mecury sport jet 120 boo boo

[skmpmm2002]

Hi I own a mercury sportjet 120 1995 on a regal<br />boat.<br />My father and I noticed that I had a leak comming from the exhaust manifold at the gasket.<br />So we decided to try to change it out.<br /><br />WELL.Two of the bolts broke off at the Top of the bolt (the bolt heads)so no real big deal we can deal with that right.<br /><br />The problem was that the manifold would not come off easy because the bolts were hanging it up .<br />NOW i have a big problem I have somehow put a Hole in the block at the manifold .<br /><br /><br />My question is can this be welded or glued back together or am i Screwed.<br /><br />Thanks Peter

 

[DHPMARINE]

Re: mecury sport jet 120 boo boo

A repair may be possible,can you post a picture of what you did ?<br /><br />DHP

 

[skmpmm2002]

Re: mecury sport jet 120 boo boo

I am unable to put the pictures I do have up on line but I can send them to you in an email.<br /><br />I will also keep trying to get them on here in some sort of link.<br /><br />thanks Peter

 

[Capt Ken]

Re: mecury sport jet 120 boo boo

The bolt head broke off due to the corrosion around the bolts that has them frozen. Removal of the manifold will be near impossible while in the boat. Remove the engine and get it somewhere that you can work on it easily. The bolts will probably have to be drilled out. Until you get the manifold off, don't worry about the block.

 

[eli_lilly]

Re: mecury sport jet 120 boo boo

Since I see this problem mentioned a lot, I'd like to ask in advance, is there any way to _keep_ the bolts from corroding?

 

[funpilot]

Re: mecury sport jet 120 boo boo

I'm not sure how much can be done with corrosion on a boat motor, except regular flushing (after every sea water use) and rinsing with fresh water. The Sport Jet has a consumer flushing kit which does a job of flushing the engine, and you can also use a garden hose adapter on the hose to the engine to flush it. Don't run the Sport Jet engine without water, or on the consumer flushing kit.<br /><br />On assembly of a motor, you can apply antiseize to the threads, which is a gray slippery paste. You need to reduce the torque values if you do, as it will be easier to turn the bolt and possibly stretch the threads in the aluminum to failure. I reduce by 15%.<br /><br />I'm sure better guys than I have thoughts, I'm your basic home wrench.<br /><br />fp

 

[skmpmm2002]

Re: mecury sport jet 120 boo boo

We cut the bolts, the manifold is off, I am getting the new gasket today, we are going to drill out the old bolts and replace them. I am still stuck with the dilema of the chip that came off the block. The chip is in the shape of a crescent, about 1 inch wide and 1 1/2 inches long, any suggestions for repair?

 

[funpilot]

Re: mecury sport jet 120 boo boo

Without knowing exactly where the damage is, I would have to say that a one inch wide crack is daunting. My recommendation would be to take the block out of the boat (if you haven't already) and take the block to an experienced boat motor shop, and get their opinion as to whether it is repairable or not.<br /><br />If it isn't, a Force style block from a 120 outboard may be the best choice. On your sport jet, the crank is different from the outboard models because of the splines which mate to the jet pump. This may necessate an engine rebuild either way, because I would be leary of applying a lot of heat and distortion to the block with other parts inside.<br /><br />Make sure that the block you buy is compatible with the pistons you have, but chance are new pistons will be needed because the block will probably need machining, or it wouldn't be a used block. You have to keep the crank case and the block together as a pair because they are bored for the crank as an assembly.<br /><br />good luck<br />fp

 

[Capt Ken]

Re: mecury sport jet 120 boo boo

I got a block for a 120. Problem is, it has a exhaust manifold stuck to it also. Only way to keep the bolts from corroding is not to use the boat in salt water.