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LOUD Vibration at about 3000 rpms

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OK, I got it started (by rolling) just because I couldn't stop thinking about the noise. WOW, it's not just at 3000 anymore. There's a LOUD knocking constantly, although it increases in intensity when the accelerator is depressed. It seems to be coming from the valve cover, but deeper, and much louder and more expensive sounding than the tappets. I've only managed to put about 400 miles on the B since I got her 14 months ago. I don't want to get her running again just in time to put her up for the winter kike I did last year. So, there are two issues:
1)No start with key (even with a jump) but starts with a roll; battery checks out fine; ignition light, interior light go on in first key position and fuel pump clicks away; when key is fully engaged all electrics shut down (lights no longer light); after time - like overnight - the minimal electrical stuff works again, but same result when key is turned.
2) Loud knocking sound from below valve cover area; tappets adjusted by pro about 150 miles ago; oil volume/pressure read OK; car was sitting for a few weeks while radiator expansion tank issue was resolved (driven a few miles with low coolant before leak was discovered, temp stayed in mid-range, no overheating); began the noisy condition only at certain revs (@3000) at first but is now constant.

Any thoughts or help anyone can provide would be appreciated. I'm beginng to think it's time to seek professional help (and I might take the B in too.)
Gary
 
Might as well throw in a couple more lovelies. Usually, if it's a rod bearing, it will momentarily quiet down during acceleration. If it's the cam, it won't run. If it's a broken piston, it will run but knock like crazy, sometimes with a miss. It could also be the timing gear chain adjuster is falling apart. Sorry, but they all make noise! /ubbthreads/images/graemlins/hammer.gifPJ
 
Is this when it is not moveing, yea guess it is if you can pin point where it is comming from.

My list of maybes is much longer than the above but includes them.

I would suggest expert advise of someone who can hands on. Could be too many things to do via msg board without some real experence on the other end. In fact I don't think I would even run it again till I had it figured out.

Sorry.
 
Is the sound coming from in the bowels of the engine or is it coming from around the starter?

Do you have access to a doctor's stethoscope?
 
Well, that puts a new wrinkle in it...
[ QUOTE ]
There's a LOUD knocking constantly, although it increases in intensity when the accelerator is depressed. It seems to be coming from the valve cover, but deeper

[/ QUOTE ]

I suspect that we have a rod letting go.. may be wrong, but...

The good news is that with a modicum of skills, an MGB engine can be rebuilt with some time, effort, and only about $1- 1.5k...Unless the crank is shot, then add about $500. I have rebuilt many.... find a good machine shop to do the boring, milling, and mic'ing...

Good luck... /ubbthreads/images/graemlins/cheers.gif
 
Park it before it comes unglued and gets real expensive.
 
I agree with Jack... until you find out what the problemn truely is... don't turn the key....

There is a big difference ($$$, time, effort) between fixing something planning to break and something that already has...

If you are so inclined, you can drop the pan and take a look. After you have eliminated the easier possibilities that is...
 
If indeed it is a rod or piston giving way and it does so it could break the crank or a cyl wall, or scare it up real bad in any case.

I agree, a teardown is in order.
 
I agree with those of you who suggest not running her letting a professional have a go. I tried to get in touch with the ex-British Leyland mechanic that helped with the installation of my twin SUs (I helped by paying him). My luck... he's actually gone back to England for a year. Can anyone recommend a good shop in southeast Pennsylvania?
 
gawd... Western PA was my "old stomping grounds" so I know who to call there, but not where you are. Conshohocken? Macungie? Red Lion? Philly (Gawd forbid)?
 
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