How can I turn the crankshaft after the head is removed? - Page 2

Gary · 19th April 2010, 22:38

You don’t say if you have the front of the car jacked up or whether you are doing the work over an inspection pit but if you have the car in gear and both front wheels on the ground that will prevent the crankshaft from tuning. Or have you put a pin in to lock the flywheel and forgot to take it out? With the head off it should turn easy.

RobRoy · 19th April 2010, 23:28

No, nothing has been disturbed. Nothing is jamming. The Haynes manual states that the crankshaft will be difficult if not impossible to move when the head is off. Does anybody know why they give this advice. Why should it be difficult to move the crankshaft

James.uk · 20th April 2010, 01:15

If all else fails, try knocking the damaged piston down with a wooden hammer shaft till you can reach the big end bolts. Once the bolts are undone you can remove the bottom housing and drive the piston back up and out the top. Be carefull not to damage the con rod..

But I agree, the engine should turn very freely with no head on it.

I think you have a badly damaged piston skirt jamming in it's bore somewhere.

... Fingers crossed..
...

Fraser Mitchell · 20th April 2010, 07:46

I think if you read on in the Haynes manual you will find that the piston/conrod assembly cannot be removed from the top as the big-end eye is too big for the liner. It has to come out the bottom, so it is a crankshaft removal job. Funny old engines, these K4s

sworks · 20th April 2010, 08:33

The cranks usually are difficult to start moving initially but ones this is overcome it should turn easier (providing the damaged piston isn't jammind on the liner), are you using a ratchet or big bar? The piston definately comes 'up' without removing the crank.

Gary · 20th April 2010, 08:39

I replaced all four of mine a few weeks ago and the piston will push out through the top of the engine. If you haven’t already done so you will need to think about replacing the liner because you will probably find, if you look closely, that has been damaged as well.

T-Cut · 20th April 2010, 09:49

As mentioned by RobRoy, Haynes says:

'Due to the design of the engine, it will become very difficult, almost impossible, to turn the crankshaft after the head bolts have been slackened.'

There's no explanation of why this is, but it's clearly a fact as demonstrated here. I suspect there must be some form of relaxation in the structure when bolt tension is released and this causes flexure, which effectively locks the crank/pistons in position. There may be a completely different reason, but I couldn't guess what.

The next question is how can you remove the crank for example, if you can't turn it? Very wierd.

TC

RobRoy · 20th April 2010, 10:06

Gary, How did you turn your crank, was it OK. Did you have any trouble removing the gudgeon pin from the old piston or did you replace the conrod as well?

Gary · 20th April 2010, 10:21

Quote:

Originally Posted by T-Cut

As mentioned by RobRoy, Haynes says:

'Due to the design of the engine, it will become very difficult, almost impossible, to turn the crankshaft after the head bolts have been slackened.'

There's no explanation of why this is, but it's clearly a fact as demonstrated here. I suspect there must be some form of relaxation in the structure when bolt tension is released and this causes flexure, which effectively locks the crank/pistons in position. There may be a completely different reason, but I couldn't guess what.

The next question is how can you remove the crank for example, if you can't turn it? Very wierd.

TC

This is very strange and contradictory. You are told to lock the liners because if you don’t they may become dislodged when you rotate the crank, then you are told you can’t rotate the crank with the head removed. Doesn’t make sense to me!! All I can say is I replaced all four pistons a few weeks ago and had no problem rotating the crankshaft.

Thinking about it you need to lock the flywheel so the crank will not rotate so you can undo the nut on the bottom pully.

Gary · 20th April 2010, 10:41

Quote:

Originally Posted by RobRoy

Gary, How did you turn your crank, was it OK. Did you have any trouble removing the gudgeon pin from the old piston or did you replace the conrod as well?

Remove the drivers side wheel and part of the inner cover to expose the bottom pulley, then put a socket with a long extension on the bottom pulley nut and it should turn easy. The only thing that I can think off that would stop it is if the gear box is locked eg. you have the car in gear with your foot on the brake.

Too expensive for me to replace conrod as well. If you put the piston in a vice with a bit of brut force you can punh the gudgeon pin out but remember to mark the conrod so you replace it the same way it came out. You will need to heat the conrod to replace the new pin.

