scottie
Well-known member
Maybe time to start the post again
Engine does not give full power after x years without use perhaps ?
Engine does not give full power after x years without use perhaps ?
Possible gearbox trouble - oh woe
- Thread starter Robert Wilson
- Start date
charles_reed
Active member
To summarise - certainly not a slipping gearbox.
The other things to check:-
1. if the exhaust elbow is blocked, usually cleaned out every 1000 hours. Take it off and clean it out.
2. Lack of compression due to worn or sticking rings. Have a compression test carried out.
3. Overpropped. put on the old 2-blade propellor.
Worn oil seals or guides are just a red herring - put up lubricating oil use.
However - if I understand that your sump seems to miraculously fill itself - its definitely broken rings.
The other things to check:-
1. if the exhaust elbow is blocked, usually cleaned out every 1000 hours. Take it off and clean it out.
2. Lack of compression due to worn or sticking rings. Have a compression test carried out.
3. Overpropped. put on the old 2-blade propellor.
Worn oil seals or guides are just a red herring - put up lubricating oil use.
However - if I understand that your sump seems to miraculously fill itself - its definitely broken rings.
Robert Wilson
Well-known member
Pertinent, and may be the cause, but what is the process?
Time will tell as I go through the possibilities and eliminate one by one!!
Thanks
Robert Wilson
Well-known member
1. Accepted. May be the next process to be eliminated, or may be the answer!
2. Investigating local source of compression tester.
3. Already replaced the old two blade. It made a miniscule improvement.
The sump doesn't miraculously fill itself in the few seconds it takes to put the dipstick back in. But it does miraculously show adequate oil on the dipstick.
This phenomenon is apparent after a long period of engine non-use. e.g. a month.
So it may, or may not be rings. If the problem isn't cured in the next few days//week I'll wait til the off-season and attack the whole engine. Possibly new injectors and pump. To get at the rings, valve stems etc it'll mean the engine out and this will have to wait until I have enjoyed some sailing.
Thanks for your contribution.
LittleSister
Well-known member
I find it hard to believe it’s piston rings, valve stems or seats, etc Presumably the motor was running fine before lay up, so not engine wear. and presumably starts fine now (as I cannot recall you mentioning problem) so it ain’t compression problem.
Presumably the dipstick mystery is longstanding and predates the loss of power.
Prop size has been eliminated.
Still looks to me like not enough fuel getting in or not enough exhaust getting out.
Presumably the dipstick mystery is longstanding and predates the loss of power.
Prop size has been eliminated.
Still looks to me like not enough fuel getting in or not enough exhaust getting out.
NorthUp
Active member
when the engine/ boat was laid up, did you plug the exhaust outlet? It's common to have whatever exhaust valve was open to develop corrosion on the seat and valve face in a damp atmosphere ( eg Scotland!)
Is the engine firing on all cylinders? Crack open the injector pipes one at a time while running at idle, the rev drop should be equal if each cylinder is doing its share.
Is the engine firing on all cylinders? Crack open the injector pipes one at a time while running at idle, the rev drop should be equal if each cylinder is doing its share.
Steve_N
Well-known member
Apologies if this has been suggested before as I haven't read the entire thread but in post #15 you (Robert) mention a change in prop blade to hull clearance due to perhaps not clamping the shaft as far back in the coupling as before.
Is it possible then that under thrust, with the shaft being slightly further forward than before, the forward face of the prop boss is now contacting the aft face of the cutless/shaft log/P bracket (whatever you have..) and that you are getting losses due to friction at that point? The shaft would spin freely by hand when unloaded but when the engine mounts flex under forward thrust extra drag would be introduced.
Probably a stupid suggestion but I thought I'd throw it in there.
Is it possible then that under thrust, with the shaft being slightly further forward than before, the forward face of the prop boss is now contacting the aft face of the cutless/shaft log/P bracket (whatever you have..) and that you are getting losses due to friction at that point? The shaft would spin freely by hand when unloaded but when the engine mounts flex under forward thrust extra drag would be introduced.
