Tight to turn enging
 

Hi
I have a 2 liter mag cased engine that is new to me.
Even with the plugs out the engine is unbelivebly tight to turn over (by hand) almost like frozen solid.
If I put a wrench on the pully I need like a 16" extension to break it free, then that movement is easy. If I continue to turn the engine over a full 360 degrees it loosens up and you can turn it without much resistance.
2 days later (or maybe less) and its frozen again.

The only thing I'm sure of is that the cam chafts is't binding, I could turn them when I inspected the chain tensioners.

Ideas?

Consider oiling the cylinders while turning. I had a 2.2 T that had dry walls and wouldnt turn.
Bruce

I did spray some penetrating lubricator down the sparkplugs, but maybe I should use proper oil instead.
Forgot to say, I drove this engine home, 160 miles, in oktober. It has been untouched until I pulled it 2 weaks ago. The magnetic oilplugs did look a bit like a christmas tree....

your mainline bore may be out of wack. 2.7s do that when you use new main bearings and don't align bore the mains. it's a mag case and mag is perpetually rotting and shape shifting.

The answer I was sort of waiting for.... and fearing...
This engine has a previous rebuild on it some years ago, but it's only a little 2.0 so I hoped that it might be something else....

I think I will have to tear it down and have a look. I was planing on selling it, but that doesn't feel right like this. Possibly its better to part it out.

I think that if the rotation frees up as you turn the engine over, it may not be due to the crankshaft bore mis-alignment. I have a 2.7 awaiting assembly (with a new line bore). Before teardown it wasn't stiff to the point of using a 16" breaker bar, but stiff enough where I had to bump it with the starter in order to do a valve adjustment (a wrench on the alternator/fan wouldn't do it via the fan belt). If I could reach the lower pulley bolt, it was consistently stiff and never loosened up.
I would try oiling the cylinders and/or try other options before assuming the worst.

The cases only relax and twist when the through-bolt tension is released.

Are you saying that if the case has warped it should always be tight and not release the crank after turning it?

What was strange was that when I turned the crank 90 degrees I had 90 degrees of free movement (relativly free) but it still reqiuered a lot of force to turn past the 90 degrees.

If it is the 2 liter, it shouldn't be a MAG case, no?

The -69 (mine) are mag cased.
I think that even some -68s have mag case.

thanks, didn't know that! I thought mag cases were used only from the 2.2 liters on.

No, I meant that while the engine is assembled, the through-bolts keep everything aligned as it was when first built so it will turn smoothly. When you dis-assemble the engine, the magnesium is able to "relax" to a warped shape. If you then re-assemble without line-boring, it will bind.

3 years later!
Today I split the case, and it is warped!

There are tell tale signs on the bearings and when I put a ruler over the bearing webs I can see that see that the middle bearings are a few tens lower.
Are there any tolerances for them?

Interestingly the crank was ground and the bearings were +0.50.

When I had my mag case done the builder had a jig where he placed the half cases.

My mag case bit me in the butt.

If I was you I would send it to a pro.

Well, I have no real use for the engine.
It either a fun exercise or a shelf warmer in my storage. :)

you will need a new, standard crank as oversized bearings are nearly unobtainable and when found are ridiculously expensive.

A fun project but hold on to your wallet ;-)

Chris
73 911 E