Suspected stuck piston rings

[Bryan Cedar 1Participant @bryancedar1]

I have a Farymann 18W 400cc single cylinder diesel engine coupled to a 4KW 230 volt alternator in a Fischer Panda marine generator

The engine refuses to start. Having overhauled the cylinder head and lapped the valves, the exhaust valve seat was rough and not seating. Engine still does not start. I suspect the piston rings are stuck giving low compression. I wonder if anyone has used either Auto transmission fluid i.e. TQF or perhaps Redex down the bore to free up stuck rings. I do not have a compression tester at this time.

Interestingly, the bore is tapered being wider at the bottom. The suppliers suggest that the piston should be at BDC before adding the oil so that the oil can penetrate the ring grooves more easily.

Edited By Bryan Cedar 1 on 01/08/2018 12:17:18

[Bryan Cedar 1Participant @bryancedar1]

400cc Farymann diesel engine piston rings

[ronan walshParticipant @ronanwalsh98054]

I never heard of a cylinder bore being tapered like that deliberately, usually the other way around, with the top being worn. I was told any taper is a bad idea as it causes the rings to constantly expand and contract. What oil are you going to use ? Can you not take off the barrel and inspect the rings ?

[DalboyParticipant @dalboy]

Not knowing what you have done or the state of the engine in the first place makes it a little bit of a guessing game.

Yes low compression could stop it starting as well as fuel pump timing faulty injector the list can go on. Sorry for not being much help.

When the head is assembled and everything in place when the engine is turned over can you feel compression Assuming the engine is hand cranked to start it. If when turning the engine it is hard to turn it over TDC then there is a good chance you have enough compression to start the engine in which case you will need to look elsewhere if it is easy to turn over TDC then you assumption is probably correct.

As above never heard of any engine that has a tapered bore seem strange unless someone knows better on that point

Edited By Derek Lane 2 on 01/08/2018 12:47:59

[Speedy Builder5Participant @speedybuilder5]

Reading the manual from page 55 onwards – a very comprehensive manual written by an H&S student !!

**LINK**

There are all sorts of controls to aid starting, I don't know if this helps.
BobH

[nigel jones 5Participant @nigeljones5]

Hard to believe but purposely tapered bores have been around a long time (although I dont know why they are tapered). Do you remember your granny having a chip pan with rock hard chip fat stuck to it – well thats pretty much what gets into your rings and no amount of anything down the bore will free them. The oil rings are always worse affected. I used to renovate old stationary engines in my spare time and have come across this often. Soaking the piston in penetrating oil helps free them enough to remove them so you can dig out the remaining gunk. Good luck.

[Peter BellParticipant @peterbell11509]

I recently repaired a Farryman with similar problems and ended up re grooving the piston and using slightly wider rings and both the rings and piston were worn, hope yours insnt like that!

It also had a tapered bore which according to the manual is 75.03mm bottom of bore and 74.930mm at the top so not much. I assumed it was to allow it to become the right size when hot?

Peter

[Bryan Cedar 1Participant @bryancedar1]

Thanks to everybody for replying to my posting. The engine has done very few hours, under 100 and is like new.

Compression is there but only needs to be about 20% down in compression for it not to start it being a diesel engine.

I do not want to strip down at this stage as this is a major job, there being little head room, no pun intended, to remove the cylinder barrel.

I was hoping that somebody had experience of using a light oil to free up stuck rings.

[Peter BellParticipant @peterbell11509]

Only 100 hrs so should be pretty good condition, mine is on a wacker plate so had a hard life!

Ive used light engine oil or diesel on stuck rings with varying degrees of success. If you add oil to the bore, turn it a few times so it penetrates the rings then try starting as the oil fills the gap increasing compression allowing starting and then the normal lubrication takes over.

Assume the excess fuel is working and the bore hasnt had water in to seize the the rings?

[not done it yetParticipant @notdoneityet]

Feed propane gas into the inlet as the engine is cranked over as fast as possible. Diesel engines will run on propane if there is enough compression (and diesel injection to to promote combustion).

Bradex (or other) starting fluid is another option – only use this if there is no heater starter involved. Even feeding the inlet with a burning propane torch can elevate the temperature to ignition point.

