JumbleDuck
Well-Known Member
Really? I've always just popped them in by hand. I must be stronger than I thought!
What age is my 1gm10 engine? Recommendation for Yanmar dealer and repair shop?
- Thread starter niallw70
- Start date
cherod
N/A
did you just pop them down the air intake ??
JumbleDuck
Well-Known Member
Not sure I understand. Put head on something - normally a socket - to support the valve, push spring down with one hand, place collets with the other.
cherod
N/A
never done it on the yanmar but done it plenty on car engines years ago , never liked doing it without the tool , maybe yanmar springs are a bit softer , i dont know ,,, anyway , good to read that you do not consider it to be required , for future reference
!!!
awol
Well-Known Member
A lot softer than any car engine I've ever worked on.never done it on the yanmar but done it plenty on car engines years ago , never liked doing it without the tool , maybe yanmar springs are a bit softer , i dont know ,,, anyway , good to read that you do not consider it to be required , for future reference
Slowboat35
Well-Known Member
I've just rebuilt a 3GM30F which is pretty much the same as yours but with 3 cylinders. It too had poor compression.
there are only three places where compresson can be lost.
1) past the cylinder gasket (You'd know if that was blowing)
2) imperfect valve seats
3) past the piston rings
Rocker arm gasket? That's an old wive's tale.
A ten quid kit at the car accessory shop will enable you to lap the valve seats - it's dead easy. You will need a valve spring compressor though - try to borrow one though with a little ingenuity it is possible to do without. I agree with remarks above that the springs aren't paticularly hard. It would be daft not to do this if the head is off anyway.
Check the head carefully for cracks especially between the valve seats. GM series are prone to this and it cannot be repaired.
Is the cylinder bore glazed - by which I mean it has a lustrous shine to its surface? There should be plenty of evidence of spiral machining marks on its surface. If they are absent the bore probably is glazed and that's very likely where your compression is going. (glazing is usually a result of excessive running at idle. ie battery charging. Avoid doing that in future! )The solution is a bit more complex but by no means difficult. If you're up to taking the head off you are quite capable of doing this. Sump off, big end cap off, piston out, new rings and with a £15-20 honing tool and electric drill re-hone the bores. Plenty of videos on youtube to show you how.
The precombustor chamber (concur on the woeful description in the manual) can alledgedly be hooked out of the injector aperture with a piece of wire. In reality they tend to be stuck in too hard for that. On reassembly they just drop back down the 'ole and are held in place by the injector. istr there is a little lug that matches a groove in the 'ole so it goes back pointing the right way.
If you really wanted to remove it I'd try to unseat it with a wooden drift and a tap with a light hammer from the 'inside' face of the head. Can't imagine it would be necessary unless it looks heavily carbonised.
An injector service is always a good idea at this point. Diesel engine and injector specialists are to be found locally.
Fit new valve-stem seals when the head goes back together. (
Parts4engines or Repower Marine are go-to sites for many parts and gaskets and vastly cheaper than Yanmar branded stuff which is always outrageously overpriced.
My compression went from wooly to almost unable to turn the engine over with a ratchet handle. It fired up first touch of the button and is utterly transformed.
If you did all this (it took me 2 days on my 3GM) I think you'd find you had an engine that runs like a new one.
Honed bore before reassembly
Glazed bore
reground valve seat
reground vale
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JumbleDuck
Well-Known Member
I've done it that way on Herald and DS engines. Mind you, I was too skint to afford a spring compressor then.never done it on the yanmar but done it plenty on car engines years ago , never liked doing it without the tool , maybe yanmar springs are a bit softer , i dont know ,,, anyway , good to read that you do not consider it to be required , for future reference
JumbleDuck
Well-Known Member
I had to smash mine to bits to get it out. Luckily the complete set of bits needed wasn't too expensive, especially at US prices.
Slowboat35
Well-Known Member
Two of mine blew out while I was turning the engine over for a compression test!
I certainly wouldn't make any more effort to remove one than a few gentle taps unless it looks really crudded up. Cleaning out the little apertures with a toothpick is probably as far as you'd need to go, and an injector service, valve lapping and new rings should ensure it stays clean in the future.
niallw70
Active Member
Thanks to everyone who's just responded, especially slowboat35, you've probably made the definitive goto page for anyone with compression issues on Yanmar engines!
Just tried to take pic of bore to ask your opinion, even with my cemera on lowest megapixel setting, ybw forum wont accept due to size (maybe format jpg not accepted) Anyway put some diesel down the bore to check for leak, eventually (2hrs later) had to suck it out again with syringe. Also draining my engine oil so no issues there. The cylinder bore looks ok to me, a very light smearing of soot on the bore. I'm thinking the head gasket could also be leaking, even though the head was last fitted by pro mechanic seems he didnt apply sealant between gasket and head. The gasket is adhered to cylinder side but nothing on head side??
