4age crankshaft toast?

notnilc20
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4age crankshaft toast?

Postby notnilc20 » Thu Jan 12, 2017 8:51 pm

I recently pulled a 4age engine out of the salvage yard from an mr2...and i took apart the bottom end and I noticed on cyl. 4 one of the connecting rod bolts had fallen out and left one bolt connected to the connecting rod....upon further investigation i noticed there wasn't even a rod bearing installed! So i figure the gap of having no bearing caused rocking which eventually worked the nut off the bolt. I also took measurement of the con rod jounal and it should be 40mm but i got 38.5 and 39mm on this one in question....i tried to fit a rod bearing on it for giggles and sure enough.....the bearing is too big now. Is there a way a machine shop can fix this? Should I just buy another crankshaft? Should I just part out the engine and call it a day? I originally got it just to mess around with and maybe to help out another 86 fan as he was looking for a 4ag for his swap but he may go another route. I already got new piston rings and rod bearings and a new piston as that #4 piston was damaged by the bolt. If I was to rebuild it and put new gaskets and seals and make it look nice how much could I expect to sell it for? Btw it is a 7 rib block largeport bluetop. Thanks for any advice.

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totta crolla
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Re: 4age crankshaft toast?

Postby totta crolla » Fri Jan 13, 2017 1:48 am

If the other 3 journals are the standard and correct size then the journal in question is worn badly and probably beyond repair. If the others are the same size then the crankshaft may have been reground at some point. 1.5mm regrind does seem a lot to be honest, generally regrinds are in the thousands of an inch range. Oversize bearings are available but you would be best talking to a machine shop about your options for these.

davew7
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Re: 4age crankshaft toast?

Postby davew7 » Fri Jan 13, 2017 5:05 am

I do not think you could find .060" under size bearings, and the journal would in all likelyhood have to be turned at least another .010" to get a good finished surface.
You can get the crank journal welded up and reground to the standard size. But it's still probably easier to just find a used crank to install. Dave W

notnilc20
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Re: 4age crankshaft toast?

Postby notnilc20 » Fri Jan 13, 2017 8:11 am

davew7 wrote:I do not think you could find .060" under size bearings, and the journal would in all likelyhood have to be turned at least another .010" to get a good finished surface.
You can get the crank journal welded up and reground to the standard size. But it's still probably easier to just find a used crank to install. Dave W


totta crolla wrote:If the other 3 journals are the standard and correct size then the journal in question is worn badly and probably beyond repair. If the others are the same size then the crankshaft may have been reground at some point. 1.5mm regrind does seem a lot to be honest, generally regrinds are in the thousands of an inch range. Oversize bearings are available but you would be best talking to a machine shop about your options for these.


Thanks a lot guys.....i figured it was pretty much done for.....i figure if it was repairable the labor cost would be much more than finding a used crank. But i just don't know if I want to invest the money into it. I've already got a good running 4age in my eight-six so i was just planning on restoring this one and selling it....but since i'm located where there are no other ae86 i don't want to put my money and time into something I can't get back out. On top of that ....it is only set up for mid or fwd....rwd would be even more money. What would you do?

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totta crolla
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Re: 4age crankshaft toast?

Postby totta crolla » Fri Jan 13, 2017 9:13 am

I would keep all of the usable parts as spares.

notnilc20
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Re: 4age crankshaft toast?

Postby notnilc20 » Fri Jan 13, 2017 9:45 am

totta crolla wrote:I would keep all of the usable parts as spares.


Yeah...i think you're right. But what i'll do is just post up things for sale and just sell them as time goes by, no rush...sell the parts as people need and use parts that i need but i dont think I'm going to put more money into it unless someone wants it done for them in which I would charge for the remaining parts and a little for my time.....thanks for your insight guys.

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