Bearing wear inquiry - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 9 Old 05-19-2017, 06:50 PM Thread Starter
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Bearing wear inquiry - Distorted or warped block/crank?

I was wondering the general consensus of my bearing wear.

The engine is a mostly stock 1976 Ford 302. I rebuilt the engine recently. The machinist honed the bores 30 over, no other block work. The original crank was ground 10/10. I replaced pistons and rods. Stock heads with ARP head bolts. Mains use stock bolts. Hydraulic flat tappet cam.

I plasti-gauged the bearings prior to assembly. I'll have to check my notes, but rod bearings were at the tighter end of the allowable tolerances and mains were at the loose end (~.0022).

The engine only has about ~100 or so miles over the last nine months.

I recently noticed a loss in oil pressure and decided to check the filter. The oil in the filter had lots of very fine gold dust with a handful of gold flakes. Oil pressure was 45psi driving, 20psi idle (1000rpm). However if shifted into reverse/drive from a stop, idle would fall to 700rpm, and oil pressure dropped below 10psi.

I pulled the engine and checked the bearings. The bottom main bearing halves have extreme wear. #'s 2,3,4 are almost all copper. 1 & 5 show tapered wear. The top main bearings are worn, but not into the copper.

Rod bearings have some wear, not into copper. The rod bearings are reflecting the surroundings (wood ceiling).

Thanks for any insights!

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post #2 of 9 Old 05-19-2017, 07:02 PM
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I had the same thing happen to me, your bearings were too tight imo. need a better way to check clearances, plastigage is a nice check after verifying with a bore guage. I needed to polish the crank and put in new bearings on mine. hopfully your crank is ok.

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post #3 of 9 Old 05-19-2017, 07:08 PM
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Sorry about that.. What grade oil did you use?
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post #4 of 9 Old 05-19-2017, 07:41 PM Thread Starter
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I used Brad Penn break in oil for the first 20 minutes while breaking in the camshaft. Drained and refilled with Brad Penn 5w-30. Then switched to 5w-30 synthetic.

The last oil change was to Mobil 1 5w-30 synthetic with a K&N oil filter. On startup of the most recent oil change it took about 10 seconds for the oil pressure gauge to read anything, at the time I thought it was the pressure gauge but perhaps something blocking the oil. I did not look inside the filter prior to installing it.

I haven't checked all the oil passages yet, but didn't see anything blocking the passage from the oil filter housing to the central passage between the camshaft and #1 main bearing.

My thoughts are either oiling issue or bock warpage. I did *not* align hone the mains or have them checked for straightness. I did cursory checks for roundness of crank journals and main bearing sizings. My skills (& equipment) are limited in such that I could only really determine nothing was grossly out of round.

It's all about learning. As the assembler the end responsibility lies within myself for not ensuring *everything* measured correctly prior to assembly. It's my engine, so I assumed the risks.
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post #5 of 9 Old 05-21-2017, 12:51 AM Thread Starter
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Adding a complete picture of the five main bearings. I'm leaning toward a warped block, the main lowers are worn substantially more than the uppers and the wear tapers at the #1 & #5 mains.

There is wear on the bottoms of the camshaft bearings. The dull gray layer has been worn away on the bottom (oiling hole) sections.

The wear on the rod & camshaft bearings could be because of debris from the main bearings.

If the block is warped, will a line hone fix the issue?
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post #6 of 9 Old 05-21-2017, 02:24 PM
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I had this happen and I was getting gas in my oil from a choke that was set too rich. MSD box would allow it to continue to run without flooding. I also had significant ring wear and that was the tattle tail. If your EFI then disregard but if carb it's worth a look.
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post #7 of 9 Old 05-23-2017, 10:32 AM
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when assembling your engine you should be able to spin it by hand before the pistons are installed and of course you checked with micrometers on the crank and bearing sizes before assembly to make sure they match. Platigauge is only a last check and not very accurate. Then with the pistons all installed it should take much more than 20lbs of torque to spin it over and finally with heads and valvetrain you should be less than 65lbs of torque to spin it over
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post #8 of 9 Old 05-25-2017, 03:13 PM Thread Starter
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During the assembly process there was no binding of the crankshaft. I was diligently checking this as I went. There was some drag, but couldn't have been more than a couple of in/lbs and I attributed it to the thick assembly oil (red melling assembly oil) and the rear seal.

I'm leaning toward distorted block or improperly machined journals.

I did drop the engine (components) off at a local engine shop. The mechanic there mentioned that detonation could've caused the damage as well. I'm dubious only because the calculated static CR would've been 8.6. That said, I didn't actually measure the deck height (8.229") or the cylinder head volume (58cc).

We'll see what the shop finds out!
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post #9 of 9 Old 05-25-2017, 10:13 PM
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Probably oil starvation from clearances being too tight initially, then of course all the bearing material didn't help afterwards.
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