VOLVO exhaust riser bolts

[pine island fred]

Got involved today with a friends VOLVO PENTA. Could not get any nbrs. off the engine, it is an 06, 350 block, raw water cooled. Risers are secured with 4 bolts, 3/8 diam. , 8 ins long. Big risers. We replaced the gaskets and when he was torqueing bolts in front bolts, they would get tight and then get loose.
Last time he replaced the gaskets he did encounter problems with pieces of thread coming out with the bolts. Question is, the threads in the manifold. Are they tapped directly into the manifold cast iron or are they somekind of heli-coil or pressed in insert? He will be pulling the boat and taking it to the dealer so my assistance is done, but am just courious as he did not seem to be putting excessive force on the bolts. thanks FRED

 

[Bondo]

Re: VOLVO exhaust riser bolts

Are they tapped directly into the manifold cast iron

Ayuh,... Right into the base metal, be it cast Iron, or Aluminum, or SSteel...

 

[bruceb58]

Re: VOLVO exhaust riser bolts

Are you using a torque wrench and tightening to the torque listed in the manual?

 

[zbnutcase]

Re: VOLVO exhaust riser bolts

Sounds like he might need some Heli-Coils installed. 'nutcase

 

[bruceb58]

Re: VOLVO exhaust riser bolts

Sounds like he needs that or new manifolds.

 

[JustJason]

Re: VOLVO exhaust riser bolts

Sounds like he might need some Heli-Coils installed. 'nutcase

Sounds like he needs that or new manifolds.

Sounds more to me like pine island fred needs to buy a tap and die set and learn how to use it.

Seriously... Whenever you remove a bolt, especially something from a rusty/corroded hole or something that has serious torque value... You need to run a die on the bolt (unless your making the executive decision to use new bolts) and run a tap down the hole. Followed by some compressed air.
If you don't tap and die... at the very least you need to clean the threads with some compressed air. I've been doing this for years, and now a company has an all in 1 kit. But for holes I choose not to tap clean, I use metal (not the nylon cheapies) gun brushes for cleaning bores of guns. I stick them in the old dewalt cordless and have at the hole, followed by compressed air. ANYTHING you do to clean up bolts and holes will make it go together easier (and more importantly... get rid of false fastener torque)

 

[rodbolt]

Re: VOLVO exhaust riser bolts

Fred
if he was pulling threads the threads are simply done.
time for the quick and easy heli coil treatment if the manifolds are still ok.
its not uncommon in the salt pond for cast iron to simply rot .
dealer is either gonna replace or helicoil the manifolds.

should have heli-coiled them the last time.
they work great.
next time your in town Ill show ya how to install them.
BTW I bought a house on a canal in colington harbor.

 

[pine island fred]

Re: VOLVO exhaust riser bolts

Thanks all for your replys. Gentleman does have a torque wrench. Bolt are torqued in a strange to me unit. Something like KRUGERRANDS per CUBIC CALORIES but his wrench is set up for that. His initial torque was something like 11 units and then 30 units. Could not get past the initial torque. I stayed above deck and just watched while trying to support those monster risers.
What was strange to me is that it was the front riser bolts that were the problem even though they are easy to get at while the back bolts which are a bear to install tighten down correctly once you get them started. Just a side note. Friend had ordered new bolts from VOLVO. No way you are going to install them in the aft position. They have the built in washer type flair under the hex. Riser casting is to narrow to pass the bolt head and you are also not going to get a 9/16 socket on the bolt until you get them started by hand. Maby a thin wall socket would work.
While I am rambling, just a thought. Why the 8 in. bolts on the back of the riser? Can understand the long bolts at the front to secure the riser and support it as it is a convenient place to stand or sit on but why the back? Seems to me 1 in. bolts thru the riser flange to maniford would be sufficient in the back. Might be missing something like harmonics and that area prone to corrosion that I am missing but think it would be worth considering. Talking enough.
RODBOLT, know where you live. Remember the late evening/ night high speed run to the BLUE CRAB? No check points there. Did not think you had as much beer as I did. Will have to do it again. regards FRED












When I get involved with

 

[rodbolt]

Re: VOLVO exhaust riser bolts

now that ya mention it yep, I remember the run.
just enough daylight to run for a beer then back to the dock.
can ya post a picture of the riser.
sounds more like either the old style risers or something just aint quite right.
with an 06 they should be the OMC syle 4 inch but be aware not all the bolts are always the same length.