Yanmar 2GM20F starting problems when left for a day or two.

[vas]

Oil in the coolant can usually only be a failed head gasket or a perforation in the block, liner or head caused by corrosion. Your engine looks to be in good nick so you can probably rule out the latter.

The good news, as you say, is that the coolant circuit should be corrosion-free.

Richard

actually due to the fact that PO was largely incompetent and considering that the generator is placed in a way that there's less than 10cm clearance from oil and water intake to e/r ceiling, I'm seriously considering that at some point he mistakenly just added oil in the heat exchanger Hopefully he realised, stopped but I have to live with this oil...
We'll have a better idea tomorrow.

cheers

V.

 

[ShinyShoe]

I have a brother who put screenwash in the radiator of his car! Anything is possible!

If the engine would be happier at 1.5k, is there no way to provide a gear/pulley big to small to make a crankshaft at 1.5k spin the Genny at 3k? Is this a rediculous question from someone who never expects to have a Genny!?

 

[RichardS]

actually due to the fact that PO was largely incompetent and considering that the generator is placed in a way that there's less than 10cm clearance from oil and water intake to e/r ceiling, I'm seriously considering that at some point he mistakenly just added oil in the heat exchanger Hopefully he realised, stopped but I have to live with this oil...
We'll have a better idea tomorrow.

cheers

V.

Indeed. I included the word "usually" because it did occur to me that someone might have done something silly in the past.

Richard

 

[vyv_cox]

Useful tip for tight bolts (assuming you have combination spanners), Put the 17mm ring on the bolt/nut, then put the ring of a bigger spanner onto the open end of the 17mm spanner. :encouragement:

Problem with that is that ring spanners are 12 point and can tend to round the corners of stubborn bolts. A six point socket is better if it will fit in the space. A big breaker bar is worth investing in.

 

[PaulRainbow]

Problem with that is that ring spanners are 12 point and can tend to round the corners of stubborn bolts. A six point socket is better if it will fit in the space. A big breaker bar is worth investing in.

Thanks for the advice, after 40+ years of spannering one still learns something new every day. I'll nip out in the morning and treat myself to a socket set and a breaker bar :encouragement:

 

[ShinyShoe]

Paul - 6 point sockets...

I may be wrong... A big standard set of sockets would also be 12 point... Certainly I'm pretty sure my cheapo ones are 12pt

 

[vas]

I have a brother who put screenwash in the radiator of his car! Anything is possible!

If the engine would be happier at 1.5k, is there no way to provide a gear/pulley big to small to make a crankshaft at 1.5k spin the Genny at 3k? Is this a rediculous question from someone who never expects to have a Genny!?

I asked the same Q but the catch is that:
A. at 1.5Krpm the small yanmar wont be strong enough for a 8KW generator
B. the double/triple pulleys you'd have to use would be at their edge and prone to slipping/snapping/etc
C. a v.complicated setup in order to do so and engine vibrations wouldn't help on B. either

Indeed. I included the word "usually" because it did occur to me that someone might have done something silly in the past.

Richard

if you'd followed the rebuilt thread, you'd have seen some funny nasties, plus lots of stupid ones by PO

Paul - 6 point sockets...

I may be wrong... A big standard set of sockets would also be 12 point... Certainly I'm pretty sure my cheapo ones are 12pt

my ACESA spanner set (bought 30yrs ago) where all 6sided and still in good shape (except for 13 which was overworked on car repairs...)

I didn't manage to get to the boat today, so tomorrow I should have the cyl head at home and will post photos.

cheers

V.

 

[PaulRainbow]

Paul - 6 point sockets...

I may be wrong... A big standard set of sockets would also be 12 point... Certainly I'm pretty sure my cheapo ones are 12pt

Sorry, i was being a little facetious, was a bit surprised that Vyv though i needed a lesson in bolt undoing

I have several socket sets, 1/4, 3/8, 1/2 and 3/8 and 1/2 impact, in short and long reach, plus some individual ones up to about 40mm, all either 6 point or surface drive. Plus a selection of breaker and ratchet bars. I've still got some a/f and whitworth sockets, but i think the whitworth are 12 point.

