engine rattle under load

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Dru
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engine rattle under load

Postby Dru » Sun Dec 15, 2013 2:29 pm

Just started- I'd been up a short but very steep Bristol hill, in 2nd and then 1st gear, and quite high revs- then the rattle appeared, when the engine was under load. A sort of tonking rather than pinking, to my ear. Foot off accelerator, it stops. Foot on again, there it is. Checked under the bonnet when home; the carb damper cap was unscrewed, which may be unrelated; checked the rocker clearances; they were all reasonably in spec. Just been hunting through the forum, to see what others' experiences have been.... Does this sound like the big end? Or what indeed? *worry worry*

bmcecosse
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Re: engine rattle under load

Postby bmcecosse » Sun Dec 15, 2013 2:33 pm

Oil level? Oil pressure??
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Dru
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Re: engine rattle under load

Postby Dru » Sun Dec 15, 2013 2:34 pm

oil level is good, and the oil pressure light goes out when the engine starts. No pressure gauge fitted

bmcecosse
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Re: engine rattle under load

Postby bmcecosse » Sun Dec 15, 2013 2:35 pm

I do suggest an oil pressure gauge..urgently!
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Dru
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Re: engine rattle under load

Postby Dru » Sun Dec 15, 2013 2:42 pm

Good idea. The MOT's 6 weeks away; so I am concerned that the car may not get through it (bodywork's a bit ropey) -so this noise is just an extra worry right now. Shall add a gauge if I can get it sorted :(

lambrettalad
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Re: engine rattle under load

Postby lambrettalad » Sun Dec 15, 2013 2:49 pm

I wonder if numbers one and /or two,main or or big ends were starved of oil?

If you back of the gas on the flat,does it go away ,them come back on acceleration? Is it a deep knock rather than a rattle? or deep rumble?
Cheers Alex
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Dru
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Re: engine rattle under load

Postby Dru » Sun Dec 15, 2013 2:56 pm

it's a sort of tok tok tok tok, and it is there under load. Quiet on idle, or at steady speed on the flat. Sorry, it's hard to describe noises accurately!

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Re: engine rattle under load

Postby bmcecosse » Sun Dec 15, 2013 3:11 pm

May be simple exhaust manifold gasket blow - or head gasket blow......
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Dru
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Re: engine rattle under load

Postby Dru » Sun Dec 15, 2013 3:14 pm

that's something to start on then. Thank you.

lambrettalad
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Re: engine rattle under load

Postby lambrettalad » Sun Dec 15, 2013 5:33 pm

is the steep hill a clue or a red herring ?
Cheers Alex
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MorrisMinor-65-1000
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Re: engine rattle under load

Postby MorrisMinor-65-1000 » Sun Dec 15, 2013 8:15 pm

As LambrettaLad says, the hill element could be a red herring!

Don't rule out the basics - it could be something as simple as a dynamo bearing on its way out - or a loose mount. These would be more inclined to let out a tok tok tokking when under load through the belt during acceleration. It all depends on how audible it is.

If you can make the noise appear when revving the engine, it is more likely to be something ancillary that is loose. If so, pop the bonnet and gradually open the throttle whilst listening to where the noise is coming from. If you can't replicate it when revving in neutral, I'd be more inclined to believe it was something oil pressure related, or a blowing exhaust.
Cheers,
Michael

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Dru
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Re: engine rattle under load

Postby Dru » Mon Dec 16, 2013 7:34 am

good points all, thank you. I'm going to do some more tests when the weather allows (have to work in the road, and it's blowing a hooley and occasionally pouring down - don't you just hate it when that happens? :-) )

...hmm, just run it up again (wanted to get the nearside wheels up on the kerb to make itr easier to get underneath). Engine sounds OK in neutral and when not in motion. I remember the last time there was a Mysterious Noise (with juddering, that time) it was the forward UJ . Though this does sound different. Must have a good look around.

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Re: engine rattle under load

Postby simmitc » Mon Dec 16, 2013 9:54 am

Is there any reduction in power/performance? If yes, then check the compression on all four cylinders - it could be a blown head gasket. Although the noise is quite distinctive once one has heard it. I have know a great many different descriptions of the same sound, and this could just fit.

Dru
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Re: engine rattle under load

Postby Dru » Tue Dec 17, 2013 12:22 pm

Right, the head's off and I'm relieved to find a very obvious failure in the head gasket. Relieved because it's always good to know what the problem is, at least. On the other hand, now I'm hoping that the damage to the head and block is not such that they are rendered unserviceable....

blowing between 1 and 2

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damage to head

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damage to block

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bmcecosse
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Re: engine rattle under load

Postby bmcecosse » Tue Dec 17, 2013 4:54 pm

Ohhhh - is that just a dirty mark - or can you feel it with your finger/nail?
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Dru
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Re: engine rattle under load

Postby Dru » Tue Dec 17, 2013 5:27 pm

I *thought* it was a groove, but after running a brass wire brush on it, it's disappeared. Major relief :-)

bmcecosse
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Re: engine rattle under load

Postby bmcecosse » Tue Dec 17, 2013 7:51 pm

Excellent! New gasket - wipe of grease both sides - surfaces spotless and clamp it gown to 44 ft lf. Set the valve gaps - warm it up, let it cool (but not to cold) and retorque - then reset the valve gaps.....12 thou inlets and 15 thou exhausts........and stay away from that bl**dy hill ! :lol:
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