Serious oil burn

[spharis]

All right,
I'm chalking my oil burn up to something else now. I ran about 16 gallons of fuel yesterday, and I burned 1/2 quart at a minimum. No smoke on startup or when running that I can tell. The only time I saw smoke was when I was in neutral, and goosing the throttle, there was some faint smoke. I didn't have time to run the boat and check everything underneath that one would normally think to check. So any engine guys out there have any recommendations. I am unsure if I have a pcv valve, though I now on carb engines, if that is clogged it will do some hefty oil burn. No oil in the bilge, boat is running good. I didn't pull any plugs yet as it hasn't been running bad.

Ideas? '97 5.7 mercruiser sport pac. New Holley carb was installed mid summer, along with new gaskets and engine seals everywhere (oil pan, valve covers, etc). I do not believe the head gasket was replaced though. According to first owner, there was no problem with oil burn, so it seemed to come after the new carb was put on (if that is a correct statement , he knew nothing about boats or engines; was a marina guy). The carb was replaced, vs a rebuild at the marina, and the fuel system had some serious junk in it; so much that the filter and line were partially clogged causing bad starts.

I still need to pick up a fake-a-lake to run it at the house, but any ideas of things to check would be great. I am hoping if it is internal to the engine that it will end up being valve guides, head gasket or something, and not rings.

[chpthril]

WAS A MARINE CARB PUT ON?

[spharis]

Dont know. How can I tell the difference? Inboard newb.

It's a 4 barrell with vaccuum secondaries and cable primaries. Has an electric choke, though I had to manually hold it down for the first start this Sunday.

I think the head bolts were not torqued correctly. That or the gaskets are blown. I have oil seeping out from under the heads on both sides, but more porminently on the starboard, same side as the PCV, which seems to be working OK. The amount of oil that is leaking and the age of the engine makes it hard to be certain, but I am going to see if they are set to the proper torque, assuming I can fins a manual to let me know what that should be.

Supposedly the head gaskets, valve cover gaskets, oil pan gaskets were all changed this season. Maybe it was to cover up a problem....dont know. It doesn't run like it has a problem with with compression, or stutter, so I don't think the heads or block is damaged. It also holds a steady temp ~140-150 while running. Seeing as how both sides are leaking, it makes me think the mechanic was in a hurry and forgot to torque them correctly. If only one side had issues, I would assume something else.

Does anyone know the proper torque for the head bolts? Can I use the same torque as a GM 350?

[spharis]

240 inch/pounds is what I found, but that seems a little high. Small blocks are usually 25-45 ft/lbs DOA. I also read where the heads should be retorqued after a run. I doubt these were as the mech did not test drive afterwards (or so I was told), and completed the work on the next visit (carb adjustment).

Anyone with a 99 back have any underhood photos. Something else I want to see. Wish I had a manual.

[chpthril]

Dont know. How can I tell the difference?

Marine carbs usually don't have vacuum ports, and most marine engines do not use a PCV valve. They just have a hose from the valve cover(s) to the spark-arrester so any fumes/pressure that build up in the crankcase will be pulled back into the cumbustion chamber and burned. If one of these plugs up, it could cause pressure to build up in the crankcase and force oil out a seal or gasket.
Marine carbs dont vent gas fumes from the float bowl to the atmosphere, as this would allow fumes to build up in the bilge.
Most over-head valve engines don't leak from the head gaskets because the oil is not under pressure in the heads, it is just running back to the oil pan after it exits the pushrods. I would look real close at the joint were the cyl heads, block, and intake come together. An oil leak here likes to run down and around the heads and looks like the headgaskets!
The oil rings may frozen up, causing the engine to burn oil. (this would not affect compression)
Worn or improperly installed valve guide seals-burns oil.

[spharis]

It has a hose from the port valve cover back to the filter that is unrestricted. It has a pcv on the starboard vc that goes just under the carb. It appears to be working fine. Holding it in my hand.

I just ordered a fake a lake so I can have a look while it's running. Anyone have some engine pics with the arrestor removed?

This is my carb. Marine Holley 600 4160? with vac secondaries
http://www.holley.com/0-80364.asp

[chpthril]

[QUOTE]Originally posted by spharis
[B]It has a hose from the port valve cover back to the filter that is unrestricted. It has a pcv on the starboard vc that goes just under the carb. It appears to be working fine. Holding it in my hand.

When you say it's working, have you checked for vacuum at the engine side of the PCV w/engine running? Also check for vacuum at the vent hose w/the pcv hooked up and eng running. This will let you know if ether valve cover is plugged up.

[spharis]

nope, thats next on the list, assuming the fake a lake gets here before the weekend.

[Tip]

Have you noticed anykind of oil sheen around your boat when it's running? If your engine is not burning the oil it has to be going somewhere. Maybe the gaskets were not put in properly.

[TeamAllen]

You can oder a manual from Mercruiser. They are very detailed. I purchased a set years ago. I will look up the torque spec for the head bolts later today.

https://appcenter.mercurymarine.com/...rm.jsp?type=mc

I have some pics of my 97 5.7. It is fuel injection (TBI) though and the arrestor is on. Will that help?

[spharis]

Well I just got some good news.

A guy that used to work for local (almost) Marina is now mechanicing for my Pop; so looks like I get a free checkup.

Did some more inspecting and it looks like I have the classic Chevy/GM intake manifold leak. I think when the mechanic siliconed the intake, he tightened everythign down and didn't wait for the silicone to set before the final torque on the intake. Apparently these Marine engines have the same issue with that corner that almost all Chevy big and small blocks have.

TeamAllen....yes photos would be awesome. Thanks....I want to check a couple of hose routings. Something on the way this crankcase return vents does not look right.

[spharis]

Originally posted by Tip
Have you noticed anykind of oil sheen around your boat when it's running? If your engine is not burning the oil it has to be going somewhere. Maybe the gaskets were not put in properly.

No oil sheen, but there is a bit of sludge beciming present on the bell housing. I did not think it was enough to warrant a problem, but apparetnly it is more than it looked like. I also noticed there is some light sludge building in the hull toward the rear of the boat, under the tranny. One thing I do not like about my boat is that in order to lift the transom access, I have to remove the rear seat, and unsrew the seatback, or at least that's what it seems to be. If I could get in there, I would know a little more. I want to inspect my packing anyway. Of course there are no owners manuals for the boats anywhere, and apparently basic maintenance is not included in them, so I really do not know how to get access. I am not even sure if the outline I see is a transom access. It just looks like a couple of edges in the carpeting so I assumed it was an access panel under there. I have not had the boat long enough to go over everything, and other than the oil loss, it has been a champ.

[TeamAllen]

The cylinder head bolt torque values are 65 Lb. Ft. for non Gen+ engines.

Cylinder Head Bolt Gen+

First Sequence = 22 Lb. Ft.

Angle Torque Second Sequence
Short Bolt = 55 degrees
Medium Bolt = 65 degrees
Long Bolt = 75 degrees

Is there a particular side of the engine you need to see?

[gman]

spharis, 240 in-lbs is 20 ft-lbs.

[spharis]

Thanks for the photo. Mine is the same. Did you have a pcv valve on the starboard hose?