motor problem

[lynnboy021]

my 5.7 omc motor has a knocking noise when cold and then when it warms up the noise goes somewhat away. the motor had 2 bad head gasket and the guy left it alone, so the motor was almost getting stuck but it did not so i installed two new head gaskit new plugs and i just did a oil change with 30w oil and a fram ph30 oil filter. i think i am still off timing alittle but the motor has no problem starting up and the oil press is at 40 or 60 i forgot and when you give gas it has a ***** load of power and you do not hear any kind of noise at all. so my ?s are

1. would alittle off timing couse it?
2. would old gas maybe 1 or 2 yr old gas couse it?
3. do i need new lifters?
4. can it be piston slap?

you hear more of the noise at the back of the motor.... 88 omc 5.7

 

[Bondo]

Re: motor problem

(A),...so the motor was almost getting stuck but it did not
1. would alittle off timing couse it?
2. would old gas maybe 1 or 2 yr old gas couse it?
3. do i need new lifters?
4. can it be piston slap?

1, 'n 2, No...
3, lifters click or rattle, but don't Knock...
4, might be related to (A), which is probably the Real cause of the Knocking...

 

[lynnboy021]

Re: motor problem

so is the motor junk? the thing is that the cyl walls are nice and clean. so should i take the heads off and see if there is play on the pistons?

 

[oldsub86]

Re: motor problem

Take the motor out, take off the oilpan, and have a look at the bearings.

Randy

 

[lynnboy021]

Re: motor problem

i really dont think its coming from the oil pan area but i will check tomorrow.. the thing is that my boat is only a 22ft but the motor is so deep into the boat that i need like a car lift to remove the motor

 

[lynnboy021]

Re: motor problem

plus i dont get it when the motor is really cold its really loud then its somewhat quiter but the motor does not shake does not stall out on idle you really cant hear the noise and when you give it gas you only hear a really nice smooth motor like its brand new motor.. like i said i put new topend gaskits and i just tight up the lifters cuz i was going to start the motor up and then adjust them by when you hear the tapping noise tight up the nut till its gone then give it a half turn thats how i do it. so my bro in law help me out and when he was adjusting the lifters thats when that noise came so tomorrow i am going to remove all the push rods and see if its not cloged or bent and then adjust them the way the manual says it and i will post back.... oh and if you put the engine cover back on you cant even hear the motor running..

 

[trihull59]

Re: motor problem

It probably is piston slap and the reason you hear it go away when it warms up is because the tolerances in the motor get smaller when it warms but it might not be. The best thing to do is pull the oil pan check those bearings and see if they have any excessive wear. They shouldn't have any major scoring on them and if they do its time to replace, but if you did all the work to look at them and they look fine you mine as well replace them because you will most likely need to eventually anyway. Also to see if there is piston slap (I think) you need to measure the cylinder walls from one side to the other with a micrometer or some sort of precise measuring tool then see when the measurement should be. But if you need to hone out the cylinders and buy pistons, it might be cheaper and easier to get a new motor from a junk yard, the junkyard by me has boats with I/O and O/B not the common case for many though

 

[Joshua Nichols]

Re: motor problem

You should post a video... That would be cool...

Here is a test for piston slap I found online.. Pretty sharp fella

First thing in the morning, start the engine up and run it for 15 seconds while you listen carefully and memorize the sound and it's intensity. Shut it down quickly, pull the spark plugs and put two squirts of motor oil into each cylinder. Reinstall the plugs, fire the engine up again and listen.

If you have piston slap the noise will have been greatly reduced or even eliminated?..for 15 or 20 seconds that is, and then your nightmare noise will come back like a Marine Corps marching band coming toward you in the parade.

Did you check for sloppy pistons while ya had the heads off?

 

[lynnboy021]

Re: motor problem

ok guys here is the video of my motor hope this helps and i hope you guys can help me.... http://www.youtube.com/watch?v=OAmELWDLKxY

 

[Joshua Nichols]

Re: motor problem

AHHHHH better... You know I noticed you was wondering, if it is outdrive noise... Pull the outdrive off and start the engine and see.. Super easy test...

It sounds like yall might of bent a pushrod giving the work yall did.. You coulda checked for piston slap when had the heads off, but too late now..

Yank the valve covers off.. Roll the push rod on a flat surface.. If one is bent.. It is pretty easy to find it that way... Might as well completely check over the valve train again.. Some times folks get in a hurry and mess up.. I have done it before.. It happens.. open that oil cap and listen...

Sometimes you can one plug wire at a time to help find rod bearing noise ( doesn't sound like that to me).. The cylinder doesn't fire, hence less stress on the bearing and it will not be as loud...

Since it almost goes away when warm I wanta say piston slap too

Good luck post your findings

 

[lynnboy021]

Re: motor problem

ok i took the motor apart well the topend and i was looking for cracks on the cyl walls and i could not find any just incase. looked at the valves and they are both closed nice and tight then i was playing with the pistons and the pistons are also nice and tight no play up down left or right. but i did see water in the middle of the motor where the intake sits so i also looked for cracks and cant find any and yes the gaskits are all new. so here is what i am thinking maybe my back lifters are no good cuz sound comes from the back and plus when i tight up the rockers to remove the lash, the valves always stays open and the motor wont run but if i adjust the lifters like the book says on some maybe 6 out of 16 are nice and tight and other 10 are lose or i am getting oil mixed with water. i did not see any water in the cyls or in the exhoust/intake ports and when i was adjusting the valves clean oil was coming out the pushrods but i had to stop cuz i ran out of oil and there was oil everywhere lol...

 

[Joshua Nichols]

Re: motor problem

So you took the head off again?

 

[lynnboy021]

Re: motor problem

yep and i did not see anything wrong

 

[trihull59]

Re: motor problem

Thats def a pushrod hitting the rocker arm. They either need an adjustment or one or more of the push rods are clogged up. When you did everything did you take a air nozzle and spray the rods out there is a little hole on each end which feeds the upper end of the motor with oil for the rocker arms ect if they are clogged you can get that noise because there is nothing lubricating the rocker arm when it hits each time

 

[lynnboy021]

Re: motor problem

yes i did and then i point the pushrod to the sky and it is clean from one end to another. i really do think that i have collapsed lifters, why? cuz some of the rockers are nice and tight so i think the rockers that are tight, the lifters must be good and then i have some rockers that have play so i am thinking them lifters are bad right? i called my friend that sells me boat parts and i showed him the video and told him what i did he said that i have collapsed lifters. he said that he will sell me all 16 lifters for me for $50.00 so i should just put in all new lifters right? tomorrow i am going to see if my pushrods are bent...

 

[lynnboy021]

Re: motor problem

oh and the rockers that are tight, oil comes out flying and the ones that are not tight hardly any oil comes out..

 

[Bondo]

Re: motor problem

i really do think that i have collapsed lifters, why? cuz some of the rockers are nice and tight so i think the rockers that are tight, the lifters must be good and then i have some rockers that have play so i am thinking them lifters are bad right?

Nope,... Not really...
As the motor is rolled over, the rockers will be tight, or loose depending on which valves are opening or closed...

 

[lynnboy021]

Re: motor problem

bond-o yes your right but it should not be so loose that you can almost stick your little finger between the rocker and the valve right??

 

[Joshua Nichols]

Re: motor problem

You stuck the rods back in the holes they came out of and all that good stuff correct?... And God no thats too much gapage

Since you got the heads off again... Stick ya some new lifters in there if ya want..

 

[lynnboy021]

Re: motor problem

Joshua yes i am just going to put in new lifters pushrods and rockers eventhough the pushrods and rockers look really good.