MG MGB and MGB GT Tech Talk
Just installed rebuilt engine into car and tried to turn the crank pulley manually, but it wont turn. Tried to get as much leverage on the crank pulley bolt but the pulley will not turn. Even put the car in gear and tried to rock it back and forth to see if it would move, but no. Pulled the starter back out to see if maybe it was obstructing the flywheel somehow, but it wasnt. Am I missing something?
When you hooked the transmission to the back of the engine, did it slide up flush or did you have to pull it flush with the bolts? If you pulled it up with the bolts you have something misaligned.
Backing up just a little bit to make sure, but did the crank turn before you put the engine in?
Crank did turn a little before installing the transmission. I do have a Nissan 280Z transmission conversion on the car however.
Is the tranny conversion new, too? Or was it installed and working OK before the engine rebuild?
Could you try and describe "a little" a bit better?
Tony, did the engine turn by hand before you bolted up the gearbox? If it did/doesn't then you should check to be certain that you have installed the correct size main bearing shells and the ones in the big ends of your rods. You should be able to rotate the crank by hand when the engine is assembled if everything is as it should be. Albeit a bit 'tight' but that should only be due to the drag from the rings in the cylinder bores.
Tranny conversion is new. I turned the crank one half rotation before the transmission went on, and turned it back to top dead center.
Could it be so tight from the drag that the crank pulley wouldnt move?
Did you cut the clearnace slots for the starter. It could be touching the ring gear if you did not and this would hold it tight. Here is what it needs to look like with the tranny conversion.
I pulled the starter back out of the car to make sure there would be no interference when I tried to turn the crank pulley.
Fortunately with that tranny you can pull it from underneath without pulling the engine too. I think you are going to have to back out the tranny and then make sure the egine spins with it off. You only turned the engine 1/2 revolution. I would consider making a few revolutions and then even use the starter to spin it for testing.
Are you using a Rivergate conversion? Did the bushing go into the rear of the crank all the way to the bottom?
Not using a Rivergate conversion, but its very similar. The bushing was pretty tight and was flush to the surface of the flywheel.
Maybe the flywheel ring gear is contacting the inside of the bell housing.
Tony, the Rivergate conversion uses a turned down MG flywheel and a Nissan ring-gear. This is because the standard diameter of the MG flywheel will not fit inside the 280ZX bell housing. Rick might be on to something here. Are you using a standard MG flyweheel?
(Rivergate has you ship your flywheel back to them then re-imburses $100.00 when you do).
Using a modified 280Z flywheel that fits the stock MGB holes.
Will the crank move counter clockwise at all or is it totally 'seized' in position?
Crank is totally seized. I used a breaker bar and a metal pipe for leverage to try and turn it, but didnt move. As much of a pain it is to move the transmission back, I might have to do that just to see if the flywheel turns a full revolution.
Was the engine back plate designed for the flywheel you have on it? The thickness of the plate really matters as a thinner plate will position the flywheel deeper in the bellhousing causing contact with the inside of the housing.. I'd loosen the bell housing bolts and move the tranny back a little and see if it will turn.
Tony, it is 6:30. Go have a bite to eat and come back after dinner. Pull back the trany and see if the engine spins...... you are at point where you need to go back to the 'last known good' version of the assembly. Pity you just can't 'restore from backup'.
Will do Peter, thanks for your help. I'll let ya know what happens...
On some engines if the big end bolt heads are facing the wrong way they will stop the crank from rotating 360 degrees. There is not much clearance at the big ends bolt heads.
I would pull the lump again and separate the engine and box. Turn the engine over a few to make sure it is free. Then mount the box and see it it still turns freely. Do this by hand with a ratchet and socket on the pully bolt.
I'm not going to comment on the tranny swap which very well could be your problem., I'll just comment on the engine itself. I would say the most common thing to lock a crank down in a block during assembly is new thrust washers, I always check my crank end thrust clearence when disassembling most of the time I find the thrust bearings to be in spec and don't need to be replaced, alot of folks think they are doing the right thing to replace the thrust bearings but they really don't wear any, and if buying new ones only means you have flat sand them down the the thickness of the old ones, have you really accomplished anything by using new thrust washers to begin with? Another source of lock down engine can be the cam thrust plate, also too much bearing end crush, I seen that with the cheap bearings. Deeves ring will cause a engine to be hard to turn over when being assembled, but it will turn over, Deeves oil control ring goes in very hard with alot of ring drag when hand turning the motor, this is one of the reasons I never liked them.
Will the engine turn back the opposite direction?
Check to be sure none of the bolts holding on the backing plate interfer with the flywheel. If you used aftermarket bolts and lock washers this may very well happen.
MGB 12 Wrote:
Unless I am missing something, this is a newly re-built engine. Why is the tranny converson the main suspect?
I am looking for the post where it says that the engine truned over fine on the stand and that plastigage or somesuch was sued to verify bearing clearances on all journals.
Failing that:
Did the crank turn smoothly during re-assembly? Most of us cant help ourselves from turning the assembly as we re-build these things!
Pete
He did post where he was able to turn it the half turn he tried before rejoining the two.
I hate to say it, but why didn't you turn over the engine with the tranny mounted to it BEFORE you installed it in the car? It could be something as simple as a misaligned backplate. Loosen up all the engine to transmission bolts to see if you can rotate the engine. Tightening the bolts could have shifted the tranny off-center and made the input shaft bind in the pilot bushing. Doing this will also help determine if the flywheel bolts are the problem!
I'm also hoping the crank spun freely with zero binding when it was first installed and torqued in the block. I'd have to speculate that the block was not align bored and the rods were not resized.
HALF a turn? I did read that and had to wonder why he stopped there. From what I can tell, there has been no attempt to spin this thing as an engine only. I would go bact to that point .
Pete
Half a turn wouldn't even set up your valve clearances.
Russ
Did you rebuild the engine, or someone else? You have to turn over the engine about 2 turns to set the valves. Anyone rebuilding an engine for you would set the valves before they gave it to you, therefore it would turn over by hand. I think the problem is the fit of the transmission or clearance of the flywheel. Hate to say it but you gotta pull the engine and tranny apart to see where it's binding.
FOUND THE PROBLEM!! Man I feel really stupid...Glen Popejoy from Texas gets the big award. One of the bolts on the backing plate had 2 washers on by accident instead of one lock washer, Thus interfering with the flywheel....Man I was stressin' big time thinking it was something much worse. Thanks guys for all the feedback. See ya out there on the road!
tonyjennes Wrote:
Maybe his piston rings are to tight. I have built engines that are tight and rings wont slide in pistons easily. I had to remove the spark plugs and put some stp oil treatment in the holes to make it slick till it would turn over easily.