New/Returned Manifolds Need Threads Fixed 5.0 GXI

FluffyChicken

Petty Officer 2nd Class
Joined
Mar 29, 2007
Messages
167
Hello,

I was at a local parts shop today and ironically they have two sierra marine 18-1986-1 manifolds sitting in their open box section. $150 each. I was going to pressure test the ones i have but the boat is a 2005 (freshwater though) and I figured replacing at least the manifolds would be beneficial even if they do pass the air test seeing as how my block froze from the previous owner. The only issue upon quick inspection is both manifolds seem to have slightly messed up threads on one of the four riser bolt holes. They appear to have been mounted to the block at one point but dont see any indication that the motor was ever ran with them on. Also the threads seem like they were messed up from the factory not stripped by the previous buyer. So my question is, can I use a time-sert on these manifolds? I could buy a kit and do it myself but was also thinking a shop would probably be pretty reasonable? What might this cost?

Thanks
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,082
Ayuh,..... I'd be comfortable with Heli-coils,....
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
13,024
Those bolts usually get only about 25 ft lbs so that should be ok. Just make sure the sealing surfaces are really flat. That’s the weak spot of this design. The pre cat converter exhaust Volvo used is the wet joint design. Just like what Mercruiser used pre 2002 or so.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
50,230
Fresh water only.... I would not waste my money. Freshwater manifolds last 40 years or when someone screws up winterizing

$300 gets you parts for new motor
 

FluffyChicken

Petty Officer 2nd Class
Joined
Mar 29, 2007
Messages
167
Fresh water only.... I would not waste my money. Freshwater manifolds last 40 years or when someone screws up winterizing

$300 gets you parts for new motor
So just pressure test my originals? Was wondering the longevity of freshwater ones actually. I took the one off today and appearance wise it looks beautiful. The only problem is the previous owners winterization awesomeness. Or should i try the acetone trick? I could make some sort of block off plate out of 1/2 - 1” plexi fairly easily.
 
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