Stainless steel coolant drain plugs

[Southern Pirate]

Has anybody switched the blue coolant drain plugs for stainless steel? If so, did you use teflon tape or anti-seize on them? While out on the river, I noticed a little drip coming from one of the blue plastic plugs. I reached down to tighten and it came off in my hand. After stuffing the hole with duct tape, I was able to slow the spray down and the bilge pump did the rest. Until I made it back to the landing.

 

[scoflaw]

no bro they have o-rings

 

[Skybolt]

Has anybody switched the blue coolant drain plugs for stainless steel? If so, did you use teflon tape or anti-seize on them? While out on the river, I noticed a little drip coming from one of the blue plastic plugs. I reached down to tighten and it came off in my hand. After stuffing the hole with duct tape, I was able to slow the spray down and the bilge pump did the rest. Until I made it back to the landing.

If you do change out to a plug, I would use brass over stainless, but if stainless is what you want, make sure it's 304/316 and not 18-8. 18-8 will rust. Brass won't need anything, but stainless will, I would use anti-seize over tape tape for that.

 

[Lazy Daze]

Just get a new set of the plastic ones. Change them every 10 years or so. You may have originals - getting close to 20 years old, now... they've certainly earned their retirement. The plastic ones are actually quite robust, but age gets to everything eventually. Plus, plastic ones will never cause any galvanic corrosion.

 

[Nater Potater]

If you do change out to a plug, I would use brass over stainless, but if stainless is what you want, make sure it's 304/316 and not 18-8. 18-8 will rust. Brass won't need anything, but stainless will, I would use anti-seize over tape tape for that.

Not meant to call out anyone, but stainless steels are right up my day-job alley. 18-8 is just another name for 304 stainless and is actually the more descriptive form of its alloy percentages: 18% chromium and 8% nickel (could go as high as 10%). For increased corrosion resistance, you're correct that 316 is preferred, shifting percentages to 17.5/11.5 with the addition of 2% molybdenum to add increased resistance to chlorides (think; saltwater). To help you fall asleep, Wikipedia has a pretty good write-up on the subject at https://en.wikipedia.org/wiki/Stainless_steel#Stainless_steel_families

 

[juggernaut1]

Has anybody switched the blue coolant drain plugs for stainless steel? If so, did you use teflon tape or anti-seize on them? While out on the river, I noticed a little drip coming from one of the blue plastic plugs. I reached down to tighten and it came off in my hand. After stuffing the hole with duct tape, I was able to slow the spray down and the bilge pump did the rest. Until I made it back to the landing.

Yes I switched mine on my cool fuel modules and installed them using Duralac. The blue plugs were weeping causing corrosion on the cool fuel module housing around the plug threads. Tried to tighten them but they snapped off.

 

[Fill Ess]

I'm swapping out all of mine to the Hardin plugs this spring along with their seawater pumps. Last fall when I did the winterizing, both plugs in the thermostat housings disintegrated when I took them out. This is not a good time I'm wondering if the PO ever tried to remove them?

Dennis how are you getting these to last 10 years ???

I have a big bag of the blue ones, and I swap them out as soon as they look like they've had enough.

Also the quality varies, based on where you get them. I bought a bag from the MM dealer, and they were expensive but OEM. I also bought some of the cheap ones on Amazon but I'm not sure I can trust them.

https://www.hardin-marine.com/p-810...-plugs-mercruiser-22-806608a02-8m2000874.aspx

 

[Skybolt]

... 18-8 is just another name for 304 stainless and is actually the more descriptive form of its alloy percentages: 18% chromium and 8% nickel (could go as high as 10%). For increased corrosion resistance, you're correct that 316 is preferred, shifting percentages to 17.5/11.5 with the addition of 2% molybdenum to add increased resistance to chlorides (think; saltwater). ...

Thanks for this. I had no Idea that 304 and 18-8 were the same. Question though, 18-8 seems to produce rust marks and in some instances actually will corrode and break, especially the stuff you get at like HD. If I order 304 from say Fastenal it never seems to rust's. But 316 is my preferred SS for use on boats. Interesting read, thanks for posting.

 

[Southern Pirate]

Here in Charleston, we can boat almost 12 months and because of this, draining the cooling system is not that important (on really cold days the boat stays in the heated boat barn). I purchased the stainless steel plugs from HARDIN MARINE because I don't plan on using them like they were intended due to not having to worry about freezing but I also want to be sure I can remove them if needed. I know the o rings seal the passage but that does nothing for galling or galvanic reaction. So for this reason I was asking about tape or anti-seize.

 

[Lazy Daze]

I'm swapping out all of mine to the Hardin plugs this spring along with their seawater pumps. Last fall when I did the winterizing, both plugs in the thermostat housings disintegrated when I took them out. This is not a good time I'm wondering if the PO ever tried to remove them?

Dennis how are you getting these to last 10 years ???

I have a big bag of the blue ones, and I swap them out as soon as they look like they've had enough.

Also the quality varies, based on where you get them. I bought a bag from the MM dealer, and they were expensive but OEM. I also bought some of the cheap ones on Amazon but I'm not sure I can trust them.

https://www.hardin-marine.com/p-810...-plugs-mercruiser-22-806608a02-8m2000874.aspx

Phil, in my area, that seems to be about the norm. Often they last longer, sometimes a bit shorter and the ears break off. But give or take, about 10 years is my experience. I think there's another variable that can partially skew this - and that's over-tightening (not to say that you are doing that, Phil - just in general). They only need to be barely snug. I also KNOW that sometimes people put these back on without the o-ring and then try to keep tightening and tightening... snap.

That's a fair price for those SS ones, though. I'm just a fan of limiting the amount of dissimilar metals.

FYI... for boats I'm working on that have plastic plugs where the ears have broken... I have a 1/2" deep socket that I cut a slot into.

 

[Espos4]

A fresh O-ring every couple of years is a good idea. That drain on the distribution housing is a weak spot so anything you can do to keep from over tightening that particular plug is a good idea. A fresh squishy o-ring will help prevent cracking the housing.

 

[Nater Potater]

Thanks for this. I had no Idea that 304 and 18-8 were the same. Question though, 18-8 seems to produce rust marks and in some instances actually will corrode and break, especially the stuff you get at like HD. If I order 304 from say Fastenal it never seems to rust's. But 316 is my preferred SS for use on boats. Interesting read, thanks for posting.

As with pretty much everything you buy nowadays, there's good and bad. Without documentation, there's no telling what you're getting. Even then...
The aerospace industry has been especially hard hit, as unscrupulous people have been reproducing legitimate-looking documents to go along with their bootleg parts. There's big money to be had there! For instance, the four bolts that hold the vertical stabilizer on a Boing 737 have material analysis performed, then x-rayed for any inconsistencies. You're looking well north of $200 for each of the bolts, but they look just like any other well made 1/2" bolt. It's easy enough to buy some good-looking bolts and strap your made-up tag and sell them at a "discount" to some unsuspecting small airline that's running on a shoestring budget.

 

[Southern Pirate]

A fresh O-ring every couple of years is a good idea. That drain on the distribution housing is a weak spot so anything you can do to keep from over tightening that particular plug is a good idea. A fresh squishy o-ring will help prevent cracking the housing.

Where are you getting the o rings?

 

[Espos4]

Nothing Mercruiser specific. Just pick out the right size from one of those assortment kits.

 

[Southern Pirate]

Nothing Mercruiser specific. Just pick out the right size from one of those assortment kits.

ok thanks