Why am I destroying rod bearings?

[SteinOnkel]

What's your preferred method for cleaning after a hone job?

Is dropping it into a hot tank a good idea?

[gbsailing]

Dropping into a hot tank is a little over kill a good steam cleaning should be all you need to clean the block.

If you haven't done any other cleaning (ie hot tank or steam cleaning) before you honed the cylinders then either would be adequate. Hot tanking is the best to start with if you are doing a complete overhaul but a re-ring steam cleaning should work.

[Nut124]

Just a few comments:

I rebuilt my 1800 earlier this year. I did the Guy Croft crank main journal oil hole modification to aid with oil pickup and rod brg oiling. This needs to be done before the crank is polished.

Hot tanking: Just make sure not to acid tank unless replacing the aux bearings.

After years of extremely hard driving, some gas in the oil etc. bearings that came out looked a lot like your better main brgs. All had at least 70-80% of original, untouched brg surface remaining. no galling but some localized surface polishing, in streaks.

[axelbaker]

Speaking of which did I order a new oil pump for my current engine rebuild...

Just finished blueprinting the new oil pump. I had to take a few thou off the top of the casting to get my end float down. It had 0.005" from the factory. I lapped it town on my surface plate to 0.002". Takes forever with the shaft in the way. I hang the shaft over the side and take a stroke, then rotate, stroke, rotate, repeat. Takes about 10 strokes on new 220 paper per thou.


I finished rolling the main bearings and installed the new rod bearings. Every thing plastigaged the same as the initial build.


1 - 5 left to right.

The bearings are all worn uniformly. At this point I am 98.3% sure I have an oil pressure issue, and for that matter not a flow issue. Nothing got hot, but metal touched metal and wore.

I'm now torn on whether to seal up the motor add oil and run it to see the pressure or if I should go after the aux shaft bearings now. I don't have much to loose checking the pressure.

Gbsailing, questions on cleanliness of the crank. It was stupid clean, along with every thing else. No, I didn't pull the welch plugs. The shop hot dipped it. Then I washed the shit out of it in detergent, (I think I ran it through the dishwasher too, I do that commonly) then went to town with bottle brushes, pipe cleaners, q-tips, and brake clean. I ran brake clean through it till it ran clear, then ran another can though.

Nut124 I considered the mod, but it didn't happen. Also the bearings that came out of the motor with 100k on them looked the same as these with less than 5k on them. So yeah, problem.

Oh also, as some one else posted one of the engineering explained videos on oil. I forgot till I saw the video again and it reminded me. The 0w-40 oil should not be the issue. Cold 0w oil is still thicker than hot 40 weight oil, it should actually protect better at startup because it has better flow while cold.

See: https://youtu.be/IKdhgKUZhPA?t=656

Dinghyguy the crank looks identical to when it went in. If you want to see fresh-from-the-crankshaft-shop-porn check my picture link or my resto thread.

Bryan, #4 is the one that was knocking. It's basically hammer finished.

So, assuming I run it and the oil pressure is low. Who's done an aux shaft bearing? I have a set of the pre-sized ones that I should have installed while the motor was out the first time. What the least painful way to do this with the motor in?

[18Fiatsandcounting]

Who's done an aux shaft bearing?

I have, but it was a long time ago, likely around 1980, during the first rebuild of my '69. I vaguely remember that my dad had access to a machine shop in the school where he worked, and he had them make a tool to remove the outer bearing. Basically, it was a 2" right circular aluminum cylinder with two different diameters: The inner diameter fit into the bearing, and the lip of the outer diameter rested on the bearing shell and you could then push the bearing into the engine and then retrieve it. The new bearing pressed in the same way, although you pressed it in from the front. The tool has a large screw thread tapped into the center, so presumably that was used to somehow press on the bearing, sort of like a gear puller in reverse.

The engine was removed when we did this, so I don't know if you could do it with the engine in the car.

Caveat: This is my recollection of what happened 40 years ago, so I could be missing some details.

Honestly, though, if the surface of the auxiliary shaft looks OK, and the bearing looks OK, and the aux. shaft has no significant side-to-side play when you move it by hand, my guess is that this isn't the issue. Of course, "no significant play" is subject to interpretation, but if you put some oil on the surface, and you don't feel much movement, I would consider that OK.

The aux. shaft turns at half the crankshaft speed just like the cams, and the cams work fine with no bearings except their aluminum housings. And the camshafts have a lot more load on them than the auxiliary shaft whose only function is to turn the oil pump and the block mounted distributor or mechanical fuel pump if the engine has those. For newer Fiats, the auxiliary shaft's only function is to run the oil pump.

I still remain skeptical of a zero weight oil in a Fiat. Fine for modern engines with much tighter tolerances, but it seems awfully thin unless you're running the car in Canada or Alaska in the winter.

-Bryan


-Bryan

[Nut124]

The aux shaft bearings have almost no load compared to main, rod brgs. The shaft journals may look fine, but if the clearance is too much, then it hurts oil pressure for the rest of the engine.

