Diesel engine bore glazing

[Heckler]

That sounds a bit like an engine with rubber conrods. I've got a 4 cylinder engine in the garage with 2 conrods and 4 pistons which is a similar concept I suppose, as those 2 central pistons travel a much smaller distance than the maximum travel! :ambivalence:

Richard

Wasnt it the Puch 250 two stroke engine that had two pistons, one to compress the charge and the other to do the biz?
Stu

 

[Topcat47]

Yes the Puch was a "split single". I also had a German bike with a similar set up. The distance moved by the piston(s) is a function of the crankshaft throw and a constant for a given engine. this means that the two pistons would travel the same distance as a larger piston of the same cross sectional area as the two (in order to give the same capacity). Deltic engines had pistons that travelled towards each other in a common bore. This reduced the distance travelled by each piston. The delta formation of the cylinder banks meant that there were three crankshafts with two pistons per crank ( and hence two piston rods) thus for a given swept volume the each pistons had a shorter travel. This also enabled higher crankshaft RPM.

 

[GrahamM376]

I think that your thoughts on low revs and low oil pressure cause glazing are wide of the mark.
Stu

When my T80 engine, previous history unknown, (boat new to me) decided to blow all the oil out, rings had stuck in one piston and all bores needed honing.

Comments from Diamond Diesels (Mitsubishi industrial engine importers) was "must have been charging batteries or motor sailing at low revs a lot, needs to be run under decent load and at maximum revs periodically to clear it out otherwise unburned fuel will gum it up" Also warned NOT to use synthetic oil.

 

[sgr143]

This is going interestingly off topic. Can I throw in the Stirling cycle engine as another hare? I find I understand how they work when someone explains it very carefully, but 2 minutes later I've lost it again. And that was even before old git memory issues started kicking in.

As an aside, I once knew someone who lived on one of the few steam powered narrowboats. It was called "Grace Under Pressure" : a nice touch, especially if you know your Hemingway.

[replaces accidentally deleted post. ]

 

[macd]

Yes the Puch was a "split single". I also had a German bike with a similar set up....

The delta formation of the cylinder banks meant that there were three crankshafts with two pistons per crank ( and hence two piston rods) thus for a given swept volume the each pistons had a shorter travel. This also enabled higher crankshaft RPM.

Possibly a DKW Ladepumpe.
There's a sectioned delta engine in the York railway museum. Fascinating thing: worth a visit on its own.

 

[ghostlymoron]

Do I sense some backpedaling here? I've always understood that simple mineral oil was the stuff to use on old marine diesels. Has that advise changed or is synthetic oil recommended only for modern boat diesels like the Beta marine 14/16 (which is based on a Kubota)

Not sure that is correct. I have a lot of experience of synthetic industrial lubricants as opposed to engine ones. These have no additives at all, just the straight product. We would use synthetics for problem machines where mineral ones had problems. Best one was a big compressor whose bearings ran very hot. Oil was changed and the temperature went down. When the machine was finally opened and checked it was found that the maker had misread radius for diameter and the clearance was half what it should be.

 

[vyv_cox]

Do I sense some backpedaling here? I've always understood that simple mineral oil was the stuff to use on old marine diesels. Has that advise changed or is synthetic oil recommended only for modern boat diesels like the Beta marine 14/16 (which is based on a Kubota)

No change in the advice for engines. I was only responding to a specific point about lubricity. Older engine advice remains the same, not only for marine but every automotive owner's forum you can find.

 

[Scomber]

While you're all gathered! What's the consensus on the correct engine oil for an 8 yr old Beta 25??

 

[RichardS]

While you're all gathered! What's the consensus on the correct engine oil for an 8 yr old Beta 25??

Consensus? Haha

Look in the manual and see what the recommended viscosity range is (probably 15W-40) then buy the cheapest oil you can find with that viscosity if you intend to change it every year.

If you intend to change it based on hours usage, which could be every 3 years or whatever, then you might wish to use a semi-synthetic. This is a minority group but has a few adherents, including me.

The smallest number of adherents belongs to the fully synthetic group. Your manual will need to specify a low viscosity oil if you aim to meet its viscosity recommendation. Otherwise you will have to use an oil with a lower viscosity range than recommended (even down to 0W-5 I believe) but this is really bleeding-edge stuff.

Richard

 

[GrahamM376]

No change in the advice for engines. I was only responding to a specific point about lubricity. Older engine advice remains the same, not only for marine but every automotive owner's forum you can find.

Older engine advice may also apply to many new boat engines, most of which are based on low tech industrial plant engines. Always follow the manufacturer's advice, particularly during warranty period.

