New engine tightspot

A

AndrewRP6

Member
I got big problem!! Just assembled my 4.6 bottom end, new bearings, new rings etc . Refitted p6 timing cover, and sump (yes I did give it a clout to ensure clearance on front conrods!). Then turned it on the front pulley with extention bar to listen for any nasty noises etc. Erm, not good, turns fine till you reach 360* then it goes really tight. Something then went crack. I quickly got the sump off, there was a very small bit of metal. I obviously aint going to push it around the tight spot again but its still there in both directions. I was very careful assembling the engine so cant think what it is. Any ideas? Will I get away with it? :idea: :(
 
The fact that it will turn through one crankshaft revolution but will not go through a second suggests the possibility of a camshaft/valve train problem ( which of course runs at half crankshaft speed ) . A photo of this metal fragment might help. Are the heads on ? If so, are you sure that the cam is timed correctly and that you have not had contact between valve and piston ? Also, did the crank rotate freely before the pistons were inserted/ rods done up ?
 
Firstly, the heads are not on, therefore valvetrain/timing not possible. To be more precise, it will not turn a full 360, maybe 350? So whichever way I rotate engine it sticks at the same point. It was ok before connecting rods, all I can think is maybe a slipped conrod bearing - but I was pretty careful. Damaged piston ring? And that wouldnt explain the metal chip I found. It is just a chip but looks fresh which worries me. I was thinking of disconnecting con rods one at a time to see if I could find the fault that way
 
AndrewRP6 said:
I was thinking of disconnecting con rods one at a time to see if I could find the fault that way
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That would be a sensible place to start, plus a pic of the mystery bit of metal with something to scale it.
 
Chipped ring is a distinct possibility.
I once tore down an Alfa 1.7 16v boxer motor, only to discover that it was missing much from one of the piston rings.
Car still flew along but had a bit of smoke come from it when the throttle was sharply backed off. (and lacked a little bit of the real meat of the torque...still went to 7000 rpm but) :shock:
Quite a few metal fragments were in the sump...but they were clearly identified as "piston ring"
The piston itself was quite damaged, and I had a guy turn up a one off piston to save buying a whole set.
Mechanic was quite stunned the motor still operated...those Alfa boxers the toughest darn motors I ever come across. You could literally drive them as hard as you possibly could all day and they would just say "more please"! But I digress...
 
Ok obviously I need to start investigating. I will do this after work tomorrow and will post when I find something. I will try to sort a pic, this laptop wont let me but I will try a different device. Thanks for your input
 
Oil pump binding up and striped the drive ??? Just another thought . As said a pic of the fragment would help .
 
stina said:
Oil pump binding up and striped the drive ??? Just another thought . As said a pic of the fragment would help .
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Didnt think of that, I just rebuilt oil pump using high volume kit. Was quite fiddly to be honest. The drive gear on my 3.9 got chewed up by the oil pump. Maybe I should get timing cover off first to check for any damage. The conrod bolts are stretch bolts so would rather not undo them. Thanks for that :?
 
Hi, to check the oil pump pull the dist out and use a long screwdriver to turn
the pump shaft. Try that first as it's an easy check, although if it has chipped
a pump gear it wouldn't end up in the sump.

Colin
 
colnerov said:
Hi, to check the oil pump pull the dist out and use a long screwdriver to turn
the pump shaft. Try that first as it's an easy check, although if it has chipped
a pump gear it wouldn't end up in the sump.

Colin
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No i was wondering that , as in how would it find it's way into the sump , but i'm thinking more the actual skew gears that drive the pump and dizzy , they are higher up in the engine , and could of found there way down to the sump through the gap between front cover , front of block ,into sump . Course i'm only visualising a standard P6 timing cover , block , sump set up in my head . With a bit of luck it'll be the problem , as it'll be a relitivly cheep fix :? :D
 
Erm, I just realised - I havent even fitted the dizzy yet! I was kinda hoping that is what it was. Thanks though, had a great nights sleep thinking that is what is was!
 
Ok, found the problem :D there was a bolt that was protruding through the casing of the timing cover (holding the water pump). Obviously not the correct bolt for that position. However, it was fouling the dizzy drive cam gear and that is what was the shrapnel and locking was. So new cog and sort bolt out problem solved. Like I said, had same problem with my old 3.9 Same timing cover!! So my error really. Engine turns tidy with cover off :) thanks for your suggestions - glad I didnt start dis-assembling my engine!!
 
AndrewRP6 said:
harveyp6 said:
AndrewRP6 said:
it was ok before connecting rods,
Click to expand...

That wasn't the case then.....
Click to expand...

Well yes, I fitted timing cover after connecting the rods
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So it was after fitting the timing case then, not after fitting the rods. By your logic you could say it was after fitting the crank, because it's happened after everything you've done already, the point of change is fitting the timing cover.
 
Harvey,

Well yes obviously, but my original quote states that it rotated fine after fitting the crank (which it did) before connecting the rods. I did not really test it after fitting the rods (which I now realise that I should have - it would have saved all this!). So the point of change is after fitting the timing cover AND connecting the rods. I just didnt know which was the problem hence why I started this thread. Thankfully I had useful and logical comments from forum users - thankyou. Problem solved
 
All I'm trying to point out is that you never mentioned the timing cover at all. You said the problem occurred after you fitted the pistons and rods, not after you'd fitted the pistons, rods and timing cover. If you give poor information when asking the question, you'll get poor suggestions as to the cause.
 
harveyp6 said:
All I'm trying to point out is that you never mentioned the timing cover at all. You said the problem occurred after you fitted the pistons and rods, not after you'd fitted the pistons, rods and timing cover. If you give poor information when asking the question, you'll get poor suggestions as to the cause.
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I did not get poor suggestions. But thanks anyway...............
 
I've just re-read your very first post and that does mention the timing cover being fitted, so my apologies for that, but what I said previously still applies. You should be checking after every move that it still turns over, and the last thing fitted before it stops is going to be the place to start looking.
 
That confuses me. I cant see that anywhere in your previous posts, I accept your apology gracefully but there is nothing in your posts here to that nature!!! You obviously contribute a lot here - please be factual!! p.s. do I know you??
 
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