main bearings
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main bearings
Guys
Do worn main bearings make a knocking sound? I replaced the rod bearings with the engine still in the truck. Now I still have a severe knock esp. when the oil gets hot. I also have a HV pump in there and HOT, i get ZERO pressure. I am using this truck to pull loads of firewoord. The engine is a 74 360. How long can I run it like this? I was thinking about running straight 50 wt oil with 2 cans of thickener to quiet the rattling down some....
ideas??
regards
Ben
Do worn main bearings make a knocking sound? I replaced the rod bearings with the engine still in the truck. Now I still have a severe knock esp. when the oil gets hot. I also have a HV pump in there and HOT, i get ZERO pressure. I am using this truck to pull loads of firewoord. The engine is a 74 360. How long can I run it like this? I was thinking about running straight 50 wt oil with 2 cans of thickener to quiet the rattling down some....
ideas??
regards
Ben
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main bearings
There is a trick to replace the mains with the engine still in the vehicle. I've not used it, but seen it in a couple of manuals. It involves removing the caps and inserting a specially bent cotter into the crank oiling holes. Then you rotate the crank half a turn and the upper falls out. Then a similar procedure is used to reinsert a new upper.
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Joined: Jan 2003
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From: Iowa
main bearings
How much pressure do you get cold? Mine I have about 10 pounds at idle hot, up around 60 when its cold. What pressure are you getting driving down the road?
Typically, a main bearing out will be felt in your foot during acceleration. Does it knock all the time, just hot, just under load, or what?
Typically, a main bearing out will be felt in your foot during acceleration. Does it knock all the time, just hot, just under load, or what?
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main bearings
OK
at cold startup, i get like 35. Then when it gets hot, she drops to zero (guage reading). on the road @60, if cruising, it looks like 20lbs but as soon as i FLOOR it, the guage falls and then slowly creeps back up. If i let it idle, then it go back to zero and stays there. Its a regular LOUD rhythmic knock all the time. At Light tip in throttle, it sounds like really loud metal thrashing (not pinging). At idle at a red light, its like 'DUMP DUMP DUMP DUMP DUMP' (say it out loud and this is what it sounds like!
Hope this helps! Remember, I put in NEW rod bearings like 600 miles ago!
regards
Ben
at cold startup, i get like 35. Then when it gets hot, she drops to zero (guage reading). on the road @60, if cruising, it looks like 20lbs but as soon as i FLOOR it, the guage falls and then slowly creeps back up. If i let it idle, then it go back to zero and stays there. Its a regular LOUD rhythmic knock all the time. At Light tip in throttle, it sounds like really loud metal thrashing (not pinging). At idle at a red light, its like 'DUMP DUMP DUMP DUMP DUMP' (say it out loud and this is what it sounds like!
Hope this helps! Remember, I put in NEW rod bearings like 600 miles ago!
regards
Ben
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From: Iowa
main bearings
Well then, sounds like you lost a main bearing. I'm surprised it still runs, thats a ford for ya. Well, now would be the time for a rebuild. It sounds like you may need a new crank and align bore on your block. I wouldn't run it like that. Sooner or later, it'll sieze one of those new rod bearings you put in (probably #5 or #8), and throw a rod. What you hear is the crank flexing down and hitting the main bearing saddle, or whatever is left of the main bearing in question (probably not much). When that happens, it also skews the rod journals to the rod bearings, creating heat. I think you know where this is going. Better to rebuild now and save the block. Good luck!
Edit: That's about what my old '86 bronco 2 sounded like when the bottom end went out on it.
Edit: That's about what my old '86 bronco 2 sounded like when the bottom end went out on it.
Last edited by rusty70f100; May 8, 2003 at 09:47 PM.
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main bearings
Hey Matt
Thanks for the lil personal insight on yr 66. However, I didnt appreciate the sarcasm that followed. Thought I'd let ya know.
Thanks for the lil personal insight on yr 66. However, I didnt appreciate the sarcasm that followed. Thought I'd let ya know.
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Joined: Mar 2003
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From: Corvallis oregon
main bearings
It sounds too me like you have bigger problems then bearings. A little gear oil in the case never hurt any worn bearings, but no matter what I think you need to get under there again and I bet if you look hard enough you will find big problems.
If I had to guess I would say it is a rod.
If you ever get board you can start the motor with one spark plug out at a time, and find the problem rod.
If I had to guess I would say it is a rod.
If you ever get board you can start the motor with one spark plug out at a time, and find the problem rod.
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main bearings
ford_nut,
Sorry that bothered you. It wasn't so much sarcasm as it was a sad-but-true story.
That old truck had lots of problems (mostly severe rust) and the bad motor pushed it over the edge. I didn't know much about engines back then. I knew even less about pulling a motor. When I was pulling the hood off it slipped, cracking the windshield. I used an old swing-set with the come-along to lift the old engine out that wasn't stable and also swung into windshield, finishing it off. The costs were adding up too quickly, so we gave what was left of it to our scoutmaster.
I learned how to drive in that truck. I learned how to shift a manual transmission with it. I miss that old truck. I'm vowing to do better with my '72 and hope to have it running again in a couple of months. I'm picking up my freshly ground, balanced, and polished crank tomorrow.
Sorry that bothered you. It wasn't so much sarcasm as it was a sad-but-true story.
