m20b25 bum deal. worth fixing it?

[e30leigh]

so i picked up my m20b25 bottom end monday night.

i originally thought that i was paying for just a bare block. no attachments.

when it arrived i was super glade to see that it was a complete bottom end.
super happy at this point!!!
so it sat it the trunk of my car for awhile as it was dark by the time i got home, and then had work. finally managed to have a look at it today.

SHOCK AND HORROR
all 6 cylinders have scoring and scratches in the bore. cylinder one has what looks like an alloy deposit on the top of the cylinder about 1/2" in diameter. its not high enough that it catches the piston. and its above where the 1st piston ring reaches, also about 1/2" above the pistons location at bdc the bore has a odd ring around it. its hard to say if it was a crack as it was getting dark and i dont have a torch at home. but theres a lip to it. as there is at the top of all the cylinders. only cylinder 6 has a decent sign of hone marks.

this is bad news. its apparently only done 190,000km's
and its from a 89 525.

has anyone seen damage like this before? would it be worth saving? id say it would require .040" (1mm i think?) oversized pistons at least, a rebore, hone, rings, bearings ect. its alot of money for whats ment to be a budget turbo build.

also it doesnt have a factory oil cooler, oil filter housing. can i fit a factory e30 m20 oil cooler straight onto it? i guess the 5 series m20s just never got them. hopefully its a case of unbolt and swap over. can anyone shed light on this?

so i guess in general im really pissed off with this deal. any help towards my ordeal would be appreciated.

thanks, leigh

[FLG]

Pics would help.

You might be able to get by ball honing it yourself and changing just the rings

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[e30leigh]

i thought about that too. but im worried the lip at the top might be more then just carbon build up. obviously id need the bores measured correctly for wear.
the dude i bought it off said it ran well and didnt blow smoke. but i am sceptical.

i just dont know how hearty these motors really are.

[ttrousdell]

To be honest you will probably have to go overbore. The hone is ment to recondition the bore surface and not remove scratches and grooves. What you're saying doesnt sound good and damage like that might come from severe overheating or lack of lubrication. Does the engine turn over or squeek when turned over? I wouldn be surprised if the crankshaft's bearings are garbage as those are the first to go if the engine runs without oil. Break it down and let us know what you find.

[e30leigh]

ill be posting pics soon. as soon as i get a clear day to break it down. i got the torch out. and had my boss eye ball it for me quickly.

he basicly said what i thought. it has gotten stupidly hot.

with light on the situation we could see piston one has gone oval, the front edge has been breaking off from the heat. and theres signs that the head gasket has been leaking.
and number one has picked up leaving the alloy on the bore.

we also think it might survive the scoring. but the wear low in the bore mainly again on number one is a worry. so once its broken down. ill document it. and ill also post the measurements i get from the engine reco guy. hes basically going to measure it and say ditch it or go for it.

and to answer the question before. no it doesnt make any noise when the crank is turned. its free and smooth. so its had plenty of oil.

[jrdeamicis]

Just bore up .025 and re-ring it, throw some bearings at it while you are down there and have your self a nice little B25 bottom end.

[e30leigh]

do you think rings can take up .025" and still hold the compression? also ill be running boost. would doing that still hold the boost?