Another 1GM10 question

[Magic_Sailor]

All

I've very nearly completed a full service on my Yanmar 1GM10 engine. I must say it has been excellent fun - very rewarding - saved money and learnt a lot which may be of use in an emergency.

Anyway - my manual says I need to torque the head down and shows a diagram with 4 nuts on it (not surprisingly) numbered in the correct order.

Problem is, I can only see 2. Am I right in thinking that the other 2 are inside the rocker cover?

Thanks for any respondents

Magic

 

[30boat]

Yes you'll have to remove the rocker cover to get at them.Don't forget to apply some gasket cement to the cover when you put it back on.There is probably a paper gasket there but I used anaerobic gasket cement only and have had no leaks.

 

[John7]

I think its rubber, I got one as I am going to check is the adjustment on the valve as a lot of places recommend that checked. The service manual says to says to use Three Bond No 4 (what ever that is) on he rocker arm chamber side. So I take it if the cover comes off with the seal cleanly still attached you can just put it back. I have wondered about is the nut that holds the cover on, I haven’t been able to find out is there is a torque for that?
Out of interest where did you see you need to retighten the head nuts, my owner’s handbook says after 600 hours use and I haven’t seen any thing in my service manual?

 

[jleaworthy]

If you haven't found all the head bolts I assume you haven't removed the head. So why are you torquing it down? Is it really part of the service? Unless you've had a problem I'd be very tempted to leave well alone. I've snapped too many head bolts/studs in the past trying to shift something that's been in place for a long time.

 

[John7]

ThreeBond have come back to me to say 4 is 1104 but I am even more puzzled as this is used "to seal metal-to-metal surfaces such as engine cases where no gasket is used. Can also be used w/gaskets." which doesn't sound like sealing a rocker cover?

 

[john_morris_uk]

The intruction manual with a new 1GM10 says that you have to check the torque on the head nuts after the first so many hours - can't remember how many, but I remember having to do it on our last boat. Also the tappet clearances have to be checked at the same time. I also remember fiddling for ages to fit the rocker cover back on...

 

[John7]

Iv had another look and the only thing Iv found in my hand book is to check the valve clearances after 50 hours and headbolts after 600.

I found differences between the hand book and service manual in some areas, but nothing on the headbolts.

Maybe they have changed it?

What you remember what the problem getting the cover back on was and about
about the seal?

 

[LadyInBed]

Yes, 2 head nuts under the rocker cover. But remember, if you retorque the head, you MUST do the tappets.

How many hours has the engine done?

 

[Guest]

the rocker box has a rubber ring type seal - not necessary to use gasket cement. if fact, better simply to replace with a new ring.
the cylinder head bolts are also the rocker shaft bolts. you need to remove the rocker gear to tighten, but this is simple. you will also need to adjust the tappet clearances afterwards - again simple.

 

[Magic_Sailor]

Less than 100 since last service. nm

.

 

[Magic_Sailor]

Your point is a very good one - as an engineer I agree - generally, if it ain't broke, don't fix it. But

I have no record of the job being carried out at the previous 2 services by the Yanmar agent and the manual says it should be done after 100hrs (I recollect) use.

Also, I want to get to know the engine much better as we're considering a longer cruise and may well need to be self sufficient (money!) Carrying out this service was a way of achieving more confidence - its some years since I used my tools on cars etc.

I've found that it has been great fun and very satisfying - like being a teenager with my first Ford Anglia!

Magic

 

[Jools_of_Top_Cat]

I have the Yanmar service manual on board, worth every penny, covers 1,2,3GM engines, it was not cheap, my father bought it, but has everything you will ever need with respect to servicing, repair etc.

Unfortunately it is 80 miles away otherwise I would have been able to answer your original question.


Julian

http://www.ukstaffords.com