Plastic Plugs in Exhaust Manifold

[Locke]

I recently bought a 2000 Sea Ray with a 7.4L Mercruiser I/O. The starboard exhaust manifold showed some rust on it so I pulled it to investigate. Turns out the leak was caused be two plugs on the backside seeping and when I removed them it turns out they are plastic. The replacement part from my local Mercruiser dealer is steel, so I?m curious if the plastic plug is stock or some strange factory mistake. The portside is dry as a bone.

 

[BAYLINER185]

Re: Plastic Plugs in Exhaust Manifold

I have an 07 BAYLINER w/ 4.3 V6 Mercruser.

The STOCK plugs are plastic blue colored!

Im intregued about those steel plugs your talking about.

I get some water in my bildge area, not a lot and I have a feeling its those damn drain plugs. Ive checked them while the motor is running at idel in the lake but I feel and see no drips so I dont know why I get a little water in the bildge.

But yes my stock plugs are plastic blue colored plugs!

 

[JustJason]

Re: Plastic Plugs in Exhaust Manifold

there's sorta a rule in boat wrenching.... and the older the boat the more it holds true........
what it is, is just because you found it like that... doesn't mean it's supposed to be like that!!

 

[Locke]

Re: Plastic Plugs in Exhaust Manifold

I picked up my replacement plugs today and installed them. The parts guy told me that years ago the plugs were steel then went to plastic and now they're back to steel because the plastic one tended to leak. I had to hunt around to find a 3/4" pipe tap and clean the threads. The plastic drain **** is also metal now. One of these days when I'm really hard up for something to do I'll update the other manifold before it leaks.