4.3 Merc oil leak on top of intake

[Alpheus]

Re: 4.3 Merc oil leak on top of intake

So let get this straight. Some of you are suggesting that the bolts that hold the intake manifolds to the head are running through an oil passage and that oil is seeping UP through a bolt and puddling on his intake?

Let me just say that its not gonna happen.

There is no oil there in the heads where those bolts are. The only oil thats in the heads is the oil that comes up through the push rods and returns (by gravity) into the oil pan via holes under the intake. Those bolt holes are not drilled the entire way through any part of the head for oil to get to...

Its getting there another way...

 

[Evinrude Boater]

Re: 4.3 Merc oil leak on top of intake

Let me just say that its not gonna happen.

Well, I confirmed it today. I had my son driving the boat while I watched the intake very closely. I saw oil and air bubbles in the oil as it came out from under the intake manifold bolt head. It's not the valve cover, not the intake gasket, not dripping off the carb or breather hose. It's coming out of the bolt hole. Alpheus, you probably have some worse news for me now.
Here's a video link. Watch it on full screen. It's hard to see since some of the video quality is lost in the process.
http://www.youtube.com/watch?v=eptcdJjDzJ8

 

[Alpheus]

Re: 4.3 Merc oil leak on top of intake

I will admit that I am wrong in this case.

I just Googled this hoping to find evidence to prove my point and ended up learning something new. Turns out that this is a big controversy in the SBC community. No there is no oil pressure that can make oil come through those bolts but internal block pressure along with vibration can make oil from the lifter valley wick up those threads and come out.

Check this post out and you will see exactly what Im talking about.

http://camaroforums.com/forum/archive/index.php/t-26994.html

http://www.clubhotrod.com/forums/showthread.php?threadid=10156

Looks like you have to pull the bolts and seal them up...

 

[Evinrude Boater]

Re: 4.3 Merc oil leak on top of intake

Pretty sure it's oil, it's the same color as the oil and it's not milky. I've seen it pool. I thought that was an exhaust cross over where it pools.

 

[coheej]

Re: 4.3 Merc oil leak on top of intake

Some of those holes do go through to the pushrod area. You do need to put pipe thread sealer on those bolts or you will get oil up through them just like you are seeing. Remove them one at a time and put sealer on them.

 

[Evinrude Boater]

Re: 4.3 Merc oil leak on top of intake

Alpheus, Im glad I went back over this thread and noticed you changed your post. When you mentioned water leaking I couldn't imagine water in the middle of the intake since the coolant crossovers are at the front and rear. I'm glad to read more on this problem and I feel confident on sealing the threads. One additonal question though, is the sealer going to seal now that the threads in the head are oily?

 

[John_S]

Re: 4.3 Merc oil leak on top of intake

I'd chase the threads with a flat ended tap, to make sure you get a good torque reading. A little oil film should not prevent the sealer from curing.

 

[coheej]

Re: 4.3 Merc oil leak on top of intake

I'd chase the threads with a flat ended tap, to make sure you get a good torque reading. A little oil film should not prevent the sealer from curing.

If you chase the threads, some of the crud & shavings will go into the pushrod & valley area.

 

[John_S]

Re: 4.3 Merc oil leak on top of intake

If you chase the threads, some of the crud & shavings will go into the pushrod & valley area.

Put grease along the three "valleys" of the tap to catch and minimize any particles from falling in. If you are still worried, do an oil and filter change after the retorque.

 

[Fishermark]

Re: 4.3 Merc oil leak on top of intake

I always use either some Permatex #2 or Avition Sealant on those bolts. Common problem on small block Chevys.

