Who has had to replace pistons and/or regrind a crank during rebuild?

sizemoremk

sizemoremk

Registered User
Who has had to replace pistons and/or regrind a crank during rebuild?

It seems that most find the stock bottom end fairly bullet proof, so I am hoping I can get away with polishing the crank and new bearings, rings and a gasket set...

Do most of you tearing egines apart find pistons and journals to be within spec?

Thanks!
 
sizemoremk said:
Who has had to replace pistons and/or regrind a crank during rebuild?

It seems that most find the stock bottom end fairly bullet proof, so I am hoping I can get away with polishing the crank and new bearings, rings and a gasket set...

Do most of you tearing egines apart find pistons and journals to be within spec?

Thanks!
Click to expand...


Yup. Mine was a 1991 auto with about 125k on her, and all we did was polish the crank. It was within spec. I now have about 10k on the motor and running strong. I also go new rings, bearings, and gaskets, though I had the cylinders honed out because it was only liek 5 dollars a hole or something cheap. So I decided to have it done. I also had the had a 3 angle valve job done even though he said my heads were fine, and I replaced the valve seals which I consider a good idea if you have higher miles.
 
My crank measured out good so polishing was all it needed.
My pistons had a little wear and the bores were just allitle out of round, so I bored it .020 over and put new pistons in.
The motor had 128,000 miles on it.
 
I put my faith in the machine shop that did the work. the first one said I had a collapsed piston skirt, so they overbored 0.020. The second one said I needed to overbore 0.020 and they ground on the crank too (which is NOT recommended by the shop manul) next time, i'm gonna spend the money on a good set of mikes, and check it for myself.
 
RE: Rebuild

One thing for sure, buy a new 94-95 front timing cover and 8 lobe oil pump. If your old cover is worn or scored where the oil pump runs against it you can loose oil pressure and spin a bearing like I did.
 
SonySC said:
One thing for sure, buy a new 94-95 front timing cover and 8 lobe oil pump. If your old cover is worn or scored where the oil pump runs against it you can loose oil pressure and spin a bearing like I did.
Click to expand...

Does that swap require changing anything esle???

Thanks!
 
Im doing this as we speak. Only needed to polish the crank and im haveing the pistons dipped and cleaned. Rods are being magnafluxed and reconditioned. If you have a bearing failure then your looking at cutting the crank, new rod and possable piston. Im going to check with my machinest about resurfaceing the timming cover to oil pump surface. Along with the oil pump rebuild kit it should be fine. The 94-95 timming cover is obsolite. Only used ones floating around out there.
 
scbird1 said:
Im doing this as we speak. Only needed to polish the crank and im haveing the pistons dipped and cleaned. Rods are being magnafluxed and reconditioned. If you have a bearing failure then your looking at cutting the crank, new rod and possable piston. Im going to check with my machinest about resurfaceing the timming cover to oil pump surface. Along with the oil pump rebuild kit it should be fine. The 94-95 timming cover is obsolite. Only used ones floating around out there.
Click to expand...
I just bought a new 94-95 timing cover from the ford stealership a few months ago here in Mass. They claimed that it came with a new oil pump and that is why they charged me something like 250.00 but the oil pump never came with it, but they were still selling them.
 
haha

well the late model timing cover is available from ford-although it is over 200 bucks new. the only problem is its not interchangable with an early model cover as it mounts the crank sensor differently. The late model oil pump does work with the early covers, but thats the part thats been discontinued-even if you go to ford and order a 95 one youll still recieve the inferior early model-best bets to get a melling HV pump from autozone or somewhere like that-they for some reason still have the late models, and for WAY less than ford-lastly, make sure the thrust surface (where the oil pump gears ride) on the timing cover isnt scored-if it is clean it up by using some very fine grit sandpaper-dont take off too much, if its deeply gouged buy a new or used one-good luck, Mike
 
Just getting a new cover, one that isn't scored itself, can be a challenge. Is this surface something that could be fixed?

Perhaps relining it somehow with new steel, similar to what can be done on wear surfaces on construction equipment?
 
Re: Timing Cover

Mike8675309 said:
Just getting a new cover, one that isn't scored itself, can be a challenge. Is this surface something that could be fixed?

Perhaps relining it somehow with new steel, similar to what can be done on wear surfaces on construction equipment?
Click to expand...

I had Bob Johnson (Jim Demmett's engine builder) do my engine. He showed me the old cover and it was all scored. I don't know where he found the new cover.
I also have wondered if a machinist could bond some kind of new surface (brass, bronze, steel) onto an old cover's oil pump mating surface.
Maybe this is something that TBird88 could look into.
 
Most of the covers I have seen only needed .002" milled off to clean them up. Expect to pay about $60 for a competent machinist to fixture and machine it in one pass. I have sucessfully taken as much as .006" off of one and it hasn't shown any issues after over 40k miles of usage.

Paul
 
Damn, when does it stop with these cars!!!

Glad ya'll brought that up, about the T/C cover, becasue I would not have know to pay particular attention to that....

Thanks!
 
I didnt think it would be a problem but any kind of sanding sounds risky. I will take mine up to my machinest and see what he would charge.
 
Hmm, might be something to chat with those "billet" boys (heartland fab I believe) looking for some things to make. Though I can't imagine a new front cover made from billet would be all that reasonable in price.

Oh, and I wouldn't do it myself for sure. It would be difficult to keep the surface on the same plane without using some precision tooling. A machinist should be able to do it for a more than reasonable fee.
 
I had my car for about 2 weeks when I snapped the crankshaft between 1 and 4. During my rebuild, I found that the guy who owned it before me rebuilt it about 15,000 miles prior. The crankshaft I replaced was surprisingly within specs, however; the rear main journal was undersized! :eek:

And anyone who's at least read the shop manual knows why NOT to do that.

Anyway, the replacement crank I picked up was totally within spec.. all I had to do was get it magnafluxed and spun. The pistons were okay, but I figured I'd take a step ahead and I got a set of custom Wisecos.
 
I talked to my machinest today and he told me it would be very hard to set it up for a cut. He told me that if has scratches simply fill them with pure silcone and let it sit over night. This might work but im in no hurry so I will look into differnt options.
 
No

dont use silicone-the rotation of the gears will peel it off imediately-then youll have crap in your engine. chances are if theyre very minor imperfections you can use scotchbrite or steel wool and gently buff them out-its perfectly acceptable if the cover isnt gouged
 
scbird1 said:
I talked to my machinest today and he told me it would be very hard to set it up for a cut. He told me that if has scratches simply fill them with pure silcone and let it sit over night. This might work but im in no hurry so I will look into differnt options.
Click to expand...
The setup is not difficult at all. If you want me to do it, contact me offline to discuss price and turnaround time.

Paul
 
Well I dont need cut it anymore as its cracked. After cleaning I found a crack from the bottom to the crank shaft seal. Just as luck would have it I was looking around under the work bench and I found the one off of our old 93 engine with only 87k on it so it worked out perfect. Engine should go in this weekend. Here is what I have been up to. Mark
 

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