Knocking sound on acceleration

[ChrisCarter]

Hi .... I bought my 156 2.0TS (2001) from an Alfa Specialist just over 3 months ago. It was advertised as having had a complete engine rebuild and needed to be run in after a split piston ring problem. The big ends, cambelt, variator and all gasgets were replaced. It has ran for 2500 miles without fault. The dealer advised me to have the oil changed after a few thousand miles due to engine rebuld which I have just had done. They used 5w30 fully synthetic.
The car started this morning fine but I thought someone was cutting their grass when I reasiled it was my engine! On accelerating it knocks loudly and goes quieter on lift off or at constant speed. On tickover it now sounds like its knocking. but if you slowly build up the revs it sounds fine. It is still as powerful as ever but obviously drove it very gently todayand haven't had it over 3000 revs since I got it.
I have booked it in to my local garage on Tuesday to find out whats happening but if anyone has any ideas to ease my worry I would be very grateful.
No suprises the 3 month warranty ran out 2 weeks ago !
Thanks

[Cuore_Sportivo_155]

5w30 is FAR too thin for a 2.0... though that shouldn't be audible on a cold start...

other than that, not sure about the sounds you're hearing. could be the big end bearings, but would hope not... could also be the hydraulic tappets... could be the variator...

[symon]

5w-30 is too thin, but I wouldn't expect it to cause damage on it own. It will tend to burn quickly, and when the oil gets low then problems will start.

It sounds like the big ends are knocking, if it is it will get wore very rapidly.

I think that you will find that a car needs to be fit for purpose when sold by a dealer, usually if something terminal goes wrong within around 6 months then the dealer is responsible for fixing it whether there is a warranty or not.. The fact that they have advertised it as having a full engine rebuild also goes in your favour.

If they won't play ball, speak to the citizens advice bureau or trading standards, they will be only too happy to help.


Just don't tell the garage when you take it back that you used 5w-30 oil, as they may use it as an excuse to wriggle out of fixing it.

You used a 10w-40 Semi, synthetic didn't you.

[ChrisCarter]

Thank you for your help....It was my local garage that put that oil in it when they serviced it for me! I will have words about that. I did think it should have 10w40 but they are the 'experts' !!! NOT!!!
I'm really gutted its broken.
Thanks again

[Alfa 156 JTD]

Originally Posted by symon

5w-30 is too thin, but I wouldn't expect it to cause damage on it own. It will tend to burn quickly, and when the oil gets low then problems will start.

It sounds like the big ends are knocking, if it is it will get wore very rapidly.

I think that you will find that a car needs to be fit for purpose when sold by a dealer, usually if something terminal goes wrong within around 6 months then the dealer is responsible for fixing it whether there is a warranty or not.. The fact that they have advertised it as having a full engine rebuild also goes in your favour.

If they won't play ball, speak to the citizens advice bureau or trading standards, they will be only too happy to help.


Just don't tell the garage when you take it back that you used 5w-30 oil, as they may use it as an excuse to wriggle out of fixing it.

You used a 10w-40 Semi, synthetic didn't you.

Why should they be responsible for fixing something that's possibly not their fault ?

If the "Oil Lab"
http://www.theoillab.co.uk/index.html
are used by the garage for an analysis they will soon see what oils have been used in the engine.

Perhaps being honest with them from the start will have a better conclusion
as a high quality 5w-30 oil shouldn't damage the engine.





.

[symon]

Originally Posted by Alfa 156 JTD

Why should they be responsible for fixing something that's possibly not their fault ?

If the "Oil Lab"
Oil Lab Fuel Analysis Service, Fuel Testing Car Engine Oils and Lubricants, Industrial Machinery, Marine, HGV's, Aircraft
are used by the garage for an analysis they will soon see what oils have been used in the engine.

Perhaps being honest with them from the start will have a better conclusion
as a high quality 5w-30 oil shouldn't damage the engine.





.

Because the 5w-30 almost certainly didn't cause the damage, and the dodgy rebuild did. Why give them an excuse not to fix it, especially with the sums of money involed?

[Alfa 156 JTD]

Originally Posted by symon

Because the 5w-30 almost certainly didn't cause the damage, and the dodgy rebuild did. Why give them an excuse not to fix it, especially with the sums of money involed?

Then it should have gone back to them for the first oil service to keep any warranty in order.

Something's missing in this story................





.

[ChrisCarter]

Originally Posted by Alfa 156 JTD

Then it should have gone back to them for the first oil service to keep any warranty in order.

Something's missing in this story................





.

Yes, I travelled 250miles to buy it being absolutely immaculate and low mileage after looking at some very rough examples. The warranty that I had with the car was a warranty 2000 one so could take the car anywhere to have it serviced, so didn't see the point of travelling all that way. I also paid over book price due to all the work it has had done, and its exceptional condition.
So the only thing now missing is whats wrong with it!
The reason I brought up the type of oil originally was that I also thought it should have 10w40 and my comment was a suggestion that a superior grade has been used.
5W30 is on the list of approved grades for this engine and my garage know I always ask for the best. But I have mentioned this to them.
It has been delivered to them and I await the verdict!!! But missing it already

[symon]

The 5w-30 is only specified for cold climates.

Plenty of newer cars specify it for all year round use, so it is thick enough not to cause any damage, but it will tend to get burned rather quickly in a TS

[ChrisCarter]

Thanks again Symon....I will definitely have it changed ...assuming engine is brought back to life

[ChrisCarter]

Turns out it is only the exhaust manifold gasget and unfortunately for me that is what my wife diagnosed!! I won't hear the end of that for a very very long time.
I feel a bit like the guy on here who struggled to change his door check strap because there was a piece of glass in the way !!
Moral is just relax and enjoy

[symon]

That is good news.

I would still get the oil changed to a 10w-40 semi, or 5w-40 fully synthetic however.

[Joss]

sounds like big ends to me

[Alfa 156 JTD]

Unfortunately most assume............

Alfa + engine noise = £££££££££

Where simply listening to your wife would have been the less stressful option in the long run.
Wife
"you never listen to me do you"

[symon]

Originally Posted by Alfa 156 JTD

Unfortunately most assume............

Alfa + engine noise = £££££££££

Where simply listening to your wife would have been the less stressful option in the long run.
Wife
"you never listen to me do you"

To be fair, it is difficult to give an accurate diagnosis just form the description "Knocking under acceleration".

Leaking exhausts usually make a chuffing or a ticking noise.