0W oil is for arctic use. Want to avoid troubles like this in the future? Run 15-50 racing oil and get rid of any 0W, 5W oil.

The problem with thin oils is that the pump was not designed for them. Not enough volume -> pressure.

[axelbaker]

So fun with aux bearings today. Now understand why no one wants to deal with them. Front was ok-ish but worn, rear is thrashed, enough to probably cause low oil pressure. I hope the front quished while installing it... it had 6 thou clearance before install. It got dark, I will mic it installed tomorrow, but judging by how the shaft felt it should be good.

Also did some research on oil weights. I keep it said 0W-40 is some how lower viscosity than 10W-40 while hot. For SAE J 300, they must undergo a ASTM D445 viscosity test. In short, at 100c all 40 grade oils will be between 12.5 and 16.3 centistokes. There are some minor differences in the spec for 15W-40, 20W-40, 25W-40 & 40 single grade, at 150c. 50 grade only increases to 16.3 to 21.9 cSt. at 100c.

So let's end the oil discussion.

[axelbaker]

So updates.
The engine went back together. After a bit of running it in a bit it seems to be much happier. My oil pressure is 30 psi at idle off of a real mechanical gauge at the engine. It peaks over 70 psi as i rev it. The Veglia gauge and sender are impressively inaccurate. It reports nothing at idle and never gets over 50 psi through out the rev range not to mention has an amazingly slow response time. I'll install a 20psi pressure switch for the light eventually. I'll probably also run some AN line and install a mechanical gauge in place of the Veglia.
At this point I guess the Aux shaft bearing where the culprit, but I suspect it really was a combination of warm day, hard cornering and hard, high rpm driving for an extended time uphill.

[SteinOnkel]

So updates.
The engine went back together. After a bit of running it in a bit it seems to be much happier. My oil pressure is 30 psi at idle off of a real mechanical gauge at the engine. It peaks over 70 psi as i rev it. The Veglia gauge and sender are impressively inaccurate. It reports nothing at idle and never gets over 50 psi through out the rev range not to mention has an amazingly slow response time. I'll install a 20psi pressure switch for the light eventually. I'll probably also run some AN line and install a mechanical gauge in place of the Veglia.
At this point I guess the Aux shaft bearing where the culprit, but I suspect it really was a combination of warm day, hard cornering and hard, high rpm driving for an extended time uphill.

I'm always careful with mechanical gauges in the cabin. Yes, they are much more accurate. But if they break, you will have hot oil spraying over you

Glad you got it all sorted. I'm assuming these numbers are all piping hot?

[18Fiatsandcounting]

Looks like good oil pressure to me, thanks for the update, and yes, the stock gauges are not all that accurate. It's usually the sending unit that is the problem, in which case a new one solves that problem. The gauge itself does have some mechanical "inertia" to the needle movement, probably to keep the needle from bouncing around as you go over rough roads.

-Bryan

[Nut124]

So updates.
At this point I guess the Aux shaft bearing where the culprit, but I suspect it really was a combination of warm day, hard cornering and hard, high rpm driving for an extended time uphill.

Hello Axel, I'm glad to hear your engine is looking good.

What kind of hard cornering did you engage in? Or high rpm driving?

I ran my 1800 extremely hard for 20 years including repeated runs over the years at the Gingerman road race course in MI. I was running Yokohama AWS (AVS?) track tires and the car was always on the absolute edge. This is unlike anything folks would ever see while occasionally "flooring it" on the street.

I was running a stock oil pan but with an oil cooler, so with some extra volume. It could be that I ran a quart or more over stock oil volume. When I took the engine apart last spring, for rings, the bottom end and rods, all bearings, were perfectly normal.

[axelbaker]

Nut24:
8 miles, uphill, shifting above 7000 rpms, second and third gear, canyon road, Miata trying to pass, sliding the corners. Effectively race pace.
https://goo.gl/maps/Y5KyftzsEaJUXvPh9

I assume your tracked car had much more prep than mine. Mine is stock including the cooling and oil system. Almost all the work I have done on the car is to remove crap aftermarket, generic, or rotted out parts and replace with new or used OEM. Car had a good body, shit mechanicals.

Bryan, yes, most gauges are damped... maybe my gauges is more than usual but compared to the oil filled mechanical gauge it's a glacier. I have a russian built sender I can try.

SteinOnkel, I still prefer a direct reading gauge. And if I can manage to build -AN lines for brakes, I can certainly build a line to withstand 100psi oil in the cockpit.

[axelbaker]

Just an update. Less thank 1000 miles later ... knocking again. Getting a new block from Wine Country. Lets see how this one does.

[SteinOnkel]

Stop running thin oil.

How are you breaking these engines in? You're not assembling them dry, are you?

[Nut124]

Just an update. Less thank 1000 miles later ... knocking again. Getting a new block from Wine Country. Lets see how this one does.

Axel, Sorry to hear. Something is not right here. ?? Properly built and oiled, the Fiat bottom end is very strong.

What oil were you running?