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I'm asking about a 350, but I guess it could apply to any motor:
If you remove all the main caps to roll the bearings, how long can you leave it hanging by just he pistons? It's still on the timing chain and has the tranny stub stuck in the crank end.
I ask because I read somewhere that they'll warp if left with no support.
I'm thinking about 3 weeks until I stick the caps back on.
Thanks,
-B.
Tim, please move this post as you see fit. I didn't know where to put it.
Brian,
Good question. I have never left one like that for more than a few days. I really don't know the answer, but I would suggest putting one of the middle caps back on. The piston/rod assemblies will start to slide down and put a lot of weight on the crank. Since you are not going to try starting it or anything, put a bearing in the cap and torque it back down. You don't need to put the block side bearing back in just the cap bearing.
I think that this is a good general discussion post because it will apply to any engine and should stay here.
Please discribe your engine side bearing removal tool/process in more detail. I didn't understand what exactly you used. Thanks
I've heard that too, but I've never seen it.
I'd at least put two caps back on to hold it up there.No reason to press your luck.
Be sure to put something around the crank journals so it doesn't get scratched because the bearings have been removed.
Oddly I agree with Ben. I've only ever done that w/the 2 end caps on. Then when the middle ones are done, do the ends. Of course... in my case new bearings didn't help.
Ahhh, thanks for the response- and Tim, thanks for the add-in. I can tell by it that we're fine and that means alot as I value you as a bud.
You know a ring clamp, like you use on a radiator hose. I opened it up and used the flat side to push the seal out from behind the crank. It was strong enough that I could put some pressure to it, but had a natural bend that followed the crank around.
I reckon I'm gonna have to put new bearings in it in the next couple of days since all you hippies said so. Ironically- my bottom 1/2 of each bearing was toast, but the top half looked fine. Is this normal? The crank was fine too.
Thanks guys,
-B.,
were the oil holes lined up??? that is strange. Could need a line bore. Hope not.
One more thing. Do you think you could have had an oiling issue when you had the problem with the filter leak. This is sounding closer to something like that than heat. Low pressure from the leaking oil filter could have oiled the top half but not had enough pressure to force the oil around to the bottom. This is just a guess. I have never personally witnessed this before. Usually have somewhat consistant wear between the two havles?
Brian,
When you said ring clamp earlier, I was thinking piston ring. You cleared that up, thanks. I know that it has been a running joke about you and torque wrenches. But, could you have not torqued the mains down all the way? To me this would explain your low oil pressure, your leak in the rear, some of your overheating problems and would put all of the load on the caps without a constant oil supply.
Just an idea and not an add on to the joke.
I don't think so- they were as tight as they should be. I had to use a cheater bar to get them off. Are you saying overtighten them? Maybe that, but they were not undertightened.
I think that it was the heat. I had no temp gauge in my truck for a while and was towing tractors and such with it and on several occasions it blew the radiator. After I got a temp gauge I saw it was up to 250. The heads had cracked and so I should have expected this.
I guess I need to check the rod's too.
-B.
You probably heated it up to the point where the oil thinnned out so badly that it wasn't thick enough to keep the crank off of the bearings in the caps. The lions share of the cranks exerted pressure is on the lower caps. The crankshaft bending from not being supported is a long term storage type of thing. Not a couple of weeks. Myth: Busted. When you put your new bearing in get a bottle of STP Engine Treatment and put some on the bearing face of the bearings...It should be in a blue platic bottle. I use this stuff on ALL my new bottom ends and got the tip from a pro engine builder.
Brian,
Do not over tighten. The factory torque spec will do. Tom is right about the oil probably being too hot to work. How did you manage to keep driving with the truck that hot? Wasn't it pinging like mad? I am not accusing, just asking. I have a truck that will run 220-235 pulling a load in the summer. It never pings or breaks.
Tim,
Well.....Here's the deal- I had a mechanical temp gauge on it and when I was reassembling the motor the cable to the gauge twisted and gave me no reading. I kept thinking that the motor was just puking out water since I was overfilling the radator. I quickly figured out that it was getting too hot, but I didn't know how hot and just assumed it was 220 or so. I finally got the gauge replaced and it showed 250. The heads were cracked, and I had been running too much timing in it in an effort to make up for a vacuum advance problem that I had been battleing.
Basically- I learned alot from the first attempt to build a motor. The major lesson was that it's not good to take 2 crapped otu motors and mix and match parts and expect them to work forever. The motor may have pinged, but I never heard it.
In the last 2 months I got all the issues resolved- new exhaust pipes, new distributor, new heads, my oil filter boss bypass repaired. Now the motor is running at 11* and stays at 180* no matter what I tow or how hard I push it. I'd like to think that all is well. These bearings weren't knocking, and only a couple of them had copper showing. I just want to roll them now whilst I have it apart. I think it's a problem from previous problems and as such won't be an issue anymore........of course- if it stops giving me trouble then it won't be much of a hobby as I like working on it much more than using it.
I think I'll wait until saturday to do the bearings. It's 12* here and I hate to work on it on a school night.
Thanks all,
-B.
Brian,
Since you have it apart and have spent time and money replacing the other things, go ahead and pull the crank out and have a machine shop turn it. You are running an auto trans so you don't need to pull the trans out. Your arms will hate you, but it will eliminate any doubts or possibilities of future failures. Just my opinion.
