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Author: Subject: Alfa Engine rattle - help with diagnosis?
novacaine

posted on 19/7/11 at 09:22 AM Reply With Quote
Alfa Engine rattle - help with diagnosis?

Hi all,

My beloved 156 has developed a nasty engine rattle that has got me all worried

It starts fine, no noises at tickover, nice and smooth but the noise starts at around 2-2.5k rpm and gets louder with revs

Heres a youtube clips for help explaining the noise



Youtube Linky


really hope its not bearings

thanks in advance



***edit to say - its the 2.0 TS manual if this helps at all with diagnosis***

[Edited on 19/7/11 by novacaine]





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ashg

posted on 19/7/11 at 09:28 AM Reply With Quote
sorry to tell you mate the big ends have gone





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T66

posted on 19/7/11 at 09:38 AM Reply With Quote
Thats not good if your attached to it...





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Thinking about it

posted on 19/7/11 at 09:47 AM Reply With Quote
Sounds like bottom end
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britishtrident

posted on 19/7/11 at 10:22 AM Reply With Quote
Big end bearings are more of a solid knock rather than rattle ----- as it is an Alfa suspect the camshaft variator wear as this gives a rattle from the top end

[Edited on 19/7/11 by britishtrident]

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Alfa145

posted on 19/7/11 at 10:24 AM Reply With Quote
Could be bearings but didn't seem a consistant enough rattle to me, a few other options to check before your wallet panics.

Sounds like something was loose somewhere to me, check everything is tight that you can get to. Maybe something inside the cam belt cover? Cam belt tensioners were always a weak point on this engine. 36k miles for belt changes is recomended, check its still tight and not jumped.

Also look up the cam variator this tends to go on the petrol engines and rattles. Although when mine went on my 1.6 I don't think it sounded like that.

AlfaOwner.com forum might provide more help with specifics of this engine.

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novacaine

posted on 19/7/11 at 10:31 AM Reply With Quote
the cambelt and variator were done less than 5000 miles ago,
oil level is ok too, ever so slightly on the low side but a good 4mm above the min mark on the dipstick


Will post this on alfaOwner, thanks for the recommendation


Thanks for your help everyone





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Alfa145

posted on 19/7/11 at 11:25 AM Reply With Quote
Do you still get the rattle when you've topped the oil up? I know mine had a slight rattle when the oil was below 1/2 on the dip stick. Alfas normally don't like running on low oil levels. It could be the variator isn't getting enough oil pressure to turn the cam which might be causing the rattle. But thats just a random guess.
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MikeRJ

posted on 19/7/11 at 11:34 AM Reply With Quote
Variators tend to produce a constant diesel-like rattle when worn, and also tend to be most noticeable at lower engine speeds.

Does it get worse when the engine is hot? Have you checked the oil pressure?

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UncleFista

posted on 19/7/11 at 01:02 PM Reply With Quote
quote:
Originally posted by ashg
sorry to tell you mate the big ends have gone


Sounds like it to me too





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big_wasa

posted on 19/7/11 at 01:23 PM Reply With Quote
ouch.
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whitestu

posted on 19/7/11 at 02:17 PM Reply With Quote
Isn't it possible to drop the sump and change the big ends in situ?

If they have just started rattling the crank may be OK.

Stu

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ashg

posted on 19/7/11 at 03:34 PM Reply With Quote
there isnt any ifs or buts the big ends are shot, simple as that really the sound of dead big ends is rather distinctive. get the sump off and have a look, im 100% sure the shells will be shot. if your lucky the mains will be ok. there are three routes to fixing it. take the engine out measure and check everything and re machine where necessary flush and blow out all the oil ways and crank to make sure there is no swarf from where it picked up then reassemble. option two take sump off clean it out along with the strainer fit new shells and hope there is no swarf hanging around in any of the oil ways, refit sump and start. or option three stick another engine in it.





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martyn_16v

posted on 19/7/11 at 03:52 PM Reply With Quote
quote:
Originally posted by novacaine
oil level is ok too, ever so slightly on the low side but a good 4mm above the min mark on the dipstick


On this engine, that's not OK. The bottom end is made of chocolate, and will eat itself well before the oil gets near the min mark (or the oil "warning" light thinks about coming on)

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steve m

posted on 19/7/11 at 04:32 PM Reply With Quote
I go with the big ends as well,
Normally it is a fairly easy fix with the engine in the car, i would also change the mains, or at least the ones you can get to

Steve

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