jimi
Well-Known Member
I think a lot depends on regularity of use, paradoxically the more its used (assuming regular oil changes) the less servicing it requires IMHO.
glazed bores?
- Thread starter Ardenfour
- Start date
chippie
Well-Known Member
The pressure is probably from blowby past the compression rings. While a total rebuild as suggested by others is ideal, in an old and obsolete engine a re ring job may be a viable way to help extend the useable lifespan if the rings arent too expensive(it is indeed a bit of a gamble). Even though parts are unavailable, an engine reconditioner can probably source a set of new rings that will fit. He may recommend regrooving the piston to accept them.
A cylinder hone and ridge reamer arent that hard to use, why not learn a new skill on an old engine, that's how I learned.(This is Practical Boat Owner after all!)
I would remove all the carbon if you replace the rings, including any carbon on the valves.
I agree with oldharry, sometimes a hone and new rings will see an engine go on for many years, For the price of a set of rings it is worth the gamble in my opinion.
What brand is the engine?
Ring gap is often expressed in terms of so much per inch of bore, I'm sorry I dont have the figure for air cooled diesels. The reconditioner should know.
Valve grinding paste will not wear out your seats, you may be surprised at how much effort it takes to remove those small pits. If the valves leaked, are you sure the clearences were correct? The engine was running so it cant have been too bad.
Good Luck
A cylinder hone and ridge reamer arent that hard to use, why not learn a new skill on an old engine, that's how I learned.(This is Practical Boat Owner after all!)
I would remove all the carbon if you replace the rings, including any carbon on the valves.
I agree with oldharry, sometimes a hone and new rings will see an engine go on for many years, For the price of a set of rings it is worth the gamble in my opinion.
What brand is the engine?
Ring gap is often expressed in terms of so much per inch of bore, I'm sorry I dont have the figure for air cooled diesels. The reconditioner should know.
Valve grinding paste will not wear out your seats, you may be surprised at how much effort it takes to remove those small pits. If the valves leaked, are you sure the clearences were correct? The engine was running so it cant have been too bad.
Good Luck
Ardenfour
Well-Known Member
Engine is a Ducati 9hp. Loads of clearance on the tappets, so I dont think valve clearance was the problem. There was dark staining on the head/block mating surface at the exhaust side, possible evidence of leakage. The engine would start very easily, I just wanted to reduce the smoke problem. Going by the paint on the engine, it hadn't been oppened up in 25yrs.
LittleShip
Well-Known Member
TYCE
[ QUOTE ]
"honing should only be done by pros"
absolute cobblers a piece of fine emery ran up and down the liner at 45 degrees angles is all that need be done.
[/ QUOTE ]
Just where did I say that in my post !!!!!!!!
[ QUOTE ]
"honing should only be done by pros"
absolute cobblers a piece of fine emery ran up and down the liner at 45 degrees angles is all that need be done.
[/ QUOTE ]
Just where did I say that in my post !!!!!!!!
tyce
Well-Known Member
Re: TYCE
it wasnt you that said that, it was ccscot
it wasnt you that said that, it was ccscot
Avocet
Well-Known Member
Re: TYCE
Absolutely agree with Chippe! It's an old engine, you have very little to loose, you'll probably learn lots of useful stuff AND IT'S FUN!
P.S. When you put the new rings on, make sure you stagger the gaps in them so they're not vertically above each other! Also, (sorry if teaching granny to suck eggs) the top ring and the second ring might be subtly different - look for labels on them or tiny engraved writing. Many rings have "top" engraved on them, this surface should face upwards but doesn't necessarily mean it's the "top" ring. Also, some are gorund with a slight taper or a step in the top, outer corner when you look at them from the side.
Good luck!
Absolutely agree with Chippe! It's an old engine, you have very little to loose, you'll probably learn lots of useful stuff AND IT'S FUN!
P.S. When you put the new rings on, make sure you stagger the gaps in them so they're not vertically above each other! Also, (sorry if teaching granny to suck eggs) the top ring and the second ring might be subtly different - look for labels on them or tiny engraved writing. Many rings have "top" engraved on them, this surface should face upwards but doesn't necessarily mean it's the "top" ring. Also, some are gorund with a slight taper or a step in the top, outer corner when you look at them from the side.