Is it trying to fire? Is there a fuel spray at the injector? Air in the high pressure fuel ine is the most likely culprit, or the non return valve exiting the pump, if there is no spray.

Fresh fuel? I needed to put fresh fuel in my Hatz diesel genny to get it started last year, after it had stood for twenty years.

Using detergent oil prevents ring gumming. Non-detergent oil is bad in any diesel.

[Neil WyattModerator @neilwyatt]

Does a blast of Bradex get it to run at all? Might free up the rings if they are glazed in.

[Speedy Builder5Participant @speedybuilder5]

If there is un-burnt fuel, you should get white smoke – if not, then you have a shortage of fuel. Black smoke unburnt but combusted fuel.

[Bryan Cedar 1Participant @bryancedar1]

This engine is sea water cooled and the discharge is via two silencers containing water through which the exhaust gasses pass. There is not enough compression to ignite the fuel. I do think it is a matter of freeing the rings, hopefully without dismantling. Everything else seems fine, I have had the injector checked and it is OK. Injection pump produces a tiny amount of discharge on each stroke which is to be expected. Unfortunately due to the configuration of the high pressure pipe I cannot couple it to the injector to observe the spray output. I do however believe it is OK.

[Bryan Cedar 1Participant @bryancedar1]

Forgot to mention. Although the makers say do not use easy start sprays, I did try the Holt Easy Start without success. That was before the head clean and valve lapping. Am reluctant to try again due to the makers warning not to use start sprays. Not sure what damage it may cause.

Edited By Bryan Cedar 1 on 01/08/2018 16:57:07

Edited By Bryan Cedar 1 on 01/08/2018 16:59:50

[Neil WyattModerator @neilwyatt]

Posted by Bryan Cedar 1 on 01/08/2018 16:56:32:

Forgot to mention. Although the makers say do not use easy start sprays, I did try the Holt Easy Start without success. That was before the head clean and valve lapping. Am reluctant to try again due to the makers warning not to use start sprays. Not sure what damage it may cause.

Edited By Bryan Cedar 1 on 01/08/2018 16:57:07

Edited By Bryan Cedar 1 on 01/08/2018 16:59:50

They wash out lubricants, and are not good is regularly used.

A quick try shouldn't do any harm.

[Peter BellParticipant @peterbell11509]

Ok well that should have made it do something!

Does the injector "creak" when you turn it and atomise cleanly when out of the head but piped in?

Lots of useful advice previously, like does it smoke etc? Does it smokes a you swing it and how difficult is it to get over compression, can you hear anything squeezing passed the rings if you listen with the rocker cover off as you slowly crank it?

[SillyOldDufferModerator @sillyoldduffer]

Posted by Bryan Cedar 1 on 01/08/2018 16:56:32:

… I did try the Holt Easy Start without success. … Am reluctant to try again due to the makers warning not to use start sprays. Not sure what damage it may cause.

Easy Start and friends contain volatile fractions. Like as not they will ignite very early on a healthy diesel engine, possibly early enough to drive the crank backwards. Wouldn't be good to have some cylinders on an engine firing forward correctly while are pushing the crankshaft in reverse due to severe premature ignition.

If it were my single cylinder engine with suspected low compression I'd try it in moderation. In a confined space the stuff is a good solvent and it might help degunk the rings. Not sure that's how a professional would use it though!

Dave

[ronan walshParticipant @ronanwalsh98054]

Have you checked the valves clearances ? I know you said you lapped them in, but has anything, Tappets etc, moved ? An old trick for getting pistons free in bores is to chuck boiling olive oil down the plug holes (on a petrol engine obviously) but it might work to get the rings moving.

[MikelkieParticipant @mikelkie]

I had the same problem a few weeks back and a friend gave me a product made by MOMAR CHEMICALS in my country. this stuff is used for removing carbon deposits from engines etc. I removed the injectors and pored about half a cupful down the bores which was in mid position an left a day or two, then cranked it out and washed out with paraffin. Problem solved. Try google for a similar product in the UK.

