Upgraded 5.0L to 5.7L Vortec head eng - Bad oil burn/smoking problem - not usual suspects

I have a 2000 Sea Ray 240DA with a 1yr-old reman'd 5.7L Vortec head marine eng that has a bad oil burning/oil leak problem that only arises when left at idle for several minutes. Since this problem has been happening since the day the engine was installed, it has taken a lot of effort to discount all the possible causes and has lead me to what I have found written below.

I have carefully tested & re-tested with very consistent results and have found the following:

1. All cyls test well with Compression - 150+lbs & leak-down tests - 10-20% max loss.
2. Vacuum test steady 19" at idle with increase to 23" during throttle up and then down to less than 5" at higher RPM if out of gear and less than 5" at all RPM above idle while under power. New PCV valve in use, no excess oil residue in it or hose to intake.
3. Oil pressure steady at 40-65lbs throughout RPM range increasing with higher RPM.
4. Oil level good - never over filled and allowed to get to 1 qt low before refill. - 25W40 Mercruiser oil is in engine.
5. Engine power is excellent at all RPM ranges - Idle to WOT of 4700RPM @ 42MPH GPS(45MPH dash gauge) takes only 9secs to achieve top speed. This is a 24ft 5000lb overnight cabin boat.
6. No valve tapping or other oil related problems have ever been noticed. Engine has always run very smooth and quiet.

Oil burns/blue smoke(at times billowing profusely) from exhaust outlet and noticeable oil residue in water when engine is allowed to idle for 2-4 minutes or more. If engine is ran at higher RPM (3-4k) out of gear or run in gear above 2k RPM, the blue smoke disappears within 1-2 minutes and does not return unless engine is left to idle for more than 2-4 minutes.

Smoke is much more pronounced if eng is gun'd from idle to higher RPM if after 2-4 minutes of idling. After several minutes of higher RPM and smoke dissipates, engine can be brought back down to idle and gun'd with no smoke at all. Smoke returns if idled for 2-4 minutes.

Each and every time after running engine, fresh oil(slightly blackened) is seen coming from each exhaust manifold gasket at the mating surface at the cyl head on starboard side. I have packed oil soak-up material around all areas of engine and I am confident the oil is only coming from this point. All other gasket areas (oil pan, dips stick, valve cvr, timing cover, etc) all remain very dry. No actual exhaust leak is noticed - carbon/soot/sound. Only oil is noticed dripping from exhaust gasket. Oil will cover 2-3 finger tips with fresh oil after 20-30 minutes of engine running.

I believe the oil burn/oil leak is being caused by the normal higher vacuum at idle and oil is being sucked into the intake cavity at this time and when less vacuum at higher RPM it is not being sucked in.. Does this seem likely or is there something else you would offer to resolve this issue? When I remove the intake manifold to inspect for a gasket breach, is there anything else I should look for in case this is not the problem?

19 inches of vac is normal at idle......

you have one of three issues,
1. bad oil controll ring on one or more pistons.
2. bad valve guide (s)
3. bad valve stem seal (s).

What do your spark plugs look like???? One or more should look different from all the rest.........

Report back on spark plug apperance.......

Hi kghost, thanks for the quick reply. Ok, now we will get into why this problem has been so confounding to me.

From recollection of last season when I first pulled the plugs (and from detailed notes I wrote up at the time) are as follows:
Spark plugs from port side of engine #1 & 3 and from starboard side #2 & 6 were a good light tanish color. Spark plugs removed from cylinders on the port side #5 & 7 and from the starboard side #4 & 6 were black/oil fouled. There was no evidence or smell of fuel on any of the plugs.

If oil is being sucked into the intake cavity rather than a single cyl rings/valve being bad would explain why multiple cyls are getting fouled by oil.

From this season just 1 week ago when I performed the compression & leak-down tests:
All 8 spark plugs were a good light tanish color. I performed the leak-down test on 2 separate occasions and both times all plugs looked good. Again, I can get the engine to start smoking badly on command if I just let it idle for a few minutes.