Just tried to take pic of bore to ask your opinion, even with my cemera on lowest megapixel setting, ybw forum wont accept due to size (maybe format jpg not accepted) Anyway put some diesel down the bore to check for leak, eventually (2hrs later) had to suck it out again with syringe. Also draining my engine oil so no issues there. The cylinder bore looks ok to me, a very light smearing of soot on the bore. I'm thinking the head gasket could also be leaking, even though the head was last fitted by pro mechanic seems he didnt apply sealant between gasket and head. The gasket is adhered to cylinder side but nothing on head side??
niallw70
Active Member
Those guys talking about removing valves, you must be using a G clamp to compress the v spring?? Or some special tool that allows you to compress and get access to collets to release spring pressure.
As i write waiting on machine shop getting back to me with price to service my CHead. If less than £100 think i will let them deal with it.
As i write waiting on machine shop getting back to me with price to service my CHead. If less than £100 think i will let them deal with it.
awol
Well-Known Member
You do not need sealant on cylinder head gasket. Correct torquing of bolts in correct order and retorquing after IIRC 50 hours is all that is required.
awol
Well-Known Member
Bounce the valves by tapping the top plate with a light hammer to loosen the collets and do like the video above with a suitable spanner - the springs are not strong.
GrahamP
Well-Known Member
To help you date your 1GM10, mine has a serial number of 10255 and was installed in 1995.
Graham
Slowboat35
Well-Known Member
Niall,
If your cyl. head gasket was bleeding compression you'd have fumes in the boat and muck and soot all over one side of the engine and engine bay. It would also sound odd. You'd know about it!
No sealant or grease is used on reassembly according to Yanmar. I take it they assume the wads of $ your gasket costs is enough to seal the pressure in. It bloodywell needs to be! (try parts4engines/repower marine instead)
You've already got the engine dismantled and are half way to solving the problen - ie head off. Don't waste your good efforts so far by trying/hoping that a lazy approach of a half-measure will fix it. With the head off it's daft not to re-lap the valves and if the bores look shiny it's not much extra effort (really, it isn't!) to finish the job and ensure your compression is guaranteed to be restored instead of taking a half-assed gamble...
I know there's always a worry that work you start might you might begin a snowball effect. On this particular route a head job and hone the bore is a self-contained event. You're disrupting nothing else. The tetchy fuel metering and injection pump isnt being touched (I wouldn't dare!) and injectors don't even have to be removed from the head.
Parts required are head gasket, rocker box gasket (sorry - extreme Yanmar ripoff unless you find someone with a gasket making kit - try asking around...) valve stem seals and a set of rings. You may need/want a valve spring compressor and will need a valve lapping kit. Bet ypu can borrow one of those too. No! Fuggit! You pay postage, I'll loan you a piston slipper, grinding paste and the honing tool. As long as I get them back! Tutorials on their use are on youtube aplenty.
This is very basic stuff! You've got the confidence to take the head off, that's by far the hardest thing with the torques involved (getting my head bolts undone required a 24" extension bar on the socket and a fence post wedged in the starter motor aperture to my arse to heave against. 75Ft/lb? To undo them must have taken twice that!
I have never taken a diesel apart before. It's a breath of fresh air - really! There's no timing to screw up! The iron work is identical. Don't be intimidated, it's just a bolted together bit of lump of iron just like any other.
Seriously, my first foray into a diesel rebuild convinced me that they are actually easier (though perhaps grubbier) to work on than a petrol engine as long as you stick to the mechanical as opposed to the 'fuel-draulic' bits.
You'd have the piston out and on the bench in half an hour.
You'll spend barely half hour cleaning the coke off the top of the piston and checking ring/land clearance with a feeler gauge if you are that bothered. An hour packing the bottom of he bore with a protective barrier (cardboard and rags) against carborundum debris and then honing and cleaning the bore, ten minutes more fitting the new rings, ten minutes putting the piston into the slipper and tapping it into the bore, ten minutes fitting the big end cap and torquing the bolts and another ten refitting the sump. Reassembling the rest of the engine with cyninder head already done is a couple of hours max. You'd do all that in an afternoon!
Seriously - it's a doddle! You're almost there already!
And the result is an old engine that suddenly is transformed into an apparently new one!
It'll give your starter motor a nasty surprise! The compression mine now has bears no resemblance to what it used to be.
PM me if you want to borrow the tools.
If your cyl. head gasket was bleeding compression you'd have fumes in the boat and muck and soot all over one side of the engine and engine bay. It would also sound odd. You'd know about it!
