Engine knocking LDS-456

[Oerthedge21]

I found a NOS piston liner combo on eBay for 95$ so I just ordered the pair, better deal than trying to buy separately. Plus the lower rod bearing looks like it's been beat up, so I'm just gonna buy a full set of those too instead of just doing one.

 

[doghead]

How did you confirm your journal size?

 

[Oerthedge21]

Allow me to correct myself, I'm in the process of figuring that out and ordering the bearings and such. The only thing I've bought and paid for is the gasket kit so far

 

[Menaces Nemesis]

I found a NOS piston liner combo on eBay for 95$ so I just ordered the pair, better deal than trying to buy separately. Plus the lower rod bearing looks like it's been beat up, so I'm just gonna buy a full set of those too instead of just doing one. View attachment 774565View attachment 774566

Okay, Please help a brother out here... I see what looks like some rather light rotational scoring, a bit of pitting, and what appears to be a few tiny gougies, but it appears the majority of the bearing surface hasn't seen much wear due to the perpendicular lines still being readily visible, and rather unbroken/uninterrupted across the width of the bearing. I'd imagine those perpendicular lines are there from the manufacturing process rather than use, and look to have very little depth. Given the relative softness of the bearing surface in relation to the crankshaft, that stuff doesn't look too terribly bad to my bleary eyes. So my question is, is it usually common pratice to replace rod bearings with any discernible scoring or pitting, no matter how shallow/sparse? Or are you just replacing them since you're already in there and have access to them?

 

[Oerthedge21]

I had always thought it was just the right thing to do, however I may well be wrong. To be completely honest, I've never done this before. I've rebuilt several of my dirtbikes over the years but I've never done any repair like this on a vehicle. If that wear is considered runnable then by all means I'll run it, I'm going to plastigage it anyway to check the clearences, but if that somewhat minor wear is still servicable I'll leave it be and put the savings towards the axle boots and brake job after this.

 

[rustystud]

Okay, Please help a brother out here... I see what looks like some rather light rotational scoring, a bit of pitting, and what appears to be a few tiny gougies, but it appears the majority of the bearing surface hasn't seen much wear due to the perpendicular lines still being readily visible, and rather unbroken/uninterrupted across the width of the bearing. I'd imagine those perpendicular lines are there from the manufacturing process rather than use, and look to have very little depth. Given the relative softness of the bearing surface in relation to the crankshaft, that stuff doesn't look too terribly bad to my bleary eyes. So my question is, is it usually common pratice to replace rod bearings with any discernible scoring or pitting, no matter how shallow/sparse? Or are you just replacing them since you're already in there and have access to them?

OK, Nemesis has a valid point here. The proper way to check the bearings is with "plasti-gauge" . You install a thin strip on the bearing, (which is still installed in the rod) then reinstall it on the crank. Then after torqueing the rod to spec you remove it (being sure not to move it !) and using the chart supplied you can tell the clearance. After checking the crank journal with a micrometer you then can tell if the bearing is bad. Yes it is a bit of a process, so most mechanics just slap in a new set of bearings and call it good.

 

[Oerthedge21]

But now to install new bearings aren't you supposed to use a micrometer and bore dial gauge to check crand and rod wear/specs and do all this fancy math to figure out if you need different bearings or something like that? All I know about this so far is what I've been watching and reading online

 

[cattlerepairman]

I was in the same boat as Oerthedge21 a couple of years ago. I did use plastigauge. A friend of mine who is a heavy equipment mechanic asked me "Why? You spend money to buy the plastigauge, spend time to measure the bearings (you need to open and re-assemble bearing caps), only to find out that, yes, they have significant run time and are near or at the wear limit. Then you go and replace them, doing half the work over. I, on the other hand, am already done because I ordered new bearings and switched them in. One disassembly only."

I think, given the relatively low price of bearing sets, he does have a point.

As for size, I went with was stamped on the data plate of my engine (oversized mains and rods due to a previous overhaul).

 

[Oerthedge21]

I think I might just do that then, I gotta inspect the crank first, didn't really check yet. Once I pulled the piston I slapped the pan back up with 2 bolts to keep crap outta here and havent been back under there yet

 

[Menaces Nemesis]

I'm just way too frugal for my own good sometimes...
As long as my oil analysis reports kept coming back clean and steady from the lab, and given the average mileage on these trucks is maybe 25k, in relation to the hundreds-of-thousands of miles most diesel engine rods and mains are capable of if maintained properly, I'd have pulled each cap, visualy checked each journal and bearing, and if they didn't look any worse than that one, with no signs of localized wallowing on the bearings, I'd have torqued them right back in place and moved on. As weird as it sounds, with my luck over the years, I'd have more confidence in that old bearing, already ran and looking the way it does, instead of a new, untested bearing, hoping I measured right, they (the manufacturer) measured it right, and the geometry and material quality was correct in the new part. Yep... weird, I know.

 

[Oerthedge21]

I haven't ordered anything or made any decisions just yet, today or tomorrow I'm gonna get under there and do just that, I'll plastigage one or two and if all checks out then I will likely put it back in, still gotta get the injectors to the diesel shop too

 

[davidb56]

I use plastigage too, BUT you still have to mic the journal to determine if its still within tolerance, so you don't assume all the clearance is in the bearing wear. BTW you used to have to plastigage the New bearing clearance too, so there wasn't any way to get out of buying some. Nowadays bearings are so much better than from the 70's, I doubt its really needed to check new bearing clearances.

 

[gringeltaube]

Nowadays bearings are so much better than from the 70's, I doubt its really needed to check new bearing clearances.

It is needed - for peace of mind, at least...

 

[rustystud]

It is needed - for peace of mind, at least...

Actually for more then piece of mind. My good buddy who is also a Master Mechanic had the machine shop turn a crank and supply a set of rod and crank bearings with it. He didn't check the clearances and after installing and running the engine sent it out. It came back blowing smoke and sounding like a thrashing machine ! The machine shop had supplied the wrong bearings ! He thought it was a little tight, but after all the machine shop should know what their doing right ?
So my buddy didn't check it, and now had a mess on his hands.

 

[Oerthedge21]

Exactly the kinda headache I'm looking to avoid. It's only maybe 10 minutes of work to check a bearing, just to know where it's at for so little effort is worth it to me

 

[Oerthedge21]

Some of my parts have begun rolling in, and I finally have some free time with the 3 day weekend. I was just about to plastigage rod #2 when I realized I do not know the clearence specs for the 465-1A. I've been reading through TM9-2815-210-34-2-2 and although I've found the torque specs for everything I can't seem to find the acceptable clearences for the crank. I may well have read past it, in he meantime I'm gonna read through it a few more times and see if I'm just blind

 

[davidb56]

page 4-44. has the chart 4-7.

 

[Oerthedge21]

Got the rear head off yesterday, pulled he valves out of the front one, wetsanded and polished them all, had some nasty buildup on the intakes. In the process of doing the same to the rear head now. Thankfully neither head is cracked or warped as far as I can tell, and all of the valves are pretty decent, no bad pitting or scoring.

 

[rustystud]

Got the rear head off yesterday, pulled he valves out of the front one, wetsanded and polished them all, had some nasty buildup on the intakes. In the process of doing the same to the rear head now. Thankfully neither head is cracked or warped as far as I can tell, and all of the valves are pretty decent, no bad pitting or scoring. View attachment 775046

Sounds good. Did you take a straight edge to the heads ? I've found several that needed machining due to warping. I believe the cause was loose head studs and the high compression of the Multifuel. I plan on installing "ARP" studs when I rebuild my engine.

 

[LowTech]

Arp ?