Rod Bearings overheated, Need Advise

[Guest Hauler308]

Earlier I posted a request for some info about my 1986 Chevy Silverado C30 1 ton dually with a Big Block 454 that was overheating like a "some of it itches" when I towed my 13000lb 5th wheel trailer. From worse to more worse I got a Knock in my number 7 cylinder, (3er back drivers side) pulled the plug wire and of cause the knock went away. I then pulled the oil pan and the number 7 and number 3 rod caps and of cause the number 7 insert bearings showed signs of heat cracks an quite possibly were spinning or at least had the tabs that lock them in place worn off. The number 3 insert bearings looked good but showed signs of wear at their sides. I would suspect that the other 6 sets are probably worn too, but not knocking yet. The journal that I exposed that held the 7 & 3 rods looks pretty dam good. It has some slight signs of wear such as minor lines but nothing that appears to have been abused to long.

 

MY SITUTATION IS… I am not in a position to pull the motor and have the crank turned or replace the motor, so I have decided to replace the Rod bearin inserts and try to get the truck home to Arizona from California as soon as my business trip is over.(a 700 mile ride done in to short days) NO MORE TOWING OF CAUSE.

 

MY QUESTION IS…. 1) Do you think that replacing the bad insert bearings might buy me a Good bit of time, if not fix it for a few thousand miles. (My wife Loves this Truck) 2) Do you think I should go 10 thousandths or so over size in the bad cylinder to compensate for ware or leave it stock. 3) And last do you think I should go ahead and change them All while its open thicken back up to stock and to be sure another one doesn’t crap out on me next week.

 

Any help would be appreciated. I can also send some photos.

 

Thanks………..

[BRAAP]

Spun rod bearings, either due to lack of oil for one reason or another, or this is a brand new rebuild and the clearances were wrong.

 

Most likely lack of oil. One scenario is plugged oil pick up screen from excess silicone that squeezed out from the gaskets during the build, or the oil pick screen is too close to the bottom of the pan due to not checking it during installation or something hit the oil pan closing that gap, or you just ran it out oil.

 

At any rate, my opinion is that until you resolve "what caused this", just swapping in new rod bearings wont do anything other than offer your neighbors and bystanders entertainment as those bearings quickly turn into junk.

 

I feel you are better off with a new engine or “completely” rebuild that one.

 

BTW, You do understand this is a Datsun/Nissan Z car forum and that we are dedicated to extreme performance Datsun/Nissan Z cars, right? We are not a generic mainstream V-8 troubleshooting forum. We do talk about our other vehicles and their issues from time to time, but we also keep at least 90% of our discussions on the subject of this forums mission, extreme Datsun/Nissan Z cars.

 

The “Site Support” portion of this forum is for posts regarding this forum on whole, not engine related issues, which is why your thread is here now.

[Clifton]

If the rod ID and crank OD hasn't changed, my cheap a$$ would just replace the bearings and run it. Towing 13k lbs from Az to Ca first thing out would concern me though.

[Careless]

Im going to take a wild guess and say you loaded the hell out of crowns of the bearings when you decided to tow and stop a 13000 trailer in that truck.

 

what were you thinking?

 

a lot of load is transfered to the thrust surfaces, and trying to slow down 13,000 lbs is uh..... exponential in comparison to regular abuse.