HELP Bad News Sounds Coming From Engine (VIDEO)

beefey · July 31, 2020

Hi Guys--

I just got my truck back from a local mechanic to fix a broken exhaust manifold bolt (photo attached).

Tonight I start up my truck and hear THIS! Could he have put too much heat on the block and distorted a push rod guide or something? Doesn't it seem too coincidental that this nasty noise pops up RIGHT when he touches it?

Thanks much for your help!

Edited July 31, 2020 by beefey

CamGTP · July 31, 2020

Pull your dipstick and check the oil for glitter.

That sounds like a lower end engine knock for sure. If you rev it up and the knock gets faster/louder it's probably a rod bearing.

beefey · July 31, 2020

Yes it does change with RPM

beefey · July 31, 2020

Could it be a lifter that failed?

CamGTP · July 31, 2020

Lifters will make sound that is about half the speed of the crank because of the camshaft only working one lifter at a time. The noise in the video sounds like it goes along with the speed of the crank.

To me that says rod bearing all the way.

Formulabruce · July 31, 2020

How this happens. Many of the head Exhaust manifold bolt holes are Blind ( sealed bottom). It is possible if the hole was drilled and re tapped

that a bolt is now in the water jacket. This can allow water in the oil in some locations.

Check the oil for any milky~ness.

PPK · July 31, 2020

hammering pretty loud. sounds like it has a lot of rough miles on it...its too late to do anything about it now.

beefey · July 31, 2020

1 hour ago, Formulabruce said:

How this happens. Many of the head Exhaust manifold bolt holes are Blind ( sealed bottom). It is possible if the hole was drilled and re tapped

that a bolt is now in the water jacket. This can allow water in the oil in some locations.

Check the oil for any milky~ness.

That's a great insight. That could have happened. I don't see any obvious water contamination but it is probably pretty difficult without an oil analysis. The truck literally came back from the mechanic earlier today and has only had 25 miles on it since the service. Could coolant in the oil shell out a rod bearing that fast?

The coolant expansion tank is not black by any means...

It never made any noise really at all until this service was performed at the mechanic.

Edited July 31, 2020 by beefey

davester · July 31, 2020

No, if there was enough coolant in the oil to cause problems, it would be pretty obvious to the naked eye.

It's Tim · July 31, 2020

I don't think that damage could happen overnight. Coolant in the oil usually takes out the cam bearings first resulting in low oil pressure. That engine is just worn out.

Edited July 31, 2020 by It's Tim

diyer2 · July 31, 2020

Just a coincidence after repairs.

Rod knock IMO.

How many miles.

And for us curios minds, oil changes were done at how many miles?

beefey · July 31, 2020

55K Miles-- I bought the truck at 35K Miles and changed with the ECM meter with mobile one 5w30.

4ws f 7 · July 31, 2020

I a mechanic and really want to think it is a coincidence that it happened right after the manifold bolt repair but, really only 55k miles on engine? It can be hard to be sure if it’s a rod and/or cam/lifter, try disconnecting each fuel injector one at a time if it’s a rod noise should change when unloaded. Are those correct manifold bolts?