From my motorcycle days I learned that if you want to see how your engine is running by looking at the spark plugs, you can only tell how it's running at the certain RPM you had it running when you shut the engine off. By this I mean, I believe that last year the engine was shut down after it had been burning oil at idle for several minutes. This is why multiple spark plugs were fouled. Last week I ran the engine at high RPM with no smoke burning when it was shut down leading to all the plugs looking good when I pulled them.

you have one of three issues,
1. bad oil controll ring on one or more pistons. I would think if this was the problem, it would burn worse with higher RPM & gun'g engine. Also if multiple cyls the engine wouldn't have the great performance that it does have.
2. bad valve guide (s) Since this is a newly rebuilt marine engine (the long block was purchased from a reputable marine engine repair company. I did the engine/parts swap as I have 6 previous engine replacements under my belts on other boats/cars,etc.), would doubt that there are multiple cyls with the same valve guide/seal problem causing them all to foul the plugs fairly evenly.
3. bad valve stem seal (s). If I run the engine at high RPM with no smoke and shut it down, then a day later start it up, there is no smoke at first until let it idle for several mins. This is not indicative of bad stem seals - I thought they would burn every time after cold start and then smoke would go away after engine gets hot.

I have used this link as a guide on what are the causes for oil consumption. The one that satisfies all the symptoms, imo, is #33:
http://www.smartsynthetics.com/motor_oil_consumption.htm

I pretty much discounted all(most) of the other reasons because they just don't fit all the symptoms.

I just don't want to have to pull the engine out again to get to rings or pull heads if I don't have to. I don't really even want to pull the intake manifold off if it was some other simpler reason, but I'd be ok with just having to do that.

I attached a pic of the smoke @ idle. That will all disappear if I simply run it at high RPM for several minutes (clearer pic).


I can re-pull the plugs after it is smoking to se what plugs are bad this time. I'm willing to perform any other test you'd suggest just so I can make sure what the real cause is.

I disagree with 33. Not a gasket issue in my ipionion. You are burning oil. A bad oil control ring s does not affect compression. It simply allows oil up past the top two rings. Oil will improve a compression test to a.devree.

Unless the wrong head gaskets.were used and oil is seeping in....

Need to think more on this.... Maybe some others.have some ideas.

OK Vortec heads, do you have a Vortec intake? I know it's a stupid question, but gotta ask.

you know thats a great question no chit.

Ditto!!

o2beatsea: "OK Vortec heads, do you have a Vortec intake?"

Yes, I wasn't clear on what the prior 5.0L was. It had Vortec heads on it as well and of course an 8-bolt Vortec style intake manifold, which was re-used on replacement 5.7L. Everything has bolted up and worked fine with the switch over to the 5.7L. Did not have any of this oil burn problem with previous engine, though. That one had other problems.

chiefalen: "you know thats a great question no chit."

Tis' but an average question. The answer is what I'm hoping is going to be 'GREAT'!

kghost: "You are burning oil."

Yes. And quite a bit. Profusely I would say. But, only at idle or if I gun it while at idle and already smoking.

"A bad oil control ring"

Everything I've read on bad rings causing oil consumption has the oil consumption greater as the RPM's increase or while gunning engine and during deceleration. Higher RPM is when the smoking disappears in my situation. And after the smoke does dissipate with the higher RPM, I can gun the engine all I want even from idle with no smoke evident. But, if I let the engine idle for a few minutes, then here comes the smoke.

"Unless the wrong head gaskets.were used and oil is seeping in"

Maybe a possibility, but where exactly would oil flow from and into where for it to be burned? I have never had problem with water in oil, so not too sure about bad head gasket. I do get oil in water(coming out exhaust), but I guess that's natural since when oil gets burned it does exhaust out and mix with water/exhaust manifold output.

And no matter what is causing this, it needs to make sense why it only happens at idle and not at higher rev or while gun'g engine. I think the intake gasket breach/engine vacuum explains and works with all symptoms.

