Crank main bearings
Hotshot
Joined: May 2003
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From: south louisiana
Look at the thrust bearing first. If it's worn to ****, then chances are the crank is too. I've had one 5.0 like this from a 90's van. The torque converter had too much internal pressure and forced the crank into the bearing. Wore all the way thru it, and into the crank thrust face another 1/8" inch. The transmission was an AOD. If this is the case the crank needs to be replaced.
Junior User
Joined: Jul 2003
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From: St. Pete, Fl.
"Now another question, I have to have the bearing journals re-welded and ground? I can't just spin in another bearing? If so, I might as well take the crank out so that I can get it machined."
I probably didn't explain myself as well as I should have.
You don't have to take the crank out. Roll the thrust bearing in place and check the endplay of the crankshaft. If the endplay is within specifications, roll in the rest of the bearings and you're done.
The only reason that you would remove the crank at this point is if the endplay (with the new thrust bearing installed) is out of specifications.
I probably didn't explain myself as well as I should have.
You don't have to take the crank out. Roll the thrust bearing in place and check the endplay of the crankshaft. If the endplay is within specifications, roll in the rest of the bearings and you're done.
The only reason that you would remove the crank at this point is if the endplay (with the new thrust bearing installed) is out of specifications.
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From: St. Pete, Fl.
Baddad457 is right. "Look at the thrust bearing first." Determine the condition of the thrust faces on the crankshaft. If they are blue in color, have scratches/gouges in the thrust face or worse....your goose is cooked ! The crank will have to come out. However, if it looks nice and pretty, roll-in the new thrust bearing and check the endplay of the crank. If the endplay is excessive....with the new thrust bearing installed....then you will have to replace the crank. Let us know what you find. Good Luck to you !!
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From: Williamson, NY
When I bought my 77 F150 w/ a 302 I had the exact problem you have with too much end play, so I attempted to replace them while the engine was still in the truck. Doing it this way was difficult, but can be done. If you do decide to do it this way I would suggest you remove the thrust bearing first to see how much it is worn before doing the others. What I found when doing mine was that the thrust bearing was worn, but not enough to account for the end play I had. I then felt the crank where the thrust bearing rides and found it had an 1/8" groove cut into the rear face of the crank, so that ended the in-truck repair right there. What causes this I have been told could be two things, one being if you have a standard transmission that if you have a HD clutch or ride the clutch a lot can cause this kind of wear, and the second condition is when your torque converter balloons do overloading or heavey towing. Add infrequent oil changes to either of these just accererates the problem. I have an automatic transmission, so after the engine rebuild I replaced the torqu converter as well to prevent this from happening again. Here are some pics of the crank damage I found:
Junior User
Joined: Jul 2003
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From: St. Pete, Fl.
Nice Photo ! 
) Nasty looking crank ! 
(
"What causes this I have been told could be two things, ..... and the second condition is when your torque converter balloons due to overloading or heavy towing."
An automatic transmission will force the crank against the thrust face of the bearing all of the time that the engine is running. If you increase the pump pressure (H.D. or racing applications) the wear will be accelerated. The reason being that the interior surface areas of the torque converter are not equal...the shaft opening reduces the surface area so that more hydraulic force is applied the opposite direction. This results in the crankshaft being pushed. A larger thrust bearing surface area would help with this problem in conjunction with a more durable crankshaft material. Either way, it's added expense to the manufacturer. A steel crank and different bearings would all but make this problem go away.
) Nasty looking crank ! ("What causes this I have been told could be two things, ..... and the second condition is when your torque converter balloons due to overloading or heavy towing."
An automatic transmission will force the crank against the thrust face of the bearing all of the time that the engine is running. If you increase the pump pressure (H.D. or racing applications) the wear will be accelerated. The reason being that the interior surface areas of the torque converter are not equal...the shaft opening reduces the surface area so that more hydraulic force is applied the opposite direction. This results in the crankshaft being pushed. A larger thrust bearing surface area would help with this problem in conjunction with a more durable crankshaft material. Either way, it's added expense to the manufacturer. A steel crank and different bearings would all but make this problem go away.
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Joined: Apr 2004
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You stated that you were trying to replace a pilot bearing and you feel you may have damaged the bearing doing that, WRONG. The problems with thrust bearings comes from the clutch being dissengaged for longer than normal lengths
of time in traffic, or the driver habit of riding the clutch. The best practice is at lights and stop signs and what ever other traffic sitiuation you come to where your stopped for then a few seconds it should go into nuetral and the clutch released to take pressure off the trust face of the bearing.
I would make one more suggestion when you pull the pan drop the thrust bearing cap first and get a good look at the rear thurst surface of the crank, ifit is worn down the shaft will have to come out, this will help you make a wise decision. One eight of an inch is quite a lot I can almost see the depression worn in the thrust surface of the shaft, as I have seen quite a number of them in nearly sixty years of twisting wrenches.
Kotzy
Yes torque convertors can cause the same problem.
of time in traffic, or the driver habit of riding the clutch. The best practice is at lights and stop signs and what ever other traffic sitiuation you come to where your stopped for then a few seconds it should go into nuetral and the clutch released to take pressure off the trust face of the bearing.