That old truck had lots of problems (mostly severe rust) and the bad motor pushed it over the edge. I didn't know much about engines back then. I knew even less about pulling a motor. When I was pulling the hood off it slipped, cracking the windshield. I used an old swing-set with the come-along to lift the old engine out that wasn't stable and also swung into windshield, finishing it off. The costs were adding up too quickly, so we gave what was left of it to our scoutmaster.
I learned how to drive in that truck. I learned how to shift a manual transmission with it. I miss that old truck. I'm vowing to do better with my '72 and hope to have it running again in a couple of months. I'm picking up my freshly ground, balanced, and polished crank tomorrow.
Last edited by mlf72f250; May 8, 2003 at 11:43 PM.
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main bearings
Matt
its ok. its hard to tell here between sarcasm and a story. Its cool. I can relate to yr attachments to an old vehicle. I am very attached to my junk as well. I need to run this old bear for a lil while longer til i can fix up my 69 F250 4x4. I have to replace a busted ring and pinion and do the brakes but I am having trouble with getting that carrier out of the front housing. Besides, I need to locate the proper u-joints for the front axleshafts. I posted a question in the axle forum here.
I hope this one truck holds out a lil while longer. I mean its really rapping away. Its almost like a bad death rattle. I forgot to mention that I just noticed that it is starting to smoke. It never did that before. I wonder if this has anything to do with the knock. As far as pulling the plug wires to isolate the noise, I did that and it still knocked each time. Like i said, Im hoping for 2 more weeks out of this! Id hate to see a rod go through the block. Ya think 50 weight oil and additive will buy me more time??
regards
Ben
its ok. its hard to tell here between sarcasm and a story. Its cool. I can relate to yr attachments to an old vehicle. I am very attached to my junk as well. I need to run this old bear for a lil while longer til i can fix up my 69 F250 4x4. I have to replace a busted ring and pinion and do the brakes but I am having trouble with getting that carrier out of the front housing. Besides, I need to locate the proper u-joints for the front axleshafts. I posted a question in the axle forum here.
I hope this one truck holds out a lil while longer. I mean its really rapping away. Its almost like a bad death rattle. I forgot to mention that I just noticed that it is starting to smoke. It never did that before. I wonder if this has anything to do with the knock. As far as pulling the plug wires to isolate the noise, I did that and it still knocked each time. Like i said, Im hoping for 2 more weeks out of this! Id hate to see a rod go through the block. Ya think 50 weight oil and additive will buy me more time??
regards
Ben
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From: suburban atlanta
main bearings
You probably already lost some bearings, but I'd check the oil pump gasket and pickup... When you installed the pickup, you *DID* make sure that it was in place before tightening the mounting bolts...
It could be cracked or sucking air... and have enough pressure with thick oil, and as it heats up and thins out... NOT.
You did torque the rod cap bolts with a torque wrench, right?
The other guys were right on, but down to copper will run a loooong time if you are gentle, so something else happened, I think. Drop the pan, and throw a set of mains in there. Check the rod inserts one more time. Check the pump when you drop it. It CAN last if you don't go too many miles with the shot bearing.
Heck, I had a 390 with the rearmost main insert turned inside the cap... NO NOISE??!?!??!!!?! Just a bad rear main seal leak... New inserts, new seal, and off she went....
tom
It could be cracked or sucking air... and have enough pressure with thick oil, and as it heats up and thins out... NOT.
You did torque the rod cap bolts with a torque wrench, right?
The other guys were right on, but down to copper will run a loooong time if you are gentle, so something else happened, I think. Drop the pan, and throw a set of mains in there. Check the rod inserts one more time. Check the pump when you drop it. It CAN last if you don't go too many miles with the shot bearing.
Heck, I had a 390 with the rearmost main insert turned inside the cap... NO NOISE??!?!??!!!?! Just a bad rear main seal leak... New inserts, new seal, and off she went....
tom
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main bearings
I'd like to be encouraging, but I get a sick feeling in my gut when I read the symptoms. Keep driving it? It depends on the consequences of it throwing a rod. If you're going to be rebuilding it anyway, you can probably risk it throwing a rod and then get a junkyard 390 core to rebuild for less than $100.
If it's only a matter of it lasting a couple of more weeks, I think I'd borrow a friend's car until your other wheels are back on the road. Then you can take your time with a nice rebuild.
I'm in the process of rebuilding mine. Got the crank back today and will bore the cylinders next week. Heads will be done a couple of weeks after that.
Good luck!
--Matt
If it's only a matter of it lasting a couple of more weeks, I think I'd borrow a friend's car until your other wheels are back on the road. Then you can take your time with a nice rebuild.
I'm in the process of rebuilding mine. Got the crank back today and will bore the cylinders next week. Heads will be done a couple of weeks after that.
Good luck!
--Matt
Last edited by mlf72f250; May 9, 2003 at 07:16 PM.
Post Fiend
Joined: Jan 2003
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From: Iowa
main bearings
I wouldn't drive it. When it does go, you can ruin the ENTIRE engine. I mean the whole thing. Pistons hitting valves, rods puncturing the block and oil pan, all sorts of bad things. If theres any way possible to avoid driving it, I would. That said, if you ABSOLUTELY NEED to drive it, run some 50w, or some people even run 80w90 gear lube until they get it fixed. Dont run it with that stuff in there for too long, though.