20th April 2010, 01:15	#13
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	If all else fails, try knocking the damaged piston down with a wooden hammer shaft till you can reach the big end bolts. Once the bolts are undone you can remove the bottom housing and drive the piston back up and out the top. Be carefull not to damage the con rod.. But I agree, the engine should turn very freely with no head on it. I think you have a badly damaged piston skirt jamming in it's bore somewhere. ... Fingers crossed.. ... Last edited by James.uk; 20th April 2010 at 01:21..

20th April 2010, 08:33	#15
sworks Been absent for a while… Rover 75 Tourer, Classic mini Cooper S, Abarth 595 competizione, MG TF and a Hyundai Tucson PHEV Join Date: Feb 2007 Location: Cumbria Posts: 13,065 Thanks: 1,033 Thanked 1,686 Times in 1,040 Posts	The cranks usually are difficult to start moving initially but ones this is overcome it should turn easier (providing the damaged piston isn't jammind on the liner), are you using a ratchet or big bar? The piston definately comes 'up' without removing the crank. __________________ ................................................. 'Marmite' Possibly one of the most famous 75 tourers produced! left the production line as the last of only Three Rover 75 tourers produced in Trophy Yellow. 48 hours later Longbridge closed. The last sold ordered 75 Tourer. Paid for by the Phoenix Four and handed over by John Towers to the Warwickshire Northampton Air ambulance service as a Rapid Response vehicle Last edited by sworks; 20th April 2010 at 08:40..

19th April 2010, 22:38	#11
Gary Avid contributor Rover 75 1.8T Club - Mitsubishi GTO Join Date: Apr 2009 Location: Weymouth Posts: 107 Thanks: 0 Thanked 0 Times in 0 Posts	You don’t say if you have the front of the car jacked up or whether you are doing the work over an inspection pit but if you have the car in gear and both front wheels on the ground that will prevent the crankshaft from tuning. Or have you put a pin in to lock the flywheel and forgot to take it out? With the head off it should turn easy.

19th April 2010, 23:28	#12
RobRoy Regular poster Rover 75 Join Date: Apr 2007 Location: Liverpool Posts: 66 Thanks: 4 Thanked 4 Times in 4 Posts	No, nothing has been disturbed. Nothing is jamming. The Haynes manual states that the crankshaft will be difficult if not impossible to move when the head is off. Does anybody know why they give this advice. Why should it be difficult to move the crankshaft

20th April 2010, 07:46	#14
Fraser Mitchell Gets stuck in Rover 75 2.5 V6 Club Auto Join Date: Feb 2007 Location: Crewe Posts: 898 Thanks: 0 Thanked 0 Times in 0 Posts	I think if you read on in the Haynes manual you will find that the piston/conrod assembly cannot be removed from the top as the big-end eye is too big for the liner. It has to come out the bottom, so it is a crankshaft removal job. Funny old engines, these K4s

20th April 2010, 08:39	#16
Gary Avid contributor Rover 75 1.8T Club - Mitsubishi GTO Join Date: Apr 2009 Location: Weymouth Posts: 107 Thanks: 0 Thanked 0 Times in 0 Posts	I replaced all four of mine a few weeks ago and the piston will push out through the top of the engine. If you haven’t already done so you will need to think about replacing the liner because you will probably find, if you look closely, that has been damaged as well.

20th April 2010, 09:49	#17
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	As mentioned by RobRoy, Haynes says: 'Due to the design of the engine, it will become very difficult, almost impossible, to turn the crankshaft after the head bolts have been slackened.' There's no explanation of why this is, but it's clearly a fact as demonstrated here. I suspect there must be some form of relaxation in the structure when bolt tension is released and this causes flexure, which effectively locks the crank/pistons in position. There may be a completely different reason, but I couldn't guess what. The next question is how can you remove the crank for example, if you can't turn it? Very wierd. TC

20th April 2010, 10:06	#18
RobRoy Regular poster Rover 75 Join Date: Apr 2007 Location: Liverpool Posts: 66 Thanks: 4 Thanked 4 Times in 4 Posts	Gary, How did you turn your crank, was it OK. Did you have any trouble removing the gudgeon pin from the old piston or did you replace the conrod as well?