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Grahamgl

Pushrod problem HELP PLEASE

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Gentlemen,

On from my post on Angle torque, yesterday I started to re-torque the cylinder head using a calibrated and certified torque wrench.

 

After removing the rocker gear I then removed all the push rods. I re-torqued the head to 143 kns, after relieving the original torque by one flat. And yes, all of the head nuts turned a little further than before.

 

When it came to re-fitting the pushrods some of them went in without turning the engine but, for three of them I had to turn the engine over by using the fan blades to get the pushrods to drop in. However, pushrod 6 is refusing to go down fully, it stands approximately 2” higher then the rest off the rods. I spent 3 hours yesterday afternoon turning the engine over and then trying to insert the pushrod, I was turning it by about and eighth of a revolution each time. When I remove the pushrod it is picking up the cam follower for a short distance and it then drops off. It appears to be dropping back onto the camshaft as the adjacent pushrod vibrates when it drops down. On occasions it appears that the tappet follower is sitting at an angle as the pushrod will not go into it. In retrospect perhaps I should not have removed all the pushrods before tr-torqueing the head nuts.

Any advice would be extremely welcomed.

Graham

 

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I can’t visualise how the follower could be at an angle, it’s in a close fitting bore. Worst case it’s broken in two and the two parts have shifted so they don’t mate up. Could it be stuck in the bore? A gentle tap on the pushrod with a rubber mallet might seat it.

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leave the pushrod in and turn the engine over and see if there is any movement ,if no then the follower is not on the cam.Not sure how this can happen though

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Thanks for the above advice.

A though t has occurred to me. Is it possible that by dropping the pushrod down the bore that I have burred the inner top edge of the cam follower thus preventing the pushrod fully entering the cam follower? How deep is the recess/ hole in the cam follower? I have compared the length of the depth of the push rod to using a smaller diameter piece of dowel rod and both depths are the same.

Thanks

Graham

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leave the pushrod in and turn the engine over and see if there is any movement ,if no then the follower is not on the cam.Not sure how this can happen though

Roy,

I have just put a clock on it and there was no movement at all. I also put a rod down the tube and moved the follower side ways and the push rod in the adjacent bore moved so it seems to me that all is not right. It seems strange as all I did yesterday was to re- torque the head.

Graham

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The follower could have come part way out and now be angled over preventing it dropping down into position. Try using a magnet to pull it up and centralising it.

Alan.

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The follower had come up with the pushrod and is now out of its bore so you need to try and get the push rod back in the follower and realign it in the bore. if you cant get it to line up the head will have to come off. Taking the pushrods out was not a good idea, good luck.

 

Graham

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On my race engine the cam follower has stuck on the pushrod by " stiction" and oil and when the push rod was removed the follower came also and OUT of the follower hole in the push rod chest and hid on top of it's partners follower hole...tricky.

Before you ask how ? race engines have all sorts of weird "advancements" made to them ( well mine do anyway) and the followers were reduced in height items, no we didn't have to remove the cylinder head, about 40 mins of using strong bent wire to shuffle the follower around and then pressing into the roughly located follower with the push rod relocated it into it's hole.

 

To avoid mistakenly pulling a cam follower as itemised above first hold the push rod between your palms and rub back and forth furiously (like a Boy Scout making fire with wood) whilst applying a gentle upward motion. The movement displaces the oil and removes the suction from the end of the rod.

Sounds like the follower is misaligned, by using previously described implement ( stiff piece of wire) and disassociating your mind ( I close my eyes) gently locate the follower down the push rod tube and by tracing the outline come to understand the lie and location of your errant follower in case it also has left the chest follower hole. If it's actually in the hole normally you'd expect it to be able to be pressed down with minimal pressure, if it doesn't press down when it's in the hole then it's head off anyway, I wouldn't advise using considerable force because of the risk of gouging the follower which will then likely pick up in the chest and let you down at an inconvenient and costly manner in future.

 

Mick Richards

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When I did my apprenticeship (Many years ago!!) I was taught to remove the rocker gear and then hold each push rod

between finger and thumb and rotate it inorder to break the oil seal between push rod and cam follower.

If you just pulled the push rod out then you risked pulling the cam follower out.

 

Tom.

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+1 for previous 2 posts, the followers can all too easily come up when you pull out the push rod.

I lift the push rod a little, then rotate it until you feel the follower drop down.

After a while you get used to the feel of the rod when you pull it up - it is heavier if there is a follower stuck to it.

 

Bob.

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