Crankshaft seisure?? New rebuild!

[biggtbiggt]

I have just completed a fresh rebuild of a 1975 2.7L 7r case.
When I finished putting the case halves together the crankshaft felt tight but would loosen up after about a 10 degree turn. I thought that this might have been caused by a bit of case sealer on a bearing and would go away after the engine was run. I have now got 200 miles on my engine and I have to hit the starter about 10 times to break the crank loose before the engin will spin. after it turns even slightly it will then spin freely. The engine will spin freely after. but if it sits for 3 or more hrs it will tighten up again. I know it is not a starter problem as I have put a bar on the crank pulley and have turned it by hand sometime the first little bit to loosen it.
any help would be appreciated. I am wondering if I torqued the case throug bolts to tight or in the wrong sequence but after the crank turned just a bit it would then turn freely with no tight spots so I was not concerned. Now I am wondering if I should loosen them off a bit?

[Jim Sims]

2.7 l magnesium cases often need to be trued up and line bored when being rebuilt. If this wasn't done, I suspect your case is warped. Did you check the clearances between the main bearing and journals with "Plastigage" during a "dry assembly" (no sealant on case halves)? The case warpage is likely causing a bind when the engine is cold. If you loosen and retighten the through bolts it may or may not help (probably not) but such action will almost certainly result in cracked case sealant followed by oil leaks. I wish I could offer you a better prognosis but I think the engine is going to have to come apart and the case trued up and line bored. Jim

[biggtbiggt]

I did not line bore the case wich is probably the problem!! I am also concerned that if I disturb the case bolts I will end up with oil leaks. the reason I took this engine apart in the first place was to fix the leaks. I now have a totaly leak free engine!! Since the engine seams to loosen so easily by just hitting the starter a few times, I am going to drive it this summer and see if it loosens up a bit. If not I will have to split the case again in the fall and line bore
I will post if the engine frees up.

[911pcars]

Not that this is the cure for the "tight" engine, but is your cranking system in order? Battery, starter, solenoid?

If indeed, the crankcase bearing saddles are out of line, then I guess the engine might have to come apart. The main bearing wear pattern should reaffirm your diagnosis.

For this reason, I recommend installing the crank w/o the piston/rod assembly. Without the rods and pistons in the way, you can check the rotation of the crank while tightening the case bolts to final torque specs. You may have to modify the tightening pattern so the crank doesn't bind. If the crank doesn't rotate freely, then at least you can disassemble and find out why at this stage rather than later on.

Let us know what happens.

JMHO,
Sherwood Lee
http://members.rennlist.org/911pcars

[john walker's workshop]

it's a rare 2.7 that allows the crank to turn easily, when new bearings are installed. the crank will wear out the bearings and probably itself, and the case too, if you keep running it. you need oil clearance all around the journals, not just on the side that has some. you should tear it down and get the case align bored before it freezes up and you're left with a junk case and crank.

[biggtbiggt]

I sure don't want to take this apart again!! It sat for 4 hrs today and still turned over fine. but the first start this morning took a couple clicks of the starter. I do not hold the starter on for very long when I am trying it. I think if I left it in the start position it would turnover but I would think that would be hard on the starter. will the case not align itself as it heats and cools a few more cycles? Since it turns so freely after it turns just a bit I feel that it is very close to aligned properly. The engin will turn easily wiht the sparkplugs out. but the compression mixed with the friction must be just to the limit of the starter.

[john walker's workshop]

all i can say, is that it could go either way. either it wears in and you get lucky, or you will have a problem. the fact that the starter won't even budge it for a while is worrisome. nobody wants to do a teardown after all that work, but sometimes things don't work out for the best mechanics, and they just bite the bullet and get it over with. it's a tough business sometimes, but you learn from your experiences. after all, you knew about the binding as soon as the case was torqued up, and kept going. always question things that don't look/feel right. it won't happen to you again.

[Wayne 962]

I agree 100% with JW. You should have stopped when you felt some tension on the case during assembly. It was a bad call to continue, but no use crying about it now. If you continue to run the engine, there is a high degree of chance that you will destroy the entire engine, and need to buy a new one. Weigh that against the trouble of removing it again.

The 2.7L cases cannot be simply removed and rebuilt - they must make a trip to the machine shop. Sometimes they are so warped that when you take them apart, let them sit over night, and then bolt them together, the crank will not spin at all (this sounds like your engine).

I have all of this info in my new book:

http://www.101projects.com/rebuild.htm

You might want to read it before you do anything. Then you will determine for yourself (after reading), why it needs to come apart, instead of just listening to us tell you...

-Wayne

[john walker's workshop]

just think how much easier it will be the second time. all the parts are clean too. you could have it out and torn down in 5-6 hours.