Probably a stupid suggestion but I thought I'd throw it in there.
Robert Wilson
Well-known member
Not stupid at all, and an error I could be quite capable in making - but this time I'm in the clear (no pun intended!).
There is a good gap. Actually, I have checked the location of the shaft in the coupling and it is almost spot on compared to its initial position. I think my concern stems from never having really considered the props closeness to the hull. It's probably been like that since I bought the boat.
Thanks for your input.
Robert Wilson
Well-known member
Another item on the ever-lengthening check list.
Something in the back of my mind is beginning to nag away at either damage to rings n seats, or injector pump. Of course, after inspecting the exhaust elbow.
Thanks for the alert to plug the exhaust next lay-up/winter.
charles_reed
Active member
"The sump doesn't miraculously fill itself in the few seconds it takes to put the dipstick back in. But it does miraculously show adequate oil on the dipstick."
All the small Yanmars, at least the 4 with which I've been involved, seem to need to have the dipstick taken out and replaced before checking the level.
Unfortunately for all the immediate diagnoses in the thread, the only way to check out possible causes for engine power reduction is to carry out a series of tests, in inverse order to their probability.
If the engine has done more than 8000 hours it's probably least tedious to replace it.
All the small Yanmars, at least the 4 with which I've been involved, seem to need to have the dipstick taken out and replaced before checking the level.
Unfortunately for all the immediate diagnoses in the thread, the only way to check out possible causes for engine power reduction is to carry out a series of tests, in inverse order to their probability.
If the engine has done more than 8000 hours it's probably least tedious to replace it.
NorthUp
Active member
Maybe drain the exhaust water lock too when laying up..
RichardS
N/A
Tranona
Well-known member
Many waterlocks have plugs at the bottom for just that purpose, including the popular Vetus types.
macd
Active member
...in fact the Vetus NLP you (rightly) recommended has two such valves, one for each chamber.
Robert Wilson
Well-known member
Gee, thanks
That advice is directly proportionate to the crap weather up here today made worse by listening to reports of the continuing "Mediterranean" weather over the rest of Britain.
RichardS
N/A
I think mine is a Vetus watertrap but I've never noticed any drain plugs. I think mine is plastic or GRP rather than metal but I've never looked at it that closely. I don't know if that makes any difference but I'll have a look next time.
Richard
macd
Active member
The NLP type, as said, definitely have drains (more a valve than a "plug"). Other Vetus versions may have a different arrangements. They've been injection-mouled plastic for ages, but of course many boats will have older stuff of differing materials which works perfectly well.
charles_reed
Active member
Gee, thanks
That advice is directly proportionate to the crap weather up here today made worse by listening to reports of the continuing "Mediterranean" weather over the rest of Britain.
Just trying to save you a lot of time and heartache - having been there myself with a 2GM - it becomes a very large hole in the pocket!!!
Robert Wilson
Well-known member
From talking to the late previous owner, during his ownership and then my own I estimate the usage to be about 1,000hours - BUT, he installed an ex-dumper truck unit from his plant fleet.
So, it's possible your 8,000 hours may be a big problem.
Big hit on my finances, but I'm getting tired of scrambling around in tight, dark, painful spaces and coming home stinky and filthy- and I'm not as lithe as I used to be.
I know it won't add the overall purchase and installation costs to the sale value of the boat, but I want to enjoy fear- and hassle-free sailing.
So, it's possible your 8,000 hours may be a big problem.
I'm now looking at racking-up some large expenditure for parts and labour because I'm at the limit of my own DIY abilities.
If the next tests (exhaust, injectors/pump) prove a failure then I'm thinking of a new engine plus various ancillaries. Big hit on my finances, but I'm getting tired of scrambling around in tight, dark, painful spaces and coming home stinky and filthy- and I'm not as lithe as I used to be.
I know it won't add the overall purchase and installation costs to the sale value of the boat, but I want to enjoy fear- and hassle-free sailing.
