Did I get hosed by the machine shop?

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TjmedicQuinn
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Joined: September 4th, 2012, 1:09 am
Stroker Displacement: 4.6
Vehicle Year: 2001
Vehicle Make: Jeep
Vehicle Model: Wrangler

Did I get hosed by the machine shop?

Post by TjmedicQuinn »

Let me just start off by saying I'm just learning about all this... and It's been the hard way. Hears the skinny. So my old 4.0L blew up at 140,000 miles. When I dissembled it the number one piston was in a thousand pieces and the rod punched a hole through the block. I went to the local machine shop after finding a donor block for a rebuild. He said he could do a 4.7 stroker for the same price, he had a 4.2 crank that someone didn't use or something like that. This is where the nightmare started. Long story short he put it together as a long block. He told me "I can't warranty because Its a performance engine, but if anything goes wrong I wont leave you hanging." The total cost parts and all was 2,821.47$ I installed the engine EXACTLY the way I instructed with the new 24LBS injectors from Bosch, as well as the break in procedure. Ran great at first for 1,500 miles then started to tick. He then told me is was a collapsed lifter, I replaced the on my own dime. Same noise now with a misfire. I got angry and just pulled it out to look it over. Looked closely at cylinder walls and the number six had vertical scoring in it. I called him and said "what the *^%$ is this all about." He told me the only possible thing that could have happened was 1. my injector leaned out 2. the intake or manifold gasket leaked cold air in and made that cylinder overheat. He re honed and replaced the piston(300$ more) I didnt trust him so I took it to a very reputable shop (that I didn't know about at first) to have everything measured for 150.00.
This is what they came up with and told me was wrong...
Crank Shaft Run out .0025 on #4 "out of tolerance"
Crank Shaft mains .002-.0005 ""undersized"
Crank Shaft rods .008-.0018 "Undersized"
Line Bore .0002-.0007 "big"
Block Rake Front 79 Back 81 + .002
Retlaw01XJ
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Stroker Displacement: 4.6
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Re: Did I get hosed by the machine shop?

Post by Retlaw01XJ »

Price is in the ballpark for parts and labor.
How bad is the scoring on cylinder #6?
Could be anything from piston rings damaged during install, insufficient piston/wall clearance, leaky injector, or debris getting there. If he's saying it was lean, there may be be other indications such as burned valves. Poor piston clearance would be my best guess.
Crankshaft specs are way out. Did it have decent oil pressure?
Sometimes lifters go bad. They don't make them like they used to. Any idea what brand they were?
Walt K
Eastern Pa
2001 Cherokee 4.6 stroker 90 day build
Buick GS's and Saab turbos for other days...
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IH 392
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Re: Did I get hosed by the machine shop?

Post by IH 392 »

TjmedicQuinn wrote: Crank Shaft mains .002-.0005 ""undersized"
Crank Shaft rods .008-.0018 "Undersized"
Line Bore .0002-.0007 "big"
I'm an ASE Master certified machinist, I don't understand these measurements?
Mains, TWO THOUSANDTHS to FIVE TEN THOUSANDTHS undersize??
Rods, EIGHT THOUSANDTHS to EIGHTEEN TEN THOUSANDTHS undersize?
:huh:
Line bore, TWO TEN THOUSANDTHS to SEVEN TEN THOUSANDTHS over size??, .0002" is nit picking to the nut!.0007" if it really is on the high end of tolerance maybe?
You can get more power out of ANY engine!!!
ASE Master certified engine machinist, gas and diesel
TjmedicQuinn
Posts: 3
Joined: September 4th, 2012, 1:09 am
Stroker Displacement: 4.6
Vehicle Year: 2001
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: Did I get hosed by the machine shop?

Post by TjmedicQuinn »

Retlaw01XJ wrote:Price is in the ballpark for parts and labor.
How bad is the scoring on cylinder #6?
Could be anything from piston rings damaged during install, insufficient piston/wall clearance, leaky injector, or debris getting there. If he's saying it was lean, there may be be other indications such as burned valves. Poor piston clearance would be my best guess.
Crankshaft specs are way out. Did it have decent oil pressure?
Sometimes lifters go bad. They don't make them like they used to. Any idea what brand they were?
Oil pressure was good all the time. The valves were burned in #6. All parts in the block were new, except the crank. Even with the lifters replaced the same noise/ misfire before I took it to him.
TjmedicQuinn
Posts: 3
Joined: September 4th, 2012, 1:09 am
Stroker Displacement: 4.6
Vehicle Year: 2001
Vehicle Make: Jeep
Vehicle Model: Wrangler

Re: Did I get hosed by the machine shop?

Post by TjmedicQuinn »

I'm an ASE Master certified machinist, I don't understand these measurements?
Mains, TWO THOUSANDTHS to FIVE TEN THOUSANDTHS undersize??
Rods, EIGHT THOUSANDTHS to EIGHTEEN TEN THOUSANDTHS undersize?
Like I said this is all new to me, and I don't want to go pointing fingers without the correct information. The original shop that built it did not give me specks. Also the handwritten work order/receipt said that the engine was a 4.7L.
These are the specs from the I shop I took it to for measurements/inspection because I didn't trust the original after he replaced the bad cylinder and honed it.
3.9" stroke 3.895 bore with 20over pistons = 4.569L. (check my math, but a 4.7L it is not )

Crank Shaft Run out
#2 .0010
#3 .0015
#4 .0025
#5 .0010
#6 .0050

Line Bore
#1 +.0012
#2 +.0007
#3 +.0005
#4 +.0008
#5 +.0007
#6 +.0009
#7 +.0009

Mains Rods
#1 2.4991 2.0930
#2 2.4991 2.0940
#3 2.4991 2.0940
#4 2.4990 2.0940
#5 2.4991 2.0940
#6 2.4993 2.0940
#7 2.4990
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Re: Did I get hosed by the machine shop?

Post by IH 392 »

Well if the stroke is 3.9" it's been offset ground?, the stock 258 stroke is 3.895", a .020" over bore will put the bore at 3.895" also for a "square" engine, and it will displace 278.5 ci= 4567cc's.
Looking at the run out you posted I have time believing the crank would even turn with the main caps torqued in place!? and they only gave you six of the seven mains, plus I don't know how they got run out on #1??
It would have been nice if they actually given you the main bore dimensions rather than just saying they are over size, there is some tolerance, are they going off of minimum??
The mains at 2.4491 are right on at the high side f .010" under, tolerance is .0005", a .010" bearing on #6 should lock it up too.
The rods give or take are about .0005"=.001" under standard, std spec is 2.0948"-2.0955"
You can get more power out of ANY engine!!!
ASE Master certified engine machinist, gas and diesel
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