In a lot of the more modern engines, the whole bottom of the engine unbolts in to two parts to allow access to the crankshaft and rod bearings. The oil pan is just a small cover on the bottom portion.
In the past removing the oil pan would allow access to all of the piston rod bearings. Even removing pistons with the engine in the vehicle was possible by removing the cylinder head.
I was talking to someone about the Kia engines that were needing replacement at 60k miles, and it reminded me about this. You can’t just remove the oil pan and get to them easily anymore.
A similar thing has happened with more modern automatic transmissions.
I don’t know but it seems to me more and more it is easier just to pull the engine for major work. Of course often involves needing a lift for the engine cradle that rules out most DIYers. At some point people are going to need to accept the fact that pro shops are going to need to do more and more of the work wether we like it or not.
Manufactures have mostly moved to 2 piece oil pans, the upper aluminum one and the lower metal, plastic or whatever one, with the lower one having the drain plug in it, if it strips out or whatever, then it is much easier to replace vs an one piece pan…
The upper one can also add in block strength, whereas a one piece tin (metal) one does not…
Some transmissions don’t have pans on the bottom due to various reasons, one being the valve body being on the side of some transmissions now a days, the other is no serviceable filters, so no need for any pans on the bottom or at all…
I can’t think of any transmission that I have ever rebuilt that I did it mostly from the pan, you normally either slit the case or go behind the torque converter (front pump on most) area to remove the parts…
All depends on the vehicle/engine, but you can hang the engine and drop the cradle on a lot of them to remove the upper oil pan… But again, like said before, if you are having to remove the upper pan, you are probable needing to remove the engine anyway, probably even easier on a lot of newer vehicles…
You can’t clean out the sediment if there is no pan on the bottom. Also the valve body and the solenoids can be accessible from the pan which allows for some service.
A lot of that “sediment” is clutch/band material, so it is probably time for a rebuild anyway…
Manufactures have been putting valve body’s on the side of transaxles for many decades now, GM’s 440-T4 (1983ish) has the valve body on the side as one old example… So even though it had a side pan for the VB it did not need one on the bottom other than to change the filter, no filter, no need for the pan…
My 1996 Dodge has a bedplate securing the crankshaft/crankshaft bearings. I have been satisfied with the engine’s bottom end strength, the engine exceeds 5000 rpms each time I drive the car.
What happens if the gasket on the top of the bedplate needs to be changed, and the bedplate removal requires engine removal? It’s not always just to access rod bearings.
I don’t worry about these things. Camshaft cradles tend to seep oil more frequently than engine block bedplates and that only bothers certain people.
Technically the flywheel/flex plate (transmission) will hold the rear of the crankshaft in place and the serp belt and or a jack under the harmonic balancer (can be re-attached if removed) will hold the front of the crankshaft in place, so again, it all depends on the vehicle/engine if the engine requires removal or not…
Again, it might be easier to remove the engine to do the work…
You can NOT put a blanket statement on this subject…
