new 2.4 engine hard to turn by hand

[hbrand]

After a rebuild ( including new cylinders, pistons, rings, new crank bearings, crank turned freely),
engine is very hard to turn by hand, but runs good.
Same with spark plugs removed, and transmission in no gear

After 350 miles driving engine is still very hard to turn by hand.

Shop said the crank is the problem.

So I drove 350 miles with a problem from the crankshaft !

Is this possible or would not the crank bearings overheat???

Thank you
Harald Brandner

[john walker's workshop]

the case probably should have been align honed. cranks are rarely the problem. what is their reasoning on the crank?

[Steve@Rennsport]

John is spot on.

Magnesium crankcases distort once the clamping pressures are removed and must be machined flat and re-align bored back to standard to permit the crank to turn properly.

[Walt Fricke]

John and Steve would have a much better idea than I about just how case distortions affect the crank turning.

Like you, I'd wonder how it is that the crank turned freely when installed and the case halves torqued together, and I suppose through out the rebuild process (because you have to turn the crank often for this or that purpose) as the pistons (with rings) were put in the cylinders, and the heads torqued onto everything, and then when the cams were timed.

But only after running the engine some did this hard cranking become apparent?

At what point did anyone become aware that the engine was harder than it should be to turn over? Does the shop agree it is harder than it should be? the valve springs are no weaklings.

If you do get the case halves shaved, and the case align bored, be sure that it is not bored oversized. Especially not the #8 or nose bearing (which doesn't wear). That's the beauty of the shave and then bore method - can use standard bearing ODs.

[hbrand]

Originally Posted by Walt Fricke

John and Steve would have a much better idea than I about just how case distortions affect the crank turning.

Like you, I'd wonder how it is that the crank turned freely when installed and the case halves torqued together, and I suppose through out the rebuild process (because you have to turn the crank often for this or that purpose) as the pistons (with rings) were put in the cylinders, and the heads torqued onto everything, and then when the cams were timed.

But only after running the engine some did this hard cranking become apparent?

At what point did anyone become aware that the engine was harder than it should be to turn over? Does the shop agree it is harder than it should be? the valve springs are no weaklings.

If you do get the case halves shaved, and the case align bored, be sure that it is not bored oversized. Especially not the #8 or nose bearing (which doesn't wear). That's the beauty of the shave and then bore method - can use standard bearing ODs.

Walt hit the nail:
Engine was turning normal during assembly and harder with the new rings, then driven 350 miles, then car got sold overseas, the shop there adjusted the MFI and said engine runs good and quiet, but then got so hard to turn that the starter could not do it anymore. They disassembled the engine without my approval and said the crank is the problem.
Will get an update soon. Harold

[docrodg]

Two things:

1. They disassembled your engine without your permission??? Don't let them touch it! Unknown yet if it need line bored and decked, but they do!

2. The only way I can think of it being a crankshaft problem is a bent crank, which is not at all likely. Probably does need line bored and they are saying it is the crank because they stripped everything else off and it was still hard to turn.

Personally I would get that engine back from them and do a few simple checks on the crank and on the case. Crankshaft dimensions of the journals and runout, if that was good then it is the case.

[kwikt 911]

Right on target with the align bore. Been down that road before especially with the magnesium case with new bearings.

[hbrand]

When we did the engine, there was no need to linebore, but since the engine is now bad, we will pay for the repair.
We sold the car to a good person in Switzerland.
Their labor rate is $ 120 per hour.
Makes no sense to ship back engine to us for repair, so we will pay $ 7000 to get it properly repaired over there and WE HAVE LEARNED ANOTHER LESSON.

Thanks for all your thoughts, you all where right.
Harold
Bmc Classics,Inc

[docrodg]

Glad it is getting fixed, but still... letting someone who disassembled the engine without your permission get away with it? With the gaskets and all that must be replaced and materials etc, what if you had told them to put it back in the car? Would they have put it back together correctly and with new gaskets with no charge? Even if they would do it without charge, this is not like removing a tie rod to gain better access to something else in troubleshooting... this is tearing down a major component all the way that requires significant costs in materials to put back together. Such actions should always be approved by the owner PRIOR to doing the work. I would question whether the shop is practicing good business and not just trying to get more money from their customers when something like that happens.