YANMAR 4JH2E

[bretto55]

Hi fellow boaties. This is my first post. I need to remove my cylinder head. Do I need to remove the thermostat housing etc? Or will the head lift off without doing it?

[boden36]

I would expect that the head should lift off with thermostat housing, but if you are pulling the motor to bits you really should not begin until you have a workshop manual and have familiarised yourself with it.

Regards,
Richard.

[bretto55]

Hi Richard,
Thanks for your reply. I think my problem stems from the anti-siphon device. I got the head off and water and salt is in all 4 pots. I tipped lots of eucalyptus in the pots. Hoping that it will free up the rings. Then I can assess the damage.
Cheers
Brett

[GordMay]

Greetings and welcome aboard the CF, Brett.

Service Manual ➥ http://boatinfo.no/lib/yanmar/manuals/4jh2.html#/0

[boden36]

Brett,
For an anti siphon I use a loop which goes up quite high above the waterline on the centre line of the boat. At the top of the loop is a tee which takes a small pipe . (about 3 to 5 mm)
This pipe discharges into one of the cockpit drains so there is a visual indication of water flow and a foolproof siphon break.

Regards,
Richard.

[bretto55]

Hi Richard, thanks for your reply.
I don't know if my pic loaded or not. I've never heard of anti-siphon valve. I think I have found it.

[Alii]

On my 4JH2E the anti-siphon loop is a 5/8" hose that takes off from the exhaust manifold discharge, to a valve about 3" above the waterline, then back to the exhaust elbow via a funny side inlet. None of this as in the Yanmar manual, rather all one-off adaptations. The elbow is not the standard Yanmar for this model.

But it has worked just fine for 8500 hours. Tried to upload photos but that's just not happening.

[bretto55]

Hi , Thanks for your reply.
In the pic the red hose goes to gearbox and black hose the bend in exhaust next to the join flange.