Merc 153 cu.in. 4cyl excessive oil leak

[redgoat]

My 43 year old Sea Ray with a mercruiser 153 cu in stern drive has a bad oil leak on the starboard side of the engine--the side with the plugs, oil filter, fuel pump and distributor. Oil is splattered over a large portion of the engine on this side and eventually drips to the bilge area. Boat runs fine and I monitor the oil level frequently and add as needed. My question is where is the leak(s) probably coming from? And what gasket needs to be replaced to stop it. And finally, what would be an estimate of cost to have this done? Does the engine have to be pulled from the boat? Would I be money ahead by just continuing to add oil when low over a huge repair bill for a gasket replacement. The intake/exhaust manifold gasket, valve cover gasket and mechanical fuel pump gasket have all been replaced recently. So the leak must be somewhere else.

 

[EddiePetty]

Re: Merc 153 cu.in. 4cyl excessive oil leak

....well, the place to start is in the driveway with a five gallon bucket under the open drain plug.

Soak the cold engine down with your favorite degreaser, rinse and allow to air dry. (catch the degreasing liquid in the bucket)
Hook up the muffs, start the engine and lie down beside the engine with a flashlite and towel in hand.
Report back with your findings!!!

 

[Bt Doctur]

Re: Merc 153 cu.in. 4cyl excessive oil leak

lifter gallery gasket, oil pressure sender

 

[redgoat]

Re: Merc 153 cu.in. 4cyl excessive oil leak

Where is lifter gallery located and oil pressure sender located? Is oil pressure sender round with a threaded end that screws into engine? And where might I get these gaskets?

 

[marlboro180]

Re: Merc 153 cu.in. 4cyl excessive oil leak

The lifter gallery is the thin looking metal plate bolted onto the starboard side of the block.

Degrease the bilge/ block to determine where it is coming from, as Eddie said...

 

[redgoat]

Re: Merc 153 cu.in. 4cyl excessive oil leak

I finally got the correct gasket for the lifter galley. In attempting to remove the 4 bolted plate, I encountered a problem with the distributor being in the way. Does the distributor need to be removed before the plate can be fully pulled away from the engine allowing me to replace the gasket? If so, what steps do I need to follow to R&R the distributor? I have never removed a distributor in my life. Is it difficult to do? Will I need to reset the timing after the distributor is replaced?

 

[bigskiohio]

Re: Merc 153 cu.in. 4cyl excessive oil leak

pull the cap and mark where rotor is then pull it and drop back in so it is the same

 

[redgoat]

Re: Merc 153 cu.in. 4cyl excessive oil leak

I assume from the responses that the distributor MUST indeed be removed before I can change the lifter gallery gasket. I do have a genuine Mercruiser shop manual but the instructions are not totally clear. It talks about marking the direction of the rotor and about marking something else on the rotor. Also, does this distributor drive the oil pump? If so, that's something else I'll have to contend with when I replace the distributor. Also, if I remove the bolt that fastens down the distributor won't I have to readjust the timing when the distributor is replaced? It would be nice if someone could just lead me by the hand and explain step by step how to R&R this distributor. I've located the oil leak and know how to stop it but this distributor is in the way. I don't want to mess up my 43-year-old Sea Ray.

 

[ziggy]

Re: Merc 153 cu.in. 4cyl excessive oil leak

yes, ya gotta remove the dist. to R&R that lifter cover.

ya can pull the dist. where ever it stops at. but ya gotta put it back where ya found it.

or ya can bring #1 piston to tdc on the compression stroke and the rotor will point to #1. put the dist. back pointing to #1. the line the s/m talks about is just so ya orient the rotor the same as it was when it came out.

when ya pull the dist. the rotor will turn as the dist. comes out. when ya put it back, compensate for it turning as it'll turn back the opposite direction when replacing it. it needs to end up right where ya left it when ya removed it. hence the scribed line the s/m talks about.

if ya can't get it to drop into the hole. the very bottom end of the dist. is just like a flat blade screw driver. it drives the oil pump. look at it's orientation and stick a screw driver down the dist. hole and line up the slot that the dist. mates too.

worse case is it get's all messed up. which will be hard to do unless ya turn the engine over. still no biggy. ya will just have to go through a few more steps to get it back in right.

yer gonna have to make the move. like in do it. go slow. watch what happens when it comes out. do the reverse when ya put it back.

mark everything. spark plug wires. where wires go to the dist. etc.
take photos even. then you'll have a reference.

good luck on stopping that leak. i had to do my covers more than once for a persistent leak... of course mine was the ft. cover which requires dist. removal too... good 'ol murphy..

 

[redgoat]

Re: Merc 153 cu.in. 4cyl excessive oil leak

UPDATE ! ! !
Thanks to all who submitted advice and suggestions for correcting my oil leak. I was able to replace the lifter gallery cover gasket which was the source of my leak without too much trouble. The old cork gasket was replaced with neoprene. I did have to R&R the distributor for the first time. I just marked the direction the rotor was pointing and marked the location of the distributor body in relation to the engine by using whiteout. Putting the distributor back was a challenge. It took perhaps 40-50 tries to get the bottom to mate with the oil pump cam AND still line up with everything. But I DID IT! Rechecked my dwell and reset the timing and the old Sea Ray is ready for the water. No leak found after running engine on driveway. Really proud of myself for tackling this job. Probably saved $100-$200.

 

[daydreamer1252]

Re: Merc 153 cu.in. 4cyl excessive oil leak

Congratulations redgoat.....half of what this forum is about is exactly what you
state....proud of a job well done...to that add the bonus of saving money and the people you meet along the way....it doesn't get much better