Yanmar 1GM - is this normal

[Spuddy]

Totted up nearly 4 fig sum on this over past year incl injector pump and injector recondition. To get it going today used a 12 V hairdryer down the intake plus lengthy cranking. It's not that cold - should it be more responsive ?
Start procedure means:
lift hatch covering most of cabin sole;
Clip in hair dryer
battery isolator plus key switch on
Switch on hair dryer and point
reach in companion to push starter button
and wait.
If it starts then down into cabin to put cooling water on.
So can imagine situation of wind over tide with a wave top or two coming over and me with hole in cockpit, dodging up and down stairs. Is this the best a man can get ?

 

[abbott013]

Are you useing enough throttle to start the engine, have you primed engine before starting, is there enough compression when turning the engine over. does the engine start after previously being run. not sure about this particular engine but does it have a glow plug for easy starting

 

[whipper_snapper]

No, that is far from normal.

Mine started first time every time. Even in cold weather and after not being used for weeks.

How fast does it crank when you press the starter ?
What colour exhaust do you get ?
When it is running, does it run evenly ? And does it pick-up fast when you open the throttle quickly?

 

[Pye_End]

I did used to find it took a few more turns to get it going, and it was important to get it really going before stopping the starter motor - too early and it stopped and you had to rest it a while before trying to re-start.

Otherwise no not normal! Compression test?

 

[QuietFlight]

No that is not normal and frankly sounds nuts! I use mine all the year round, two thirds throttle and she usually catches either first time or second push. Once she has been used for a while will fire up first time in neutral, for those odd scary moments when you suddenly need the motor. I would assume that you have good fuel, its getting through and a decent battery, that really is all these very simple engines need. They are well known for both being reliable and bullet proof.

 

[Spuddy]

Thanks everybody. Works OK when started. Yes I give it plenty of throttle. Black exhaust smoke indicating enough fuel getting through ? Battery taken off and fully charged to make sure it was spinning enough.
Looks like a compression test then. How's that done and what with, folks ? Something screwed into injector hole ?

 

[pampas]

All the diesel engines that have worked on, particually small ones such a boat engines need full throttle to start, especially if no hand operated cold start device is fitted, as soon as the engine fires bring back to a fast tick-over.Two things to check are that the starter runs at full speed, the battery is fully charged and not cold then I might start think about timing,, before going to all these tests I would remove and clean all earth and positive main connections as with the engine being cold you may have a slight high resistance, that during the summer is not noticed but is during winter.

 

[Neddie_Seagoon]

In cold weather I used the decompression lever on top to turn my 1GM10 over a few times before starting - then half throttle and fired up quickly.

 

[Pye_End]

Compression - racking my brains over something I read recently - something about seeing if the sump pressurised when turning it over. Can't remember where I saw it. Perhaps somebody else did - forget if it was using the dipstick hole or opening the the lid where you put the oil.

Never tried it but makes sense.

 

[Bilgediver]

I wonder if you are suffering as do some nearly new Yanmars ie the valve tappet clearances have become reduced due to the valves and seats bedding in. I have seen this before and simply resetting the tappet clearances as per manual might improve matters.
For a quick test remove the tappet cover and check that the tappets have clearance on the back of the cam. I have seen a 2 cyllinder yanmar totally loose its tappet clearance after just over twelve months in service. After that things settled down.

I assume you are giving plenty of throttle as there is no cold start position.

 

[crg]

Had a starting problem with my 1GM, traced it to a build up of carbon and rust around the exhaust port which reduced the port exhaust to half its original size!! the build up of carbon and rust was caused by a corroded exhaust mixing elbow allowing a path for the cooling water to mix with the engine exhaust gas near the engine exhaust port.
Suggest you take exhaust elbow off and inspect exhaust port and mixing elbow, cost you a new gasket.

 

[Pye_End]

Air - good point, and other end -ie air filter. Presume this is ok?

 

[oilyrag]

Listen to CRG - Achilles heel of 1GM is the exhaust elbow - if there is no restriction in inlet ((blocked filter) or exhaust (f'instance hoses can collapse internally) causing the problem, and you seem to have ruled out any problem with the fuel system, and the elbow has not been replaced in the last 10 years (should be replaced every 2 years!!), at worst you are looking at a new cylinder head beacuse the exhaust port will have corroded away. Otherwise, if the head is salvageable, you may still have a bent conrod resulting in compression loss and poor starting (because the exhaust water has been drawn into the cylinder from the perforated elbow). You can check the piston height easily to verify this.
Whip the head off and the answer to your problem will be revealed - wallet will start suffering badly again though /forums/images/graemlins/frown.gif

 

[oldharry]

[ QUOTE ]
Compression - racking my brains over something I read recently - something about seeing if the sump pressurised when turning it over. Never tried it but makes sense.

