Author Topic: Screeching noise ??????  (Read 1281 times)

Offline michael snellin

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Screeching noise ??????
« on: 24.09. 2013 16:14 »
Hi , after a long rebuild, every thing has been renewed, valves ,guides, springs, rebore, new ends everything,! the problem that i have is that when the engine is turned over there is a slight SCREECHING NOISE from the rocker box area having removed the rocker box the engine turns over very nice i realise that the valves are not  working . when fitting the rocker box the manuals states that nothing to be forced which i carried out just wondered if you may have any thoughts ?????
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Offline wardleybob

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Re: Screeching noise ??????
« Reply #1 on: 24.09. 2013 16:39 »
Hy have you checked the valve springs .I think yours are coil bound . I had this problem with pattern parts.'
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Offline Topdad

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Re: Screeching noise ??????
« Reply #2 on: 24.09. 2013 16:49 »
also take the tappet covers off anf have alook at what is going on when you kick her over with plugs removed could show what Bob suggested or maybe something else best of luck BobH
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Offline A10Boy

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Re: Screeching noise ??????
« Reply #3 on: 24.09. 2013 19:23 »
Do you have a later type alloy head? The later one used wider valve springs and caps and needs a different rockerbox. In fact it's the same box and BSA used to relieve the area around the exhaust springs by hand. Wondered if they could be binding?

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Offline muskrat

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Re: Screeching noise ??????
« Reply #4 on: 24.09. 2013 21:15 »
My 1st thought is the push rods aren't located properly in the rocker cups or followers. Are there any marks on the pushrods?
Cheers
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beezermacc

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Re: Screeching noise ??????
« Reply #5 on: 24.09. 2013 21:52 »
Could this just be lack of oil on either the rocker shafts or the spacer washers and springs between the rockers and the rocker box casting. If you haven't run the engine yet it may just be insufficient lube. However, I would  examine the rockers with the rocker box off to see if they are free on the shafts. When tightening the rocker shafts with the dome nut you need to make sure the rocker spindle springs and washers are not interfering and binding with the grooves and ends of the rocker shafts. My money is on a stiff rocker caused by binding on the spindle springs and shaft.
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Offline Gerry

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Re: Screeching noise ??????
« Reply #6 on: 25.09. 2013 11:24 »
Hi Michael, I recon' Muskrats right on the money.....as usual, I had a hell of a job aligning the pushrods into the rockers and into the followers. Took me four or five attempts even with my home made pushrod tool. If the pushrods are correctly fitted and the valves are not moving then either the rockers are too tight and the valves are all in the open position or you have a set of bent pushrods. Hopefully the first option is the right one. Kick it over slowly with the plugs in and see if there's any compression as that will tell you if the valves are open plus you will have a huge tappet clearance where the valves are supposed to be shut and a good chance that one or more pushrods could have become dislodged from its seat at the followers or the rockers. Good luck. Gerry
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Online RichardL

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Re: Screeching noise ??????
« Reply #7 on: 25.09. 2013 21:39 »
Those having more skill than I have can probably do without them, but a small-diameter telescoping mirror and a flashlight (torch?) is my approach to assuring I have the pushrods in place at both ends (...uh, within the engine).

Richard L.   
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Offline duTch

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Re: Screeching noise ??????
« Reply #8 on: 26.09. 2013 00:00 »

 Michael, you may need to clarify-
Quote
having removed the rocker box the engine turns over very nice i realise that the valves are not  working .

 This is normal, as (for obvious reasons,) there's no gear to do it, I suspect you mean you removed the 'Rocker (inspection) Covers' ?

 All the above ideas are good,as A10boy suggests, maybe see if you can fit something, like a piece of thin wire between the top of valve springs and the box, if the rockerbox is already off, look for scuff marks where top ov valves would be...??
  Also I expect you checked the pushrods in the lifters for up and down (located correctly), without the R-Box on??
 Good luck, duTch
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Offline wilko

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Re: Screeching noise ??????
« Reply #9 on: 26.09. 2013 02:25 »
Can't imagine any type of SCREECHING noise at kick over speeds. Try using another description please??? Clunking? Moaning? Laughing? Mocking???
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Online orabanda

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Re: Screeching noise ??????
« Reply #10 on: 26.09. 2013 03:26 »
Pillion passenger?
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Offline muskrat

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Re: Screeching noise ??????
« Reply #11 on: 26.09. 2013 11:20 »
It might be the sound of a push rod scraping on the head gasket protruding into the push rod tunnel. That's why I asked if there was any marks on them.
Cheers
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Online RichardL

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Re: Screeching noise ??????
« Reply #12 on: 26.09. 2013 15:13 »
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