Good luck!
Heckler
Well-Known Member
whats wrong with grinding the valves in? thats the normal way of doing things in diesels of this age, of course if we only know about the latest car engines we are showing our ignorance and should perhaps be thinking twice before posting, ccscotts posting is the definitive answer.
Heckler
Well-Known Member
yeah and you used to stand on top of the piston shovelling the carbon off!!
why dont you stop digging? never read such a load of cobblers in all my life, valve grinding is what you do except in the latest car engines. the grey mark all around is what we aim for. in our racing days we used to cut the valve seats and the valves at a slightly differing angle so that when we ground them we got just a fine line all round but that was more to allow a better gas flow that anything to do with "thermal expansion" cobblers.
why dont you stop digging? never read such a load of cobblers in all my life, valve grinding is what you do except in the latest car engines. the grey mark all around is what we aim for. in our racing days we used to cut the valve seats and the valves at a slightly differing angle so that when we ground them we got just a fine line all round but that was more to allow a better gas flow that anything to do with "thermal expansion" cobblers.
tcm
...
Re: bit more help
"loads of clerance on the tappets" isn't necesarily a good thing. They should usually be "just" clear, say er 25thou so when it warms up they don't click.
It wd be an idea to make friends with a local engineery type perhaps to help find new rings as another says. You may need reassmebly help.
If the piston is nice and tight, it doesn't need a rebore so that's ok.
Yep, the carbon should all be removed. Remeber which way the piston went in if not too late - it should have a thrust (fwd) side.
the so-called assembly donkey work is indeed fairly donkeyish but you need various tool like valve clamp and circlip pliers etc. Good fun tho as others say. Favourite mistake is to drop things down the crankcase just as the thing is nearly done...
It is tempting to utterly utterly clean it but not really necessary. You should gloop some oil around everything so it's lubricated properly.
the oil pressure is not necesarily a bad thing, it needs to pump oil around anyway doesn't it and it's only 9hp so you can just lead a breather pipe either er somewhere else out of the boat , or proably better back to the crankcase. I wdn't try too hard to replace/fix the over pressure thingy really.
Bluish smoke sounds like some engine oil is being burnt somewhere so new rings shd fix it. If the valves or valve guides are knackered that wd let oil into the chamber too. Did it burn much oil?
It's usually the injectors or air filter. Hope you have some fun.
For others tempted to do this - it's fun but not too likely to be the cause except for incredibly ancient rattly engines which *don't* start too easily so not much to lose. The compression must be fine for the thing to start -so just how badly does it need a rebuild? Not much. Whereas stripping down an engine thatworks is usually done by F1 teams frantic for an extra 1% power- altho note how the race cars have gotten more reliable with rebuilds restricted.
Replace the air filters, get an injector service, change the oil, is the first stage and solves most stuff.
Extra tlc involves changing the oil, then using flsuhing oil and geting rid of that and mebbee even more flsuhing oil till all lovely and clean, then new filter and oil - this should sort any gummy sticky rings - a possible cause of oil smoke which disappears.
If you really must, de-coking chemicals can be injected into the air intake and coughed out of the exhaust but you have to be careful - not too much at a time.
"loads of clerance on the tappets" isn't necesarily a good thing. They should usually be "just" clear, say er 25thou so when it warms up they don't click.
It wd be an idea to make friends with a local engineery type perhaps to help find new rings as another says. You may need reassmebly help.
If the piston is nice and tight, it doesn't need a rebore so that's ok.
Yep, the carbon should all be removed. Remeber which way the piston went in if not too late - it should have a thrust (fwd) side.
the so-called assembly donkey work is indeed fairly donkeyish but you need various tool like valve clamp and circlip pliers etc. Good fun tho as others say. Favourite mistake is to drop things down the crankcase just as the thing is nearly done...
It is tempting to utterly utterly clean it but not really necessary. You should gloop some oil around everything so it's lubricated properly.
the oil pressure is not necesarily a bad thing, it needs to pump oil around anyway doesn't it and it's only 9hp so you can just lead a breather pipe either er somewhere else out of the boat , or proably better back to the crankcase. I wdn't try too hard to replace/fix the over pressure thingy really.
