Hello i have a 26 foot formula with twin 4.3 mercruisers one of then is leaking water to the inside trough the exhaust Y pipe end side that seals with transom side i posted a video to be more exact , i need to know thats necessary to repair this problem is my first boat thanks here is the video of the Y flange leaking http://youtu.be/ZYMccnovm-E http://youtu.be/ZYMccnovm-E

Water will leak into the boat even when it's not running. And it will rot the transom if not addressed

easiest is to pull the motor to get to it unless you have access to an 18" tall mechanically inclined anorexic midget. Sorry to be the bearer of bad news...

Ok thanks buy my question is do you seal it from the inside or the out side or both sides ? Someone told me I have to.remove engine and drive is this true?

Yes - you need to yank the engine. The Y-Pipe bolts up from the inside and it would be impossible to get to with the engine installed.

That is a lot of water leaking too and the transom is exposed there from the inside so you need to fix this sooner rather than later. It sounds daunting the first time through, but it will be easy..... Lots of help to be had here on OSO so feel free to ask a bunch of questions.

i take it this is on land with a hose to the drive? cuz this is a BIG leak. will leak worse when engine is shut off. do NOT put this in the water!! not even for a 10 min test drive. something goes wrong and it quits 100 yards from the ramp, you could be in real unpleasantness real quik.

Yea the video was on land with the hose on I brought this boat 3 month ago and I found out about the leak just after lowered through the ramp it got full of water till the oil pan in less of 5 minutes I really want to fix this before the colombus day regatta here in Miami

then pull tjhe motor right away...it is probably a bad y-pipe. a dropped bolt or socket into pipe will rot it out cuz of differential metal electrolysis. where are you? i have a y-pipe. but shipping is a bit of a hassle for something that big. a quik leak test is to pull motor and back boat down the ramp. then u can really see what's going on.

I remove the drive today and pulled the motor forward the y pipe is rusted and the bolts were to long and stuck thats why it wasn't sealing what am going to do is seal the exhaust from the outside with a rubber cap and also eliminate the Y pipe if I can then go with straight pipes thru the transom and problem solve what do you guys think?

Would probably work. You better have a LOT of confidence in that "cap"