Kinsale373
Active member
Hi Robert,
Ive been watching the thread and as I've been suffering with issues on a Hurth ZF15 for the past year I appreciate the frustration.
My issue was that regularly my Z15 (on a Volvo 2040) would not go into foward gear correctly. It would drive the prop ok but without enough power to accelerate the boat or apply enough power for a quick turn. Stopping after reversing into a marina was fun!
Sometimes after 3-4 secs it would finally "clack" into gear and away I went full power.
I believed I had the dreaded slipping plates. I made contact with Mike Pilkington of Pilkington marine who are long time agents for ZF Hurth.
The first thing Mike asked me to do was to disconnect the gear change cable completely from the Gear change lever at the box and operate the gears on a sea trial manually with someone below changing gear, You can do it tied to a marina. I found that in my case the box seemed ok and I had full power with the cable removed. The tell tale for correct gear selection is the defined " clack" from the box when it goes into gear correctly.
Mike Sent me on a set up procedure for adjusting the Cable and the gearbox lever. I went through this as best I could with the gearbox still in position and I managed to get to the situation where it now goes into gear most of the time and If not i go back to neutral and on 2nd attempt it always goes in.
I was surprised at how detailed and fine the set up procedure is for the gear change. It comes down to +/- 2 mm of movement. There is a fine adjustment on the plate that holds the gear lever itself to the box. Im waiting for the end of season to take out the box and repeat the procedure properly. I think that it is in the realms of possibility that you adjustment was knocked out during re propping.
Ill send you a copy of the ZF set up if you want to have a look. Send me an EMAIL address.
Just some thoughts,
I presume you have put the box into neutral and rotated to shaft by hand to see if there is any resistance?
Have you tried disconnecting the gear change cable at the gearbox and changed gear manually at the box to see what happens?
Do you have the loss of power in both forward and reverse?
I found Mike Pilkington of Pilkington Marine to be incredibly helpful and he has has many years exeprience on these gearboxes. I wouldnt hesitate to contact him before making any changes.
best of luck with it,
Kinsale 373
Ive been watching the thread and as I've been suffering with issues on a Hurth ZF15 for the past year I appreciate the frustration.
My issue was that regularly my Z15 (on a Volvo 2040) would not go into foward gear correctly. It would drive the prop ok but without enough power to accelerate the boat or apply enough power for a quick turn. Stopping after reversing into a marina was fun!
Sometimes after 3-4 secs it would finally "clack" into gear and away I went full power.
I believed I had the dreaded slipping plates. I made contact with Mike Pilkington of Pilkington marine who are long time agents for ZF Hurth.
The first thing Mike asked me to do was to disconnect the gear change cable completely from the Gear change lever at the box and operate the gears on a sea trial manually with someone below changing gear, You can do it tied to a marina. I found that in my case the box seemed ok and I had full power with the cable removed. The tell tale for correct gear selection is the defined " clack" from the box when it goes into gear correctly.
Mike Sent me on a set up procedure for adjusting the Cable and the gearbox lever. I went through this as best I could with the gearbox still in position and I managed to get to the situation where it now goes into gear most of the time and If not i go back to neutral and on 2nd attempt it always goes in.
I was surprised at how detailed and fine the set up procedure is for the gear change. It comes down to +/- 2 mm of movement. There is a fine adjustment on the plate that holds the gear lever itself to the box. Im waiting for the end of season to take out the box and repeat the procedure properly. I think that it is in the realms of possibility that you adjustment was knocked out during re propping.
Ill send you a copy of the ZF set up if you want to have a look. Send me an EMAIL address.
Just some thoughts,
I presume you have put the box into neutral and rotated to shaft by hand to see if there is any resistance?
Have you tried disconnecting the gear change cable at the gearbox and changed gear manually at the box to see what happens?
Do you have the loss of power in both forward and reverse?
I found Mike Pilkington of Pilkington Marine to be incredibly helpful and he has has many years exeprience on these gearboxes. I wouldnt hesitate to contact him before making any changes.
best of luck with it,
Kinsale 373