 

[muc]

Re: 4.3 Merc oil leak on top of intake

You might want to remove the bolt and clean it. Paint the bolt with perfect seal and reinstall.
Good Luck Muc

Just clean the bolts good and remove and replace one at a time.
Good Luck Muc

 

[Evinrude Boater]

Re: 4.3 Merc oil leak on top of intake

I'm thinking this oil leak on the manifold bolt is a sign of something worse. I took the boat out of the water for the season and I noticed excessive crankcase vapour and a louder knock or tapping. I didn't dare open her up, just idled to the ramp and took her out. I had the blower running and we still smelled the fumes so I opened the engine compartment and it was a bit more cloudy than usual. The gauges were reading normal on the short ride. I guess I'll pull the plugs and do a compression check and see if that tells me anything. The one thing that has always bugged me is that I measure out the engine oil when changing yet it's still over the full line. I was reluctant to drain off almost a liter to bring it down to the full line. I've measured the dip stick and it's the correct length. I just can't solve that one. Could being over full cause an engine problem of this nature?

 

[wire2]

Re: 4.3 Merc oil leak on top of intake

....... The one thing that has always bugged me is that I measure out the engine oil when changing yet it's still over the full line. I was reluctant to drain off almost a liter to bring it down to the full line. I've measured the dip stick and it's the correct length. I just can't solve that one. Could being over full cause an engine problem of this nature?

You measure the oil to what? The volume spec'd in the manual? Manual is not always accurate (for whatever reason)
e.g., the manual for my Dodge Charger SRT "fluids and capacities" table calls up 7 quarts of 0W-40 synthetic oil.
I do my own changes, (dealer wants $110, parts cost me $50) replace the filter, pour in 6 quarts, run the engine, it's dead center of "normal". 2 weeks later, it's showing exactly the same level.

If you're sure you have the proper dipstick, go by that, rather than a table of specs.

 

[Evinrude Boater]

Re: 4.3 Merc oil leak on top of intake

Oddly the 4.3 liter engine takes 4.3 liters of oil. The Merc manual states that and so does the parts counter. Is that a selling feature since they sell oil in 4 liter jugs.

 

[wire2]

Re: 4.3 Merc oil leak on top of intake

Oddly the 4.3 liter engine takes 4.3 liters of oil. The Merc manual states that and so does the parts counter. Is that a selling feature since they sell oil in 4 liter jugs.

That's gotta be a fluke. I can't see that an engineer designing an engine will specify an oil pan to mimic dispacement volume.

Is 4.3L the volume spec'd for when it's in a car? And maybe the marine version has a slightly smaller oil pan? Just a thought.

My other car, a 300M has a 3.5L V6, it needs 5.3 L of oil. Also easy to remember.

 

[Alpheus]

Re: 4.3 Merc oil leak on top of intake

If its over full the crankshaft will hit the oil and agitate it with air causing lower oil pressure.

 

[Evinrude Boater]

Re: 4.3 Merc oil leak on top of intake

If its over full the crankshaft will hit the oil and agitate it with air causing lower oil pressure.

The gauges don't have numbers on them but the oil pressure has always been on the high end of the gauge. At times it was very close to the top of the gauge and that had concerned me but I guess high pressure is better than low pressure.

 

[John_S]

Re: 4.3 Merc oil leak on top of intake

While the merc manuals gives the oil capacity, the procedure to fill always says to check the dip stick at boat at rest, in water position. Hopefully, your issue is just an overfilled crankcase. Remove some oil to bring it down to the mark. Won't hurt to go through the compression test. Its good data to retain, year to year.

 

[wire2]

Re: 4.3 Merc oil leak on top of intake

If its over full the crankshaft will hit the oil and agitate it with air causing lower oil pressure.

Actually, the counterweights of a crankshaft do need to hit the oil to make it splash. That's the only lubrication the cylinders/rings get.
But you're correct in that overfilling will cause foaming, lower oil press, and eat up energy.

 

[coheej]

Re: 4.3 Merc oil leak on top of intake

Actually, the counterweights of a crankshaft do need to hit the oil to make it splash. That's the only lubrication the cylinders/rings get.
But you're correct in that overfilling will cause foaming, lower oil press, and eat up energy.

Yes, the cylinder walls and cam lobes get oiled by the counter weights slinging oil, but it's not from running in oil in the pan. It's slinging oil that's draining back from the top of the motor.