Hmmmm....GIL says that "silver" was a factory finish for small block risers. Powdercoat?
Since Corsa took on Gil 6 years ago, they don't have info on the older product.
Good point on the chip...maybe the finish coating is suspect.
Anyone know the proper operating temp range for an exhuast riser?
Maybe the boats not in danger, just the finish on the riser.

I don't know the actual temp, but I can place my hand on mine with the engine running.

Thanks Griff. I'll see if I can get near them while running.
BTW - Good flow through the exhaust while muffing and idling thru harbor.

If that setup has an Alfa drive, it doesn't pump enough water at idle to reach the top of the riser. We recommend welding up the bottom two or three holes of the riser to force the water to the top.

Alpha is correct. Good call, Brownie!
Sounds like you've seen or done something like this before.
Just to make sure I'm clear on what your're saying....there's a sleeve inside the riser with holes at various points to disperse cooling water. By sealing the bottom 2 or 3 holes, I'll reduce cooling a bit on the lower riser, but will increase cooling flow at the top of the riser. This should be done equally on all 4 risers.
Questions:
Start with sealing 2 holes and go to 3 later, if not enough cooling to top of riser?
How will this affect the riser / manifold connection area (flange?), which also look to be heating up? See pic 2.
Appreciate your help. Dave911

In that case, don't try putting your hand on the riser

Matt from Mobile Marine in Huntington Beach diagnosed and hopefully fixed the problem (need to run her first).

Upon removel of the GIL risers, Matt noticed there was no clearance for cooling water between the inner and outer sections of the top of the riser. Meaning cooling water was being forced to the side and away from the top of the riser where the paint was cooking. Likely a manufacturing defect.

To remedy, the 2 hot risers were removed, split, re-welded and then re-powder coated to allow cooling water to hit the top of the risers.

Hopefully this will end the saga, without resorting to external cooling.

Thanks all. D911

Nice, Thats how I check for cooling also
Jr.

Matt just put Stainless Marine manifolds on my boat. Good dude!

Good luck with your boat!

Oh and the manifolds are really nice! I'm very happy with the work and the product.

The heat / discoloration problems have been remedied, with testing complete at both low and high-speed!

Thanks to Matt et all for your input. D911