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metalic clonking only at low revs (and now imps)

Posted: 08 Apr 2014, 20:40
by itchyfeet
Well last night i thought the engine was doing this, it only appears at low revs sub 700 rpm, a horrible metalic knocking that could be felt as you touched the engine :cry:
i listened with my plastic tube and could not pin point where it was coming from , came to the conclusion it was something seroius with the engine.

i had changed the alternator for a newish second hand bosch a few months ago ( mine is non std lucas) so i thought i best swap it back to rule it out,
thankfully noise has now gone :D but appart from some play in the alternator bearings there is no signs of the noise when spun by hand and using an electric drill, im surprised it could make such a loud noise was quiet at revs.

fingers crossed

Re: metalic clonking only at low revs

Posted: 09 Apr 2014, 08:01
by ghost123uk
Phew, worrying moments there then !

I had a Hillman Imp once, with a highly tuned engine. I was cane'ing it up a muddy hill once when there was a big bang followed by a horrendous clattering. Oh pooh I thought, there goes my Skip Brown engine :( But it was similar to you. In my case, the alternator had over-revved and self destructed inside :shock: Soon replaced and a bigger pulley fitted :)

Re: metalic clonking only at low revs

Posted: 10 Apr 2014, 16:51
by Ian and Lins
Sort of same thing happened to me. I was belting it down to Taunton on a Triumph T150v, well over the 'ton' when there was a hell of a bang. Quickly pulled up and looked underneath...guess what? It was just a bloody big hole in the crankcase with half the middle con rod sticking out. Oh the relief!

Re: metalic clonking only at low revs

Posted: 10 Apr 2014, 17:16
by Wychall
Ian and Lins wrote:Sort of same thing happened to me. I was belting it down to Taunton on a Triumph T150v, well over the 'ton' when there was a hell of a bang. Quickly pulled up and looked underneath...guess what? It was just a bloody big hole in the crankcase with half the middle con rod sticking out. Oh the relief!

I bet it WAS a relief to be stood on the hard shoulder looking at that, rather than inspecting the interior fittings of an ambulance :rofl

Re: metalic clonking only at low revs

Posted: 10 Apr 2014, 19:37
by itchyfeet
Ian and Lins wrote:Sort of same thing happened to me. I was belting it down to Taunton on a Triumph T150v, well over the 'ton' when there was a hell of a bang. Quickly pulled up and looked underneath...guess what? It was just a bloody big hole in the crankcase with half the middle con rod sticking out. Oh the relief!


Thanks off camping tomorrow :roll:

Re: metalic clonking only at low revs

Posted: 14 Apr 2014, 19:42
by itchyfeet
So 150 mile round trip and all us well, looks like it was the alternator after all

Re: metalic clonking only at low revs

Posted: 15 Apr 2014, 20:55
by Smosh
I had a mk3 festa that was knocking. probably big ends, but, it took a hell of a ragging before I could get it to blow. Particularly on an island wth a 35mph speed limit! i drove around at in second gear accelerating hard and braking hard. I eventually gave up, was driving home and went to over take cyclist. I think I almost scared there speedos off when it went bang! :lol:

Re: metalic clonking only at low revs

Posted: 16 Apr 2014, 06:03
by ghost123uk
OK, as this thread is now a blog (glad yours is ok by the way itchy)...

I have 3 blown motor tales :roll:

Company Viva = blown motor in a big way (3 bearing crank :roll: ) ring the dealer to book in for a new engine. They say "bring it down and we will look at it to see if it needs a new motor". I say "it does". They say, "we need to inspect it first, to be sure" I say "It has a big hole in the side with a con rod sticking out". They say "we still need it in for a preliminary inspection first" :roll: etc etc :?

Traffic lights, I am on my BSA Gold Star. A cop pulls alongside on his Norton Commando. He was obviously in the mood to show off. As the lights went green he tore away at great speed, he ragged it so hard that 50 yards from the lights he must have been doing 50+ still in first gear :roll: There was a mighty bang and a lot of smoke and oil :lol: I cruised past thinking "plonker".

Similar incident when an Alfa Sud (worst car Alfa ever made) tried to out drag my Skip Brown tuned Hillman Imp Sport. He was actually managing to pull away slightly, when his motor blew up in a big way. I won I reckon ;)

Re: metalic clonking only at low revs

Posted: 15 May 2014, 20:20
by Jakemate
ghost123uk wrote:Phew, worrying moments there then !

I had a Hillman Imp once, with a highly tuned engine. I was cane'ing it up a muddy hill once when there was a big bang followed by a horrendous clattering. Oh pooh I thought, there goes my Skip Brown engine :( But it was similar to you. In my case, the alternator had over-revved and self destructed inside :shock: Soon replaced and a bigger pulley fitted :)

We could talk all night about imps :)
I had a 998cc ;)

Re: metalic clonking only at low revs

Posted: 15 May 2014, 20:50
by Smosh
I've always wanted an imp or the stilleto... I always liked the fast back design!

Re: metalic clonking only at low revs

Posted: 15 May 2014, 23:05
by Jakemate
I had a 1969 imp, 998cc, r20 cam, big valve head with wills rings, twin 40 webers, janspeed exhaust and manifolds, forged pistons, rad converted to front, twin deep grooved pulleys for fan belts as they flew off at 9000rpm !

Negative camber kits, space adjustables all round, lowered, full roll cage, foam filled race bag fuel tank up front, I could go on and on.

Put out 103bhp on rolling road and blew off xr3i's in the day of my boy racer years but I've grown up now hence the camper.

I bloody loved my imp :(

Re: metalic clonking only at low revs (and now imps)

Posted: 18 May 2014, 18:18
by itchyfeet
Just got my alternator back from repair £50 and its got a new brush/regulator but its 14.5v
anybody think thats too high or is that right for a 90A?

metalic clonking only at low revs (and now imps)

Posted: 18 May 2014, 22:58
by Jakemate
Nope that voltage is ok. It will also drop a little when using lights etc.

Plus it also depends how accurate your meter is ;)

Re: metalic clonking only at low revs (and now imps)

Posted: 19 May 2014, 01:57
by Oldiebut goodie
I have a 14.5v one on my alternator and it gives 14.2v running. It replaced a 14v one that gave 13.7v so they both seem to drop 0.3v.

Re: metalic clonking only at low revs (and now imps)

Posted: 19 May 2014, 05:08
by itchyfeet
Thanks :ok