Well last week i bit the bullet and put the ute on a trailer and took it to the tuner/shop to get the job finished off. Now i hadnt had the engine running long enough to really see if there was a problem, which there is....
I knew there was a nasty clunk in the bottom end which is half the reason i took it to the shop, but on further diagnosis they tell me that its not running on cylinder number 4 for some reason. The dizzy is firing the right shots etc. and theres compression in the cylinder but just not firing.
What could this clunk be anyone? And why would it prevent that cylinder from firing?

Ive whipped the head off and the piston isnt cracked, the bores are smooth but theres a fair bit amount of carbon residue on the piston crown...

I didnt touch the bottom end when i took it out of the sunny, just had to fit the new cam and that was it, the thing didnt have a clunk before hand so i duno what could have happened

Any commments welcome.

Cheers
Dave

have you checked the ign. leads? that and the spark plug could have something to do with it running on 3.

as for the clunk.....
big end bearing maybe....
dropped nut or spanner? hope not....
dented sump....
for it to just clunk all of a sudden is a bit odd

I thought it was your ute at chris colgraves last week.
I went there to drop off some parts and had a quick squiz.
the chrome grille looks quite good.

cmon dave, you detective you... lol
if im not working sunday i'll come round for a look, what do ya say?

Yeah james that was my baby, got a new front apron to put on it but just gona leave as is for the moment.
Well i pulled the engine last nite and will most likley strip it down tonite for further investigation, im gona take the carbs into procarb to for a look over and for new accelerator pump gaskets (other ones shagged)

It will most likley be a bottom end bearing but i dont see how one could go in 4000k of a new engine
Maybe i should take it to the engine shop for them to worry about...

Dave

Umm sunday mite be a bit hard tom, well see

bearing issues can go that quick if a few of the following might of happened- bearing in the wrong way, wrong bearings, conrod not torqued properly, theres a couple if the shop put it together its the shops problem to fix the problem

Well heres the pics of the bottom end and no. 4 piston.




The troubling areas i think seem to be the blueish tinge to the edges of the crank between the bearing caps of the mains and piston ends. Most likley due to some sort of oil starvation.




This is the bearing of the number 4 piston, a fair few scruff marks on this bottom bearing and the other side had a few scratches to.




Thats the only scratches on the side of the piston i can find, the bores are smooth and no score marks in the bore either. The top of the piston isnt cracked or the ring land hasnt nipped the side of the bore at all.

The only conclusion ive come to is that theres been a slight lack of oil on that piston and that piston bearing needs replacing, i cranked the engine over by hand with the sump off and i DID hear a slight click or knock jsut as no. 4 was passing thru BDC (and on its way up again).

Any other noticeable defects anyone can spot? What about other diagnostic's that you guys can point me in the right direction?

Cheers
dave

I guess just check the rod bearing and bore clearances and see whats doing there.

What do the bearings on the main caps look like ok ?Because from those wear marks you might you got some foreign matter on that bearing.