Smoking engine & rattles

[melanddoug]

Hi all, I wonder whether you could help by confirming some assumptions for me ..

My mum's dear moggy (1967 saloon, 1098cc, name of Daisy) has quite suddenly gone all smoky and a bit rattly in the engine dept.
The symptoms are :
small amount of smoke (blue) when tickover, or when holding accelerator above tickover (car is stood still)
large puff of blue smoke when accelerator is released to tickover
also large puff of smoke when pulling away (eg after waiting at lights)
seems a bit more rattly than usual- tappets and possibly big ends etc
rough running at high speed (50-60mph etc)
oil pressure light (orange one on speedo) comes on at tickover, goes out with slight revving, when egine is warm
no oil leaks at all (er, but it does have oil in it!)
when I remove the oil filler cap while engine is running, I can't see any smoke coming out of it.
no unusual crank case pressure - the breather tube doesn't puff particularly, and isn't blocked. I can blow through it easily.

Most but not all of these symptoms point to work piston rings and/or valve guides, and bearing shells. It might be that the engine needs a rebuild.

What I was wondering was ..
1) Any thoughts on what could cause this to happen suddenly? I think it's been well maintined, oil level looked after etc (by my dad and a garage). I've wondered whether the smoking and rattling could be because of the oil being too thin for some reason.
2) If it does need a rebuild, I can handle some of that myself but one part I've never done is the Main bearings. Some cars can have these replaced with the engine in situ- is that possible on the moggy? I've read conflicting reports.

I think they've been using 15w40 Carlube oil- the viscosity is about right but I've never heard of carlube before. Is it ok for moggies?

Many thanks again in advance ..

Doug

[bmcecosse]

Far better to use 20W50 oil - that make is fine, but so is cheaper ASDA/Morrisons/Wilko oil. Does sound like the engine has been run short of oil - or perhaps has overheated. You can try rings and shells - and yes engine out to do the mains, but I believe it really needs a rebore and crankshaft regrind - with new timing gears and chain, and of course a new oil pump. Worth checking is the oil is being properly filtered - is the plate (and spring) present under the paper filter cartridge? But - perhaps if you just want to 'keep it going' for a bit longer, then a change to 20W50 and a new filter cartridge(and check that spring/plate) - and making sure the rocker cover breather is clear and connected into the carb side inlet - will get it by for a while yet.

[melanddoug]

Good to hear Wilko oil is ok at £7 a gallon

I hadn't thought of overheating. The lack of a temp gauge means this could happen without anyone knowing I guess. Interesting thought about the oil filter too.

If all that lot needs replacing, I wonder whether it would be better to just buy a new engine (ouch).. Unfortunately I don't live to near my mum so she'll probably be using a garage for any repairs.

Thanks again for your excellent help !

[bmcecosse]

It's encouraging that you say there is no smoke from the breather - is this really the case with a hot engine if you take the oil filler cap off and rev up? You mention valve guides - and although these can contribute to exhaust smoke if badly worn, they are rarely the only problem.