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Engine destroying itself - detectives wanted !

Posted: Tue May 25, 2010 3:16 pm
by Murray
My 1986 GTV6 2.5L has decided to give me grief right at the start of summer :evil: I rebuilt/blueprinted this engine completely about 80k kms (50k miles) ago.Recently it developed a knock when lightly loaded and started sounding "cammy" if that tells you anything.In the hope that my oil pump wasn't up to task (I didn't replace it during the rebuild and don't trust my gauge) I decided to pull the lower pan and swap the pump from another engine.When I saw what was sitting in the bottom of the pan I decided that that wasn't going to be the solution ! I found a bunch of metal debris - most of it is copper colour ? I also found a chunk of a green valve guide seal.I pulled my driver's side valve cover (it's easiest) and expected to find signs of destruction,but all looks normal and there doesn't appear to be any unusual movement in the camshaft up or down or side to side.Tomorrow I'll pull the passenger side.My question for the "detectives" among you is what do you think is the most likely source of these copper-like chunks of material ?

Re: Engine destroying itself - detectives wanted !

Posted: Tue May 25, 2010 3:54 pm
by fedezyl
Copper like...hmmm...valve guides?? :roll:

Re: Engine destroying itself - detectives wanted !

Posted: Wed May 26, 2010 12:43 pm
by kevin
money :lol:

Re: Engine destroying itself - detectives wanted !

Posted: Wed May 26, 2010 12:46 pm
by kevin
No really , check gear on oil pump drive under distributor. Sometimes on 24v the 10mm nut comes loose and the gear moves up and down then teeth break off which lands in sump and looks just like that apart from the coin :lol:
Engine siezure follows after those teeth go

Re: Engine destroying itself - detectives wanted !

Posted: Wed May 26, 2010 2:25 pm
by Murray
fedezyl thanks for the suggestion on the guide but I don't think that's it because my guides are bronze and this stuff is truly copper coloured.Strange thing is it's partly ferous because I can pick it up with a magnet.

kevin I'll take your suggestion and peer down that hole - maybe I'll find some money :lol: I hope so looks like I'll be needing it.

Re: Engine destroying itself - detectives wanted !

Posted: Wed May 26, 2010 2:33 pm
by Zamani
If I am not mistaken, from oil analysis forums, copper could mean it could be big or small end bearings. That would be consistent with the knock.

Re: Engine destroying itself - detectives wanted !

Posted: Thu May 27, 2010 2:58 am
by Murray
Zamani unfortunately your probably in the right ballpark :evil: but I'm still hoping to find something less drastic ! - fat chance eh :cry:

Re: Engine destroying itself - detectives wanted !

Posted: Thu May 27, 2010 7:53 pm
by GregoryV
Ugh! My bet is it's the rear main bearing - this happened for who knows what reason on my first rebuild after around 10 or 15K on it :x the only thing I could come with is that the engine had not been started after a numerous months due to "life" getting in the way. GV

Re: Engine destroying itself - detectives wanted !

Posted: Thu May 27, 2010 10:13 pm
by Zamani
I remember reading on the 155 forum of how some 155 V6s would eat their mains if left unused for a long time. So Murray, was the car left sitting for 2-3 months prior to this?
actually the same thing happenend to my 155 V6. My dad hit something then it sat in the workshop for a few months. After that the mains went south.

Re: Engine destroying itself - detectives wanted !

Posted: Fri May 28, 2010 12:28 am
by Murray
Yes guys the car has been "sitting" still for 5 months - short Canadian winter :) If it turns out to be the rear main I'll let you know.

Re: Engine destroying itself - detectives wanted !

Posted: Fri May 28, 2010 8:18 am
by Giuliettaevo2
I've read somewhere about a modification for the rear mains... if i remember corrctly they used Nord bearings which are supposed to be a bit wider. :?

Re: Engine destroying itself - detectives wanted !

Posted: Fri May 28, 2010 3:16 pm
by GregoryV
Well this will be interesting indeed... I have heard that the rear main gets oil last or that the route for oil to it is not the best, but some of you might have a better thought at that one. GV

Only upside for me was that I replaced it with a 3.0 :) GV

Re: Engine destroying itself - detectives wanted !

Posted: Sat May 29, 2010 1:09 pm
by ChrisS
Giuliettaevo2 wrote:I've read somewhere about a modification for the rear mains... if i remember corrctly they used Nord bearings which are supposed to be a bit wider. :?
I used NORD mains throughout on my recent 12V build. As you say, they are about 3mm wider, and another bonus, they work out slightly tighter than V6 shells colour-for-colour as the NORD jobs are fractions thicker. Slightly cheaper too.

As for the debris...whatever it is...it doesn't look nice :(

I've heard tell of long layups causing problems, theories vary (!), but one I heard was that gunk in the blind ends of the crank oilways dries up, gets dislodged, then blocks the active oilways. Given the dead ends are all effectively further out from centre of rotation than the active oilways, I don't necessarily see how this could happen....but who knows. If a crank was removed from an engine and stored dry for a long time...and didn't have the oilways cleaned out, then maybe....dunno.

Re: Engine destroying itself - detectives wanted !

Posted: Fri Jul 30, 2010 2:04 pm
by shures
Murry,

Find anything yet?


My GTV-6 has been waiting on a timing belt for 4 months

Re: Engine destroying itself - detectives wanted !

Posted: Sat Jul 31, 2010 1:07 pm
by Murray
Scott yes I found the culprit.It was the big-end rod bearing on cyl no.3 which spun itself.I have myself to blame because it seems I didn't do a very good job of measuring my crank journals when I rebuilt and should have gone with oversize bearings :evil: Fortunately I had a spare 2.5 to put in to save my summer.Lesson learnt on that one too.I failed to turn the engine over sufficiently by hand with oil in the cylinders.It ran for 2 days then got rough.I pulled it and discovered the piston rings had broken on 2 cylinders -no doubt due to extended storage.Well being a true Alfa addict I just happened to have a new set of Borgo pistons/rings/liners and I threw those in and now it screams and pulls like a freight train again - pure joy :D