violent shaking on mercrusier 120 i/o

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

Check timing and dwell too. Dwell is VERY important. If your ganna keep the boat, buy a dwell meter. Feeler guages just are not as precise as a dwell meter.

timing is good. i dont have a dwell meter, but it was set right, i dont think it would change by itself.

 

[Alumarine]

Re: violent shaking on mercrusier 120 i/o

timing is good. i dont have a dwell meter, but it was set right, i dont think it would change by itself.

Timing would change if the "distributor cap kept moving"?

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

Timing would change if the "distributor cap kept moving"?

the new cap wasnt moving, just the old one.

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

pull the plugs and see if #4 is rusty or wet.may have popped a hole in the riser killing #4 cylinder

i checked the plugs and #1 and #4 were wet but not rusty. i didnt check 2 and 3 to see if they were wet or not.

 

[JustJason]

Re: violent shaking on mercrusier 120 i/o

well.... i think a compression test is in order here.

 

[Bondo]

Re: violent shaking on mercrusier 120 i/o

i checked the plugs and #1 and #4 were wet but not rusty. i didnt check 2 and 3 to see if they were wet or not.

Ayuh,... Take it to a Mechanic.....

It appears you're not capable...Or you just don't want to be bothered with doing it Right....

 

[cooter2506]

Re: violent shaking on mercrusier 120 i/o

were the plugs wet from water? If so you need to find where it is coming from

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

well.... i think a compression test is in order here.

weve test that and it was to specs.

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

Ayuh,... Take it to a Mechanic.....

It appears you're not capable...Or you just don't want to be bothered with doing it Right....

i didnt have time to check all 4 of them. number one we had loose already and i just check #4 because of the post someone put on here.

btw there are no mechanics with in a hundred miles from here, our town has 42 people in it.

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

were the plugs wet from water? If so you need to find where it is coming from

they were wet with gas, but i think it was from running the engine the day before, when we adjusted the carb, it might of been getting to much gas.

 

[JustJason]

Re: violent shaking on mercrusier 120 i/o

So... what where your numbers?

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

So... what where your numbers?

i dont remember, we tested it last fall. all i remember is it was within specifications.

 

[JustJason]

Re: violent shaking on mercrusier 120 i/o

well... time to test again. It's 1 of the very first tests you do in diagnosing a problem.

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

well... time to test again. It's 1 of the very first tests you do in diagnosing a problem.

ok, why would the compression change from when we tested it before and now, the engine hasnt been run since the test, besides a couple days ago where it ran for less than 5 mins?, just wondering. i did some more looking in the book and it says that in the exhaust manifold it could be corroded. and there could be a hole in between the intake and exhaust, that was one thing the my friend said.

 

[JustJason]

Re: violent shaking on mercrusier 120 i/o

a small hole inbetween the intake and exhaust ports isn't going to do anything. You'll either suck a little air into the exhaust, which does nothing, or blow a little exhaust into the air, which doesn't do a whole lot either.

Even if you were sucking a small amount of water into 1 of the cylinders it wouldn't hurt much. If you were chugging a ton of water, as in just enough not to hydrolock it, it will make it run like crap. But if there was that much water, when you pull the plugs(step 1 in the compression test) It will be rusty. If your dead set against redoing the test (because I know it takes AGES) on a 4 banger... Throw a set of brand new plugs in it, run the snot out of the motor for a few minutes, then let it sit for a day or two. Pull the plugs out and see if any rusty.
If you can't do that..... take it someplace.

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

a small hole inbetween the intake and exhaust ports isn't going to do anything. You'll either suck a little air into the exhaust, which does nothing, or blow a little exhaust into the air, which doesn't do a whole lot either.

Even if you were sucking a small amount of water into 1 of the cylinders it wouldn't hurt much. If you were chugging a ton of water, as in just enough not to hydrolock it, it will make it run like crap. But if there was that much water, when you pull the plugs(step 1 in the compression test) It will be rusty. If your dead set against redoing the test (because I know it takes AGES) on a 4 banger... Throw a set of brand new plugs in it, run the snot out of the motor for a few minutes, then let it sit for a day or two. Pull the plugs out and see if any rusty.
If you can't do that..... take it someplace.

ok, thanks. were gonna work on it tommorow and see what we can do.

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

a small hole inbetween the intake and exhaust ports isn't going to do anything. You'll either suck a little air into the exhaust, which does nothing, or blow a little exhaust into the air, which doesn't do a whole lot either.

Even if you were sucking a small amount of water into 1 of the cylinders it wouldn't hurt much. If you were chugging a ton of water, as in just enough not to hydrolock it, it will make it run like crap. But if there was that much water, when you pull the plugs(step 1 in the compression test) It will be rusty. If your dead set against redoing the test (because I know it takes AGES) on a 4 banger... Throw a set of brand new plugs in it, run the snot out of the motor for a few minutes, then let it sit for a day or two. Pull the plugs out and see if any rusty.
If you can't do that..... take it someplace.

ok, we did a comp test and 1 and 4 were 140, 2 and 3 were 150. the spec on the motor is 140.

 

[JustJason]

Re: violent shaking on mercrusier 120 i/o

how'd the plugs look?

 

[nightsniper1]

Re: violent shaking on mercrusier 120 i/o

how'd the plugs look?

they were alittle wet. when we rolled it over with out the manifold on the 4th cyclinder valves, one of them had some blow back. were probably gonna get a new head for it.

 

[J. Mark]

Re: violent shaking on mercrusier 120 i/o

Why a new head. If compression is good your valves are seating and your head gasket isn't blown (well probably)

A leak down test will tell you more without pulling the head off.