Mr_Asa UltraDork
3/30/21 12:44 p.m.

This was the engine in my F150, she had a little over 360k when I pulled her, and except for my berkeley ups she never let me down.   Since I am gaining steam with my LS head and need a jig I figured I would finally break the engine down and check out what the hell had happened with her. 

I was fairly sure I knew what happened, considering that I lost oil pressure in the middle of a drive from Tampa to Tallahassee and I had to nurse the truck to Tally.  Motor honey, thicker oil, every trick I could think of.  Finally got to Tallahassee and instead of spending time with my sister and my new niece I had to pull the oil pan and throw in a high volume oil pump I picked up on the way up there.  Filled it with 15W40 and hoped.  

Got back to Tampa and drove her back and forth to work and whatnot.  Developed a horrible clatter.  I thought it might be a collapsed lifter, but I was fairly sure that the bottom end hadn't survived the oil pressure loss.

So, now lets look at the pics.  We'll start with the worst one, then go through the rest.

Pretty sure this is where my clatter came from.  When I removed the head I spun the balancer around to see what everything looked like.  I noticed at TDC the #1 piston would hesitate if I rocked the balancer back and forth where it's pair piston #6 would move exactly in time with the crank.  When I pulled the piston, I found the below.  The cap was difficult to remove, as if the cap bolts had been bent somehow.  The entire crank end was dark which I can't explain.  If you look at this pic and then look at the others you'll get an idea of what I'm talking about.

The bearings are definitely shot.  One of them had actually slid down around the other bearing, and the other was had somehow worked its way against the crank a little bit and started to deform up against the crank. (rust is from when I cleaned everything off)




#2-6 are fairly standard.  I'll post #2 and then just link to the rest of them so you can check 'em out as you like.  Rod caps lifted off with no issues.

Like I said, compared to these the #1 crank end is dark, like it was soaked in soot and carbon?








There's also some evidence of some form of coolant leak, but I don't really see anything on the headgasket.  Makes me wonder if the head is good.  Maybe someone else will see something I missed?

Rust here is as you see immediately after I removed components.









Cylinder head:



Finally we have the main bearings.  Upper bearings look fairly good, other than the front and rear bearing, which is to be expected as that's where they're constrained.  Lower bearings are fairly shot.




However the lower portion of the bearings are pretty fudged.

CrustyRedXpress Reader
3/30/21 12:56 p.m.

Darker rod end is probably from heat. If dissassembly was tough it might have gotten hot enough to distort as well-probably wouldn't reuse that one.

EDIT: I'm terrible at reading headgaskets, but it looks like there might have been a breach between cylinders 3 and 4 as well. 

Streetwiseguy MegaDork
3/30/21 1:05 p.m.

That is a classic example of a "spun bearing".  The bearing gets oil starved, it starts to hammer, which takes the tension off the bearing/rod interface, the bearing rotates and blocks the oil hole, then no lube and it welds stuff.  Makes very hotness.  Much garbage.

Edit- the "rotates and blocks the oil hole" only applies to a main. The rest of the story is true.

FMB42 Reader
3/30/21 1:29 p.m.

Yep, badly 'spun bearing' it is. And the rust on the push rods and rockers points to an internal coolant leak (of course). And it does look like the H. gasket failed between 3 & 4. And I'm going to guess that the #1 rod caps bolts stretched out due to hammering. Meanwhile, 360k on an in-line 6 is pretty good if you ask me.

Mr_Asa UltraDork
3/30/21 1:35 p.m.

Spun bearing makes perfect sense.  Hadn't even thought of that.

Kubotai New Reader
3/30/21 1:42 p.m.

As the others have said, the big end turns purple/black from heat due to friction when the lubrication fails.  I'm not sure I'd reuse a rod that had turned black like that.  I would also suspect a blown head gasket between 3 and 4 like CRX said.  What do the rod journals on the crank look like?

Mr_Asa UltraDork
3/30/21 2:31 p.m.

I don't think I have a pic of the rod journals, and I coated everything I'm going to drop off at the machine shop in grease to prevent rust.

Streetwiseguy MegaDork
3/30/21 2:41 p.m.

Rod will be repairable by resizing, but a good used one might be a better choice.  Crank will have to get measured.  50/50 that its machine-able, but it might be too worn, or bent.

Mr_Asa UltraDork
3/30/21 2:57 p.m.

Not sure what I'll be doing in regards to the crank or the rods.  I might try building this as a Challenge friendly build, or I may just build it for my truck.

If Challenge, well... Challenge pricing.

If DD usage, and I kind of like the idea of having the stock block in the truck, I may use my forged crankshaft I have been hoarding.  Of course, it is also potentially Challenge priced...

barefootskater (Shaun)
barefootskater (Shaun) PowerDork
3/30/21 3:51 p.m.

You killed a 300. 


berkeleying legend. 

Stealthtercel Dork
3/30/21 4:39 p.m.

1. <notices thread title>

2. <opens thread>

3. <is initially puzzled by complete lack of modern Mopar content>

4. 360,000 miles?!  That's, like, "To the Moon, Alice!" and more than half way back.  I hope it lives on after this, um, minor hiccup.

Appleseed MegaDork
3/30/21 4:52 p.m.

Somewhere there is a half a million mile Slant-6 laughing.

Mr_Asa UltraDork
3/30/21 8:58 p.m.
Appleseed said:

Somewhere there is a half a million mile Slant-6 laughing.

Somewhere else there's a guy throwing 15 PSI at a stock 300 with over 380k on it and DDing it (that I know of, at least)

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
3/30/21 10:01 p.m.

The black end of the rod is oil coke.  It got hot and cooked the oil.

Pretty standard stuff.  I do see the 3-4 head gasket leak.  Notice how the chambers have spots where the carbon has been replaced with rust?  They've been "steam cleaned" by coolant.

Nothing I see in the pictures tells me it's dead.  I might not re-use the rods that got hot.  If the cylinders fall into spec, I would put it back together with new rods, new bearings, and new rings.  Turn the crank .010" under.  If it needs an overbore/new pistons, I might consider just running a good junkyard longblock for now until you get the LS 300 done.

Mr_Asa UltraDork
3/30/21 11:21 p.m.
Curtis73 (Forum Supporter) said:

I might consider just running a good junkyard longblock for now until you get the LS 300 done.

I should have clarified, I pulled this engine in Fall of 2018 for a rebuilt Craigslist engine on a budget.  Like I've said before, I have a problem with follow-through sometimes.  If I don't have a reason to do something I'm going to work on another project till I have to do something.

I really should do a owner's log post for the truck.  I've lost so many pictures due to hard drive crashes, though



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