yamaha 3.0 l4 blew head gasket help!

kenny nunez said:

Be sure to seal the head bolt threads with #2 Permatex or similar compound. Torque the bolts to 100.

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I went by the industrial engine manual and the Yamaha publication also stated 90 lbs is that not correct.

matt167 said:

The engine itself was used by OMC, Volvo and a Mercruiser along with many other manufacturers for things like water pumps and fork lifts. So there is no shortage of parts for them.. where your going to have issue is with anything that is Yamaha specific. You’ll need to get an exhaust riser to fit the exhaust on your boat. It shouldn’t be impossible but you’ll have to figure out what fits.

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I was able to get a low hours head , manifold with riser and even a xtra lower outdrive assembly

kd4pbs said:

Sorry - I was reading that on a little screen without my reading spectacles and thought you were referring to the engine circulating pump.
If the age of the impeller is unknown, replacement is wise.
As far as the thermostat goes, search for these:
Mercruiser 59078
Mercruiser 18-3650
Mercruiser 18-3550

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Thanks for the updated info. I will pull the outdrive and check the impeller. I found a kit that was OMC cobra that will work I’m told. My AZ local store is ordering me the thermostat so I’m just waiting on that & gaskets now. The thermostat gasket is something I’ve not been able to find even off eBay where I found the thermostat housing gasket.

If you just can’t find anything, paper, gaskets are easy to make.

kd4pbs said:

If you just can’t find anything, paper, gaskets are easy to make.

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I found the thermostat gasket and it is paper so I could just make one. My biggest obstacle has been trying to find the exhaust elbow riser gasket. I’ve had people searching tried , eBay companies , wholesale marine , I boat , crowleys. Etc etc. cannot find the gasket they are all a little too big or small and the bolt holes won’t line up. . Any help would be greatly appreciated.
Part number from Yamaha is

I dont think the gasket is available from Yamaha anymore. Yamaha pretty much got sued for blatantly copying other outdrive companies and quit selling in the US about the time your boat was made in the early 90s. most of the parts have been NLA for about 10-15 years

I've pretty much found everything gasket wise except for the riser elbow gasket its metal or something similar and its virtually non existent i have called , texted and emailed dozens of shops ,dealers and e bays sellers and no one can find the right gasket. i ordered 3 of them and they looked like they would fit but always too big or too small where the bolt holes wouldn't match up & no one seems to offer a different brand that will work. mercruiser , volvo,sierra,omc all different & driving me crazy as this is last piece of the puzzle !

You can make that one too. One can find some gasket making sheets at most auto parts stores. I have made riser gaskets out of the thicker gray colored gasket material. Slather that thing with some Permatex #2 and it won't leak.

I was able to make my riser gasket. I’m looking for a diagram of the throttle linkage coming up from under the engine not sure how it’s supposed to go into the y piece mounted on manifold. Does it snap in and lock in place and if so where does the black rubber piece go into relation to the part with the black plastic clip. Should have taken better pictures before I took it apart. It’s been a while and I’m not having much luck. Thanks. Tom

kd4pbs said:

Sorry - I was reading that on a little screen without my reading spectacles and thought you were referring to the engine circulating pump.
If the age of the impeller is unknown, replacement is wise.
As far as the thermostat goes, search for these:
Mercruiser 59078
Mercruiser 18-3650
Mercruiser 18-3550

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Is the engine circulating pump the one under the thermostat housing to the left of it actually. Runs off a belt from the pulley I haven’t checked either this one or the raw water pump not sure where that one is. I wasn’t having an issue with either when it blew head gasket it was from bad manifold and the freeze out plug blowing out of manifold. I’ve got it all almost back together and was going to try and run it on the muffs to get it warmed up so I can change the oil mixed with sea foam and then adjust the valves with fresh oil and a new filter.
Just want to make sure I’ve covered my bases. PS. Can you tell me if the throttle linkage that goes to the y piece on manifold is supposed to be like in picture. I’m not sure exactly how it was before and I can’t seem to get it to secure even with the clip. Thanks tom

My Yamaha I/O was a V8 so I can’t really guide you with the throttle cable issue. There’s a cast iron circulating pump bolted to the front of the engine block that is driven by a belt. My V8 had a separate brass raw water pump driven by a belt, which was mounted near the front of the engine. I’m not sure where it would be on that 3 L. Could you take a picture showing all of the pieces driven by the belt on the front of your engine?