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 son of a *** when I towed my 13000lb 5th wheel trailer. From Bad 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 bearing 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 if you drop me an e-mail or reach me at hauler308@earthlink.net


P.S  I measured 2” + 170 thousands across the journal. Would any one know if that’s close to normal Spec.  I’ve never done a rod job before and don’t know if I need to measure the rod as well and if some of the numbers like 0022 or 0025 are referring to actual bearing thickness.


Thanks………..  

You're gonna need to use some plastiguage and see how much bearing cleance you've got with standard size rod bearings. If the bearing clearance is out of spec, then you'll need to look at an oversize rod bearing.

As for how long this band aid will last, don try to stretch it beyond getting your truck back home. As soon as your home, pull the motor and either rebuild or replace it. IF you wanted to replace it, I'd suggest a 540 crate motor from GMPP, might has well get some extra cubic inches to help your hauling. And I'd definitely look at some cooling system upgrades, for both the motor and trans.  

How does the rod journal(s) look?  whats the part number on the back of the rod bearing?  should give you a part number and state over or under size...replacing bearing (s) should get you home, if the jounal is not to bad....also replace oil before trip home with a good synthetic oil such as mobile 1 fully synthetic....why was engine over heating in the first place?   any water in the oil?  pick an easier route home....email some pics to jhos70@hotmail.com