Technical Noisy valve 20 vt

[Magnus Jahnke]

Hi!
Last fall my 20 vt started to make a knocking sound like if a tappet was empty of oil.
Since other projects came in between I didnt get time to fix it untill a month ago.
I took the cams out and dismantled and cleaned all the tappets. When I was putting it all together again I noticed that one cam lobe on #1 exhaust was worn down about a millimetr and a half.
Aha thats it! I thaugt (stupid I know). Got a new cam and tappet,got it all tgether again and got it started. Same noise still...
Someone told me that the tappets are pressurized via the cam variator and if the variator is leaky the tappets may not fill up.
Can anyone confirm that?
It sounds a bit strange to me.
Most engines I fiddle with have rocker arms or valve in head so the 20 vt is a bit overcomplcated for me, Im learning though.
Rgds. Magnus

 

[dante giacosa]

hi Magnus-

a distinct 'knocking' is most likely bearing-damage down at the crank unfortunately.

The variator adjusts only the inlet valve timing on the left-most cylinder (standing looking into the engine bay).
I'm not aware of it pressurising anything; the oil (wet sump) is derived from the pump at the bottom on the same end of the engine and delivered from there.

If this is you fiddling; you have done really well to dismantle this engine!

what can happen- although it is more prevalent on Alfa Romeo's than FIATs, is the variator itself can fail; leading to a diesel type sound.

 

[Magnus Jahnke]

Hm?
Yeah it sounds like it could be a bottom end problem.... even though it is a bit more of a softer sound, one per rev. or two.
Ok i,ll get sump off and meassure the crankbearings just to be sure.
Are the bolts to the conrod big ends once only or can they be reused?

 

[Magnus Jahnke]

Just got all the stuff in the way to get the oilsump off and struggled a lot to break the sealing. Now it seems like the drive shaft has to come out too. Correct?
Can the bolts to the conrods be reused and whats the torque on reinstalling them?
Rgds : Magnus