[biggtbiggt]

I agree that it would be easy to take apart as most of the work is in the cleaning!! I just feel that it is not extremely tight as it will spin without the spark plugs. and it will start freely up to at least 4 hrs before it starts to get sticky. If I had a high torque starter I probably would not even notice it. I am just so happy that it is not leaking oil that I don't want to take apart again! The stupid part is that the block was sitting right beside the line bore machine and we did not put it through

I am also wondering if it would be normal that the engine would restart without sticking for hrs?? and if it frees by just clicking the starter a few times is that still sound that it is real tight and will not free up with a few miles? I only have about 250 miles on it now!

[biggtbiggt]

BTW

Wayne I have the preview copy of your book and it was very helpful!! Thanks! I thought that the crank was free as once it was in motion it turned easily and freely. I rotated it many times as I wanted to see if it was binding in any peticular spot.

[dtw]

For some reason I was thinking of this movie. "The Shawshank Redemption". Good flick. This guy busted through a wall with an otherwise unlikely instrument- all he needed was time and pressure. Time and pressure. Time and pressure. There's a connection here somewhere, but it's 5am for me and goshdarnit, I just can't put my finger on it.

Anyway, good luck ignoring your problem and rolling the dice! Can't say I respect it or that I won't laugh when you're buying a replacement engine, but good luck! If it lives you can give us all a big fat "HA HA".

[/Insomnia-induced sarcasm]

[Wayne 962]

You have two pretty smart people telling you that you will probably have big problems in the future - I would take our advice.

Every time that the engine sticks and then kicks over, you are scraping your crankshaft against the bearings. Even if the clearances open up when it gets warm, you are grinding your crankshaft against your bearings (most likely) when you start it up. The best case scenario is that your crank is then ground or the bearings are ground, and the clearances open up. Needless to say, this friction and grinding is not good for your engine.

In fact, it lends itself to an explanation of why starting your engine is bad for it. The engine is cold, and doesn't have oil pressure, so it spins against the bearings and can actually wear them physically. Theoretically, if you never shut off your engine and run it forever, the main bearings would never wear. This is because the crankshaft actually rides on a layer of oil, not the bearing itself. When starting the engine, the crank will ride on the bearing itself and wear it, until oil pressure builds up.

In your case, you are wearing your bearings very quickly. You may have already damaged your crankshaft beyond repair. If it were my car, I wouldn't drive it anymore, until the problem is fixed...

-Wayne

[biggtbiggt]

I have started it about 10 times and now am in the proceess of engin removal!! What gaskets will I be able to reuse or should I buy another complete gasket set??
I will be able to leave the cam covers attached to heads, and the pistons in the cyls, so that will save some time.
I am just on checking to see if I should leave tranny in or remove it with engine like I did before.
I suppose that it should not take as long the second time.

I am also wondering if I can reuse the oil pump lock tabs as they also took awhile to get?

[john walker's workshop]

you will need all new gaskets. pulling the assembled heads and cam towers together saves mucho time. gut and remove the chain housings first. don't try to pull them off still attached to the cam towers. too much hassle. the oil pump lock tabs will probably live if they were new. i always leave the trans in the car. disconnect the shift coupler from it first so when it hangs down, nothing breaks or bends. trying to remove the pistons without pulling the cylinders off them would be a PITA. how would you get the pins out with another cylinder next door? just pull off all the cylinders, and then take off all the pistons. all you would save is ring compressor time, and that's not worth the hassle. you're doing the right thing.

[biggtbiggt]

I put cyls on with pistons on them. It is easy as long as you do it in the proper order.

I was talking to mechanic today who suggested that I should get an oil analysis to check if there is any metal contamination.

I talked also to the machine shop and they said they will not be able to look at it for at least 2 months. The worker had put his fingers in a machine and got hurt.

[Oldporsche]

Drop the motor. Open it up. Get the case trued. If you're lucky, you might not need to turn the crank. If you keep going, odds are you will need a new crank or reconditioned one.

Just do it.

Good luck,
David Duffield

[john walker's workshop]

ship it to competition engineering in cailfornia. wayne would know the number.
lots of folks take the piston/cylinder out of the box, tap the piston out just enough to get the wrist pin out, and install it that way without arranging the rings with the gaps in the proper position. you didn't do it that way hopefully.

[Doug Zielke]

bigg',
JW is right about Competition Engineering, top shelf outfit, but as you live in Canada, the costs may be prohibitive.

As an alternative, I would suggest you call Stuart Davidson at Weissach Performance in Vancouver. Ask him who they use for machining cases.
Stu is a great guy, and will try to help you. Mention my name if you wish.

[biggtbiggt]

I sent an oil sample away today but with the long weekend I will not get results back until Monday. I could not visibly see any metal particles but who knows! I talked with some more people today and most of them are puzzled at the fact that the engine does not get stickier as it warms up! Some figured that it should have blown up by know if it was going to as I have 265 miles on it which would be around 6 hrs including breakin. Maybe I am just paranoid and have a weak starter that will not turn it over. But it seems strange that if the starter was weak that it would turnover fine after it had ran for a bit??