Mike

[Howard LewisParticipant @howardlewis46836]

Using ether starting aids, other than in extreme low temperatures is asking for bore/ring problems. Th ether washes out any lubrication, so that scuffing occurs, and the ether fores earlier than the gas oil, producing very high peak cylinder pressures. NOT a Good Idea.

If you can once get the engine to fire, the piston should expand with the heat and the ring(s) should then free off.

Hopefully, the ring movement brought about by the tapered bore, may help to free it off.

Maybe the engine has run for long periods on light load, and this has caused it to carbon up?

If so, a few hours on full load may effect a cure.

(Once, I oversaw the strip of a 300 bhp 6 litre engine which had run, effectively on a thermal cycle, without any sign of a problem, but the strip showed one second compression ring to be sticking. Obviously free when hot, but stuck when the piston contracted onto it).

Howard

[not done it yetParticipant @notdoneityet]

A friend of mine found that standing pistons, with stuck rings, close in front of my space heater soon effected a freeing off. So, getting the engine really hot may allow it to get started.

Using ether based starting fluid will do as Howard says. Often used to start engines with worn rings (with too much side clearance between ring and groove) resulting in cracked rings due to the detonation pressures – which often eventually results in the rings breaking through to the crown, along with scoring of the already worn bore. But that is on an already worn out engine. Worn crank bearings are also hammered.

Some engines have an auto feed of starting fluid from cold. Sensible use is OK. Try it again, now that the valves are not leaking.

[anthony smith 4Participant @anthonysmith4]

REDEX in the bore will free the rings some years ago i had a 2000cc petrol engine had not run for two years one ege cup in each bore left a day tried this for five days on the fifth day engin ran for 65000 miles till the body fell to bits due to rust engine was ok when it went too the dump

[I.M. OUTAHEREParticipant @i-m-outahere]

Have you bled the injector line up to the injector ? Even the smallest air bubble in the system from the pump up to the injector will stop it running . One way of testing is to make up an air fitting that fits in the injector hole and set the engine at tdc on the compression stroke . You will need to use something to lock the engine at tdc , i use a length of angle iron bolted to the flywheel ( use the puller holes if it has them ) DON'T try to hold it by hand you WILL get hurt – don't ask how but i just know ! . If you then pressurise the cylinder with compressed air and listen for either serious blow by past the piston ( i take the filler plug out and listen to what comes out of it ) There will be some leakage – a very slight hissing is ok but if air gushes out you have problems ! And for valve leakage by listening to the exhaust and inlet ports ( should be no leakage at all ) you can at least determine what is leaking .

This is the same basic procedure of doing a leakdown test on an engine except you have no gauge to tell you the rate of leakdown in % .

On two stroke engines i have used some engine oil squirted in through the plug hole to help seal up some very old worn rings , once running the speed at which the piston travells doesnt give time for gas to leak as much . If you try this with a diesel be very sparing on the oil or you risk a hydraulic lock up if you whack too much in .

Did you check the valve lash ?  Were the valves nice and free in the guides ? What condition are the valve springs in ? If it sat for a long time with a valve open the sping may have  collapsed / lost its rated pressure . 

How bad was were the valves and seats ?  Lapping may have not been enough and getting them re cut may be required .  Lastly have you checked to ensure there is no compression leakage into the water jacket ? 

The injector pump may be pumping a small amount when you turn the engine over but at what pressure ? 

If you have tried one of the various starting sprays and it still won't fire that negates a fuel issue and only leaves compression and cam timing   .

 

Edited By XD 351 on 02/08/2018 02:40:13

Edited By XD 351 on 02/08/2018 02:50:11

[HopperParticipant @hopper]

Back to the beginning of the thread, I have come across tapered bores on old 1920s Harleys, smaller at the top, larger at the bottom. This was so that when the hotter top region of the cast iron cylinder expanded, the bore became parallel. So I don't think that is the cause of your problem. Not much help I know, but interesting, hey.

[Bryan Cedar 1Participant @bryancedar1]

Hello Hopper

Thanks for your response, When I wrote the bore was tapered, I should have stressed that this was intentionally done by the makers, not something that has occurred in use.

[Author]

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