Chris,
Well, I pulled the engine out of the truck Friday. Saturday I cracked the bottom open to peer inside the guts to see what the cause of the knocking was. I first removed and reinstalled the caps from each rod one at a time. All of the bearings looked like they should. I then removed the main caps one at a time. Each caps bearing had 1/4" bright shinny streaks running the entire side length of both sides. Some varying in widths, but all of them had these bright streaks running the long side of the bearing. The dull grey centers were untouched except for the thrust bearing, it had a small bright streak in its center. I carried the caps with the bearings down to a local machine shop, he said it was telling him that the crank was not "true" and that he got three readings:

Cheap Bearings (Federal Mogal)
Crank had unevenly worn journals causing the uneven ride
All 4.9L blocks should be line honed to correct the distortion in older blocks.

Now, I had the crank checked and polished by the shop that did the block work. They said the crank just needed polishing and it was fine. Why would I get bearings telling me one thing but the machine shop telling me another?

I understand the line honing deal, but how common is it to line home a 4.9L?

So, I replaced the crank with another crank I had turned 10/10. I used Cleviete (SP) bearings on the rods and mains. I stuffed everything back in the block, and stuffed it back in the truck. This was no small task, I had no help during any of this.. I fired up the truck and it idles quite, but it also idled quite before, only made the knocking under load. I have not test driven it yet.. Needed one night where I believed I solved the problem. Tonight I will confirm or disprove my "I fixed it" theory. IF this happens again, LINE HONE? SH*T....

Justin

 

Good Luck.

 

Line hone. it depends. Inline sixes are more prone to becoming warped than V8's, but it depends on the cicumstances. It's never a bad idea, but I don't worry about it unless the engine died a death associated with overheating. Also, the bearings sound like the way I said they would, which tells me there was too much clearance. If the block was warped, and it needed to be line honed, the marks in the bearings would have displayed a pattern, like getting wider towards the middle, then thinner towards the end, or thin at one end and wide at the other, or wide on both ends, and none at all on the middle. Since every bearing had substantial marks, there was too much clearance. Either the wrong crank, or, more than likely, the wrong bearings.

You will find out today. Did you mike them with plastigage this time??? (if you say "no", I will hunt you down and shoot you, and make you wear an "I LOVE Macs" T-shirt at your open casket funeral)

Take care,
~Chris

 

I did NOT use plastigage, I was told I was stuck with 10 over bearings and I could not find 11 or 12 over.... So, if I was to find more than usual clearance, I was hosed.

So why would I plastigage, if I have no recourse if the clearance is more than the tolerance allowed?

I do have a Steve Jobs for President TEE Shirt.


I do pray for the silence death will bring.

 

Let me tell you a little secret: if you had miked them anyway, then you would have eliminated that as ever being a possibility again. You also would have known how much clearance you have, which would affect your choice of oil viscosities, life expectancy, and it would have given you more peace of mind. And how long would it have taken? 15 minutes? 20, tops?


Man, no wonder you like PC's so much. You're used to doing the same thing over and over again until it finally works.

Good luck.

Take care,
~Chris

 

They say a sure sign of insanity is doing the same thing in the same way over and over again expecting different outcomes.

 

Well, You are right, I should have miked them, but I fear it would have proved what I now know, the block needs line honed. Either way, it is and was the death call for the truck. If I had miked them and if it had revealed that the block needed line honed, I would have scraped the truck, so I spent the labor installing it (crank) and reinstalling it (engine) in the truck which was free, so I am really not out anything less time, which I have plenty of....

To make a bad story worse, it still knocks at load. Has to be the block, I doubt I could have had two bad crank clearance problems in a row, possible, but doubtful. Had to be the block is out of line.

It is off to the auction...

Have my eye on a 94 F150 XLT Ext. Cab, 4x4, V8, LOADED 5 speed. $4200.00, not worth messing with my current truck.


Thanks again.

Justin

 

How can you build an engine without plastigage?? Even if you can't get thicker bearings you would know that your screwed before you spend the night reinstalling the engine. Good luck, maybe you can get your money back from the machine shop. They should have measured and seen the taper on the crank before they polished it.

-Jon

 

Man, that sucks pretty bad. You sure did a lot of work. Reminds me a little of a job I had a couple years ago. A kid with a 65 Chevy truck, needed a rebuilt straight 6. Got it, painted it, installed it, everything. I was filling the radiator and getting ready to fire it, when coolant/water started pouring out of the #3 spark plug hole.

Anyway, please use plastigage in the future. I won't hunt you down and shoot you, because I think you've suffered enough, and certainly learned your lesson. BUT, if this happens again, you're toast.



Take care,
~Chris