1989 Merccruiser 3.7 CLY Head leak ?

[karayj]

So I started the boat today shot a little starter fluid and she started up and then I heard a noise and exhaust noise and I said what the hell is that. Well upon looking a little bit closer, I noticed a leak that looks to be like a freeze plug, I may be wrong. Now I’m just looking for some advice. I really don’t want to change the entire head. Do they sell this where I can pop it out with a screwdriver and put the new one in or do we get Mr. JB Weld involved? Im hearing drill out install new one. . Also what do I have for a head I heard it would be a Ford.
290 ?

 

[karayj]

Are they 460 heads actually and the 43/64 expansion will fix 555-120 part .666 expansion cap ?

 

[matt167]

Yup. That's where the EGR would have went. They are off the shelf 460 heads.

 

[karayj]

Yup. That's where the EGR would have went. They are off the shelf 460 heads.

Now I have to find the correct part. My research leads me here

https://shop.advanceautoparts.com/p/dorman-steel-cup-expansion-plug-43-64-in.-height-0.270-sold-by-each-555-120/22140416-P

 

[matt167]

.666 thermactor plug. Napa probably has them

 

[karayj]

OK, so I’m really confused because looking at the picture and some videos I’m seeing an expansion plug and then listening to other people here I’m getting stories about screwing it in. Now I don’t see any threads on mine so I’m really confused because according to my research, I have an identical head of a 460 ford . And that looks like it should be a plug not something you screw in so now I’m getting two different sets of stories here and it’s pretty confusing. So which one is it for the 3.7 MerCruiser cylinder head is it a screwing or is it a cap?

 

[karayj]

Are you suggesting that I pop the expansion plug out that’s already in there and then put in this thermal plug as a way of plugging up the whole rather than waste my time putting another expansion plug-in. My plan was to remove the existing expansion plug and try to get another one in there if I can’t get it done and it’s not clean then as the last effort I put in your thermal coupling. Because once you put that item in there if it doesn’t seal properly, you’ve destroyed your option to seat another expansion plug-in.