Bill,
You could plug the hole on the bottom or a portion of it, and drill some holes above, if the water flow above would capture enough to keep the drive cool. It doesnt really matter where the water comes from, just so there is enough flow to cool the insides.
If you had to block it off and couldnt get enough water induced in other holes, you could cool the lube externally.

Same thing happened to mine right about 95mph, but I was also over trimming to get to that speed. I put some jb weld on lower section and rounded the bottom of the inlet.

I thought about that but it seems like JB weld would last about 5 minutes! I also reshaped my inlet a bit to ensure adequate flow at higher trim.

you are boiling the water around the drive causing this..is the prop showing any blueing ? I would talk to a good prop shop like BBlades about this...

FWIW PC 7 epoxy seems much stronger than JB Weld, and Marine Trex is what some people use to mount/blend nose cones. I would tend to think that either one of these products would hold up better than JB Weld.

ive desided it's best not to block off the pickup, but may move it to the top of the cone, but i will have the mark welded up and i will sand the weld down, i have already tried different epoxy's already and they only lasted one run. Like Aqua Banshee, i may be trimmen over a touch. once again Thank's for the info.

When I added my Thru Hull pickups I ran the drive water thru the drive and dumped in out the transom back on top of the drive for extra cooling. This way water runs as intended thru the drive.:kiss:

What I found out was the bottom of the inlet was causing cavitation when trimmed high . I used jb weld and re shaped the lower portion on the inlet made it more round just a little. Also re shaped reduced the upper section to lower water psi. The jb weld has held up for over a year a 90 plus for miles. After that I worked on getting the boat to carry the nose without so much trim and it started getting faster again. I used jb weld cause that is what I had in the tool box at the time. All I know is that what I did and it worked for me.

The cavitation burns on an IMCO lower can be stopped by extending the opening hole all the way to the front tip of the nose of the lower unit. The water needs to be able to run horizontally from the tip of the nose...straight into the intake slot.

I did a lot of testing to find the fix to this.

I noticed that IMCO does not locate the water intake consistantly from front to rear on all the lower units...those placed closer to the nose...have less cavitation burns.

Opening the intake up all the way to the nose has stopped this on two other boats so far besides mine.

Chris