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Engine knock...do I bodge it or rebuild?


Ian65

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Coming home from work yesterday I laboured the engine slightly on my 1500 Spit on heard a slight bottom end knock from the engine. ( I only heard it once)
The car runs fine, nice and cool and the oil light doesn't flicker so it seemed o.k.
I changed the oil today and then started it up and it sounded fine. I then got in the pit underneath it to check for any drips and when my head was near the sump, I could hear a knocking sound inside the bottom of the engine. ( sounds like ball bearings rattling around inside the sump.)
I reckon it's probably the big ends rather than the mains but I'm unsure of the best course of action.
I have another 1500 spitfire engine in the garage which I intended to rebuild at some point and mildly tune it.

Do I?
1. Run my existing engine as it is until it stops and in the meantime, rebuild my spare engine ready to drop in.
                                                            or

2. Drop the sump and change the big end shells. Hopefully this would then get me through this summer and I can swap the engine in the winter months when I use the car less.

Obviously, with the nice weather I want to use the car as much as possible but  I don't want to get standed on a weekend away in the Cotswolds. I don't want to end up in the position where my spare engine is half built and the one in the car packs in.


Is it possible to gauge how many miles more I'm likely to get on the engine as it is or will it just let go.


What do you think I should do?

cheers,
Ian

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The choice is yours mate, depending on what kind of inconvenience you can handle! If its not (yet) giving a good rattle on start-up then you're PROBABLY good for a few miles yet, and you'll also PROBABLY find both main and big-end failures are quite progressive and that you'll get 500 miles real warning unless you boot the pants off it.
If it were me I'd be doing number 1 already, 'cos I'm an ex-boy scout and I like to be prepared.
Other opinions may well be along in a minute - quite possibly differing from mine.
Since I live in the Cotswolds I can defend it as a good place to be stranded. :)

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Thanks for that, I've been thinking about it this afternoon and you're right, it would make sense to do the mains at the same time.
I just don't fancy pulling the engine and the top mains are a bit awkward from underneath.
It rattles like a bitch on startup until the pressure builds up but every spit I've ever owned has done that.
I suppose I'll just have to bite the bullet and do them all.

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Swap the bearings. Will save grief in the long run, buy you plenty of time (or panic you into getting the other engine in PDQ). Should be OK for ages, give you a chance to clean the sump etc etc and fairly easy. I have found losening all the mains helps when changing them, takes the presuure off the upper bearing so it will slip round easier.

Clive

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just the caps should do it, just relieves the pressure a touch. usually need a bit of a tap to get them moving amd a bit of plastic to push them round. Well it works for me, others may have other cleverer ideas. Don't undo them too much or it could damage the seal lip?

Clive

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Sorry this doesn't sound like big end bearings. It sounds more like a case of pinking when you laboured the engine. When big end bearings start to go you get a rattle when the throttle is lifted. There is no noise on accelaration or when you have totally lifted off the throttle. That is what mine started off sounding like and I got them changed (well I actually got a trick engine instead)

Please just make sure it is the bearings as pinking when labouring the engine is normal nd perfectly accpetable.

Neil

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It was definitely a bottom end knock I heard when driving although when the cars just ticking over, it sounds fine.
Last time I had crank bearings go on a spit, it had really low oil pressure on tickover, the oil light came on and it rattled as the revs dropped.
This car doesn't have those symptoms but when I started it and got underneath in in the pit, there's something making a hell of a noise in the sump.
I think that I've caught it just in time and I'll drop the sump during the week and have a look.

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Fair enough Ian. The two sounds can easily be confused. It was when you described it when you made the engine labour. Dropping the sump can't do any harm and changing the big ends as a matter of course.

Sorry to go off tack! Adjusting the timing slightly (or not) just sounded much more appealing!

Neil

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