I guess it should be mentioned that you really should get a bottoming tap and chase every bolt hole so that there is nothing in any hole to alter the torque...if all the bolts are new and all the holes are clean and all the threads on both the bolts and holes are good, the torque aplied will be accurate and consistent...do it once and take yor time, you wont be doing it again because of one of the little things you missed...a good acurate torque wrench too...and chamfer the oil holes on the crank...al basic stuff but lots of gus overlook these things and wonder later why it didnt hold up
brue4c
Note to masses: If one would decide to chamfer the oil holes in the crank DO NOT get carried away AND don't chamfer it evenly the entire way around the hole. Chamfer it just lightly on the leading edge and heavier on the trailing side of the oil hole. ?? Chamfer it so that the larger chamfer will be behind the rotation and the oil will pulled out not pushed back in to the chamfer and hole like it would be if the leading side was chamfered big. Make sense? If you're sitting in the drivers seat, the crank rotates toward the drivers side so you'd want to chamfer the passenger side of the oiling holes.
First- my holes are tear shaped...so I think they are chamberfered. It came like that as it is a Scat forged crank.
Second- I did that whole cleaning out the bolt holes when I had the motor apart. I chased each one with the tap and then cleaned all the bolts with my bench buffer. Despite all that it crapped out, thus dissproving your theory that if you do it right the first time then you won't have to do it again. I now vote to do it quick and just know you're gonna have a hobby that lasts and lasts and lasts.
I run a manual tranny (since autos are for girls) and hate to pull the crank out. It really looks and feels fine. I think I'll chance it.
-B.
At one point, did you have a M715 with an auto tranny? For some reason I thought I had read that you had a TH350.
It broke in half two 4th of July's ago. We changed a crank then without pulling the tranny out...took all night and was a pretty good time!
Thanks
You were having fun? I was thinking "This prick acts like my music ain't any good, but I didn't see him bringing down any CD's. And what's up with those pants? Doesn't he know the crotch is all blown out?".
Remember Jean Ellen going "Why is it funny that the transmission is broken in half? You two were up all night working on the motor?". Classic.
That was 2 weeks after you e-mailed me all "Naaaaa- you don't need a jackshaft! A single u-joint will work fine! Trust me, I'm MR. 4X4!!!!!"
____I just realized that this thread is spiraling out of control into a BS post. Sorry. Feel free to delete it. No need to move it as it has no value.
Sorry again,
-B.
Anyhow- Yup, Tim, for about 50 miles I had an auto. Then I had an auto in 2 easily carried parts. It was alright, but I really prefer a manual.
Hey Brian, I have a bearing service manual and troubleshooting guide. In that manual it shows bearings that are like what you describe. It can be caused from lugging the motor. You mentioned you towed heavy loads with it. Do you recall lugging it much? I guess it can happen with or without a towed load. Anyway, I thought I would post that. Lugging can cause you to scrub bearings into the under lying babbit material...A.T.
The reason lugging is tought on bearing is that when the engine is lugged it isn't turning up the RPM, in turn not building good oil pressure, and the cylinder pressure and load squeeze the oil layer to the point where I cannot support the load and the bearing comes in contact with the crank. Don't be afraid to keep it one gear lower when pulling a good load. I had a friend with a bulldozer trailer and dump truck that replace the bearing three times in the 8 or 10 years I've know him. He runs through the gears as fast as he can and is always lugging it.
Brian's damage was probably from the oil thinning out...same basic effect...thins to the point it can't support the layer.
I got all new bearings today- rod and mains. And some STP and brake cleaner. $71 for Clevite's.
I have no idea what it was from, since there were so many problems with that motor....or more with me making it. The motor was my first effort and I learned alot, but it cost me alot. There was a while where I had the rockers too tight and it ran poorly and then on only about 6 cylinders. Then I ran it for the majority of it's life with the timing on 16-18*. It also had a messed up oil boss that sent oil shooting everywhere.
I learned alot, and have repaired alot of the problems that I think lead to this.
Thanks!!!
You use the "77" tri-metal bearings? The Michigan77 and the Clevite 77s are the same, different boxes. The factory that makes these is right in my home town. I drive by it on the way to wal-mart all the time. I drink beer with one of the guys in on the inventing of those things. My H.S. shop teacher invented one of the broaching machines in the manufacturing process of them. Got one uncle and one aunt that still work there. Dana bought the factory and rights to the bearings.
Yup, I'm nearly famous.
Now for the tech part to keep me from getting bounced - you use STP fro assembly lube? How about some "lubriplate" white grease, instead? and DON"T touch the bearing surface with bare hands! Also, if you ever get a cracked head or other way of contaminating your crankcase with ethylene glycol coolant - flush it with clean engine oil with Rislone addative - it has an ingredient that leeches the coolant out of the mearing material. Coolant will displace the oil in the bearing and not let it build a proper oil cushion - early bearing failure may soon follow.
Moderator Notice: this topic has been split. The cracked heads thread is it's own topic now. Please refer to the Open Discussion board to continue. Thanks, Evil Nazi Moderator Tacoma
B
It shuldn't be a problem, But if youre concerned put one of the old bearings in the center main and snug it up. that should take care of it
I think it has been said before, make sure the back side of the bearing and the bearing cap are spotless. No oil, rag fibers, dirt ect... That will change/reduce your clearances. Have fun and good luck...