2&3 too lean (?)

Post by **bigginger** » Sun Mar 26, 2006 9:58 pm

A question for all you clever engine types - the answer doesn't matter much as I'm replacing the carb, manifold, head and piston, but cylinders 2 and 3 appear to have been running lean (?) - plugs white and dry, and 1 and 4 rich (?) - plugs black and wet. Number 3 piston has bunt out/melted too. 1098 Austin engine with signs that the oil changing hasn't been a high priority, BTW. Anybody know why it might be - and care to correct me over the rich/lean thing?

Post by **Cam** » Sun Mar 26, 2006 10:07 pm

Don't suppose you checked the compression on the cylinders? If there is an imbalance as you describe then it's usually a leak somewhere. Being as it's the centre two cylinders I'd be looking towards the head gasket and probably a leak from one cylinder to the next (2 to 3 and 3 to 2).

Post by **bigginger** » Sun Mar 26, 2006 10:11 pm

I didn't - imagine I wouldn't have had much luck with bits missing from no 3 anyway

It's only apart to replace the head with an unleaded one, and I discovered all the above today while de-carbonising... 2 days before the MOT and 5 before the L2B

Post by **Cam** » Sun Mar 26, 2006 10:20 pm

Eeep!

Is piston No. 3 knackered? or will it go again?

Well, if it's any consolation, I finished transferring the gearbox over from my traveller to Gracie today ready for the L2B! I now have 4 forward gears + reverse, and none of them jump out. I have not gone over 40MPH in her yet but I'll give her a test in the next day or so at high speed (65-70).

Post by **bigginger** » Sun Mar 26, 2006 10:27 pm

I was getting on with taking the crank and pistons out of another Austin low compression unit this afternoon when I spotted the bit that says you can replace con rod/ piston with the engine IN the car, so that's what I'll do. I know I shouldn't really use a second hand one - but the engine needs a proper rebuild soon anyway, and it might get me the MOT

Post by **Packedup** » Sun Mar 26, 2006 10:32 pm

You do know it's a visual smoke test only on this age of car don't you?

It has to really be rather sick to fail the MOT!

Post by **Cam** » Sun Mar 26, 2006 10:33 pm

Hmmm... never done that. I mean put 2nd hand bits in. What about the bearing shells and the piston rings? If I HAD to use 2nd hand bits then I'd probably use the shells from the original con-rod as they might well have 'worn' to the crank. Probably doesn't matter though. Are you going to check the ring gaps? or just slap 'im in and away we go!

Post by **bigginger** » Sun Mar 26, 2006 10:42 pm

Packedup wrote:You do know it's a visual smoke test only on this age of car don't you?

It has to really be rather sick to fail the MOT!

It was, believe me - if I thought it could have scraped it, I wouldn't be bothering

Cam, I don't think I'll do the ring gaps - the plan is only to get to the L2B and back really - good call over the shells, it shall be done. No sign whtsoever of the head gasket having blown, BTW, though it does look like a modern replacement rather than an original. Given the amount of carbon in there (presumably burnt oil from the 'piston broke' syndrome, it could have happened years ago and just been given a new gasket and kept in use

Post by **Cam** » Sun Mar 26, 2006 10:45 pm

Good stuff. Looks like a day with oil dripping in your face then.

Keep us updated. I'm sure it'll be fine.

Incidently, how many miles is it for you to do the L2B? and are you starting in London or going straight to Brighton?

Post by **bigginger** » Sun Mar 26, 2006 10:49 pm

Gonna go up to London the night before. Note to self - FIND SOMEWHERE TO STAY - and maybe on the Coast too.

Post by **Packedup** » Sun Mar 26, 2006 10:56 pm

So no chance some stop smoke would've cured it then?

Post by **bigginger** » Sun Mar 26, 2006 11:02 pm

Tried that

Post by **grahamt7** » Sun Mar 26, 2006 11:06 pm

Seen it mentioned before....so how exctly does this "stop smoke" work, and who sells it?

Post by **Cam** » Sun Mar 26, 2006 11:06 pm

Cool. Hopefully see you in London then! I'll be starting off at 5am from Stoke.

Post by **bigginger** » Sun Mar 26, 2006 11:24 pm

5am? Madman... Stop Smoke is a golden syrup like substance that you add to the oil - I presume it thickens it up and is meant to make it harder for it to get through ring gaps and valve guides. Not enough to stop it gatting through big holes in the edge of the pistons though

Post by **Packedup** » Sun Mar 26, 2006 11:43 pm

Is that stuff that comes in a toothpaste type tube still available?

Called Piston Seal or something like that - I think it was meant to sort of stick to something somewhere to bodge up a really sick engine.

I've had some limited success with stop smoke type additives, though not to stop smoke so much, more to stop death rattle bottom end knocks. Part of the joy of Triumphalism over Minoring I suppose.

Post by **bigginger** » Sun Mar 26, 2006 11:58 pm

Should've said that Halfrauds sell it, BTW. I've not seen the toothpaste, just the Golden Syrup - but NOTHING would have cured this. I'll show you the piston...

Post by **Packedup** » Mon Mar 27, 2006 12:12 am

I never quite figured out how that piston seal stuff would work anyway, although I do have a very vague recollection of sticking some in a Mini out of boredom many years ago.

As it's a 1098 (if I'm reading correctly), surely you've got another lump you could've dropped in? That's my way of fixing anything but the simplest engine probs normally

Surely taking the rockers off the offending cylinders valves and dropping the piston would've cured it, if left you a smidge down on power...? ;)

Post by **bigginger** » Mon Mar 27, 2006 12:36 am

It is a 1098, and I do have spares - one with a sheared cylinder head stud, which I can't shift, so it's contributing a piston, and two which are rather dead and siezed

Oh, and a Maestro engine. Did you mean just ditching piston 3 altogether? Interesting... I also have 2 1275s, but I'm astonishingly reluctant to go through an engine swap yet again, and I have 4 more P-Ups, 2 of which I'd earmarked them for - I've had all of them in there at one time or another already, and I'm just not confident of getting it done in time. Plus I wanted to go back to 1098 (was 1275) and take the chance to switch to unleaded, even if it does mean an Austin engine in a Morris P-U. It's probably not forever - I think I'll rebuild the Morris one and drop the head onto that, but that'll have to wait. I just NEED one back on the road...

Post by **Packedup** » Mon Mar 27, 2006 1:30 am

You could propbably get away with a sheared head stud to be honest - I have a few times on different engines

Yeah, if you ditch number three you'll have a bit of a vibraty engine, not a lot of power... But no means of it smoking, which should get it through the test if nothing else!

Surprised with the number of Minors you seem to have you've only got the one spare (and not great) engine. Unfortunately I don't think o'll have chance to see if any of the ones lurking under the piles are worth trying to flog... ;)