But, I'm definitely not an expert at this! And have never seen/heard of it happening before.

You sound knowelgable so I will repeat my first statement.

burning oil in the combustion chamber (if gaskets, head and intake are good?) can only come from three sources, rings, guides, seals......end of story.

So it has to be one of those three........

by the way a leak down of 20% on a fresh motor is not really that good....5 to 10 % is what I would think would be more normal.

You are assuming that the rebiulder got everything right. Just because the engine runs well does not change that fact that something is wrong.

From what you wrote the four back cyclinders have a oil issue or possibly all four, we shall say all four for now.

WHat could be the common thing that would be on both sides of the block?

head gasket installation issue (maybe not torqued propperly), maybe the wrong one for a 350 vorrtec vs old style (not sure if there is a difference myself) but if it is not correct and the oil returns are open to the cyclinders then that would do it (not likely but for now entertain the thought).

Not likely that four different pistons would have the same issue.

Very likely the guides and or seals are no good.....that could happen as the heads were bieng redone. Very easy to use or impropperly machine guides from one end of the machining center to the other...bad guides causing wobbily valve stems would reak havock on the seals.....

Other than that unless the intake has a hole in it and allowing oil in..........

What will the motor idle at? is it carbed? or efi? The motor should idle with no effort at 400-500 rpms. Although your idle vaccum is right on the money.

I just reread your first post,

"""Vacuum test steady 19" at idle with increase to 23" during throttle up and then down to less than 5" at higher RPM if out of gear and less than 5" at all RPM above idle while under power. New PCV valve in use, no excess oil residue in it or hose to intake"""

Do you have the PCV installed to it is directly connected to the intake manifold??

I do not believe it is suposed to be there. The crankcase vent is a open line to the flame arrestor. No checkvalve as in automotive.Is this the case??
direct vaccum on the valve cover would most likley generate a great deal of oil vapor, how much I am not sure...

My answer would be to contact the engine rebiulder and ask what they will do for you, I say a new set of heads and head gaskets..........That is my opinion

I don't know who did the rebuild, but if it were me, I'd drop them a line. I should think that they would want to know if one of their engines was doing this since start up.
This wouldn't be the first engine with a 40 over grind that has 30 over pistons in it.

I tend to doubt that would be it........he would not be seeing 150 psi compression or at least I dont think he would....... would be funny if they forgot some oil rings though, bad day at the factory after a six pack lunch......lol

Well, I like the way you're all thinking.

Yes, I've already contacted the engine reman place - http://www.usengine.us/mercruiser.html engine has 7 year warranty (we'll get into what that's worth in a minute)

His first response was, "We have not had an engine returned for oil usage or smoking in 10 plus years."

Total shirking of their responsibility, imo. After another attempt of giving all the symptoms, he tried to convince me the timing was done incorrectly (they say don't do it by how the book says to do it with the MerCruiser Special Timing Tool (Quicksilver 91-805747A1) like I did, but to do it 'Also timing 32 to 34 at 3,000 RPM when hot, do this without disconecting any computer wires. Sounds like timing is not enough.'

This is an EFI Throttle Body 5.7L engine. On the questions of vacuum - I tested by hooking up vacuum guage to TBI port at bottom of plate/top of intake manifold - this is the same port that the PCV valve on port side valve cover is connected to through a hose. i can hear the PCV valve fluttering while engine is running. Yes, there is a straight through breather fitting/hose from the starboard valve cover that connects openly at the top of the flame arrestor.

Why couldn't oil enter the intake manifold at some point, which would then be sucked into each cyl and be burned along with the fuel/air mix creating the blue smoke? Oil could enter through PCV hose or as I think is the issue, a breach in the intake manifold gasket. When the vacuum is greatest (at idle) is when the most oil would enter. Is this not logical?

If leak is on starboard side, then that is where most oil is sucked in and burned, but then some gets to the port side and gets burned there, too. I'm only using logistical thinking here rather than mechanical knowledge.

