Lost my bearings

1941 - 1945, MB, GPW Technical questions and discussions, regarding anything related to the WWII jeep.
pkozak1
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Lost my bearings

Post by pkozak1 » Tue Jun 02, 2020 4:48 pm

Well here is the scenario, It was this past Memorial Day and was 92* out the Jeep was running at 190* with 38-42 psi oil pressure using 15/40 Rotilla. I had the timing advanced to highest vacuum reading and then backed off 1/2”. I screwed up and went for the non-ethanol fuel not realizing it was 91 octane. The engine had 150 miles on it after I rebuilt it. Now so down, I have been rebuilding Diesel engines for over twenty years at least and have never had a “re-do”. I marked everything, took pictures for reference if I was unsure while going back together as this is my first flathead and followed the TM and the updates. I used plastic gauge to check clearances, all was good. Until the 38 mile (we will bring the parade to you - due to the Covid 19) Parade. About halfway through I heard a knocking and looked down to see my oil pressure bouncing around 10 psi. It maintained that pressure with a knocking sound only on acceleration. Until we made it back. I know I should have shut it down but I figured we had “lube”’pressure so wasn’t to worried. So now I got it back and and found so far a very worn bearing into the copper rigidly on # 2 rod. The crank will need to be turned. My question is could all of the factors that day lead up to this unfortunate situation? Thanks guy.


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Re: Lost my bearings

Post by OldGPW » Tue Jun 02, 2020 5:49 pm

What was the position of the bearing shells on #2 rod when you took them apart, any sign they spun? I'm no expert, but #2 was clearly starving for oil so the question is what happened after 150 miles to cause that? Something changed that led to the failure. Did you clean all the oil galleys in the block out the best you could? Sorry to hear a rod bearing went, it could have been worse though. Did you take the crank out (since you mentioned it is scored and will have to be turned) and note the position of the main shells (oil holes in the right place?). The oil system is a good place to start for clues to what happened in my opinion.
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Re: Lost my bearings

Post by dpcd67 » Tue Jun 02, 2020 6:23 pm

Had the block hot tanked by the machine shop, I assume. I hope.
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Re: Lost my bearings

Post by parker007 » Tue Jun 02, 2020 8:04 pm

failer rod bearing either wrong clearance, no oil, or dirt. so did you plastiguage all journals, did you brush all pasages, I would bet to tight or dirt left in pasages. many times crank grinders dont clean pasages in crank.

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Re: Lost my bearings

Post by Mike Wright » Wed Jun 03, 2020 3:58 am

Did you verify that your bearings are assembled correctly? The oil holes are offset and can be assembled incorrectly blocking off the oil galleys, Modern engines you can "flip flop" the bearing shell with no problem, These old engines you can't do that.
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Re: Lost my bearings

Post by Wolfman » Wed Jun 03, 2020 4:38 am

You and I are on the same train of thought, Mike, but if the bearings were reversed, the engine would have not made it as far as it did.
I am wondering about the bearing locating pins in the block and main cap that locate the main bearing shells.
Were they left out ???
If they were, initially, the rod would have been getting oil, but with out the pins in place, the only thing holding the main bearing shells in position would be bearing crush. The bearings being clamped into the block and cap.
I have seen this before.
With the pins missing, eventually, the bearing shells begin to creep or slip in the block and cap and eventually the oil flow will be restricted and finally completely blocked off as the block oil galley is blocked by the slipping bearing.
This comes on slowly as the slipping bearing shell gradually closes off the oil flow to the rod bearing.
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Re: Lost my bearings

Post by pkozak1 » Wed Jun 03, 2020 7:41 am

The block locating pins were in correct. I will have to double check the rod bearings when I pull the block out. I have to admit, after I found the bad rod bearing I stopped right there and started cleaning up the take down mess and started removing everything needed in order to pull the engine out. I will have to get an engine hoist. Which leads to another question. Who’s cherry picker does everyone use? I measured between the front tires and will need one to clear 43 inches. The one I used to put it in was to wide. But back to the engine, as I can remember the machine shop only “fit” the pistons to the cylinders (bores were oversized), I measured the rods and crank journals as well did the machine shop. We were both on the same track. I did plastigauge while assembling (although it was on the tight side of the specs) and I do remember blowing out the block. This has me baffled. Maybe I did overlook something. I will be pulling the block out next week after the wife goes back to work. Thanks guys.
Last edited by pkozak1 on Wed Jun 03, 2020 7:50 am, edited 1 time in total.