 

[ShinyShoe]

Oh!

I was "surprised" by your reply!

...slinks back to my corner...

 

[vyv_cox]

Thanks for the advice, after 40+ years of spannering one still learns something new every day. I'll nip out in the morning and treat myself to a socket set and a breaker bar :encouragement:

You are not the only person reading this thread.

 

[PaulRainbow]

You are not the only person reading this thread.

Indeed, but i'm the only one you posted a quoted reply to.

I'm well aware of how spanners and sockets work, i was offering a tip to those who were undoing a tight fastening with a spanner, as the OP said he was doing.

 

[vas]

evening,

if you don't mind getting back in track there's plenty of debate potential I think at the end of this post...


Today was the first decent weather day, no wind and 8-9C, so had a go at removing the head. Easy with a long lever although I'm pretty sure cylhead bolts are too tight!

thing came straight up:

following 3 pics show the combustion chamber before even cleaning it with a piece of tissue:

unfortunately not what I wanted to see, as this looks way too good!

Cleaned it with just tissue and took a few more pics:

you couldn't easily argue that one cyl is worse than the other (me thinks at least!)

Cylinder liners are nice and smooth, and pistons are also fine. Maybe you could argue that piston2 (pulley side - not flywheel) has more carbon deposits but something that cannot be said easily for the cyl head of that piston !

next pic shows more deposits:

Now the serious question is, what's wrong with this bleeding motor???

Low compression (but not always!) is a symptom, strangely not only when cold, a few cases after working hard for 1h...
Difficulty in starting for sure unless it's being left for half and hour or so!
Diesel from exhaust making a nice oil slick in the water behind the exhaust a common occurrence.
Clapping with there's no tomorrow, especially when cold, making way more metallic noises than the 2 6cyl 330bhp IVECO main engines next to it...

TBH not too keen at taking the valves out and checking valve seats, look in excellent nick! Will just use the tool to compress the spring and see what the seats look like.
Only thing left is stuck/broken/whatever rings. Judging from the liners, I'd say stuck rings.

Does the condition of cylhead, liners and pistons justify all that?

Remember it's a 1K hours motor (according to the mase dash at least) Does this cyl head look like 1k hrs at 3K rpm constant all the time?
Also worried as I'm finding red instant gasket in all flanges, which means engine has been tampered at some point. Wonder if they replaced cyl head and never bothered getting pistons out...

Looks like next step is to disconnect the 8KW MECC Alte Spa MR2 generator and take the engine to the workshop.
Not too happy doing that (but seems like there's no other option) as generator is "hang" off the back of the engine with no other support (the four assembly mounts are all on the engine). So removing it means unbolting the 8 M8 bolts, supporting, disconnecting shaft (that will be fun without any way of supporting the 50kg of the generator and without proper space to even get behind the thing and hold it at a space that only one can work...), carefully lowering it down, etc.
THEN undo the engine mounts and taking the engine out of the e/r. That's the easy part...
NO fun at all!

All ideas welcomed!

cheers

V.

 

[black mercury]

On the back cylinder there is traces of rust on the cylinder bore, does this disappear with a wipe with a cloth or is it deeper? Also the pistons on that engine should protrude very slightly above the level of the block. If the engine is starting on one cylinder more than the other then you could compare both pistons when at top dead centre. A dial gauge on a stand would be ideal, but if you can feel or see a difference between the two cylinders then you have a problem. If that is the case the piston that is sitting lower than the other one will have a bent con rod. It only takes a fraction of a mm to cause problems. More likely caused by water ingress through the exhaust. Check this first, it may be ok but I would check this out. Then remove the valves to check the seats, they must be perfect. Then take it from there.

 

[RichardS]

As said, there is something seriously wrong with those cylinder bores unless all that staining just wipes off. It is doesn't you have no choice but to remove the pistons before deciding what remedial work is justified.