I would make one more suggestion when you pull the pan drop the thrust bearing cap first and get a good look at the rear thurst surface of the crank, ifit is worn down the shaft will have to come out, this will help you make a wise decision. One eight of an inch is quite a lot I can almost see the depression worn in the thrust surface of the shaft, as I have seen quite a number of them in nearly sixty years of twisting wrenches.
Kotzy
Yes torque convertors can cause the same problem.
Last edited by kotzy; Feb 5, 2007 at 07:57 AM.
Posting Guru
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From: Williamson, NY
Originally Posted by wormshoe
CuJo8,
I just went through your photo album. You do some very nice work!! It looks great !!!
I just went through your photo album. You do some very nice work!! It looks great !!!
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From: La Grande, OR
Originally Posted by kotzy
You stated that you were trying to replace a pilot bearing and you feel you may have damaged the bearing doing that, WRONG. The problems with thrust bearings comes from the clutch being dissengaged for longer than normal lengths
of time in traffic, or the driver habit of riding the clutch.
of time in traffic, or the driver habit of riding the clutch.
https://www.ford-trucks.com/forums/5...zf-swap-2.html
This new noise that I am thinking is the thrust bearing is talked about on page two, so if that helps all right.
For just a little more info, cuz I was sure that I might have done it....I was prying HARD. Anyways, this all started with an auto trans to manual trans swap. At first, there was a grinding noise, which turned out to be the starter, took everything apart twice trying to find out what happened, and in that found a damaged pilot bearing. Enter the incorrect prying. After putting it all together, this new noise arose.....that had never ever been there before, with the automatic or otherwise.
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I worked on a Chevy 235 six many years ago that had a noise when the clutch was depressed, and it also had excessive crank end play. The noise was the
connecting rod small ends banging against the forward side of the wristpin bosses on the pistons, you could see the rub marks. I am sure it more than likely
hit big end of the rods against the rear boss on the crank journal as well. The guy who had it wanted it fixed just well enough that he could unload it so I put a new thrust bearing in it and he traded it. He was a clutch rider +.
Kotzy
PS that shaft thrust surface was wore down at least 3/32 of an inch.
connecting rod small ends banging against the forward side of the wristpin bosses on the pistons, you could see the rub marks. I am sure it more than likely
hit big end of the rods against the rear boss on the crank journal as well. The guy who had it wanted it fixed just well enough that he could unload it so I put a new thrust bearing in it and he traded it. He was a clutch rider +.
Kotzy
PS that shaft thrust surface was wore down at least 3/32 of an inch.
Last edited by kotzy; Feb 5, 2007 at 06:39 PM.
Elder User
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Wormshoe I have to ask that you consider this a torque convertor does not exert constant thrust on the crank thrust bearing. If you pull the convertor
bolts out of the drive plate you will find you can move the convertor fore and aft nearly 1/4 of an inch in the pump bushing and into the pump drive so no forward thrust is applied except if the pumps driven gear (GM) design is put in
upside down or the convertor ballons from over pressurizing it
Kotzy.
bolts out of the drive plate you will find you can move the convertor fore and aft nearly 1/4 of an inch in the pump bushing and into the pump drive so no forward thrust is applied except if the pumps driven gear (GM) design is put in
upside down or the convertor ballons from over pressurizing it
Kotzy.
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From: La Grande, OR
so given that I couldnt have done this by prying hard, what other reason might I have this problem and why it didnt show up before I did this? The engine isnt that old.....its a 1994 with I think 60-70,000, so I dont think it should be going out this early right?
Last edited by nighthawk285; Feb 6, 2007 at 12:51 AM.
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From: La Grande, OR
ok guys, thanks for all the advice and thanks for everything, but I found out that the problem was in fact the damn starter again. Don't ask me how, because I didnt take it back out to look at it, figured it was not making the noise and working correctly, so I left it alone.
Me and a buddy went out to go pull the trans and motor tonight, pulled it into the shop, and I started unbolting the starter. I had the bottom bolt loosened a quarter turn, then I thought that I should probably listen to the noise again, just in case. Had my friend start up the truck, then told him to put in the clutch, and there was no noise.....just like it supposed to was.....took it on a 20 minute test drive, and everything worked, yet no noises.......so all is good again in the universe
Sorry that I didnt get to use the cool pin trick, and you guys are awesome. A lot of good information got exhanged here, hopefully someone else can use it now. Thanks a lot again.... will be back for the next problem
Me and a buddy went out to go pull the trans and motor tonight, pulled it into the shop, and I started unbolting the starter. I had the bottom bolt loosened a quarter turn, then I thought that I should probably listen to the noise again, just in case. Had my friend start up the truck, then told him to put in the clutch, and there was no noise.....just like it supposed to was.....took it on a 20 minute test drive, and everything worked, yet no noises.......so all is good again in the universe
Sorry that I didnt get to use the cool pin trick, and you guys are awesome. A lot of good information got exhanged here, hopefully someone else can use it now. Thanks a lot again.... will be back for the next problem
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From: La Grande, OR
I guess when I tried to find out the first time, it was too dark, and when I put my screwdriver on the flywheel, it didnt go in, it slipped and it felt like it had end play. I found the scrape mark on the flywheel, and did it again, and it makes it feel like it went in. Guess thats what happens when you're tired and working in the dark, you just dont notice things. Sorry for the misleading, but thanks again for the help. Now I will know what to do when its time to spin in new mains.