Crank/thrust bearings

[eagle jeeper]

My crank comes ahead noticably when I hit the gas so I assume that the crank bearings are done for. I have about 9 inches of lift in my jeep can The bearings be replaced with the motor still in the jeep. And I guess can the crank be removed for inspection.

Thanks

[Chevelleguy]

Yes, it can be done, but it isn't much fun. You will need help to guide all the rods back on while jacking the crank back into the block.

I did it 21 years ago on a Chevy, and they have a crossmember in the way.

[eagle jeeper]

Sounds like pulling the motor is easier. I would really like to do this work myself or as much as possible in the interest of learning. I need some advice as to where to get started. I am running an auto tranny and have read that if the convertor isn't installed correctly the extra pressure can be a cause. How can you tell if its on right. Anyway I know these are very elementary questions but help would be appreciated. I have done a fair bit of searching and come up with very little, would anyone know of a good link that covers this repair.

Thanks

[letank]

If you can grab the harmonic balancer and move it over 1/4 fore or aft, yes, the thrust bearing is gone. If the thrust bearing is too far gone, the crank may need to be fixed : a bead welded back and the journals reground.

As said even w 9" of lift, the trick part is the assembly: It is a lot easier to work on the engine when it is off the engine bay. Put rubber hoses on the rods bolts to prevent scratching the journals. The trany issue is the insert on the crankshaft that differenciate TH400 and TF727. Make sure you match the bolt hole for your torque converter and flex plate w scribed marks, felt points will disappear.

It may be a good time to replace your torque converter and the trany seal. And do all the gasket replacing you can while the engine is out. You do not need to remove the exhaust manifold, just disconnect at the pipes.

Year and type or FSJ will help as well.

Get an engine stand, and you can borow from friends or rent a cherry picker or engine lift from the local rental place, install the engine on the engine stand and return the cherry picker.... send the crank to the engine repair place..... sometimes it can take some time. Of course if the engine has other issues.... it can be time for a rebuilt, as you may discover other issues... How is the compression (rings/valves)

[yankeedog]

you are not going to like what you see.betcha your crankshaft is toast.automatic trannys are notorious for doing it .BEFORE you drive it again make sure the tranny is fixed!!!!!!! if you dont you will be doing the job again..you will double your unhappiness.

[Chevelleguy]

The only time I have ever heard of auto tranny CAUSING a thrust bearing failure is if the converter balloons and puts excessive pressure on the crank, and that generally only occurs in heavy, nitrous, drag cars.

[Ristow]

when the converter starts failing it'll do it too. either the stator or impeller. did it to my old '91GW right after i put the 401 in. i suspect the extra punch did it in as it was driven home with the old tired 360. i scrapped that converter.

[eagle jeeper]

I talked to a mechanic today and he said the same about the auto tranny shouldn't be the cause, more frequent with standards. How can you tell if the converter is pouched. He said to pull the pan and inspect the shells to see if there is wear. He also said there should be alot of noise if the bearings are totally finished. The only reason I noticed anything wrong is that I saw the crank pulley come forward. I think tomorrow I will pull the pan and check things out. Would you guys quit driving it completely or what until fixed. The tranny shift perfect I don't have a clue where to start diagnosing problems there. Oh and the engine is from an 82 Waggy

[letank]

I talked to a mechanic today and he said the same about the auto tranny shouldn't be the cause, more frequent with standards. How can you tell if the converter is pouched. He said to pull the pan and inspect the shells to see if there is wear. He also said there should be alot of noise if the bearings are totally finished. The only reason I noticed anything wrong is that I saw the crank pulley come forward. I think tomorrow I will pull the pan and check things out. Would you guys quit driving it completely or what until fixed. The tranny shift perfect I don't have a clue where to start diagnosing problems there. Oh and the engine is from an 82 Waggy

How much play do you have when you grab the harmonic balancer with the ENGINE OFF ?.... make sure that it is the crankshaft that is moving not the pulley or the harmonic balancer. Above a 1/4" I will not drive it.... I think that 3/16 is the max allowed in the TSM.

[yankeedog]

been there done that.after i had the 360 engine rebuilt on my 1990 gwag THE FIRST TIME for a wiped out crank thrust surface.the MECHANIC?INSTALLER?told me an auto tranny "CANT DO THAT"so it had to get rebuilt a second time for a wiped out thrust surface.do not repeat my mistake. i ended up putting in a t18 it cured my woes.search this site for more info,do not trust a mechanic who knows doo doo about your vehicle. do not alllow the blue bird of unhappiness to crap on your windshield.research with due diligence my friend or you will be sorrry.when you start hearing a sound like baaarrrrraaaaapppppp under load it is the crank hitting the block

[Ristow]

according to my crank shop it's the automatics that do it far more. about .010-.012" is the max i believe. if you can use inch fractions of any kind you need work done.

[eagle jeeper]

Ok so I pulled the pan and the # 2 and 3 mains here are some pics can some one tell me what I am looking at.

[eagle jeeper]

On the thrust surface of the crank there is a definite lip where the bearing seats is this normal. Another thought I had was that before I put the 727 back behind this engine I had a standard T176 in there for about 2 years. I had a 360 fly wheel but it wasn't a match pair with the balancer could this have thrown the bearings or are they even bad. What would be the negative effects of just pushing another set of mains in there and running it to see what happens.

[Chevelleguy]

Yep, those are warn slap out! If you can see copper, they are gone. Have the crank machined and get new bearings to match.

[eagle jeeper]

Any idea on the cost of getting a crank machined