As for smarts, I have some backyard mechanic knowledge, but I am a systems/computer analyst/developer/programmer. So, everything in my world must be logical and make sense to fly.

I'm sure if I were to continue calling the engine reman place, they would continue to steer me in any direction other than theirs on purpose.

Look i don't know your engine re-builder. But anyone can make a mistake, or have a bad day.

Show him this entire thread and ask him to explain why your motor is doing what it is doing.

All i can say these guys here know 100 percent more then i know and forgot more then i ever knew.

Tell them they got to look over the motor, if they are near you it's easy, if not then it has to be sent to them.

Who pays shipping and all that is between you.

jeez nowhere on the site tells you where they are i looked up the area code am i right they are on the west coast ?

i have used michigan motors, for my friends. Alot closer.

If you posted before the re-build i would have hooked you up with boat docture he's near me in jersey.

Was silicone sealer used on the intake gaskets? Gas will disolve the silicone and cause a leak, sometimes. Have needed to change intake gaskets on some engines due to folks thinking silicone is good for sealing everything. Since it is the rear holes showing signs of oil (with the exception of #4), I would suspect a very small leak at the intake sucking oil from the lifter galley and go from there. Pulling the intake isn't too much of a hassle and will allow you to look into the runners and see if the intake valves have oil on them. At least that'll narrow the field in what can cause the problem.

I would think and I repeat, I would think (as I do not have much EFI experience) That if you had a intake leak, one bad enough for oil to get in, the engine would run like crap, I would think it would idle wrong and burp and hiccup under all different conditions......

This vaccum port? is it located at the cylinders in questions based on spark plug reading and location?

If the PCV valve and its location is a susspect then pull it off the manifold, plug the manifold, allow the pvc hose to vent to atmosphere......see if the oil burning goes away........

Remember in order to have burning oil it has be getting into the combustion chambers...........so work backwards from there.......

JFarc, if you are close to the Rt50 corridor, I might be able to stop by for a second pair of eyes.

The US engines phone number googles up as Tacoma WA.

My current plan is to before I contact the engine reman place again, was to already have a definite determination(through testing, process of elimination,etc) of what the real problem is and whether it is something that they need to correct or is it really something outside their realm. I definitely don't want to go through the trouble/cost of pulling the engine out, crating it up and shipping to WA state (that is where they are, I am on East coast), just for them to say, "Hey, you got an intake manifold gasket leak, not my problem!"

I was aware of some issues folks told me about the Vortec I/M gasket when I was putting everythin together. I definitely used RTV Black on the front and back rails of the intake manifold as instructions required. Also used a little extra at the corners of the gaskets where it meets the end rails. I truly can't remember if I put any RTV on the gasket itself. I believe I did not because that's what instructions said. But, I had the help of a chev motorhead friend to back me up on the rebuild and he may have convinced me otherwise. I will need to get a hold of him and ask what we did.

This really could be the problem. I wanted to just replace it last weekend, but couldn't find any local supply house with it in stock - everyone's on 3-4 back order. I looked last night online and see places with it, so I'll go ahead and order it in.

On the 'vacuum port', I am simply using the PCV hose connection to the TBI base as my check point for testing for vacuum. Should I be hooking gauge to something else?

I will try your suggestion to play with the PVC valve and run to see what affect if any it has on smoke.

o2batsea said:

JFarc, if you are close to the Rt50 corridor, I might be able to stop by for a second pair of eyes.

The US engines phone number googles up as Tacoma WA.

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Ha! As I look out the window from my client's building on Riva Rd where I am today, I am looking at traffic drive by on Rt50 in Annapolis. I live up in Balt and boat is in boatel up in Middle River. I would greatly appreciate another set of eyes on this.

My client was looking forward to me taking the office staff out on the boat tomorrow down here for the yearly Blue Angles show. But, that just got canceled last night - some flyboy f'd up and flew too low. Although, my boat is too embarrassing to take people out with the smoking, so that is working out well.