[/ QUOTE ]

Quite right PyeEnd: A compression test on diesel is a bit of a waste of time. The best way of testing compression is a 'leak down' test which pressurises the cylinder then measures the rate at which it 'deflates'

The simple test of cylinder wear and ring problems you are thinking of is, with the engine warmed up and running: block off the breather(s), remove the oil filler cap and hold a rag firmly over the opening to seal it. Rev the engine to around 50% revs for about 5 seconds, then release the rag. If there is a 'whoosh' of gasses from the filler, then there is a cylinder problem. Dont run it up blocked for more than around 10 seconds, as the pressure can build enough to do other damage - blown oil seals for example.

The exhaust gasses are escaping into the crankcase past the cylinder rings either because of wear, or stuck / damaged rings.

Quite commonly lube oil is pushed out of the breather when the engine is working hard. The condition is known as 'blowby', and is usually the herald of hefty repair or replacement bills!

Worth trying this on your Yanmar Spuddy: it costs nothing to do, and ther is blowby, you will at least know then where to start and can sound knowledgeable when dealing with engineers!

 

[mikejames]

No that is not normal.

Compression test: take the starter handle and try to turn the engine over with it while keeping decompressor in run position. It should be extremely hard to get the engine past the compression point.

The tappet adjustment is easy. Getting the rocker cover box off is easy. Keeping the paper rocker cover gasket in one piece when taking the rocker cover off isnt quite so simple sometimes.

If you get black smoke then another problem could be the alternator is actually holding the engine RPM down to the point that it stalls because the battery voltage is low because you had to turn it over a lot.

Using the decompressor to let the cranking RPM go higher can be helpful as well.

On mine it sometimes helps to switch the battery from 1 (the one I just used for starting) via 1+2 to 2 when the revs wont pick up immediately after starting - selecting a better charged battery as a load for the alternator.

The Yanmar 1GM saildrives have some kind of time delay switch that stops the alternator from charging immediately after starting, so this problem is known.

That isnt the same as disconnecting the battery from the alternator + electrics, allowing the alternator output to go high voltage across the electrics for an instant until the regulator cuts in, which is the effect of turning off the main battery switch.

 

[Birdseye]

Start with the simple possibilities first. And whilst the use of a hairdryer is not normal, the engine will not be anything like as easy to start mid winter as mid summer since it has no pre-heat as such.

You have had the fuel system to bits so the first thing to check is that you are not getting fuel drain back because of air leaks. For example, if you stop the engine again immediately you have started it and before it can warm up, do you still have to use the hairdryer? If you dont, then its likely that air is getting into the system when the engine is shut down.

Does the engine run OK when you have got it started? If you briefly open the throttle fully when the boat is tied to the pontoon do you get black smoke as you should. Is your max speed what it should be? Has the engine been like this for some time or only since the injector pump was done?

If you still do need to get the dryer, then compression is the thing to look at because thats what heats up the wir / diesel mixture to the point when it ignites. The first thing I would look at as an ex GM10 owner are the tappet clearances - a badly seated leaking valve can cause loss of compression. If your installation allows it and you have the handle you can try a hand start - and unless your are a rugby forward you should only be able to turn the engine over (if at all) with real difficulty.

It is not worth doing a simple compression test if the engine turns easily and tappets are OK - you already know that compression is cr*p. Instead, remove and injector and put a teaspoon of engine oil down into the bores. Replace the injector and then test compression again. If you now have compression the bores are worn - if not its the valves.

 

[Spuddy]

Thanks again

for all the suggestions. I'd checked most of the stuff but nobody knew that so you were all triffically generous. I'll check the start protocol again and then enter phase two using your advice.

 

[nealeb]

[ QUOTE ]
On mine it sometimes helps to switch the battery from 1 (the one I just used for starting) via 1+2 to 2 when the revs wont pick up immediately after starting - selecting a better charged battery as a load for the alternator.


[/ QUOTE ]
Thanks for that comment! I have a 3GM in the current boat but last one had a 1GM and I never did work out why it was so slow to get going sometimes! Would never run faster than the equivalent of fast idle until it was warm (or so it seemed). High alternator load on relatively small engine explains all! A friend with 1GM plus saildrive mentioned the delayed charging switch but I had never put 2 and 2 together.

My starting technique with the 1GM was to get the motor spinning with decompressor engaged, and once there was some momentum in the flywheel I would drop the decomp lever holding in the starter button and away it would go. Turning over compression from a standstill is very hard work for the starter motor. I have had to use this technique with the 3GM once or twice, typically after a relauch when the boat has been sitting for a couple of months in the cold. It won't run with just one cylinder on compression but it does reduce the load on the starter while you drop the other levers in turn. Using summer diesel in the middle of winter can't help either!

 

[Gunfleet]

How interesting. My 1GM has a non standard alternator. The Adverc chap suggested a switch on the field side to help starting. It certainly does help. Of course, it's not the same as running the alternator with no load. More like 'not running the alternator' with a load, if you see what I mean.