Blown Piston after crankshaft and piston replacement

[Fundikali]

Originally Posted by Fundikali

First off guys thank you so much for the help you have give me so far. Thought I should post some pics to give a clearer picture of what is happening. Something important I think I should mention is that all the problems with the pistons and the rods are happening only in cylinder number 4. The first time I had the rod knock it was piston 4. The new piston was put in cylinder 2 and the one that was in 2 was put in 4. The first time it had the rod knock, the piston 4 (which I threw away) looked just as the picture above (this piston is actually for the second rod knock, the third time the car broke down). Hope I'm putting this through clearly.



The picture above is after the piston blew. This happened after I had driven the car for about a week and I was doing 5000rpm at about 140kph. Today the mechanic informed me that this also happened on cylinder 4. But this was not the new piston as he had put the new one in 2.

He then put in a new piston in cylinder 1 and put the one that was in 1 into cylinder 4. The car started producing the knocking sound shortly after during the road test. The mech opened it up and found that the main bearing was gone (badly scratched). There was no damage on the con rod or the con bearings. Below is the piston.



This time also the bore was scratched. The garage gave me some reprieve though. They said that they will put in new bearings, piston rings, piston, oil pump. They also said that they will put half block for the side with piston 4 that is damaged. By the way, how safe is it to replace half the block? All this they will do for free. do you guys think it'll work this time?

Sorry for the multiple posts, it's the first time I'm doing this.

[stiimpreza1984]

Replacing half the block why not the whole block then just to lessen costs Id reckon Id be wanting a full block just dosnt make any sense when the new half block goes and gets joined up to the older half of the block they could be out by a lot maybe not but they going to be different stress's already on the old half block now I know the piston 2 and 4 side block are the only side thats been scratched BUT its like the norm you dont just replace one side of your brake pads you do both what are the chances off when they put it all back together and it go pop again just dont understand if your going to doing it do it right, Id want the full block replaced, main and big end bearings, rods, pistons, and so on never heard of just replacing half the block just sounds ODD

[Fundikali]

Originally Posted by stiimpreza1984

Replacing half the block why not the whole block then just to lessen costs Id reckon Id be wanting a full block just dosnt make any sense when the new half block goes and gets joined up to the older half of the block they could be out by a lot maybe not but they going to be different stress's already on the old half block now I know the piston 2 and 4 side block are the only side thats been scratched BUT its like the norm you dont just replace one side of your brake pads you do both what are the chances off when they put it all back together and it go pop again just dont understand if your going to doing it do it right, Id want the full block replaced, main and big end bearings, rods, pistons, and so on never heard of just replacing half the block just sounds ODD

Good point. I've just called the mechanic and told him I want the full block replaced and he said they'll do that. I've also told them that I want to inspect the new parts before they start the rebuild. Thanks.

[stiimpreza1984]

Originally Posted by Fundikali

Good point. I've just called the mechanic and told him I want the full block replaced and he said they'll do that. I've also told them that I want to inspect the new parts before they start the rebuild. Thanks.

Great fella new everything

[Fundikali]

Originally Posted by carwisperer

ID be getting the oil pump off as well and clean or replace that just incase there is a lack of oil feed to the crank bearing theres little holes under the shell bearings that feed the oil to the crank lubricating the shell bearings in the rods around the crank possible they may not be clear enough to feed sufficient oil the the bearings or even blocked so it would only get the oil being thrown around in the oil sump and slowly finding its way around and thats would cause it,ive had these rod shells go before and the little notch in them that helps hold them in the correct position breaks off and can get stuck in these oil ways in the crank,he would have seen it im sure but with things the way they are it may be worth you checking this your self if you can..see what state the crank bearing faces are any scores etc,some thing just isnt right is it?

Are these the little holes/ oil ways you are talking about?

[STIDave]

I've been following this story of yours and pray i never have to go through any of that. I really hope it is sorted this time and as for knowledge here, you guys are awesome. Good luck in the future.

[Fundikali]

Originally Posted by STIDave

I've been following this story of yours and pray i never have to go through any of that. I really hope it is sorted this time and as for knowledge here, you guys are awesome. Good luck in the future.

Thanks a lot. Yeah, these guys are awesome, very resourceful.

[stiimpreza1984]

Also check the oil cooler aswell and give it a good clean before going back on engine as it might have metal pieces from the damaged pistons on it sure all these parts be cleaned and checked before reassembling them and replace oil pump as said before

[Fundikali]

Thanks. I will double check with the mechanic that the oil cooler has been cleaned.

[carwisperer]

Originally Posted by Fundikali

Are these the little holes/ oil ways you are talking about?

I ment the ones that are in the crank its self dude where the con rods fit to with the shell bearings to the crank!looking like your getting some where now though mate??

[carwisperer]

same design shells as what your showing me above,see the little tabs that psition the shell bearings??they break off if the shell's in the bottom of the con rod spin during failure.

[carwisperer]

Originally Posted by stiimpreza1984

Replacing half the block why not the whole block then just to lessen costs Id reckon Id be wanting a full block just dosnt make any sense when the new half block goes and gets joined up to the older half of the block they could be out by a lot maybe not but they going to be different stress's already on the old half block now I know the piston 2 and 4 side block are the only side thats been scratched BUT its like the norm you dont just replace one side of your brake pads you do both what are the chances off when they put it all back together and it go pop again just dont understand if your going to doing it do it right, Id want the full block replaced, main and big end bearings, rods, pistons, and so on never heard of just replacing half the block just sounds ODD

i have to agree with this too,same as my point before about only doing half the job when the damn things in bits any way

[johnathan2459]

hope you get everything sorted fella,ive got 52 plate bug eye mate and had the headgasket go,got it back and 500 mile later I had a knocking noise unfortunatly it was the crank i managed to get a fully forged spec c engine and someone to fit it,i hope you have more luck with yours than i did mate

[Fundikali]

Thanks Johnathan. The garage's yet to get the block so I'm still waiting. Carwisperer, I'll check the holes in the crank as advised. thanks.

[anilsub]

Any news Fundikali? i read it all and feel quite sorry for you, hope you sort it out this time...Good luck mate