Servicing crank bearings

[dna9656]

After dropping the front axle and the oil pan, (on a 4 X 4) removing the T chain cover, chain, and sprockets is it possible to remove the crank for service? What I'd like to do is remove and replace the main and rod bearings; also replace the rear main seal (it's leaking) and while I have the tranny out I'll fix any other leaks.... I am pretty sure I'd need a appliance of some kind on my floor jack to lower and lift the crank shaft. What are your thoughts/experiences?

 

[ygmn]

IF you are going to all that best to just remove engine
I mean then you can do cam and heads and check freeze plugs etc etc.
Send block to machine shop along with heads to have them checked out and cleaned up where needed etc.

 

[dna9656]

Well I have great compression, I just replaced the roller lifters, oil pump, oil pick up tube, (and the O ring), timing chain and sprockets. I know I can pull the engine but I don't WANT to! I do have an oil leak in the rear of the engine; if it's leaking because the crank bearings are worn there is little point in installing a new seal, it'll just go bad in no time... I don't have the lift to pull an engine any more. To take it to a machine shop is too expensive, I'd rather buy a long block, but then again I don't want to pull the engine. There's a LOT more to pulling an engine on a OBD2 engine than a 1971 350. The costs involved never end.

 

[ygmn]

Crank bearsin would have nothing to do with oil leak outside engine since they are inside all the seals.

IF you have a crank seal leaking - change it... I had my rear main seal long time ago... and he did it while truck in the engine.
I think it is a split seal or fits over the end.

IF you had good oil pressure before and the oil pan does not show signs of metal... you should be ok to keep using stock crank bearings.

I have never seen someone replace them when engine still in the vehicle...
I mean yeah engine out and tore down might as well... but in the vehicle and engine mounts bolted.....

NAhhhhhhhhhhhh

 

[dna9656]

Crank bearsin would have nothing to do with oil leak outside engine since they are inside all the seals.

IF you have a crank seal leaking - change it... I had my rear main seal long time ago... and he did it while truck in the engine.
I think it is a split seal or fits over the end.

IF you had good oil pressure before and the oil pan does not show signs of metal... you should be ok to keep using stock crank bearings.

I have never seen someone replace them when engine still in the vehicle...
I mean yeah engine out and tore down might as well... but in the vehicle and engine mounts bolted.....

NAhhhhhhhhhhhh

GM got rid of the split crank seal in 1986. If the crank bearing are worn the crank will sit lower in the caps and subsequently the ends of the crank will be lower relative to where it is when the bearing are new or LESS worn, if the crank sits low the seals (front and rear) will suffer greater wear.

 

[2004Slickside]

You really think that going from 0.001" clearance to say 0.005" clearance on the main bearings (that would really make it hammer) will drop the crank far enough to make the seals leak? That is (0.005-0.001)/2 = 0.002" lower in the seals.

Don't attempt to jack with bearings with the engine in a vehicle. It's just not done.

Stepping off soapbox

 

[Nick@Night]

From what I just read, hard to conclude you are actually looking for anyone's advice, or opinion.

The LS design does have its faults, but the bottom-end isn't usually one of them. The term bullet-proof comes to mind.

If you were teaching power mechanics in high school, this might actually prove to be an interesting project; but, I wouldn't expect anything positive to come from it.

The LS is not like the old small block. These engines need to be assembled "just so."

Your crank & bearings are probably fine. In my opinion, better off to order a short block, rather than mess with the lower-end.

 

[redheadedrod]

Do not touch the bottom end. You will toast your motor if not done right. If the bearings were not making noise they are fine. My engine has 285k miles on it and the bottom end is fine. I have an oil pan leak but I am swapping out the 5.3 for a Stroked 6.0 to gain some power once I finish building the motor.

If you have an oil leak it will be likely because one of the seals went on one of the covers, the oil pan or the rocker covers.

 

[Randy]

As was previously stated unless you had low oil pressure and it wasn't from false reading from a bad sending unit then your bearings are fine.. If you suspected that they bad or very worn it would not be advisable to replace them with out turning or at least polishing the journals to match the new bearings and would probably fail shortly.. Bottom line it would not be an easy task with out pulling the heads and pistons..

You can rent a engine hoist for under $50.00 a day or buy one for $150 from harbor freight with a coupon and sell it after words.. Either way cheaper than a shop if your going to do it yourself...

Good luck...