Oil pressure light

[mtb]

Re: ok but

You have not mentioned that most of the industrial engines have a far greater oil capacity than their smaller counterparts, also their cooling systems have greater capacity to cope.
Also certainly on older engines the oil throwers on the crankshafts cant operate as efficiently on low revs .
I count my self as old school but totally agree with, as you put it those who cant prove !!!!!. I would concern my self with things like the oil over heating re lack of pressure due to low revs causing bearing failure, and I'm not just talking white metal bearings.Overhead camshafts need plenty of oil pressure.
Then there's the engines that don't have gear train's and rely on throwing the oil to lubricate.
Another point to make re prolonged ticking over , with the vast majority of marine engines if you leave them ticking over for long periods there is every possibility that the raw water side of things will not supply adequate fresh cooling water for the heat exchanger !!! .
Then there's the gear box yes ok mechanical types wont suffer but hydraulics !!!!!!!!, they need to be run if only to pump sufficient oil through the cooler.
Don't get me wrong we're all entitled to our own opinions but I feel there's a risk your encouraging people to take a different approach which could lead to costly consequences.
Cheers
Mick

http://homepage.ntlworld.com/boats
I need a couple of oak tree's .. for me trawler

 

[stamfordian]

I used to be involved in the dat to day maintenance of Diesel engines ,upto 1000kva alternaters and our shedule was this:-
run on tickover for 1hour per week
run on sytem load(a raf camp) 3hours per month,
run on load bank once per year@110% for i hour after 2hours of full load running,that was one hell of a kettle we used for that!!
for smaller alternater sets of approx 500kva we used to load bank them every six months to ensure turbo oil seals were kept right ,if you use these on no load or light load they start to leak bacuse of the carbon in the turbo(cummings engines).
aghh theres nothing like the purr of a vee20 through ear defenders!!

<A target="_blank" HREF=http://www.arweb.co.uk/argallery/stamfordian>http://www.arweb.co.uk/argallery/stamfordian</A>

 

[vyv_cox]

Tickover/light load

I don't think we are in disagreement, although I will admit that maybe my use of the word "tickover" in my second response was ambiguous and "light load" might have been better.

It's not often that I mention my professional life on the forums but maybe this deserves an exception. Far from stubate's assertion that I am pontificating from an armchair, I have spent 25 years in research, failure diagnosis and troubleshooting of rotating equipment for an oil major. I know from having done it that lightly loaded (and in cases that I know of, ticking over) engines suffer considerable bore glazing. My company spent huge amounts of money in developing oils that would solve this problem and the fact that it is now less frequently encountered may be a testimony to this investment on your behalf.

It is clear from the two references I posted yesterday that other oil companies have the same experience. There are or have been engines in use by all lubricant developers that are particularly prone to these problems, two being those posted yesterday but there are others. I'm not sufficiently up to date to know whether research is still being done in the subject but I can assure you that it was widely studied 15 or so years ago.

 

[ccscott49]

Re: Tickover/light load

Maybe they were successful with their research, because as stated it is not the problem it once obviously was. Reducing the agents in the oil which produced, the laquers and varnish deposited on the bores, which caused some of the problems has been successful, what with newer additives and better ring and bore treatments. We no longer see the problems in any amounts these days.

 

[ccscott49]

Re: ok but

I am noit advocating people leave a marine engine ticking over for hours, what is the point, it won't charge the batteries, but if you rev it up with no load on it just to charge the batteries you are then asking for trouble, it might not happen to your particular engine but it might, all I was saying is that we do use engines that spend at least half their lives ticking over, to be used intermitently and they come to no harm. That was the point Stubate and myself were trying obviously unsuccessfully to make. I believe the secret here is the engine must be at full working temperature, not left ticking over to warm up etc.

 

[mtb]

Re: ok but

Yes Colin I know you were talking about the standby engine run stuff, my point was aimed at the fella who seemed to come across at saying let em tickover and no harm will come to em !!.

Cheers
Mick

http://homepage.ntlworld.com/boats
I need a couple of oak tree's .. for me trawler

 

[Guest]

Re: ok but

Just as a matter of interest, why does all the talk of bore glazing relate to diesel engines. Why not petrol engines?

And whilst all these experts are on the forum, comment on my Yanmar problem would be appreciated. The engine (a 2 gm) is 300 running hours old, has been used under load and never for battery charging, but finally developed high oil consumption (1 pint per 3 hrs) after a trip across Biscay. No top end prob was revealed when we had the head off, but some bore polishing or glazing. Oil used was Castrol.

Bottom end now being stripped, but how can an engine run OK for a year, and then suddenly glaze up?

 

[mtb]

Re: Hey I\'m no expert !!! they are

Do you think it might be the rings quality , Which Castrol did you use. Castrol is the oil I normally use .
Glazing does not suddenly occur , it takes time .
The reason I say ring quality is I have found this on the odd occasion.Are the rings chromium plated type if so has this caused it .
The temp that your engine is running at , is it ok cos if always on the high side the oil might not be working 100% .
Are the valve guides ok . What fuel grade have you been using is it foreign stuff .
It's always difficult to try and ascertain what's at fault like this, some times even when the engine is on the bench in front of you.
Cheers
Mick

<A target="_blank" HREF=http://homepage.ntlworld.com/boats>http://homepage.ntlworld.com/boats</A>

 

[ccscott49]

Re: ok but

Howrd,
Bore glazing does not just occur, it happens over a long period, are you sure it's bore glazing which has caused this sudden oil consumption? I would be looking elsewhere, was the oil burned? was it discharged? are the valve stem seals ok? I would be looking at everything else, a lot of the time "bore glazing" is used as a "I'm not sure whats wrong" get out clause, only to find later theres something else wrong, or the engine is rebuilt de-glazed or rebored, all the seals changed and the problem goes away, ah! says the mechanic bore glazing!! When it was one of the seals he changed, the message here is be careful. How polished are the bores? some polishing is expected as the rings bed in, has one of the oil control rings failed? theres a multitude of things to check. Good luck.
Colin.

