2002 Mecury 150 - Blowing oil out of cylinder

[pamlicopanther]

Well, I have never seen this before.

I have a 2002 150 (carb.) that I bought really cheap with the knowledge it had run hot. I pulled the heads and all looked decent inside so I replaced gaskets. I was planing a rebuild but with how well everything looked I decided to see what she would do. I got it where it cranks up and runs good at an idle, though it smokes like crazy when it is first cranked.

Yesterday I took it for its first water run. When I went to accelerate she would bog out and cut off. Nothing I did could get it to accelerate. I could crank it and go at trolling speed just fine, but could not go any faster.

Today I started by checking the compression to try and find out the problem. I took all the plugs out and ran compression. The bottom left cylinder blows oil out of it when I turn it over. The compression checks out, but again it is blowing oil out of that cylinder. I did try the compression in that cylinder and it hit 250. May have been thrown off by the oil that was blown in it.

So, how do I go about curing this problem? I thought I was about to get on the river and yet another setback.

 

[Chris1956]

Re: 2002 Mecury 150 - Blowing oil out of cylinder

Maybe the fuel pump diaghram is leaking? If so it would suck raw fuel into the crankcase and it could settle in the lower cylinders.

 

[j_martin]

Re: 2002 Mecury 150 - Blowing oil out of cylinder

It's flooding with fuel. Either fuel pump or a needle valve in a carb.

Try pumping it up with the primer bulb, then squeeze it firmly. You'll feel it collapse. Now while doing that open the throttles and look in the carbs. You'll see a flood if it's a carb. If you don't see it there, the fuel pump needs a kit.

It's actually a relatively minor problem.

hope it helps
John

 

[pamlicopanther]

Re: 2002 Mecury 150 - Blowing oil out of cylinder

Thanks guys.

That makes sense, though it is is pretty scary seeing oil shoot out of a cylinder. I will check that out over the weekend.

 

[pamlicopanther]

Re: 2002 Mecury 150 - Blowing oil out of cylinder

It's flooding with fuel. Either fuel pump or a needle valve in a carb.

Try pumping it up with the primer bulb, then squeeze it firmly. You'll feel it collapse. Now while doing that open the throttles and look in the carbs. You'll see a flood if it's a carb. If you don't see it there, the fuel pump needs a kit.

It's actually a relatively minor problem.

hope it helps
John

OK - Let me make sure I did this right.

I squeezed the primer ball. It didn't collapse it just held tight. I then opened the throttles. I do have gas coming out of the lower carb. I would not say a flood, but it is coming out. There has also been a lot of oil coming out through that carb too. Also, the cylinder that was blowing oil out was the lower one and the carb that has the oil coming out is the lower one too.

So, I am thinking that the problem is this lower carb?

 

[j_martin]

Re: 2002 Mecury 150 - Blowing oil out of cylinder

You have multiple problems, most of them just lack of reasonable routine maintenance.

The only thing that goes to the carbs is fuel/oil mix. If there's too much oil, it has nothing to do with the carb. It's in the oil system.

Either way, the needle valves should hold a firm, but not white knuckle squeeze on the bulb. Carb needs rebuilding. You should go through all 3.

Good bet the running hot thing was lack of maintenance also, like replacing the impeller when it needs it, or annually, whichever is soonest.

So your options are to get a manual, sit down, and get caught up on all the routine maintenance, or play Mickey Mouse with it till it blows for good.

 

[pamlicopanther]

Re: 2002 Mecury 150 - Blowing oil out of cylinder

You have multiple problems, most of them just lack of reasonable routine maintenance.

The only thing that goes to the carbs is fuel/oil mix. If there's too much oil, it has nothing to do with the carb. It's in the oil system.

Either way, the needle valves should hold a firm, but not white knuckle squeeze on the bulb. Carb needs rebuilding. You should go through all 3.

Good bet the running hot thing was lack of maintenance also, like replacing the impeller when it needs it, or annually, whichever is soonest.

So your options are to get a manual, sit down, and get caught up on all the routine maintenance, or play Mickey Mouse with it till it blows for good.

It definitely was neglected. You are right about the running hot - I have never seen an impeller as bad as this one was when I changed it. I have the lower unit doing great now, though.

I will move to the carbs now. I already have the shop manual so I am ready to go.

Thanks again for your help.