I wouldn't mind at all putting the boat in the water and cruising down somewhere that's convenient for you. I used to be in the Atlantic Marina in Pasadena off Fort Smallwood rd or I could come down to Sandy Point or even Annapolis. There is the Jazz/Blues festival @ Sandy Point this weekend, so that may be too crowded then. I can possibly make it down either Thur or Fri in the late afternoon/eve if it works out for your sched.

I was panning on taking the boat for an overnight in Kent Narrows this Sat to stay down by the Jetti. I can be open to accommodate your sched. Just let me know and thanks for offering.

JohnF

I new a guy that had a similar problem (although I think it burned oil thru all RPM ranges) and it turned out to be a missing baffle in the valve cover underneath the PCV valve. It was sucking oil directly into the carburator. Replaced the baffle and all is well. Does the 5.7 head use a different valve cover by chance?

capnlazy said:

I new a guy that had a similar problem (although I think it burned oil thru all RPM ranges) and it turned out to be a missing baffle in the valve cover underneath the PCV valve. It was sucking oil directly into the carburator. Replaced the baffle and all is well. Does the 5.7 head use a different valve cover by chance?

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Damn, it would be pretty convenient if that's all it is. I truly haven't 100% ruled out PCV for oil intro into engine, although I did replace it with new one. I have checked the hose and it does not 'seem' to be oil soaked. But I do need to disconnect it and run engine for a while like was already suggested to definitely rule it out. I only did determine 2 weeks ago through testing that the oil smoke problem is only after idle for several minutes, so maybe I did previous checks of PCV after high RPM when no smoke was present.

The valve cover in use is the one off the 5.0L, but I can't imagine it should be any different for the 5.7L, but it is easy to verify.

Thanks for the lead.

Memorial Day weekend around Annapolis or KI is a quagmire I don't care to get involved with. I will salute you as I speed past on my way to Dorchester County. I also have some history in Bowley's Quarters, but now do all my boating on the far side of the Bay away from the crowds.

Although, my boat is too embarrassing to take people out with the smoking, so that is working out well.

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Hmmm well, to be honest there have been many times when I wish I could have smoked out some of my fellow boaters at some of the more popular anchoring spots, but cooler heads won the day.

Next time use nothing but aviation form a gasket.

I have used aviation form a gasket for over 40 years and when i left the service i took a few jars with me. Wink.

It won't melt is immune to fuel and never dries out. I wish i could drink it.

Silly cone in any color should not be used on a motor period.

I puzzled about this one and actually discussed your problem with a few of my buddies.

They all came back to the rings. But them again we can't touch it, feel it, or smell it.

Got a known good intake laying around to throw on. Just to rule it out as the culprit.

Well, I did find some validation to my intake gasket breach theory reading some previous threads in some camaro, S10, and chevelle sites. One mechanic that frequents the S10 site offered:
"it is actually common between the 4.3's and the vortec 5.7's to actually pull oil thru the intake manifolds when the gaskets go bad.... ive had several customers losing really excessive amounts of oil, til i did their intake gaskets..."
http://www.s10forum.com/forum/f107/intake-manifold-have-oil-passage-348164/

And then this guy almost repeats my story from a camaro site:
http://www.camaros.net/forums/archive/index.php/t-152786.html

Several responses were the same intake gasket suggestion, but his problem actually turned out to be the rocker studs were drilled through and sealant wasn't used on bolt threads allowing oil to seep past and into the cyl chambers. The only difference between his & my symptoms was his smoked at all RPM's, while mine only at idle. That may make sense, though.

Another guy said the way to check for intake gasket leak is:
"To prove a internal intake leak.
Plug off all holes in the valve covers. I use duct tape.
Install a vacuum gauge on the dipstick tube.
Start up the car, there should be NO vacuum indicated on the gauge.
No vacuum, no internal leak. Has vacuum, pull the intake, the gasket has slipped.
Dale"

I am a little bothered by all the different opinions on whether to use sealant on the gasket, don't use sealant on the gasket, now don't use gasket, just sealant. Then there's this about the special intake bolts that need to be used:
http://www.gmpartsdirect.com/performance_parts/store/catalog/Product.jhtmlPRODID=1024&CATID=995.html

Well, at least I got a plan of attack for this weekend to do the new vacuum test on intake and then change out intake gaskets and put in new bolts of which I just ordered and should be in tomorrow. We shall see.

