearance setting is not working correctly. As mentioned, one may avoid this by using the manufacturer-recommended grade of engine oil, and by not exceeding the prescribed oil change interval. "

RAB
 
Hydraulic tappet? From Wikipedia: https://en.wikipedia.org/wiki/Hydraulic_tappet

"There are a number of potential problems with hydraulic lifters. Frequently, the valvetrain will rattle loudly on startup due to oil draining from the lifters when the vehicle is parked. This is not considered a significant issue provided the noise disappears within a couple of minutes; typically it usually lasts only a second or two. A rattle that does not go away can indicate a blocked oil feed, or that one or more of the lifters has collapsed due to wear and is no longer opening its valve fully. The affected lifter should be replaced in the latter situation. "

"Generally, hydraulic tappets are more sensitive to engine oil quality and frequency of oil changes, as carbon sludge and residues may easily lock up the tappets or block oil channels, making the clearance setting ineffective. This has negative impact, especially on the engine camshaft and valves due to excessive wear if the clearance setting is not working correctly. As mentioned, one may avoid this by using the manufacturer-recommended grade of engine oil, and by not exceeding the prescribed oil change interval. "

RAB

Thanks rab. Interestingly enough the mechanic who did the oil chain last year (weetanks cousin) took the rocker cover off and at that point everything looked good in there but I wouldn't rule out the possibility of rapid deterioration.
 
I’ve had tappet race in my Camper (sold now). It was a very concerning sound. Like someone pouring ballbearings through a funnel for a few minutes. A slightly thicker oil solved the issue by reducing drain down.

When I put a video of the sound up the folks on club 8090 were quite unanimous (although much slower than on here) about the cause.




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i get that when it is wet and car been sitting for over a day too - no idea as belts and everything else look fine, it sounds like belt squeak and goes away quite quickly - instantly if i rev it by a few hundred and let it go back to idle...

Could be the tensioner sticking maybe - tried starting with bonnet off but it doesn't do it when I'm looking.

Chucked it to normal operation as cam belt had been done not long ago at all so not a concert and have more pressing exploration i need to do on my tdi for now.
 
The squeak suggests to me something that rotates???

Have you tried taking the bonnet off when you think it is going to squeak and standing over the engine while someone else starts the car. Might give you a guide...
 
i get that when it is wet and car been sitting for over a day too - no idea as belts and everything else look fine, it sounds like belt squeak and goes away quite quickly - instantly if i rev it by a few hundred and let it go back to idle...

Could be the tensioner sticking maybe - tried starting with bonnet off but it doesn't do it when I'm looking.

Chucked it to normal operation as cam belt had been done not long ago at all so not a concert and have more pressing exploration i need to do on my tdi for now.

Sounds very similar to me indeed.
 
The squeak suggests to me something that rotates???

Have you tried taking the bonnet off when you think it is going to squeak and standing over the engine while someone else starts the car. Might give you a guide...

Yup did think this...gamble on it happening when the car has been sitting a few days and get ready for it with bonnet off and camera ready.
 
Apparently there is an oil retention valve in the oil filter assembly - in effect a non-return valve. The valve cannot be changed on it's own - you have to change the oil filter assembly. If it fails, that could lead to all tappets being noisy but if only one, it's likely due to an individual tappet. If you can insert a 0.20mm feeler gauge between the camshaft and tappet, the latter needs to be replaced.

RAB
 
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Right so no recording today but I do think I may have a possible cause.

Car did not make any noise this morning which I did not expect. As I'm not one for anti freeze I usually just pour some lukewarm water on the screen with light frost. A few seconds after pouring the water onto the screen the noise was back suggesting that water is draining off from the windscreen into the vbelt or timing belt? (Suspect the aux vbelt)

Looks like it's coming through under the spray jet on the drivers side.

Does this sound feasible?
 
The right hand drain for the windscreen goes into a drain tube that discharges near the polyV belt. I have always felt this pipe is too short and easily dislodged such that you could get water onto the belts. Worth a check.

Is the black plastic cowling at the bottom of the windscreen damaged?

Yes water could be getting past the spray jet unit, a bit clear mastic could fix that.

I guess you could take the bonnet off, chuck water on the windscreen and you will see where it goes.
 
Is there a drain pipe attached to the drain? There should be. Doesn't explain the rattle or was it just a squeak?

RAB
 
Is there a drain pipe attached to the drain? There should be. Doesn't explain the rattle or was it just a squeak?

RAB

It's a hard sound to describe rab. Theres a bit of squeak but rattle in there also. It did sound related to engine revs a bit.

I guess the only sure fire way is to remove the water element and see if the noise still comes back.

Thanks
 
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