Shoot!!! Cracked crankcase, hoping to remove exhaust to get it welded without removing engine

[Beachbummer]

So, very unfortunate, spent a few weekends looking for a leak that was eluding me... Turns out the crack in the crankcase leaks when hitting 6500rpm+ and does not leak below that.

Since engine removal increases the effort exponentially (and it's the port engine) I'm hoping to remove the exhaust to get better access (it's right by the nipple that then goes into a hose to each of the exhaust headers.) I'm hoping this will provide additional access to allow a weld for a repair.

I know a few people have already removed the exhaust without removing the engine, I'm hoping for some tips on the best strategy. Do I remove the bottom 10 bolts hooking the header? Out try to disconnect further up?

Greatly appreciate all tips!!!

 

[Brad_Ct]

Removing the exhaust with the engine in the boat can be done but it is a PITA. I have a 2006 but it should be the same as your 08, you will need to take the exhaust off in three pieces by removing the bolts that come up from the bottom into the upper manifolds first then remove the manifolds.

 

[Beachbummer]

Thanks,

I only need the manifolds off....

Any tricks for accessing the bolts on the engine side?

Do i need to undo the bottom bolts, or can the manifold come out attached if I undo the joint from the pipe as it joins the other exhaust piece near the air intake?

Thanks!!!!

 

[Brad_Ct]

If I remember correctly the manifold for the outer two cylinders needs to come off first so you can get to the bolts for the manifold for the inner cylinders. The problem is that the manifolds are bolted to the pipe that come up towards the front of the boat. In order to take the manifolds off separately all the bolts that come up from underneath that attach the manifolds to that part of the exhaust need to come out.

 

[Beachbummer]

The first picture is for reference, Not my engine. (The second one is mine)

The right-most bolt in the manifold to engine set was not accessible without removing the pipe.(Bolt marked 1 in the picture - bolt is not very visible...but it's there, right most bolt of the manifold). Maybe with a low profile socket it's possible, but not sure. I loosened the other end of the seal to that pipe (marked 2, there is the outer boot visible and then under 2 other hose clamps), along with the 10 bolts from the bottom and the 1 extra bolt holding the pipe to the engine (way under the #1) and after a lot of wiggling and effort and hammering it finally came off the manifolds. That allowed me to unbolt the blocked bolt (Same marked 1), and as you mentioned I removed those 4 bolts on the the outer piece first to remove that one and then access and unbolt the inside piece.

What I did not expect is how tight and stuck together everything is after the bolts are removed. with the dowel pin and the gasket, it was some effort to manage to separate every piece. I'll wait for a warmer day to apply the steel stick and reassemble. Even with the exhaust removed I can only see the crack with a mirror, so welding while the engine is inside the boat does not seem possible, unless they can weld with a mirror with such poor access. Maybe a magician or contortionist.



Thanks for the assist and guidance. It sure took a while, but it is off!!!

 

[Neutron]

Picture of the crack and area would be nice

 

[Beachbummer]

Something is failing in my rinse procedure. There was a lot of gummy debris in the passages even though these exhaust pieces were replaced 3 years ago with used but intact pieces. I generally flush for 2-3 minutes, most of the time with the tow valves closed for more water pressure.

I did notice something unexpected when I was troubleshooting and disassembling... It seems a good deal of water remains in the block and exhaust. when I removed the hoses in the picture a lot of water came out... but it does not explain the salt when I've been carefully rinsing after every outing for the last 3 years. the smaller middle exhaust manifold piece has consumed/corroded about a third the margin between the water jacket and the exhaust on one port on one small area at the very top. I'm replacing it, but clearly something about the rinsing is not working correctly.

 

[Beachbummer]

Removing the exhaust was very hard, but installing it back was even harder. I struggled a great deal to get it to align with the header bolts. It was not an easy job at all to do with the engine in the boat. I did need to loosen pipe 1, which required removal of the throttle body to reach the inside bolt

But it's done.

I tested it today and it appears to be holding well.

Picture before reassembly.

 

[Neutron]

Removing the exhaust was very hard, but installing it back was even harder. I struggled a great deal to get it to align with the header bolts. It was not an easy job at all to do with the engine in the boat. I did need to loosen pipe 1, which required removal of the throttle body to reach the inside bolt

But it's done.

I tested it today and it appears to be holding well.

Picture before reassembly.

I would be very surprised if that will hold long term. Did you grind the paint off and get a good clean surface. I would have tig welded it and never worried about it again.

 

[Beachbummer]

I did grind around quite a bit, but ol the access was very poor. You could barely get in position to see the crack. I can't imagine welding without engine removal. There's just no room.

There's ready very minimal water pressure, I've had very good luck with these products in the past. Time will tell. It's a 17 year old engine. If the repair does not hold I might try again, and if it does not hold then, it might be time for a rebuild anyway. We'll see.

 

[Cobra Jet Steering LLC]

I know I always flush my engines using a special pig tail hookup between the flush fitting and the hose, I use car wash soap with the liquid wax in it and it works quite well also leaves a film to coat the water jacket walls to help reduce any corrosion and build up in it.
I also let it idle for 20 to 30 seconds with the water off but NEVER rev it up as it is bad for the valves and timing chains. The m r 1 engines seem to have more of an issue with buildup in the cooling jackets than the 1800 engines .

 

[Beachbummer]

The exhaust of the MR-1 is very sophisticated, and has more room for challenges in my opinion.

Yesterday to test a theory, I used another hose to send water to the outlet holes while rinsing. First the engine cooling exit above the jet drive, which resulted in highly improved engine pisser power, then I did the same with the exhaust outlet located on the transom plate, and sure enough, the exhaust pisser came alive with plenty of water

I read from this that without more water engines are not getting fresh water everywhere during rinse


If you look for all the water in oil MR-1 issues, most are caused by corrosion on the header allowing the water jacket to pour water into the exhaust. It's a rare problem, but it's happening to some boats for sure

I'll be trying a few things this winter to see how i can improve this for my boat. I have 2 different directions... One is to decrease the exit sizes while rinsing... Maybe 2 plus with a smaller hole.... The other is to add a water inlet on the exhaust side to increase the water volume there. The idea is to increase pressure allow freshwater to reach all passages

 

[Cambo]

On the yamaha jet boaters someone did the engine block jb weld fix and reported a year later that it was holding fine and put a decent amount of hours on it. My theory of the MR1 exhaust breach and what happens. It happened to my 2005 boat and I try to catch any water in the oil posts and give them the info of this possible cause. In my case I felt some cavitation but the boat got up and ran at speed. Pissers flowing fine was about an hour away from my ramp engine light came on felt the pisser water was cool no noticeable difference. Thought it may be a bad sensor since this had happened to a few members. We had a few areas that had slow no wake speeds and the slight cavitation was there. Pulled the clean outs checked for sea grass very common occurrence in my area. A few pieces removed kept going after pulling the boat out and inspecting the jet pump i found a small piece of wooden branch wedged in the pump. What must have happened the wood caused cavatation airating the water and the cooling efficiency was impaired in the area needed the most the water jacket at the exhaust manifold. The aluminum melted away and breached in the manifold.