dont do it
I assume you mean to ask how difficult it is to change the main bearings WITHOUT pulling the engine out of the vehicle. Don't bother. To properly replace the main bearings you need to pull the crankshaft away from the engine far enough to be able to put a micrometer on the bearing surfaces of the crankshaft. To do that you need to disconnect the crankshaft from the transmission AND pull the pistons part way out. Also, depending on the type of seal used, many rear main seals must be replaced by pressing them into place after the crankshaft is in. Don't even try to replace bearings without first verifying the status of the crankshaft. It must be round and within tolerance. If the old bearings have worn there isn't much chance that the crankshaft hasn't been affected.
The main bearings support the crankshaft.
not really that expensive, all you have to remove is the main drive belt and the balancer.. i charge about 150.
on a crankshaft you have a crank journal (more commonly called a main journal) and a rod journal. the main journals of the crankshaft are where and how the crankshaft is held in the block. the rod journals are where your connecting rods are attached to.
Almost always leaking rear crankshaft seals are a result of worn crankshaft main bearings with too much clearance. Make it easy on yourself and pull the engine, turn it upside down, pull the oil pan, loosen the crankshaft, and put in a new set of main bearings, then replace the seal and put it all back together.
There is one on each end of the crankshaft. The front main seal is at the pulley and, while the rear main is at the transmission end.
The main bearings and main bearing caps.
Main bearings are between crankshaft and main journals (engine block), rod bearings are between connecting rods and crankshaft and thrust bearings ensure crankshaft does not slide horizantally between journals they hold crank in place.
You probably need to replace the crankshaft seal
You can pull the transmission or engine, witch ever you think would be the easyest for you. But you have to remove one of them to replace the rear main. It is a 1 piece seal and it drives over the back of the crankshaft.
If you are working on your main caps, then you are in an engine rebuilding situation. If they actually broke, you need to find out why, and replace or repair the parts, including the crankshaft, that are bad. If, by breaking, you simply mean that you loosened the bolts, you still need to evaluate the status of the crankshaft and bearings. This involves checking for size, remachining as necessary, replacing parts as necessary, checking bearing clearance, and torquing the cap bolts to specification.
A thrust bearing is located as one of the main bearings on the crankshaft. It maintains crankshaft end play.
do not rotate crankshaft
Main bearings are what the crankshaft rotates on.
That engine has a solid round one piece rear main seal that slides over the rear of the crankshaft. You will either have to remove the engine are transmission to be able to replace the rear seal. No other way to do it. ( BIG JOB ) and a good paying job.
385 euros @ mercedes main dealer.
That is what holds the crankshaft in the engine block and also holds the rods to the crankshaft. There called Rod caps and main caps
To keep your crankshaft held in place.
You take engine out. Remove the flywheel/flexplate and put the engine on an engine stand. Remove the oil pan, timing cover, and timing chain. Remove all rod and main bearing caps. Remove the crankshaft. NOTE: You would be much better off buying a new or used engine than attempting to replace a crankshaft.
You MUST remove the engine are the transmission to be able to service the rear main seal. Your choice. It will be driven in a housing that is bolted over the end of the crankshaft. Pry it out and drive the new 1 in CAREFULLY.