Rod knock: Why?

[Serfma]

It's been a crazy journey but here I am. I swapped a 98 Lincoln Mark 8 motor (130k miles) that I got from my brother in law into my 96 Cobra. 10 minutes into it's drive to the exhaust shop, and being on the side of the road to fix the cooling fan since the ECU coolant temp read 220, it gained a new feature called rod knock. I'm posting here to ask: Why?

It had a Kenne Bell 2.1 installed, 60# injectors, long tubes, EGR all deleted, and a base tune from my tuner whilst keeping it well under half throttle to attempt to keep it outside of boost during the drive. I do recall hearing backfiring a bit, which the intake cam on the passenger side was off by 1 tooth which I had fixed and verified timing was correct. Backfires sounded like it was coming from the same passenger side but was not as loud as when it was out of time.

Here is a video of the knocking along with oil pressure:
Is it possible the bearing was on it's way out? Contaminate got into the oil? Oil was new pennzoil 5w-30 (or -20, can't remember for certain) and sadly I was not keeping an eye on the oil pressure since I assumed I would have no issue seeing as at cold the aftermarket gauge read 100psi and I watched it just about until it got around 40psi then I kept my eye planted on ECU coolant temp.

 

[xblitzkriegx]

Seems like the engine was bad from the start.

 

[SID297]

Seems like the engine was bad from the start.

Likely. It doesn't take much to spin a bearing in these if you're just a little low on oil.

 

[Weather Man]

Backfire on a rods with 130,000 miles would be ungood.

 

[Serfma]

Likely. It doesn't take much to spin a bearing in these if you're just a little low on oil.

That's the only thing I can think of, because my original Cobra engine I beat the hell out of and it had 155k. Had temps upwards of 240F, had no oil on dipstick while doing 6k+ pulls and holding it at 6k for datalogging reasons which is how my lifters started singing. When I pulled everything, a few bearings did look a little wore out but nothing absurd.

I plan on pulling this one apart to see if I can get by with polishing / turning crank, running a new set of bearings and checking to see if cylinder walls are ok enough to send it. I have my old block still, so this one is more of a fun toy to play with and if it blows up it blows up.

 

[Serfma]

Pulled all of my bearings and they're all looking crisp and clean, outside of one or two that has what I'd call normal wear and tear. So my next idea is maybe wrist pins? Going to tighten the rod bolts back down to around 10ft/lbs so that I can grab and move the rod itself of every piston to see if I get any up and down play on them.

 

[Serfma]

#8 bearing, since I know it and 7 are the worst. They all look pretty similar to this. Have photos of them all but my internet right now is so slow it'd take an hour for them all. Lol

 

[Serfma]

I found the problem!

 

[gimmie11s]

Where the hell did that bolt come from

 

[MG0h3]

Looks like one of those little 5/16 head fastener bolts for things like coolant tanks, fans, fuel rails.

Some intake bolts have that nub at the bottom too.


Sent from my iPhone using svtperformance.com

 

[98 svt]

Dude wtf. That explains it

 

[Serfma]

I just got the head pulled off but haven't touched it yet. Going to swap heads real quick and get it all bolted back up after filing down the piston. I don't think the rings are going to be squished, but I have a deadline of Sunday to have it back together regardless if it fixes it or not. Won't have a garage for a few months - half a yr.

Bolt looks like it's one of the kenne bell bolts. It must have fell onto the rags I had filling the ports and snuck it's way down without me realizing. There was one time I didn't check the ports after pulling the kenne a few times because it's apparently nearly impossible to fully seal it. Lol.