sudden rattling noise engine and one cylinder with only 50% of the compression pressure

I have at last sussed it, the vehicle is a 1.9DI-D Diesel space star. So it should have around 20bar compression.

But why more in first than top?? Is there more gearbox backlash in top that in first in a FWD box? If there was only differential backlash to contend with the piston will travel *further* in first than in top to take up the slack.

Tim

Is this tongue-in-cheek or are you party to information not given here? ;-) Seems hard to square with the engine description given. "I have a year

1999, 1300cc, 16valve petrol engine, multipoint injection, overhead camshaft,". As I said, I smell troll.

Tim

the only space star with adjustable tappets is the diesel one, and the compressions should be 20 bar.

Hi Mr.Cheerful and Tim,

I think I understand Mr.Cheerful :

on tdc, the piston has virtually no momentum on the gearbox axis, because the moment arm is non-existent. However, because of play ( /backlash? ) in the transmission, in low gear, the piston can't turn very far from tdc expressed in angular movement because with regard to the play in the transmission behind it, it's limited tangent movement before the play is eliminated doesn't allow that much angular movement. And so the moment arm to the flywheel also stays very limited, and the handbrake can handle it easier.

I recall that on my previous leak test, I indeed blocked the flywheel throught the starter opening with a screwdriver.

Again, I have no troll mind, and I'm not sure the above explanation is clear or giving much insight, but it's there for what it's worth.

Any reactions ? thanks again for discussing it.

Edwin

Tim is right, and AFAIK the early 4G13 Mitsubishi 1.3 petrol engine had also adjustable tappets. Don't know about the next 1.3 l engine put into a space star, but that one had a coil for each ignition plug, whilst the early engine ( mine ) had a rotating ignition system with one coil.

At first I didn't really mind the 18 bar compression I had, because it made for high performance and low consumption. I figured if I would never apply much power from the engine, I would enjoy high torque proportionally.

After talking to some other people in my home environment, I fear a piston compression ring, probably the top one, could have broken and cause the rattling noise.

I appreciate any comment, so thanks again

edwin

I think this isn't a stock engine. Edwin's talked of "honing bores" etc, so I think he's had his fingers in it.

Tim

I really don't understand this. And I really haven't talked about honing bores, not on this car. I once put new piston rings on an old car, and honed the cylinders slightly as per advice of a friend who is also engineer.

AFAIK my high gauge has been functioning allright, I tend to believe that there really is 18 bars compression pressure on 3 cylinders.

The engine has never been opened, I never knew what was happening with it.

Please do not continue explaining things in my disadvantage.

edwin

Used to be common enough to simply repair one cylinder - one piston, with rings, leave the rest alone. Cheapskate but effective if you only wanted to run it on a shoestring until it went terminally bang and wasn't worth a lot anyway.

There was a lovely story in Motorcycle News in the late 1960's from a biker who had temporarily given up a middle class job because of stress to become an AA patrol-man with a combination (sorry, motorcycle and sidecar, for those who don't remember them). One time he came upon someone stuck with his family on his way back from holiday with a broken piston on a Ford Pop or similar. So he whipped off the head and the sump at the roadside, released the big end, removed the piston and con rod through the top, and cut up a bit of radiator hose and clamped this round the crankpin with a couple of jubilee clips to block off the oilway. Thus allowing the guy to get home running on three cylinders. He was subsequently berated by his supervisor for excessive diligence, not that I suspect he was too worried about that.

How much has changed in the last half century!

ISTR that the guy who won the first TT race on the Isle of Man fixed a couple of punctures in the course of the race.

I remember the 1950s, and the salutes from the AA m/c patrols, which was supposed to tell you that "your car looks ok". ;-)

I also remember in the 1970s, with the wife and 3 kids on a busy Sunday in the Lake District, trying and failing to even get through to the AA, and having to drive the Viva HC home with four cylinders which were reduced to three when any real power was applied.

It was a spark plug problem, that engine only liked AC plugs, and I had fitted a different brand.

Stories abound about the Winner of a TT using a pair of mole grips to replace a broken gear lever.

Mates dad bought a BSA M21 single shortly after WWII. It was down on power, more so than could be expected on pool petrol. He did a decoke and found it had a wooden piston.

Yep; the oak piston is sometimes decried as an urban myth, but I know of a bloke who did it for real, simply because real pistons were hard to get during the war. Low comp, crap fuel, rivet a bit of ally plate to the top, sorted. Probably turned his own rings from cast iron drainpipe too, he was that sort of bloke.

I can't think of a reason why it wouldn't work - at least for a short time. Engines were gentler on themselves in those days. I used to have a tiger cub, and we used to joke that it only had about five moving parts.

The Tiger Cub was an OHV design, and much more complicated than a two stroke, which was the norm for small bikes at that time.

Oddly, the particular gang I hung around with only really liked British four strokes. We hated two strokes (especially Japanese ones, and most especially, scooters) with that inexplicable passion that young people have about things that seem silly when you get older. We'd say they were noisy and smokey. I loved that Tiger Cub, though. I think it was slightly long stroke, so it wasn't very quick (even by the standards of the day), but it would climb up anything, especially with that very low first gear. I did envy my mates (who generally had C15s) their bit of extra speed, though. One lad (from a well-off family) had a Royal Enfield Crusader, and I think we were all a bit jealous of that. I still have a Triumph Daytona (not one of the newer ones) that has spent more time apart than on the road.

The Tiger Cub, of course, was indroduced rather before the Japanese had made the inroads to the UK market they later did. But scooters were around

- mainly Lambretta and Vespa. Some Vespas were UK made by Douglas. The Tiger Cub was as quick as anything else of its size - and quicker than many. Most others of the same size used the Villiers 197 two stroke.

The Cub was really made as a starter bike. But found favour with many experienced riders who just wanted cheap economical transport, rather than outright performance. A very long time ago. ;-)

Nothing usual about bikers not liking scooters - even then.

I got mine in something like 1975/76, and I thought it was a very old bike. In reality it was only about 10~12 years old, but that seems a bigger age when you're younger. It only cost me £40.

Mid 70's was a rather sad time for people who liked british bikes.

The first Cub came out in 1954. But it was the restriction to bikes under

250cc for learners in 1961 which really boosted sales.