Bluish smoke sounds like some engine oil is being burnt somewhere so new rings shd fix it. If the valves or valve guides are knackered that wd let oil into the chamber too. Did it burn much oil?
It's usually the injectors or air filter. Hope you have some fun.
For others tempted to do this - it's fun but not too likely to be the cause except for incredibly ancient rattly engines which *don't* start too easily so not much to lose. The compression must be fine for the thing to start -so just how badly does it need a rebuild? Not much. Whereas stripping down an engine thatworks is usually done by F1 teams frantic for an extra 1% power- altho note how the race cars have gotten more reliable with rebuilds restricted.
Replace the air filters, get an injector service, change the oil, is the first stage and solves most stuff.
Extra tlc involves changing the oil, then using flsuhing oil and geting rid of that and mebbee even more flsuhing oil till all lovely and clean, then new filter and oil - this should sort any gummy sticky rings - a possible cause of oil smoke which disappears.
If you really must, de-coking chemicals can be injected into the air intake and coughed out of the exhaust but you have to be careful - not too much at a time.
TheBoatman
Well-Known Member
6500 - 7500 hrs would not be out of the ordinary for an engine that is used and maintained regularly.
kengill
Well-Known Member
As you've gone that far please remember to carefully inspect the gearbox input shaft splines and the drive plate on the flywheel. When we took the engine out of Vitality these proved to be worn out and would have required an "re-ending job" for about £350 - as opposed to a new shaft which was circa £1000, let alone that the total amount of play betwene input and output was unacceptab£e consider also that you'll be producing a lot more power and compression and you may nee dto replace all the oil seals, rebuild and service the fuel injector mechanism, inspect and rebuild the oil pump, check camshaft wear. Just think if you do all that work and then the fuel injection wears out and B*****s the engine - or any of those other items come to that£££
I chickened out and fitted a new engine and gearbox - only when the engineer took the propshaft seal off to fit the new propshaft we found that had corroded dangerously.£££££
which meant I had to rip the battery boxes and rear bunk supports out and build new ones after the new sterntube had been fitted so we had to have a new propshaft sea£.
Be wary ... be very wary... in fact be paranoid when thinking about it.
Then remember just because you're paranoid doen't mean the B$$$$$$s aren't out to get you!
Ken
s/v Vitality
I chickened out and fitted a new engine and gearbox - only when the engineer took the propshaft seal off to fit the new propshaft we found that had corroded dangerously.£££££
which meant I had to rip the battery boxes and rear bunk supports out and build new ones after the new sterntube had been fitted so we had to have a new propshaft sea£.
Be wary ... be very wary... in fact be paranoid when thinking about it.
Then remember just because you're paranoid doen't mean the B$$$$$$s aren't out to get you!
Ken
s/v Vitality
tyce
Well-Known Member
sonsy lass re-read my post you bafoon i clearly state i was being pedantic, i was talking about 96000hp marine engines i worked on, and clearly point out i know its a load of cobblers for our engines
Sans Bateau
Well-Known Member
A couple of years ago I was buying oil plus filter s for my Volvo 2002. In an attempt to 'look after' the engine I tried to buy the very best oil that the supplier had in stock.
This was a Sat and the owner of the business was on the counter. He advised me that he sees a lot engines in the Volvo 2000 series with glazed bores, he told me that this was the result of people looking after their engines too well. Curious, I asked what he meant, he told me that cheap oil changed regularly and to run the engine at max revs/power was the best way to make sure the engine has a long life.
Why? I asked. He told me, these engines were originally designed to go on dumper trucks and concrete mixers, to be thrashed all day on cheap oil. If you put semi synthetic oil in it run it at low revs, or running it without a load in the marina, you will kill the thing.
This was a Sat and the owner of the business was on the counter. He advised me that he sees a lot engines in the Volvo 2000 series with glazed bores, he told me that this was the result of people looking after their engines too well. Curious, I asked what he meant, he told me that cheap oil changed regularly and to run the engine at max revs/power was the best way to make sure the engine has a long life.
Why? I asked. He told me, these engines were originally designed to go on dumper trucks and concrete mixers, to be thrashed all day on cheap oil. If you put semi synthetic oil in it run it at low revs, or running it without a load in the marina, you will kill the thing.