From my recollection the Fel Pro marine intake gaskets (Fel Pro Q17320) have a bead of monkey snot around all the openings, so that sealant on the gasket is not needed. The only sealant you'd apply is a small blob of silicone on each corner after the gaskets are set in place.

I don't see how they could slip out of alignment.

o2batsea said:

I don't see how they could slip out of alignment.

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Me too. But I think the culprit is more likely improper torque(only 11lbs), not using proper bolts or a combo of diff styles, wrong gaskets used, not using thread lock and bolts came loose, pinching gasket when lowering manifold during install, starting engine too soon after install not allowing sealant to cure, etc, etc. Too many things can go wrong with these Vortec heads.

I also read where there is diff opinion when using thread lock, should you re-torque after engine had been run? Some say yes you are supposed to re-torque after so many hours, some say no that's why you put on thread lock - if you re-torque it will break the locked threads. I know I did not re-torque this job after install for this reason. Maybe that's my problem.

Who knows for sure?!?!?!

Go to your merc marine store and get the can of the brown gasket goo (perfect seal) EVERYONE SHOULD HAVE/USE this.................That is what you should use on the bolt threads.

As far a torquing the bolts, Most here agree, tighten good and tight!!.............in a circular pattern from the center outward. Torquing of bolts is a important proceedure on many fastners on a motor, BUT there are some ares that are better done with common sense!! IE: good and tight!

As far as silicone on a intake gasket, No issues using it if done right.

Marine engines (chevy anyway) use a 3/8 bead along the front and rear z of the block to intake as you saidd you did.

Will do, kghost. I know the gasket already comes pre-gooked, but I think I'd feel better since I've already had a problem(I didn't put sealant on it the first time) to smear a little evenly on it this time.

This site has a nice pictorial and I like the guy's alignment stud idea. I was going to use bic pen tubes but they are not thick enough:
http://www.s10forum.com/forum/f107/replacing-lower-intake-manifold-gaskets-w-pics-328484/

Uh-oh....

I was feeling good heading to the boat this evening with new intake leak testing knowledge & new intake gaskets in hand. But, the suggested intake leak test came back negative - no vacuum(actually there was a little pressure build up, which makes sense) and this started me poking around some more.

After removing all the oil soak pads around the exhaust manifold(from the oil leak I've had since the beginning), I closely inspected underneath again. The oil leaks I was seeing weren't coming from the exhaust manifold. I finally realized it was coming from 1/8" away from them.... the head gasket. The entire length of the gasket was dripping oil and there was oil splatter on the oil soak up pads right in that place. I guess this confirms I got a head problem - need to remove them to see what exactly.

Does this make sense? I have never had a water leak problem. Meaning never any water in the oil pan or dip stick or valve cover area. Never any steam, vapor or odd light smoke from exhaust indicating there is a water leak.

How and where would oil be coming through the head and out of the matting surface between the head and block at the top of the cylinders? Are there oil passages in there? This is definitely oil and not fuel. No fuel smell or feel at all, purely oil.

If you are 100% sure there is a head gasket issue this is when the remanufaturer should be notified.

Are you sure the valve covers are not leaking?????? Oil does run down hill.

Pull the valve covers, put your oil soak pads all around the heads and run it. Observe the oil.

Oil should be shooting out of the push rod side of the rocker arm, oil should start to pool up on the lower side of the head (closest to the exhaust manifold) this is where the oil soak pads will come in handy. Watch where the oil goes.....

Remember, oil gets into the heads, It has to have a way/path to return to the oil pan. That path is a hole on each end of the heads. See if those holes are restricted......look closely at each valve stem inside the spring and see if you can see the valve seals..not that you can do anything but make sure nothing looks wrong or different.