mechanical question

Submitted: Friday, Apr 11, 2008 at 18:22

ThreadID: 56547 Views:1978 Replies:6 FollowUps:11

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F4Phantom

I took my head off today (from my engine) because i thought I had a snapped timing belt, turns out the belt is not snapped but it is loose for some reason, anyway it caused piston and valve introductions. So I took the rocker rail off to change some rockers and pedestals (the things which hold the cam shaft in place), when I bolted it back on the cam shaft the pedestals are locking it in and not allowing it to turn, mainly the end one opposite the belt wheel. So no it seems the spacers which should allow clearance to stop the cam gripping to much are not working for some reason. Can anyone tell me what to do here? Much appreciated.

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Reply By: nowimnumberone - Friday, Apr 11, 2008 at 18:40

Friday, Apr 11, 2008 at 18:40

sounds like the cams bent

AnswerID: 298013

Follow Up By: F4Phantom - Friday, Apr 11, 2008 at 18:47

Friday, Apr 11, 2008 at 18:47

its not because I have two heads to work with one is parts from a perfect engine. the parts one did exactly the same thing.

FollowupID: 564082

Reply By: howesy - Friday, Apr 11, 2008 at 18:40

Friday, Apr 11, 2008 at 18:40

Not sure of what engine your talking about for a mental picture but a common thing for people to do is over lubricate when bolting back together. If it is a setup where its like a bearing cap your bolting back over the cam, then over lubricating can give you hydraulic braking on the cam.
Again your setup may be completely different that what I am thinking of (not knowing your car)

AnswerID: 298014

Follow Up By: F4Phantom - Friday, Apr 11, 2008 at 18:45

Friday, Apr 11, 2008 at 18:45

thanks, i did not add any extra lube but this idea is the most logical so far. Without the springs adding to hard turning all it is is the cam in its bearing caps, how hard is it to turn by hand? its a 2.5L diesel from a pajero. 4D56.

FollowupID: 564081

Follow Up By: howesy - Friday, Apr 11, 2008 at 18:56

Friday, Apr 11, 2008 at 18:56

You shouldn't have too much trouble turning the cam with a socket and 12" ratchet on the sprocket. It will however be stiff.
Just make sure you can rotate the engine by hand from the harmonic balancer nut through 360 degrees twice and that should be ok if it doesnt foul on anything. better to find a foul by hand then to crank it. Pull the glow plugs out while you do it to make it easier and prevent the temptation to start shuld fuel go in.

FollowupID: 564085

Reply By: Member - David P (VIC) - Friday, Apr 11, 2008 at 18:57

Friday, Apr 11, 2008 at 18:57

maybe take cam with posts attached and place on flat surface the, wife's granite bench top :)) and rotate cam observing if posts move, if so its bent....silverback

AnswerID: 298018

Follow Up By: F4Phantom - Friday, Apr 11, 2008 at 19:27

Friday, Apr 11, 2008 at 19:27

when i loosen off the end "post" , "pedistal" or whatever these things are called, it turns so I think its only one and I dont think its bent because another one did the exact same thing, I pulled it off and replaced it exactly again in the space of 1 minute and it grabbed for no ryme or reason.

FollowupID: 564089

Reply By: burnsy - Friday, Apr 11, 2008 at 19:18

Friday, Apr 11, 2008 at 19:18

Did you put the pedestals back in the same position they came from?Alternative if someone machines the head after it's warped & doesn't line bore the cam tunnel the cam shaft will seize up when bolted down.

AnswerID: 298022

Follow Up By: F4Phantom - Friday, Apr 11, 2008 at 19:25

Friday, Apr 11, 2008 at 19:25

yeah they are all in the same place, BUT I have put new (old) ones because some were cracked in half but the new ones are from the same position.

FollowupID: 564088

Follow Up By: burnsy - Friday, Apr 11, 2008 at 19:46

Friday, Apr 11, 2008 at 19:46

Know nothing about Pajero's
1. I assume that your talking about the caps that hold the camshaft onto the head?
2. if so do you know what flexigauge is?
3. you need to be careful when changing caps.

FollowupID: 564093

Follow Up By: F4Phantom - Friday, Apr 11, 2008 at 19:58

Friday, Apr 11, 2008 at 19:58

1. yes the caps which hold the cam to the head is what I am talking about.

2. no idea what a flexi guage is but i am about to look it up

3. I was about as careful as I suppose I could have been. It locked up on the good head when I tried to put everything back as it had been only one minute before as a test. Meaning, I took it to bits, put it all right back together and it locked up. Very strange.

FollowupID: 564094

Follow Up By: burnsy - Friday, Apr 11, 2008 at 20:23

Friday, Apr 11, 2008 at 20:23

looks like you need to talk to a engine builder because the first thing you need to do is establish cam shaft bearing clearance on all pedestals.
you use the flexigauge to measure this.
I assume that you have rocker arms so firstly remove these which leaves the camshaft free of any resistance.With the belt off you must be able to rotate the cam freely,
If not It must be binding on one or more bearing point.
This is where the flexigauge comes in to measure the clearance of the cam to bearings
Surely somebody can supply you with this spec & how to do it.
If you were near Brisbane I can put you onto someone reliable
Mike.

FollowupID: 564102

Follow Up By: F4Phantom - Friday, Apr 11, 2008 at 20:37

Friday, Apr 11, 2008 at 20:37

Thanks burnsy, say I find one area is binding then what? the flexiguage I imagine will tell me how much clearence to give, but what do you do to adjust the clearance? I have a manual with all NM and feeler clearances.

FollowupID: 564106

Follow Up By: burnsy - Friday, Apr 11, 2008 at 20:58

Friday, Apr 11, 2008 at 20:58

You will need to remove the head & get a engine machine shop to line bore & resize the tunnel.
But before you do this I suggest you get the camshaft checked for trueness also at the engineering shop.

FollowupID: 564110

Reply By: Eric Experience - Friday, Apr 11, 2008 at 21:18

Friday, Apr 11, 2008 at 21:18

F4phantom.
Sounds like you have taken the bearing caps from one motor and put it on another. This is a no no. When the head is made the cam tunnel is bored in a machine to get them exactly lined up. If you swap them around you lose the alignment. You can take the head to a machine shop and get the caps lowered and then re bored. Eric

AnswerID: 298037

Follow Up By: Cruiserman1961 (QLD) - Saturday, Apr 12, 2008 at 06:09

Saturday, Apr 12, 2008 at 06:09

I agree with you Eric, also all pedestals have to be tightened evenly and slowly in small increments to prevent binding. It might pay for F4 to rip the head off and take it to a machine shop before the engine is ruined. Especially because he said some of the parts were broken.
Cheers, Udo

FollowupID: 564160

Reply By: F4Phantom - Saturday, Apr 12, 2008 at 18:39

Saturday, Apr 12, 2008 at 18:39

thanks for all the help so far, this sort of thing requires experience and thats what this site achieves. I hightly doubt I would have been able to solve the problem with a little trial and error.

AnswerID: 298138