Plastic Manifold drains

[Sundancer]

Last year I replaced the 27 year old original manifolds and risers on my 1989 300 DA with twin 350's. It has only been in salt water a limited number of times since I've owned it (2007). The manifolds were probably OK, I just FELT better replacing all of it at the same time. The kits that I ordered included plastic 90 degree drains at the bottom of all 4 manifolds. Against my own better judgement, I put the plastic ones on the new manifolds. I'm kicking myself now because all four are leaking! It appears that some folks love them and others hate them. So, do I take all four out and replace them or do I just add some Teflon tape and try again with one more twist around so they are pointing at the hoses?

When I winterized, I forgot about the blue plastic drain plugs on those 90 degree fittings and I just pulled the hose off. So, that's not a real big deal! I can't see them anyway! It's down by my toes as I'm working on it and I don't have any eyes down there!! I'm guessing new 90 degree elbows are around $20 a piece, not that it's a cost issue. I think I know the answer!!

What would you do? :huh:


Thanks in advance!

 

[BillK2632]

I am more interested in how your manifolds and risers looked after 25yrs - mine are the old V6 1 piece design, 18yrs in freshwater. I have never replaced a riser or manifold in all my years of (freshwater) boating, but this is the oldest boat I have had and I am starting to think about it.

Back to your drains - I would put some teflon tape or pipe dope on them and give them another twist, if they stop leaking they should be fine. I was looking, the Sierra ones (which appear to be plastic) are $6, but the OEM (which appear to be cast) are $20.

 

[Bt Doctur]

If you use Permatex Aviation sealant on them they wont leak. Being a tapered thread you cont "crank" them in all the way either

 

[KevinC]

Last year I replaced the 27 year old original manifolds and risers...

Ok, now I am a little jealous about manifolds lasting 27 years. :smt001

Anyway, if it seems to be leaking from the connection then they may have just backed out a little from vibration.

I would also try some sealant and see if it works the only problem is sometimes the plastic fittings do get hairline cracks. I would be prepared to replace in the event they are cracked/damaged when removing. My old 260DA had a Mercruiser which had the single point drain with the blue plug and it was leaking. No tightening or sealant were working - only upon closest inspection did I see a hairline crack down in the threads where the plug went in.

-Kevin

 

[Sundancer]

Didn't even think about a hairline crack! I just didn't think it could possibly happen to 4 of them! I'll remove them, add some tape and screw them back in. They are all held in the same position that I installed them in because they point directly at the hose. If they backed out at all, I think I would have noticed. I was pretty gentle and afraid to put one more turn in them, but maybe I was being TOO gentle. I might try that and see what happens. If I think I'm going to break it, I'll remove it and add some Teflon tape.

As far as their appearance, the manifolds were fine but the risers were corroding rapidly due to the salt water. I've seen boats in freshwater from the 80's and the manifolds and risers looked so good you wondered why you even thought about replacing them! It just depends! I did it for peace of mind. I think I might have posted some pics somewhere? I'll see if I can find those after work tonight....

Thanks again for your advice!