Richard

 

[vas]

sorry guys, should note that this is just some filthy water oil combo that was around as I removed the cyl head as I hadn't properly drained the closed water circuit. Just wipes clean but I was only using my blue thin gloves (didn't want to get too dirty...) and didn't bother to wipe it out.
BTW, feeling the bore, it's v.smooth and no step or any sort of damage I could spot.

Re piston protrusion, pics weren't taken carefully making sure I'm on TDC it was just to show the head of the piston to you guys...
Will do so and check carefully tomorrow though.
That could be an issue I guess, but I wouldn't like to think the costs involved if I need new crank and conrod...

btw, do you think this cyl head looks like 1k hours work or should I assume engine had cylhead replaced at some point?

cheers

V.

 

[vas]

an update...

after a bit of a struggle to remove the 2gm (sans cyl head) from the elevated mounting spot in the e/r, slide it a dogleg through the lazarette door for 2m and lift it off the aftdeck hatch (with around 3cm to spare with heatexchanger removed) and sliding it out to the dock through the passerelle, engine was taken to pieces and things don't look v.good.

crank has oxidisation, from water in engine which we've no idea how it happened nor when (not in the 7yrs I have the boat for sure) Could be related to the ss elbow since as far as I can make it it was originally fitted with a cast elbow.
Further, oil changes must have been rare and far between and possibly of crappy oil as all bearing surfaces are affected, and you can see the reddish metal coming up on them.
Piston rings look okayish.

Bought already a set of gaskets (third party look good quality) and a full set of metals and rings (original in their yanmar boxes) for 450euro which I find rather cheap.
Block and cylhead are sent to be skimmed as a preventive measure since gasket is metal and tolerances should be v.tight. Valves seats will be redone (should be okayish)
Crank to be cleaned carefully and all assembled sometime next week I hope, then the reverse hassle to bring it back in place and even heavier as whole engine assembled
Engineer is positive that the engine will be fine, neither he nor I are happy to grind the crank and go oversize in metals as we'll loose in hardness and wear will be fast and of course cannot find a good s/h crank...

Engineer still believes that apart from water ingress at an earlier date, the main problem with this motor is the 3K rpm constant operation from cold and the no period of cooling before turning off so I'm setting up a solenoid to pull governor to idle for a few mins at start and stop time before releasing it to the 3K rpm stop for normal operation.

Enginewise, this small motor has caused me more trouble than the main propulsion two 6.7lt IVECOs (and just as well I should add...) over the last 7yrs!

will report on completion, when hopefully all's good

cheers

V.

 

[vyv_cox]

The copper appearance on the main bearing shows loss of the lead-tin or lead-indium overlay. The cause of that, as you say, is extended oil drain periods allowing accumulations of weak organic acids in the oil. Organic acids attack lead that is present in the overlay and in the copper-lead bearing. Corrosion by water in the oil is usually more severe with a good deal of pitting and tracking. I cannot see in your photo whether the big-end bearings are the same. They usually are.

 

[vas]

a belated update as engine is getting ready to be put back in the boat early next week...

first my engine was never a 2GM20F as I thought, after a 150euro mistake I went back cleaned the rocker cover, checked the little label, I now know it's a 2GMFL-G2 (I know up to F-fresh water cooled, no idea what the L-G2 thing is, anyone?)

the "20" means newer engine larger bore by 3mm or so, so both two set of original yanmar rings and a quite expensive original cylhead gasket are in my office, any offers from 2GM20 guys only ?

Apparently cylhead was slightly warped, now both body and head are flat and back together.

Gasket set didn't include the crank front and back seals, didn't even know there are left hand seals, now I know and it costs 15euro...
By the time I add machining costs, second set of rings and gasket, engineer's labour, seals, filters, bits and bobs, I'm getting dangerously close to 1K euro and I'm not at all happy (but have no options either)

cheers

V.