Replacing connecting rod bearings, thicker motor oil...?

[Rue]

Sup guys, one of my connecting rod bearings took a crap the other day (engine was knocking), I opened her up from the oil pan and sure enough one connecting rod was loose as I could move it side to side. The bearing was shot. I'm going to replace the bearings, should get them in in the next few days.

I was advised to now use a thicker motor oil, I was using 5W-30 before this happened, any advice on what weight to use now? I am also adding some Lucas Oil Stabilizer for dry starts.

What I have found so far regarding torque specs is:
Rod Cap Bolts: 45 f/lbs
Oil Pan Bolts: 7 f/lbs

 

[Output Shaft]

The thickest stuff you can probably find readily is 20W-50 dino oil.
Valvoline 60W Racing Oil seems pretty extreme. Say goodbye to MPG & power with that syrup flinging around in the crankcase.

Toyota gives the oil pan torque spec in In-lbs (53 to 104) so 7 ft-lbs is about right.

 

[klinetime574]

How many miles are on the motor? If it went to 200k running 5W-30 I would be less concerned than if it only had say, 120-150k.

A lot of cruiser guys seem to run 15W-40 (myself included) either Rotella or Delo 400.

I just did my oil pan gasket. 84in-pounds (7ft-lbs) was perfect for me using a one piece Toyota gasket and Toyota FIPG on the oil pan side only in one thin bead. I was told that silicone on both sides will cause the gasket to squeeze out. Once I wrapped my head around that idea, it sure made a lot of sense. I recommend cleaning the mating surfaces with brake cleaner before assembly. And also to check flatness of the oil pan with a straight edge. Lay it down on some cardboard and use a block of wood with hammer to straighten then re-check.

I will say that torquing to 7ft-lbs doesn't seem like much, but with the little in-lb torque wrench I was using it was more than I expected.

HTH

 

[Mace]

Might want to identify why the bearing died. They tend to last a very long time unless something happens..

 

[SteveH]

Be sure the crank journal looks ok, and install the new bearings. You might install a true mechanical oil pressure gauge (using copper tubing, routed well) and keep an eye on oil pressure from here out. If you see less than 10 PSI at hot idle, that's probably not good. As other suggested, I would run 10w-50 or 15w-40 diesel oil.

 

[Mace]

Just a FYI, most of my old F series motors barely make 10 psi at hot idle..

Barely..

 

[daytonadogie]

Also, check the connectioning rod dimensions. You will probably need to get it resized.

 

[LAMBCRUSHER]

flame suit on, so go for it guys, but I was told to use the lightest oil that lubed the motor.....that being said, I run 10-40 in mine. A somewhat new rebuild- about 25K and an old replacement with over 250K for the older one with 340somethingK. get some plastigage and use it. I went to swap bearings on the old engine and it had already been turned down an undersize or wore the journals down, because it was like a hotdog down a hallway with the new bearings...thank goodness for ih8mud and part-out 80 series....

 

[cruisermatt]

F engine internals last forever. On the motors I've taken apart they looked perfect. I'd be looking into the chase of the issue before trying to bandaid it with thicker oil, which won't solve anything.

 

[Rue]

Thanks everyone for your input, I appreciate it. I know this is just a band-aid, but for now thats all I need until I can rebuild the engine as I was planning to anyways. Just can't do it right now.
FYI: Im at 199,389 miles.

 

[Rue]

3 week update: Its now been 3 weeks since I replaced the piston connecting rod bearings. It was pretty easy to find the problem, I could move the connecting by hand back & fourth and can see why it was knocking. The bearings on this connecting rod were pretty chewed up, and there was a small pile of shavings at the bottom of the oil pan. I replaced the bearings with no problem, new gasket and closed her up. Put in 15w-40 AMS Oil along with Lucas Oil HD Oil Stabilizer, said a little prayer and turned the key
It turned on no problem, after letting it warm up for a few minutes I began revving the engine multiple times getting it up to about 3K RPM's. No knocking at all! I have driven it multiple times around town and a few times on the freeway to work. No knocking, no problems!
Now I know this is a temporary fix, but thats all I need right now. I plan on doing an engine overhaul next year.

 

[LAMBCRUSHER]

you may be set for a while, now. Good work!

 

[Cruiserdrew]

Maybe you'll get lucky, but that's a hesitant maybe. It is likely you'll need to budget for your rebuild sooner than a year from now.

What I would do in the meantime is find a good used engine and install that. Then rebuild your existing motor at your leisure. The problem is, your crank journal is likely damaged, and you could damage it to the point that it can't be machined enough to rebuild.

Good luck, I hope it works out as you plan.