 

[rotrax]

Yes the Puch was a "split single". I also had a German bike with a similar set up. The distance moved by the piston(s) is a function of the crankshaft throw and a constant for a given engine. this means that the two pistons would travel the same distance as a larger piston of the same cross sectional area as the two (in order to give the same capacity). Deltic engines had pistons that travelled towards each other in a common bore. This reduced the distance travelled by each piston. The delta formation of the cylinder banks meant that there were three crankshafts with two pistons per crank ( and hence two piston rods) thus for a given swept volume the each pistons had a shorter travel. This also enabled higher crankshaft RPM.

I know of a Puch 4 cylinder motorbike in Czech.
The guy who owns it inherited it from his uncle who was in forced labour in Southern Germany at the end of WW2.
The uncle escaped during the last days of the Reich, found the bike stored in a shed-fully protected against the harsh winters-at an abandoned house.
He knew what he was about and got it going. He stole fuel and oil from the labour camp he had left, subsequently from the Russian Army.
He made it into Austria, Slovakia and finally to his home city of Ostrava after many adventures and narrow escapes.
After his death, and the death of Walter who inherited it, it passed to Walter jr. who still has it.
I have ridden it-its quite powerfull, plenty of torque-and feels like a proper motorbike.
It is basically two Puch split singles side by side.
The Slovak factory Manet made 100cc split single two strokes for use in lightweight motorbikes and scooters-good old Pride and Clark were the UK concessionaires.
Who remembers them in Stockwell Road, Brixton-with a neighbour I bough my first boat from them, an unpainted 16 foot plywood open dinghy with hardwood trim.
£4.00 down and £1.00 a month for 12 months................................
IIRC the paint and varnish cost more than the dinghy!

 

[vyv_cox]

Older engine advice may also apply to many new boat engines, most of which are based on low tech industrial plant engines. Always follow the manufacturer's advice, particularly during warranty period.

Yanmar have upgraded lubricant advice with the advent of the 'Y' series but still not to synthetic.

 

[GrahamM376]

What we need is a diesel equivalent of Duckhams 20/50, the 1960s cure for smokey petrol engines

 

[Heckler]

What we need is a diesel equivalent of Duckhams 20/50, the 1960s cure for smokey petrol engines

Who will forget it! Bright green!
Stu

 

[rotrax]

What we need is a diesel equivalent of Duckhams 20/50, the 1960s cure for smokey petrol engines

Try Morris Golden Film 20/50, suitable for petrol and non turbo diesel engines.

It is what I used in the Yanmar with over 4000 hours on it in our previous boat.

No smoke, never topped up between changes, started easily even when below freezing outside. With the Quicksilver 5/30 which came with the boat and was in the engine when we bought her-and WAS the wrong oil-it emptied the sump in 7 hours.

Low tech, low tempreture and relativly low powered marine engines can happily use low tech oils in some circumstances.

Our new boat with a 4 cylinder 16 valve Yanmar 110HP Turbodiesel is on GTX-so far so good.
It was smoky when we got it, but an oil and filter change plus giving it a good bollocking cleared it. I put about half a litre in in Cherbourg after 130 engine hours, no smoke while running and especially just after starting now.

Fingers crossed.............................

 

[Sandro]

A question:
Does glazing occur also in Otto (petrol), 4 or 2 stroke engines?
If not, why?, If yes, why it is never heard of?

Sandro

 

[rotrax]

Bore glazing was a serious problem for high performance motorbikes in the '70's and '80's.

Some customers were finding it a challenge to ride them fast enough to load the engines-a quick strip and bore hone usually fixed it.

None of my customers for such machines suffered.

I gave them a right good seeing to on road test after their first service..................................................

 

[gordmac]

It's generally said that running the engine for long periods not under load gives rise to the bores getting glazed. Now I'm quite happy to accept that as a matter of experience, but I am still a bit puzzled as to just why this happens. (I'm an academic metallurgist, so I worry about this kind of thing for a living...).

No load means somewhat lower gas pressures in the cylinders, but I can't see what difference that makes. I can't see that it would make any difference to the pressure the rings exert on the bores. The engine would run cooler for a while, but it shouldn't take that long, loaded or otherwise, to get up to the temperature set by the coolant thermostat; after which, no difference?

So I'm a bit stuck for an explanation. Any ideas?

Steve

The pressure rings excert on the bores is due to the combustion pressure acting on the inside of the rings. Used to bed new rings in (on petrol cars) by applying load at highish revs to push the rings against the bores then over run to draw oil up the bores.

 

[NickRobinson]

........ Pride and Clark were the UK concessionaires.
Who remembers them in Stockwell Road, Brixton-with a neighbour I bough my first boat from them, an unpainted 16 foot plywood open dinghy with hardwood trim.
£4.00 down and £1.00 a month for 12 months................................
IIRC the paint and varnish cost more than the dinghy!

Fred drift, but yes, remember the full page ad on the back of Exchange and Mart? My first boat from them too, a 8.5' GRP rowing boat-

 

[sailorman]

Possibly a DKW Ladepumpe.
There's a sectioned delta engine in the York railway museum. Fascinating thing: worth a visit on its own.

Isnt it a Deltic