View Full Version : oil leak

03-18-2006, 10:10 PM
Took the boat out for the first run today, and found an oil leak from the driver's side manifold, the boat has always had a slight smell of burning oil when running hard (keep in mind I have run her less than 15 times). The leak is coming from one of the 8 hex bolts. Does anyone know what size allen wrench I need to tighten it, I can't tell if it is the manifold itself....it does have some rust and build up, or the gasket needs replacing or if I just need to tighten down the bolts. If it is the gasket or manifold, is this a DIY project? Also, if I replace one of the manifolds....do I have to replace both? Thanks.

03-18-2006, 10:23 PM
When you say manifolds, I assume you the exhaust manifolds. If that is the case, I don't think your oil is leaking from the exhaust manifold. More likely, it is running down from the valve cover and you are noticing it at the bolt. If that is the case, replacing the valve cover gasket should solve the problem. Do not overtighten the bolts holding the valve covers. This can cause the covers to bend and as a result not seal tightly.

03-18-2006, 10:29 PM
Laurel Lake-

Yeah, that would make sense that oil wouldn't come from the exhaust :o , I will check it out. But it is a "do it yourselfer"? I guess Vince at skidim will be getting a call on Monday. Thanks for the advice.

Anyone else?

03-18-2006, 10:40 PM
Seems like it must be the valve cover gasket. Can't think of anything else that would be up that high that would leak oil.

03-19-2006, 11:00 AM
Laurel Lake-

Yeah, that would make sense that oil wouldn't come from the exhaust :o , I will check it out. But it is a "do it yourselfer"? I guess Vince at skidim will be getting a call on Monday. Thanks for the advice.

Anyone else?

Valve cover gasket is an easy DIY job. Just a few easily accessable bolts, remove the gasket and reinstall.

03-19-2006, 12:11 PM
Valve cover probably won't come off of a 351 without removing the exhaust manifold first, or at least loosening it a lot.

03-20-2006, 01:00 PM
They will come off, or at least mine will. The only problem is the nuts that are up against the exhaust manifold. They are way down there and a bit tricky to get started when you put them back on. I taped them into a socket and used a long skinny extension to get them started.

This is a very easy DIY repair.


03-20-2006, 01:42 PM
+1 on the valve cover gaskets leaking...

Mine has a slight oil smell when running hard as well. I need to look into it this spring (errr, wait, spring starts tomorrow... :rolleyes: )

very simple DIY if you have access. If not, and if you have to loosen the exhaust manifolds, you'll probably want to have a spare set of gaskets for them as well.

Good Luck!

03-20-2006, 02:26 PM
I think my gaskets are o.k. The valve cover bolts were so loose I could start tightening some of them by hand :eek: Guess the guy I bought it from never checked...and neither did I. I tightened down the ones I could reach and have to go pick up a long skinny extention and possibly a "hinged socket" to tighten the rest. The leak was so slight I can only imagine that tightening the cover will solve it, if not I will replace the gasket....the tape on the socket is a great idea...never thought of that :toast:

03-20-2006, 02:27 PM
They will come off without moving the exhaust manifolds, although it's easier if they are out of the way. If you do take them off (the exhaust manifolds) they do not use gaskets so you don't need new ones. Indmar simply puts some silicone around the ports and bolts them on. It's still easier to spend a little time fiddling with the valve cover nuts to get them back on than it is to take the manifolds off.


03-20-2006, 02:34 PM
I replaced my exhaust manifolds last year and they had gaskets on them, both where they went into the block and where the riser bolted on.

03-20-2006, 03:26 PM
I think you can put gaskets in there if you want, but they are not necessary and they come from the factory without them. Here's a quote from Enginenut who works at Indmar. I tried to link to the thread that this was in but I failed the technology test. If you do a search and put in 'manifold gasket' you'll find it. Personally I think you will increase your chances of a leak if you put a gasket in there.


QUOTE=Engine Nut]We (at Indmar) do not use gaskets between the cylinder head and exhaust manifold. There is no transfer of water between the manifold and head ... only exhaust. The head is water cooled and so is the exhaust manifold so there isn't a heat issue at that joint. All we do is put a small bead of black silicone sealant around each of the exhaust ports and mount the manifold. We have been doing it that way for many years.

Engine Nut[/QUOTE]

10-15-2006, 07:04 PM
I noticed oil residue in my nice clean bilge.. dang! The source looked to be the low end of the valve cover on the right side. I did find several loose nuts which I gently tightened. Hopefully this will stop the leak.

Is there a recomended tightening sequence and torque value to use? I figure that making it too tight could possibly warp and or crack the valve cover.

10-15-2006, 09:35 PM
I don't know the actual specified torque, but it's not much. I would guess about 12 to 15 pounds. If they still leak, new gaskets are easy to install.