My B61 Project

[pennsyjeff]

Well all, it was a great ride while it lasted, I have had a little set back with my B61...as some of you remember I got my B model running and actually pulled one load of my old cats to a small show here in PA in July, and it worked and looked awsome. I had a slight problem on the next trip though.. I lost oil pressure, ruined the turbo and spun #2 main bearing!!! Now the good news, after inspecting the crank and doing some deep thinking, I don't think the crank will have to be polished, due to me paying attention and getting it shut down as soon as I saw the oil pressure gauge drop. The babbit on the bearing is polishing off the crank and I think I can hand polish it and leave the engine in..But for my big question, WHY..... I removed the oil pump and it looks okay, the turbo has a bent shaft and of course, wheel damage so I know I have to replace that. I just can't determine why all of a sudden I lost a main bearing and a turbo... give me some thoughts guys and let me know what you think??I have studied the service manual and am trying to determine maybe which one occured first, thinking the main might have starved the turbo or if I lost the turbo it may have starved the main bearing, but I am at a loss...give me your thoughts..

[theakerstwo]

Well all, it was a great ride while it lasted, I have had a little set back with my B61...as some of you remember I got my B model running and actually pulled one load of my old cats to a small show here in PA in July, and it worked and looked awsome. I had a slight problem on the next trip though.. I lost oil pressure, ruined the turbo and spun #2 main bearing!!! Now the good news, after inspecting the crank and doing some deep thinking, I don't think the crank will have to be polished, due to me paying attention and getting it shut down as soon as I saw the oil pressure gauge drop. The babbit on the bearing is polishing off the crank and I think I can hand polish it and leave the engine in..But for my big question, WHY..... I removed the oil pump and it looks okay, the turbo has a bent shaft and of course, wheel damage so I know I have to replace that. I just can't determine why all of a sudden I lost a main bearing and a turbo... give me some thoughts guys and let me know what you think??I have studied the service manual and am trying to determine maybe which one occured first, thinking the main might have starved the turbo or if I lost the turbo it may have starved the main bearing, but I am at a loss...give me your thoughts..

You may have antfreze in the oil but being you are there at the truck you can checkit out better than we can.

antreze will get the turbo bearing also. glenn akers

[de37champ]

it would be hard to tell, but from alot of past experiance, i would say trash from the main took the turbo bearning out, we had a d9g that had a oil problem and cat claims 45 seconds at idle with little or no oil pressure wipes the mains out, also i would check the check valve on the pump if it has one and make sure it didn,t fail

[pennsyjeff]

you could be correct on the debris from the main bearing taking out the turbo, I have seen that also. I know there is no antifeeze in the oil, I thought of that but found the oil to be good and clean. I will check the bypass valve in the oil pump, do you guys see many 673 oil pump failures?? if so, what goes bad, the drive gear looks ok as do the pump gears themselves, other than some wear from being a pump for a few years...thanks for the comments, keep the ideas coming, I sure don't want to have to pull that motor out and go thru this again.

[Guest Bollweevil]

While the failure of the turbo, and the failure of the main bearing are related. These failures are a result, not a reason, or cause. While supply oil to the turbo might come from a oil galley it should not be routed through a main bearing. the turbo bushing should have full line pressure all the time. any trash from a bushing failure should go through the drain into the oil pan. exhaust wheel junk goes out the exhaust, inlet wheel junk goes into the aftercooler or intake. Make no mistake, it has to be cleaned out. sooner or later it will eat your lunch. Both of these problems are related to oil pressure. Why doe's a bearing fail? Normally a crankshaft spins on a cushion of oil , The only time the crankshaft touches the bearing is when the engine has been at rest or possibly at start up. Why then at bearing replacement do you see more wear on the upper rod bearing shell, and usually lower main shell? Detonation is why.that's what makes it run., Severe detonation closes the clearance puts more heat into the crank, and nullifies the ability of the oil to both cool and lubricate. In extreme cases the constant hammering will cause the parting edges of the bearing to contract., and just like a scrapper wipe the film of oil from the crank. Is that what happened to your engine, I don't know, Look at the bearing farthest from the oil pump, in an oil pump failure that's usually the first one to loose oil.. Check rod bearings on both side of the failed main. One or both receive oil from that main. Now, if you have actually spun a main bearing in the crankcase, Which would imply that the bearing stuck to the crank and spun with the crankshaft in the crankcase. Then that is a major cause for concern. You won't be able to just put a new bearing in and go. You will have to find another crankcase, or strip yours and have it line bored. Drop me a line if I can help you, and good luck. James

[pennsyjeff]

