oil leak on 3.0

[Fscott4]

1991 3.0, I took the boat out today for the first time. Runs very well but I discovered an oil leak on the front of the engine near where the large cooling hose connects. Seems to me this would be the timing cover gasket, but since I'm just learning about the marine engines, I have to second guess myself. I am thinking the water pump and timing cover have to be removed and new gasket kit installed, unless someone has some other ideas where to look.
Thanks!

 

[dubs283]

I am thinking the water pump and timing cover have to be removed

And oil pan gasket

Best to remove the engine from the boat and do a complete reseal

 

[Fscott4]

Is the pan gasket integrated into the timing cover gasket? The pan doesn’t leak at all and I would love to avoid engine removal, even though it is the best way.

 

[ROY WILLIAMS]

Is the pan gasket integrated into the timing cover gasket? The pan doesn’t leak at all and I would love to avoid engine removal, even though it is the best way.

remove the timing cover then inspect the pan gasket.
I took off my timing cover and I inspect the pan cover ... cleaned it and I put the sealer of the gasket ..the oil pan is not leaking .. I had to fix the water pump...
if you take out the motor , a lot of money...drop the oil pan ..

 

[QBhoy]

Before going all in and drastic…have you ruled out all other possibilities like over spill from filling with oil and it finding its way to there ? Rocker cover gasket leak perhaps ? Oil over fill perhaps ? Just in case.

 

[dubs283]

Is the pan gasket integrated into the timing cover gasket? The pan doesn’t leak at all and I would love to avoid engine removal, even though it is the best way.

Yeah, it is integrated. Not with the gasket but the lower portion of the cover

Everybody loves the easy way but it's not always the case.

If you really want to replace the timing cover gasket you should remove the engine and do a complete reseal proper

 

[airshot]

My 3.0 also had an oil leak, I was told that these engines went thru front and rear crank seals. After a good long hard run you could see oil but in reality it just looked bad. I was actually using very little oil. Not wanting oil to get into the lake, I bought oil absorbing pads and placed them under front and rear of engine. Over a period of a month with numerous runs I was using less than a cup of oil, but it looked worse. Changed out the pads every month which absorbed all the oil and just let mine go. Over an entire season I used less than one quart of mercruiser 25w 40 oil. The oil mats trapped all the oil so it didnt get into the lake. A case of oil mats was less than 50 bucks .....not worth the cost of a reseal..but, to each his own. Just sold it this spring, and gave the new owner well over half a case of oil mats with the boat. My Islander had lots of room around the engine so changing out the mats was a breeze.....

 

[Fscott4]

It definitely isn’t overfill. I can wipe the oil away and watch it start to drip. I am absolutely not interested in removing the engine and will exhaust every other option in the meantime.

 

[Bondo]

It definitely isn’t overfill. I can wipe the oil away and watch it start to drip. I am absolutely not interested in removing the engine and will exhaust every other option in the meantime.

Ayuh,.... If the boat has been run in the brine, there's a very good chance that the timin' cover, 'n probably the oil pan are rusted through,....

 

[Fscott4]

Ayuh,.... If the boat has been run in the brine, there's a very good chance that the timin' cover, 'n probably the oil pan are rusted through,....

Is this a project that can be done in the boat (regardless of being a pain in the **s) or is there no way of getting around pulling the engine? I dont know if it was run in the brine or not but the oil pan appears to be in great shape, there does appear to be rust on the timing cover. If this project is doable in the boat that would be my preference. I have the boat in one of my garage bays so I can remove the bench seat somehow, take my time and not have to work outdoors in the weather.

 

[Bondo]

Is this a project that can be done in the boat (regardless of being a pain in the **s) or is there no way of getting around pulling the engine? I dont know if it was run in the brine or not but the oil pan appears to be in great shape, there does appear to be rust on the timing cover. If this project is doable in the boat that would be my preference. I have the boat in one of my garage bays so I can remove the bench seat somehow, take my time and not have to work outdoors in the weather.

Ayuh,..... Is it Possible,..?? ya probably,.... but I'd pull the motor,....

As noted above, the timin' cover backs up the front of the oil pan gasket,....
If ya try to lower the oil pan enough to get the timin' cover back into place, there's a very high chance the oil pan will leak later,....

