1.8L exhaust manifold dumping water.

[the MfM]

Or use one of them expandable rubber plugs.

 

[Neutron]

No concern that it can’t pop out in the future being permanently epoxied?

I have done this on jetskis that rust through the manifolds. As long as its a real good epoxy that can take heat it will be fine

 

[Cambo]

Get a cheap water alarm from amazon that runs on a 9v battery this will give you an audible signal that water is filling up the hull. Every boater should have one

 

[B0at1n]

Got a handful this time. Hopefully the next one is all I need!

 

[Scottintexas]

@Julian - can we ask our contacts at Yamaha what the purpose of this plug is for ? it's not mentioned in my shop manual and especially since it's at different locations on the MR1 vs. 1.8l motors and that in 10+ years with yamaha's I've not heard of another member loosing this part,


.

 

[Tyguy]

If those new ones pop out, next question to ask is whether or not there's excessive pressure building in the manifold, and the plug is the weakest part of the system and first to give out.

 

[Neutron]

@Julian - can we ask our contacts at Yamaha what the purpose of this plug is for ? it's not mentioned in my shop manual and especially since it's at different locations on the MR1 vs. 1.8l motors and that in 10+ years with yamaha's I've not heard of another member loosing this part,


.

The purpose of the plug is to block off the hole used to empty out the "sand" or whatever is used when they cast the part

 

[Scottintexas]

The purpose of the plug is to block off the hole used to empty out the "sand" or whatever is used when they cast the part

any idea why mine also has a plug with square fitting next to it ??

.View attachment 130738

 

[Scottintexas]

The purpose of the plug is to block off the hole used to empty out the "sand" or whatever is used when they cast the part

I would normally believe you without question but....

my "plug" is on an entirely different piece than his ??? should every cast piece have this plug ?

 

[Neutron]

Not sure. Could be a different void.
Freeze plugs have been used for many many years and were to solve the problem of blocking off the void. That square plug could be for an optioned part on a different application

 

[Neutron]

I would normally believe you without question but....

my "plug" is on an entirely different piece than his ??? should every cast piece have this plug ?

Yours is an mr1 his is a 1.8 totally different animals but anything cast has to have a way to get filler material out. Now whether they plug the hole or weld over it like brp does is up to the manufacturer. The material has to come out somewhere

 

[B0at1n]

So conclusion to the questions of what this is for is just for getting the sand out of the mold. It has no use that correlated to he motor running other than plugging g the hole?

I put one back in it with loctite on it. Let it sit for 45 mins. Hose testing it the plug stays in but when I put my finger on it there is a small amount of water coming through just enough for the temp of my finger to be damp.

I did rev it a few times in the hose and see if it would shoot the plug out. Up to even 7000 rpms and it didn’t.

granted water pressure is not the same on the hose.

If this is has no use then my next step I think will be trying to epoxy the whole thing in.

I’m debating if I should take it down to the lake to run it and pop the plug out so I can epoxy all of it. Or if I should just epoxy over it the way it currently is?

 

[Bluewater272]

I wouldn't bother epoxying over it, not sure it'll add much strength. Pull it, put a fresh one into a bed of epoxy and give it enough time to cure per the package.

Just my $0.02

 

[jmargo]

How is the water flow out the exhaust ?

 

[Neutron]

A freeze plug should not go in easy. It should be a very tight fit. But i would not use locktight. It has no real sealing properties. Use Indian head sealant like @the MfM stated. Thats what we used back in the days of building chevy engines

 

[Neutron]

remember there will be more pressure when the outlet of the exhaust is in the water

 

[AZMark]

So conclusion to the questions of what this is for is just for getting the sand out of the mold. It has no use that correlated to he motor running other than plugging g the hole?

I put one back in it with loctite on it. Let it sit for 45 mins. Hose testing it the plug stays in but when I put my finger on it there is a small amount of water coming through just enough for the temp of my finger to be damp.

I did rev it a few times in the hose and see if it would shoot the plug out. Up to even 7000 rpms and it didn’t.

granted water pressure is not the same on the hose.

If this is has no use then my next step I think will be trying to epoxy the whole thing in.

I’m debating if I should take it down to the lake to run it and pop the plug out so I can epoxy all of it. Or if I should just epoxy over it the way it currently is?

They are there for casting but they have the name FREEZE plug because if your motor has water in the cooling passages and freezes hard they should pop out and keep from cracking or warping your engine/head/manifold.
If you have no worry of that ever happening then epoxy away.

 

[Scottintexas]

They are there for casting but they have the name FREEZE plug because if your motor has water in the cooling passages and freezes hard they should pop out and keep from cracking or warping your engine/head/manifold.
If you have no worry of that ever happening then epoxy away.

So my "freeze" plug is on the top of the uppermost fitting in the exhaust system

Being in position it would still protect for freezing??

 

[Neutron]

Here is a good definition and description of a freeze plug
core plug

They are not designed to pop when frozen ice builds up behind it. But it can do just that because its a weak point

 

[AZMark]

any idea why mine also has a plug with square fitting next to it ??

.View attachment 130738

Inspection port? Is it the size of a 3/8 ratchet?

So my "freeze" plug is on the top of the uppermost fitting in the exhaust system

Being in position it would still protect for freezing??

I guess it should theoretically still blow open like a beer cap in the freezer. I don’t know how effective they always are.
Since these are open cooling systems they are probably mostly for casting purposes.
That other one you have might be an inspection port or a place for another coolant line on a different model, maybe with an inter cooler?