Took Hetty for filming in London yesterday. As we were leaving the city around midnight, just off the M4 we suddenly lost power at a roundabout. I slipped her into a lower gear but the engine died so I rolled her into a layby.


I let it cool for a bit, although it didn't seem overly hot, then checked the dipstick - there was barely anything in there. Just before leaving I'd said "shall I check the oil? - No, it'll be fine there was loads there earlier in the week." School boy error.

So I filled her up from my spare can and let it run down. I turned the engine a few times on the starter handle to make sure it wasn't seized - it turned ok.

Fired her up and she ran ok. For the first minute or two she spluttered a little, but then sat happily around 50 for the hour drive home.

She is smoking like... a smoky thing that went to the university of smoking in Smokesville. It's embarrassing. Thought she was going to give up on Bury Hill, our local mile long 25% slope, but she just about made it - smelling hot.

My questions are:

By letting it run out of oil, will there have been any damage done?

And I guessing it's running out because of the shear amount its burning under load?

Should new piston rings solve this?

It won't have improved it any...

It sounds like it seized on a piston, and if it did there will almost certainly be bore damage and damage to a piston skirt. If it does have damage then new rings are just throwing good money after bad.

It is also possible you did some damage to the bearings on the crank and replacing those isn't a DIY proposition.

Is it knocking?

Shame, Sean and Ken reckoned it was a good looking engine when they had it apart last weekend, hope I haven't ruined it.

It ran ok to work this morning, seemed a bit gutless but we were into a head wind.

Nothing unusual in terms of knocking or rattling, just very smoky under load and at tick over.

It was really smokey last week when i followed it up the hill.

It probably depends on how little oil it had. If the oil level didn't drop below the level of the pickup for the oil pump then I would think there's probably no damage to the bearings, and the partial siezure (or whatever has happened) was probably either coincidental or caused by the oil getting too hot.

Perhaps it would be worth taking the heads off and having a look? You may be lucky and find that all is required is a new set of rings, you may find there is a very small amount of damage to the piston and bore, which you might be able to clean up, or you may find you need replacements with the barrels off you should be able to get a feel for the condition of the bearings, but if it's not knocking, I'd be tempted to think they will be fine.

Thinking about it, a compression test might be a more sensible place to start than just taking it apart, but if it's burning lots of oil, then I suspect you'll end up doing so anyway. Does it seem to be smokier than it was before this happened, or has it been doing it for a while?

All of the above could be bollocks, by the way!

It's got steadily smokier which is annoying, its been getting worse.

I hate fiddling, because partially solving one issue just leads to another.

Unfortunately, what it's costing me in oil is negating the fact it's tax exempt!

Sam, without actually carrying out some tests - or having at look at the bores - it's all speculation. Which is nice, but won't fix it!

It sounds as tho' the engine was showing fair wear to the bores and/or valve stems in any case due to the smoke and the heavy oil consumption you already had? So it's not as though you're 'ruined' a good engine... Clearly, though, having it partially seize up can only have made it worse.

I think the advice above is sound. Since there doesn't appear to be serious knocking going on, you may be ok in the bearings department for some time - that's very lucky. In which case new rings and valve stem seals may well keep you going for a few years yet.

But, it ain't going to fix itself. Bite the bullet - cylinders off...

You're quite right there DA.

I'm loathed to take it apart as Sean was so diligent in geting it not to leek when he put it back together. What I think I'll do, is leave it as is for the moment. I'mm off to Salbris in the D*lly week after next anyway.

When I get back I'll work on the new engine, put that in, then see what's up with the M4. That way I'll also have a running van as opposed to an engineless van.

there was nothing about the top end that gave any concern Pistons looked new-ish bores didnt have any serious wear ridge and had been de glazed by hand as the honing on the barrel wasn't even enough to have been done by machine or even a 3 legged job in a drill

possibly the rings as we never had them off to measure the gap while in the barrels

also the top end showed signs of being used and abused stripped threads etc

there was significant deposits in the combustion chamber which points to huge amounts of oil getting burnt, whether that's from the rings or the valve guides its hard to say.

depending on the splines on the gearbox, I'd be inclined to chuck a M28/1 in there ( will need new exhaust) and keep the M4 for doing up for the future.

That's what I'd do. You can always reverse the conversion down the road, and in the meantime you'll have a van with an engine which is not original, but also not absolutely shite.