While the failure of the turbo, and the failure of the main bearing are related. These failures are a result, not a reason, or cause. While supply oil to the turbo might come from a oil galley it should not be routed through a main bearing. the turbo bushing should have full line pressure all the time. any trash from a bushing failure should go through the drain into the oil pan. exhaust wheel junk goes out the exhaust, inlet wheel junk goes into the aftercooler or intake. Make no mistake, it has to be cleaned out. sooner or later it will eat your lunch. Both of these problems are related to oil pressure. Why doe's a bearing fail? Normally a crankshaft spins on a cushion of oil , The only time the crankshaft touches the bearing is when the engine has been at rest or possibly at start up. Why then at bearing replacement do you see more wear on the upper rod bearing shell, and usually lower main shell? Detonation is why.that's what makes it run., Severe detonation closes the clearance puts more heat into the crank, and nullifies the ability of the oil to both cool and lubricate. In extreme cases the constant hammering will cause the parting edges of the bearing to contract., and just like a scrapper wipe the film of oil from the crank. Is that what happened to your engine, I don't know, Look at the bearing farthest from the oil pump, in an oil pump failure that's usually the first one to loose oil.. Check rod bearings on both side of the failed main. One or both receive oil from that main. Now, if you have actually spun a main bearing in the crankcase, Which would imply that the bearing stuck to the crank and spun with the crankshaft in the crankcase. Then that is a major cause for concern. You won't be able to just put a new bearing in and go. You will have to find another crankcase, or strip yours and have it line bored. Drop me a line if I can help you, and good luck. James

Thank you for your input and you make many good points...My main bearing didn't spin within the block, it lost lube between the crank and bearing and had just started to weld itself to the crank..(luckily)..I could tell by the bearing tabs, that it was about ready to spin in the block, but I got it shut down very quickly. Maybe my oil pump is getting weak and with it idleing like it had been before I started out on this trip, the damage had begun, also, before I installed this engine in my truck, it had set for quite some time in a wrecked truck and I installed it in my truck and began to use it. It may have had a main or two (or three) dried out, which was a thought I had and it just finally spun now that I have began to use the engine again.. I am just trying to find out why both (main and turbo) failed pretty much at the same time...I am leaning toward replacing the oil pump, as there may be more wear there than I am seeing..thanks again.

[Guest Bollweevil]

I am glad to hear that the bearing did not actually spin. Now you have to put your thinking cap on and figure out what happened. For the turbo shaft to bend the turbo bushing would have to have enough clearance for the turbine wheels to touch the housing. This is old news , you have already seen this and described the damage. In owner-operator lingo this known as a Catastrophe, it's expensive and also not too uncommon. Turbos fail like this all the time, they don't have to. It only takes a few minutes during a regular PM to check for leaks and proper clearance. Is there a lot of oil in the exhaust or turbo housing? Enough to bleed off oil pressure from the crankshaft? It's something to look at. In 40 years of fooling with engines, I have had all sorts of weird things to happen to loose oil pressure. I have had piston oilers fall off into the oil pan, pressure regulators valves to stick, rocker boxes to crack. I've seen oil galleys cracked that would only open up when the engine was hot. Years ago I made a tool to pressure test and pre-lube an engine, I welded a bung into a small refrigerant tank so that could put oil into it and pressurize it, then with a #4 aeroquip hose you can go right to the oil pressure tap in the block. With a little mineral spirits, you can also flush the oil galley. Leave the front and rear main in place, and drop the others including the upper shells, then run some mineral spirits through followed by air. Inspect all of your bearings, It would probably be a good time to replace them, since you are so far into this. As you polish the crank, get every bit of the brass off. A small scratch or groove, won't hurt anything, but as you well know anything that's protruding will wipe out a new bearing. If you have a main bearing roughed up like you have described, there is going to be brass in the rod throw. a can of brake cleaner and compressed air will take care of it. As always, anytime you have an engine opened up keep everything clean and spotless. anytime you handle bearings your hands have to be CLEAN.. Check your work, check behind yourself. carelessness and dirt cause more failed engines than bad parts. I'll be waiting to hear what you find, James

[Superdog]

This is just a thought,but you said your engine came out of a wreck.By any chance did it run on it's side for a short period of time?

[pennsyjeff]

This is just a thought,but you said your engine came out of a wreck.By any chance did it run on it's side for a short period of time?

You know, I have thought about that, and the person I bought it from said no, but I bet that may be part of it or maybe the start of the problem. The truck was tipped quite severly, but not clear over on its side, the frame was bad and that is what let the box go over on its side, but the cab and engine was probably at a 45 degree angle......good thought.

[Superdog]

I'd bet that was the cause of your troubles.When I worked at the local Mack dealer back in high school,they were very careful to always replace the bearings in any engine that went on its side if there was even the slightest doubt it ran while turned over.

[pennsyjeff]

I'd bet that was the cause of your troubles.When I worked at the local Mack dealer back in high school,they were very careful to always replace the bearings in any engine that went on its side if there was even the slightest doubt it ran while turned over.

Superdog, I have a question that you may be able to shed some light on with this whole thing....it looks like the turbo and the main bearing failure occured at the same time, but the oil feed for these 2 things are fed by separate passages...I originally thought that the main spun first causing the turbo to lack for oil, but I don't think that is what happened..I am wondering if something happened to the bypass system for the oil pressure allowing the oil to dump back to sump, could that happen??? I feel both the turbo and the main bearing failing are tied together somehow, but I am not sure how..the oil pump has wear but it doesn't look like it failed...and I really think this had something to do with low oil pressure..give me your thoughts, thanks, Jeff.

[Freightrain]

If truck was over at 45degrees, then I would be it ran dry for a spell, then the quick shut down did not allow the turbo to cool thus possibly creating issues with dry bearings in it. It then was re-started by you and ran til the issues surfaced and completed its damage.

Just a thought....