Rod knocking after pulling trailer up steep hill

Truck ran perfect, 177K miles, 3.5 2GR-FKS pulled few thousand pound trailer up hill, didn't over rev or anything but was pulling hard, now rod knocks and getting low oil pressure warning. Other than that, truck still runs great (engine light, haven't checked but probably related).

Oil looks great, Toyota serviced, going to pull motor and swap oil pump and do main/rod bearings.

Anything else I should look for when I'm in there? Not sure why this happened in the first place, but if something in the bottom end was weak I want to know about it and fix it now.

 

Please report back what you find. I can't offer anything, but love a good mystery.

Maybe by the tech lunch so the results don't get lost in the paperwork?

 

Yes keep us all posted. What year? 2016?

 

We keep our mechanic busy working mostly on our vehicle fleet, in fact I might help him pull it. 2017, bought it new.

 

If it’s knocking expect to needs rods and a crankshaft as well.

 

Maybe. It didn't knock very long, and only one rod seems to be knocking, and even then it goes away almost when you rev it up, so low oil pressure. Interesting to see if there's metal on the drain plug, oil looked totally clean on the dipstick, and it was only slightly at the lower end of the fill range.

Looking at the factory manual there's a few options for oversize bearings, but unless they totally failed I don't see why it would damage rod/crank, engine still runs smooth. Will have to mic everything out, but unless there's galling on the crank or rods, I don't see why they'd be dead.

 

If I had to guess oil rushed to the back of the pan going up hill and the motor was starved for oil. How heavy was the trailer?

 

probably 3K lbs. Lots of downhill compression braking using 3rd/4th to slow me down on the backside of the hilly highway. No more than 6% highway grade.

 

I'm picking up a car and towing it in January. I think I'm gonna rent a full-size truck/tahoe and a trailer.

 

This truck has towed lots of things, but we always take it easy on the motor, never had a shred of an issue with the truck or the motor, except oil, filters, brakes, serpentine belt, spark plugs, just wear items. Toyota always did the oil with synthetic.

 

^Dealers did the oil changes? How long were the intervals, 10k? Would be curious if there's any sludge.

Was the timing cover or oil pan resealed at any point?

 

Don't remember intervals, whatever they told us to do. Never had anything done on the engine.

 

^Unless you insist, dealer will rotate tires every 5k but change the oil every 10k, which may be too long when you tow a lot. Anyway, just speculation until you open up the engine to inspect.

 

How steep you towing?? If its at proper oil level this isnt going to happen...

 

That sucks. I’m curious to see what the light is on for. Would be a good idea to read it and see.

 

It's my opinion that after 120k the tolerances are opened up enough that you may need to up the weight of oil. 177k it's a lot of miles and 0-20 is like water

 

Yes and when you are hauling a trailer up a grade, engine temperature climbs opening things up even more. A step up to 0W30 or 5w30 might be beneficial.

 

"...now rod knocks and getting low oil pressure warning. Other than that, truck still runs great..."

Sorry for your issues but I got a chuckle out of that! Hope your repairs are as expected and the truck gets back on the road soon.

 

There’s been a few failed oil pumps reported on this engine, I bet it is more likely that than some issue with the oil itself.

 

would think it has to do with the motor not towing.The chassis is rated for towing.

don't know about this motor, but other truck motors moving cross-country hauling thousands of pounds up hills repeatedly without issue is common.

If it's not neglected, the bores are not wider. If they were, you'd be burning oil. There is not much difference between 30 and 40.

Folks with maintained vehicles run whatever oil is recommended regardless of miles.