No sealant or grease is used on reassembly according to Yanmar. I take it they assume the wads of $ your gasket costs is enough to seal the pressure in. It bloodywell needs to be! (try parts4engines/repower marine instead)
You've already got the engine dismantled and are half way to solving the problen - ie head off. Don't waste your good efforts so far by trying/hoping that a lazy approach of a half-measure will fix it. With the head off it's daft not to re-lap the valves and if the bores look shiny it's not much extra effort (really, it isn't!) to finish the job and ensure your compression is guaranteed to be restored instead of taking a half-assed gamble...
I know there's always a worry that work you start might you might begin a snowball effect. On this particular route a head job and hone the bore is a self-contained event. You're disrupting nothing else. The tetchy fuel metering and injection pump isnt being touched (I wouldn't dare!) and injectors don't even have to be removed from the head.
Parts required are head gasket, rocker box gasket (sorry - extreme Yanmar ripoff unless you find someone with a gasket making kit - try asking around...) valve stem seals and a set of rings. You may need/want a valve spring compressor and will need a valve lapping kit. Bet ypu can borrow one of those too. No! Fuggit! You pay postage, I'll loan you a piston slipper, grinding paste and the honing tool. As long as I get them back! Tutorials on their use are on youtube aplenty.
This is very basic stuff! You've got the confidence to take the head off, that's by far the hardest thing with the torques involved (getting my head bolts undone required a 24" extension bar on the socket and a fence post wedged in the starter motor aperture to my arse to heave against. 75Ft/lb? To undo them must have taken twice that!
I have never taken a diesel apart before. It's a breath of fresh air - really! There's no timing to screw up! The iron work is identical. Don't be intimidated, it's just a bolted together bit of lump of iron just like any other.
Seriously, my first foray into a diesel rebuild convinced me that they are actually easier (though perhaps grubbier) to work on than a petrol engine as long as you stick to the mechanical as opposed to the 'fuel-draulic' bits.
You'd have the piston out and on the bench in half an hour.
You'll spend barely half hour cleaning the coke off the top of the piston and checking ring/land clearance with a feeler gauge if you are that bothered. An hour packing the bottom of he bore with a protective barrier (cardboard and rags) against carborundum debris and then honing and cleaning the bore, ten minutes more fitting the new rings, ten minutes putting the piston into the slipper and tapping it into the bore, ten minutes fitting the big end cap and torquing the bolts and another ten refitting the sump. Reassembling the rest of the engine with cyninder head already done is a couple of hours max. You'd do all that in an afternoon!
Seriously - it's a doddle! You're almost there already!
And the result is an old engine that suddenly is transformed into an apparently new one!
It'll give your starter motor a nasty surprise! The compression mine now has bears no resemblance to what it used to be.
PM me if you want to borrow the tools.
cherod
N/A
the valve compression tool actually looks kinda like a big G clamp
cherod
N/A
i am assuming that you have the engine unit on the floor and not in situe in the engine bay ,,, do the cylinders seperate from the block ( lower section ) ? honing ? , i always thot that was a machine job, are you suggesting doing that with the cylinders still bolted on ?? how ?
niallw70
Active Member
For Cherod, the block is still on its mountings on boat. Loath to take out again (quite a confined space its in under the cabin doorway on my Nic26)as i remember the work, blood, sweat first time, and then i had the missus to help.
The various contributers have convinced me to have a go myself as machhine shop quoted me £200 plus cost of spares/consummables.
Another thing puzzling me, for the long suffering followers of this thread! New cylinder head gaskets (as shown in online supplier pics) come with two holes for push rods, 4 for stud bolts, and only 2 more holes for water/coolant circulation.. but the head and block each have 6 holes presummably to allow extra coolant circulation if required. Its probably not a concern for me, Im unlikely to ever reach the Carribean (or maybe, who knows) but are the two small holes in gasket (one elongated the other circular diameter just 6mm enough for circulation round cylinder jacket?
The various contributers have convinced me to have a go myself as machhine shop quoted me £200 plus cost of spares/consummables.
Another thing puzzling me, for the long suffering followers of this thread! New cylinder head gaskets (as shown in online supplier pics) come with two holes for push rods, 4 for stud bolts, and only 2 more holes for water/coolant circulation.. but the head and block each have 6 holes presummably to allow extra coolant circulation if required. Its probably not a concern for me, Im unlikely to ever reach the Carribean (or maybe, who knows) but are the two small holes in gasket (one elongated the other circular diameter just 6mm enough for circulation round cylinder jacket?
Slowboat35
Well-Known Member
I was of course referring to an engine on the bench. In sutu it really isn't practical or even possible to get the sump off. That's deffo an engine out job.
JumbleDuck
Well-Known Member
That's the issue I referred to above - you need to know which way to fit the gasket, and they often don't say. It seemed to work for me when assembled OK, but it's a bit disconcerting.