 

[stubate]

Re: ok but

im the same as ccscott, go back to basics, if it happened suddenly something has broken, rings or ring probably. the bit about bore glazing is what i have been talking about, so every body is looking for bore glazing !!
if you open a run in engine the bores are nice and shiny and smooth, so what, that is what they are supposed to look like !! but because the "armchairs" say bore glazing, everbody is conditioned to look for some thing that is not there and go off down the wrong track when diagnosing.
i never in all my working life looked to try and diagnose a case of "bore glazing" i looked for worn rings and bores, or worn valve guides and when reassembling with new rings or pistons i would "bust the glaze" in the cylinder so that the rings could bed in against fresh metal.
best of luck
if you need any more specific help PM
stu

 

[charles_reed]

Re: Yanmar bore glazing

Not entirely surprising especially if it's a raw water cooled one.

I check/change the thermostat on mine every year - they fail in the open position which can result in severe overcooling.

One of the UK experts on Yanmars reckons you should have the head off every 1000 hours, because their main weakness is head-leakage problems.
It usually occurs between the two cylinders, but can be into the water-jacket.
The only symptom you get of the latter is increased steam in the exhaust, but you can get a little flame path cut which requires head-milling (you can take off up to 10 thou, before having to worry about valves hitting pistons).

It's not surprising - the engine started life as a 12hp and has been stroked and bored up to its current 18 bhp.

 

[Guest]

Re: Yanmar bore glazing

thanks for the comments. the history of this engine is that it was installed new before we took the boat down the french coast and across biscay to northern spain. in that first year it operated fine, with no significant oil consumption between changes. the engine works hard - it is driving a 33 ft cat.

when we brought the boat back across biscay this year it started to consume oil at the rate mentioned. the oil that was used in spain was castrol for diesel engines.

when we got to penzance, we had the head lifted. there was no appreciable wear on the bores, no signs of any valve seal probs either, and no head / gasket problems. there was some glazing/polishing, but not a lot. there was evidence of oil being burned on the valve heads and pistons. we decided to put the head back on and strip the engine during the winter, which is what is now happening.

there are no oil leaks into the bilges, and no blue smoke behind the boat. there is some evidence of oil in the exhaust water.

the puzzle is, if there are no probs in the head, and no bore damage, it has to be something like gummed rings/ bore glazing.

 

[ccscott49]

Did you ever solve your problem?

 

[mtb]

Re: Yanmar bore glazing

What do you mean evidence of oil burning !!!
Unless there's carbon deposits being left because the engine is over cooled thus not burning the fuel efficiently and leaving carbon deposits . This could also be poor quality oil or the wrong oil being used or faulty injection.
From what you say re bores it sounds normal , but did you do a compression test and at the same time after noting the reading put some oil in to see if the compression figure went up to ascertain if a fault was either head, piston rings or bores.
It's no good pulling an engine apart expecting to find a fault better to do a compression test first.
I cant see it being the bores it's more like the engine is being pushed to the limit re your boat and gets to hot and more likely the rings are worn .
The only thing to do is to measure the bores then check the piston ring gaps , your manual will have the spec . But with out using internal mic's and so on
If you rub your finger up and down the bore you will feel the area where the rings stop , is there a lip how much is there. This will tell you if there's wear in the bore.
You may need to either fit new rings with a ridge dodger or use a ridge breaking tool to eliminate the risk of breaking the top ring and damaging the top piston ring groove. If you fit new rings you can get a diy sikes picavant honing tool which is just three spring loaded grinding stones , pop it in a drill wet the bore and stones with paraffin then with an up and down motion you will put some nice honing on the bores ( get rid of the polishing ) which will enable the oil to be held on the bore walls helping the rings to operate . It's much much better than wet and dry by hand.
I'd consider using Cordes Rings as they are very hard rings and will cut them selves in , Cordes are in Park Royal W London and should have the size of ring you need.
Cheers
Mick

<A target="_blank" HREF=http://homepage.ntlworld.com/boats/>http://homepage.ntlworld.com/boats/</A>

 

[pheran]

Re: Yanmar bore glazing

<font color=blue>some evidence of oil in the exhaust water</font color=blue>

Are you sure that your increased oil consumption is due to it being burned in the engine? Your other indicators are less than conclusive and you say that there is no blue smoke, normally a dead give-away. Some years back, I spent a considerable amount of time and money rebuilding an engine in what sounds like identical circumstances, all to no avail. Indeed the internals were virtually perfect when I got it all apart and it eventually transpired that the oil was being lost thro' a minute leak in the engine oil cooler. Very, very small hole in one of the tubes but it is amazing how much oil you can pump out at 60psi, and indeed I only noticed the oil in the water when we came to rest eg along side a pontoon. And this could explain the sudden occurence of your problem. Engine wear certainly can't!!