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Re: Lost my bearings

Post by dpcd67 » Wed Jun 03, 2020 7:45 am

I use the Harbor Freight 2 ton hoist for lifting jeep and dodge engines, and bodies. Don't get the smaller one. You can't go between the front tires; way too narrow for safety. Go from the sides.
Back to my question, did the machine shop hot tank the block and clean the crank? That eats out crud from the passages. And you did say you plastiguaged the bearings but did the crank spin freely before you put the rear main seal in? It has to. If you had the pins in, bearings in the right order, and good clearance, that is all I check for.
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pkozak1
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Re: Lost my bearings

Post by pkozak1 » Wed Jun 03, 2020 7:56 am

I do not remember if the shop hot tanked the block or not. I to check for free spin and end to end play with each main bearing install, then do the same with the rods (side to side) then spin over to install the next rod. Everything was smooth even with the rear main seal. The saving grace is that the crank is not blue! So we will start all over again.

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Re: Lost my bearings

Post by dpcd67 » Wed Jun 03, 2020 3:45 pm

I used my cherry picker today to remove an M38 body and it is narrower at the front feet than I thought; 36 inches; it will fit in between the front wheels. It is a two tonner.
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Re: Lost my bearings

Post by Wolfman » Thu Jun 04, 2020 4:42 am

Few more thoughts while pondering this problem.
Oil pressure bouncing around 10 PSI. In a parade on a 92 degree day with 15w/40 oil. What oil pump are you running ??
Might want to check the Pressure Relief Valve in the pump.
The topic came up a while back about chamfering the oil hole on the crank journals. Was this done on your crank ??
The oil holes edges on a reground crank can be sharp as a razor. Act more like a scraper than equally distributing oil onto the journal if not chamfered.
The number 2 rod is fed oil from the center main bearing. Number 3 rod gets oil from the same main journal. What does the number 3 rod bearing look like ??
The crank had been reground. Undersized bearings needed.
I know you said you plasti-guaged the bearings. Have you checked the bearing size stamped on the back of all the bearing shells ?? I have found instances where the wrong bearing shell was in the box. Only one. The rest were correct.
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Re: Lost my bearings

Post by pkozak1 » Thu Jun 04, 2020 4:58 am

It was a brand new Melings oil pump. The crank was not turned when I rebuilt it. It was within specs, I measured it and the shop Messi it as well, all was good so actually I didn’t look for sharp edges at the oil galleries. The number three rod cap bearing was just into the copper. I have not taken the the number one and four yet. I will be going to Harbor Freight Saturday to get a cherry picker. With all the copper in the oil pan I wonder what the need for an oil filter is on these 10% or 20% oil filtration systems is for 🤦‍♂️. It was a gen engine when I procured it from a friend. It always had excellent oil pressure every time we went for a drive, until this past parade.

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Re: Lost my bearings

Post by pkozak1 » Thu Jun 04, 2020 5:00 am

dpcd67 wrote:
Wed Jun 03, 2020 3:45 pm
I used my cherry picker today to remove an M38 body and it is narrower at the front feet than I thought; 36 inches; it will fit in between the front wheels. It is a two tonner.
What brand is your cherry picker!

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Re: Lost my bearings

Post by Wolfman » Thu Jun 04, 2020 5:09 am

10 or 20 % beats nothing. Not the best arraignment, but. The way it is.
Some guys remove or disconnect the filter to get better oil pressure but with a Melling pump, oil pressure should not be a problem.
???
Any sign of anti freeze in the oil ??
Anti freeze will do a number on babbited bearings. And pretty quick.
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Re: Lost my bearings

Post by dpcd67 » Thu Jun 04, 2020 8:04 am

Harbor Freight; as I said above. All the Mellings I have used gave very high oil pressures; like 60.
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