Bent conrod

[Kev555]

Long story short i had a faulty injector which bent my conrod in No1 cylinder. Pulled engine and stripped. Im based in Ireland so limited places to shop for parts, rock Auto only ones i dealt with as shipping is cheap. I need a replacement conrod and rock auto has ones in stock. Can i use my own shell bearing in the new conrod or do i need to measure crank etc to get new shells? As you see the piston got a little bit of rubbing from the counterweight on the crank but i think its ok. Thoughts? Thanks in advance to Dino for the initial analysis as to what was wrong.

 

[Juice]

You always check bearing clearance.
That piston is done.
How do you plan on balancing the rotating assembly?

 

[Dino Dino Bambino]

You could do this one of two ways.

1. The cheap way i.e. replace the damaged con rod alone but you'd still have a damaged piston that could cause problems down the line. You'd better hope the corresponding crank journal wasn't damaged or distorted by the cylinder hydro locking. Therefore you might want to ask a machine shop to check it closely and measure it.

2. The better way i.e. new set of Gen 2/3 Coyote forged rods, forged pistons with new rings, new rod/main bearings, new oil pump.

I'd be surprised if the cylinder wall wasn't scuffed by the piston that's attached to the bent rod so you may need the cylinder rehoned or, worse case scenario, all of the cylinders rebored.

 

[Kev555]

You always check bearing clearance.
That piston is done.
How do you plan on balancing the rotating assembly?

You could do this one of two ways.

1. The cheap way i.e. replace the damaged con rod alone but you'd still have a damaged piston that could cause problems down the line. You'd better hope the corresponding crank journal wasn't damaged or distorted by the cylinder hydro locking. Therefore you might want to ask a machine shop to check it closely and measure it.

2. The better way i.e. new set of Gen 2/3 Coyote forged rods, forged pistons with new rings, new rod/main bearings, new oil pump.

I'd be surprised if the cylinder wall wasn't scuffed by the piston that's attached to the bent rod so you may need the cylinder rehoned or, worse case scenario, all of the cylinders rebored.

Thanks for the input Juice and Dino. The piston has light scuffing and no cracks etc Dino as it only ran in the garage for a few minutes but i see your and Juices point about it possibly being lighter and out of balance now? The cylinder wall believe it or not is perfect with no scores or scuffing. The issue happened in the garage after i went to start it. It only hydro locked on the starter, not while running so I'm hoping the journal isn't damaged or distorted. If i go down the new piston conrod rings route that will that mean a cylinder rebore? I will post a more detailed picture of the piston damage tomorrow so you guys can assess it better to see if theres a handy way out of this. Not a daily driver, more a summer car that i dont want to pile a ton of cash into as i will never get it out of it. Id love a manual one so hoping to let it go down the line.

 

[Juice]

Piston clearance, much like bearing clearance needs to be measured. Engine blocks are finish honed to the correct size for each piston. Engines are not an area to be "its close enough", lol, ever watch Roadkill?

That said, Ive slapped shit together stricktly by feel and it worked. So yea, you could plug a new rod & piston in there, and it would work for a long while. Or it could granade the moment you fire it up. So, do it right or do it over, up to you.

 

[Kev555]

Yeah defo dont want to strip it all down again or start looking for a complete new engine if it grenades Juice. Its also very hard access to new/upgraded parts as well due to my location. I have a gut feeling its only the conrod thats taken the brunt. I can locate a good used piston and conrod out of the same year GT as mine locally if its the same size? I'm a mechanic in years gone by, I didn't do anything in engine rebuild stuff much and I haven't got the technical tools to carry out that work, I left that to the engineering shops to leave it oven ready for me. I will have a look around locally to see what local engineers views are on it and access to pistons etc as a second opinion.

 

[Juice]

A piston and rod from another stock engine used in good shape should be fine. Lightly hone the block, and new rings and rod bearing would be the minimum I would do.
Totally understand your parts situation. A lot of parts are getting scarce even here in the US.

 

[Kev555]

I will check my piston tomorrow with a fine toothcomb for hairline cracks but the crank counter weight just rubbed it and no more. Not sure what to do for the best? Second hand rod and piston which could be a shot in the dark or a new Rod? Will a new standard rod come the same size as my old rod that i can just pop the shells into it? Rock Auto quotes "Standard Bearing Outer Diameter"

 

[Kev555]

A piston and rod from another stock engine used in good shape should be fine. Lightly hone the block, and new rings and rod bearing would be the minimum I would do.
Totally understand your parts situation. A lot of parts are getting scarce even here in the US.

Rock Auto dont seem to stock high quality parts either, mostly just generic stuff.

 

[JC SSP]

Not sure what you are talking about. RA has Motorcraft parts.

 

[Kev555]

I can only see three types of Enginetech rod listed for mine? I have seen motorcraft parts listed at times when ive wanted other stuff but not on this occasion

 

[JC SSP]

Yes when comes to reciprocating internal engine parts they as other part vendors will be limited. This is going to be a Ford item or an aftermarket solution.

 

[Kev555]

Do you know if Enginetech is OK then as a brand and Quality JC? as its the only option if I dont get the second hand piston and rod on fleabay?

 

[JC SSP]

I am not familiar with those brand sorry. Maybe someone else on the forums knows…

 

[Kev555]

Thanks for your help JC, I did a quick review check of their reputation in between times and their parts look to be OEM refurbished in a lot of cases. I will sleep on the your info, thanks

 

[MrBhp]

You asked about sizing. Don't assume on this. Make sure the one you are replacing is standard.

 

[Kev555]

I'm fairly confident engine hasn't been worked on before but i will double check that MrBHP

 

[Kev555]

This is the shell from that bent conrod, Standard sizing does anybody know?

 

[MrBhp]

Looks standard. You should be good!

 

[Kev555]

Thanks for the confirmation MrBhp