Boat motors are Extremely easy to pull, compared to a car,....

 

[Fscott4]

Well it sounds like Im gonna pull the motor. I do have a chain fall so I can get the motor right out. Any idea what the 3.0 weighs? I am going to assume I dont have to mess with the outdrive at all? just disconnect, pull forward and lift like a typical engine removal?

 

[Bondo]

Well it sounds like Im gonna pull the motor. I do have a chain fall so I can get the motor right out. Any idea what the 3.0 weighs? I am going to assume I dont have to mess with the outdrive at all? just disconnect, pull forward and lift like a typical engine removal?

Ayuh,.... The drive comes off 1st, then the motor is lifted straight up,.....

Installation is the reverse, but the motor has to be realigned, before the drive is reinstalled,....

I'm guessin' it weighs maybe 500 lbs, fully dressed,....

 

[ROY WILLIAMS]

remove the timing cover then inspect the oil leak ...then the oil pan is a break down gasket then take the motor out .............
you have to a couple of persons to take out and put in the motor ..

 

[Fscott4]

Ayuh,.... The drive comes off 1st, then the motor is lifted straight up,.....

Installation is the reverse, but the motor has to be realigned, before the drive is reinstalled,....

I'm guessin' it weighs maybe 500 lbs, fully dressed,....

 

[Fscott4]

OK. I've pulled and installed a number of motors in my time, so I don't see any problems doing the job. Is the marine timing cover the same as the automotive cover? I would like to get a kit with cover and gaskets. The oil pan is in fine condition, so I don't foresee having to replace that.

 

[harringtondav]

OK. I've pulled and installed a number of motors in my time, so I don't see any problems doing the job. Is the marine timing cover the same as the automotive cover? I would like to get a kit with cover and gaskets. The oil pan is in fine condition, so I don't foresee having to replace that.

I replaced a timing cover for a neighbor's son's 3.0L Cobra. It's been a while but I think I purchased an automotive cover. It took a while to find a GM auto application, but the cover worked. BTW, per @Bondo the cover had a rusted hole in the bottom. I first assumed it was the seal.
Also I cheated a bit. I jacked up the front of the engine to get clearance to pull the balancer, etc. Per above comments the gasket is a face gasket for the cover flange with an extension of the pan gasket which is supposed to be pinched between the pan, block and bottom of the cover.
So I cheated again and cleaned everything bone dry, trimmed the pan gasket section a bit, and gooped everything with Permatex Avaition Gasket (Merc Perfect Seal). No leaks. The kid sold the boat so I can't comment on long term success.

 

[Fscott4]

I replaced a timing cover for a neighbor's son's 3.0L Cobra. It's been a while but I think I purchased an automotive cover. It took a while to find a GM auto application, but the cover worked. BTW, per @Bondo the cover had a rusted hole in the bottom. I first assumed it was the seal.
Also I cheated a bit. I jacked up the front of the engine to get clearance to pull the balancer, etc. Per above comments the gasket is a face gasket for the cover flange with an extension of the pan gasket which is supposed to be pinched between the pan, block and bottom of the cover.
So I cheated again and cleaned everything bone dry, trimmed the pan gasket section a bit, and gooped everything with Permatex Avaition Gasket (Merc Perfect Seal). No leaks. The kid sold the boat so I can't comment on long term success.

Did you have to disconnect from the drive to bring the front of the motor up?

 

[harringtondav]

Did you have to disconnect from the drive to bring the front of the motor up?

I had the outdrive removed to replace the prop shaft. So yes. It is not that much trouble, and good to do regularly to inspect the drive shaft bellows, U joints, gimbal bearing etc.
For Mercruiser, shift to full FWD, disconnect the speedo pitot pickup, remove the rear trim cylinder pins, remove the six attaching nuts and work the outdrive off.
...you may have to hold your mouth right to get it back on. This forum can get you through it if you have trouble. Remember to buy a transom seal kit to replace the necessary gaskets, etc.

 

[Fscott4]

I’m looking for a timing cover and gasket kit as well as a seal kit for the outdrive so I can get started on the project. The outdrive inspection will be a good thing and I have to change the trim switches too.