Water in oil, Mercruiser 5.7

Bachelordude

I have a 93 Rinker 260 with a Mercruiser 5.7 in it that was rebuilt approx. 7 years ago. It sat for 5 years in my garage but I put a battery on it and cranked it over every 6 months or so. I finally got it installed in the boat 2 years ago and on the first trip out only ran it for about 5 minutes and the oil pressure went to zero. I immediately stopped and found what seemed to me as alot of water in the oil. The oil on the dipstick was a lite brownish color and I could see the same after removing the cap on the valve cover. I took it to a marina and they said it needed the exhaust manifolds replaced. $2000.00 later I took the boat out and got about 5 hours on it at low rpms and varying the throttle while doing it. Never got it up on plane. This past week I took it out and after a good warm up cranked it up to about 4000 rpms and got up on plane. Upon start up I had only 30 lbs oil pressure. After running on plane for about 4-5 minutes it seemed to be getting louder so I throttled down and the oil pressure once again went to zero. Checked and once again there is water in the oil. Not as much as first time but definately water. Also there is a small amount of water/oil mixture on the starboard side of the motor and in the engine compartment. So, question is, blown head gasket or cracked block?? Keep in mind it had a complete rebuild and properly winterized after the first summer of minimal run time. Im not sure I want to mess with this or just go for a complete new engine which I dont have the money for this year. Thanks for any help and/or advice on what to do now!! 

212rowboat

The sound gave it away. 

Intake manifold.  

Bachelordude

Really, you think so?? It is an aluminum Edelbrock manifold and 4 barrel carb. The guy that rebuilt it put it on. I bought it and shipped it to him with the carb. I found a co-worker who is a mechanic, works on boats and said he would replace the head gaskets for 300.00. I figured what the heck, let him disassemble it and verify if its a head gasket or not, then let him replace the gaskets all the way up. I do know the aluminum manifold should not be torqued to the original mercruiser specs of a cast manifold. Maybe thats the issue??

212rowboat

if it is a 93 engine matching the boat year, it is an older vortec at best- and one which used the non-angled bolts to affix it- and not in the same placement as the newer ones with the angled bolts. 

either way, vortecs are known to warp if you look at them wrong.  

add to this the mating of aluminum to steel allows for a lot of movement during heating cycles..... 

but i didn't know that last one until you offered it was an aluminum eddy.. 

the only way to tell for certain is to pull it off and investigate the water ports- it's most likely the rear one on the starboard side, which is the most common (rear) and because you said the starboard side was water/oil painted. 

head gaskets usually don't let loose oil. a bad intake will- which was my initial tell- usually that happens with the dowel gasket across the valley letting loose.  now if you were flooding the engine and intake manifold with water you could see why it would be pushed out.. (an aside, make sure and check the oring on the dizzy too)... running at more than around 900rpm, the engine produces enough exhaust pulse to push out water from exhaust manifolds.. when you come off plane (or rev down) that pressure comes back with a vengeance and can overwhelm the exhaust, but that usually kills the engine quick like (hydro-lock)... an intake on the other hand will run okay cold, but get her to temperature and when the circulating water generates pressure enough to overcome the cylinder pressure (primarily on the intake stroke) GULP... and it chases the same 'leak' on the compression stroke forcing the water into the valley and then crankcase... and it's got to go somewhere- either pushes the dowel gasket out or through the dizzy oring, or even through the PCV and/or fill cap... or..... through where the head gaskets used to be. 

it makes a distinct sound when running with a leaking water passage... i don't know how to explain it... it's not louder, per say and at first, it's just different... the loud comes when lifters deflate and things start to clank about- water makes a terrible lubricant. 

without a closed system it's almost impossible to pressure test a water jacket... that's unfortunate... without coolant it's hard to see the tell-tale marks water makes across the expanse of metal (on the heads and on the intake manifold), but i bet you can still see them when you take it off. 

in addition to the sound, another tell was the engine was good until coming off RPM... that's when you sucked it in and it blew out- relieving you of oil pressure. 

personally, i'd stick with the merc intake... they actually flow pretty dang good.. i know of several people who use them in their street machines... and.. they are steel and match the heads and the block.  what you have doesn't really hurt anything, but it isn't helping either.  if you were in salt water and raw water cooled, that would be a different story.  but because of the block temperature you're inviting marrying surface concerns with mixed head/intake/exhaust/black material.... you 'can' get by with it, but your torques better be right and you better check them a few times after initial run and subsequent runs.  you'll likely find they don't hold that torque when the dissimilar metals bounce about. 

Bachelordude

Wow, you are the man. I did not know all that. Funny you nailed the intake without knowing it was aluminum. Its is marine rated but you are making a lot of sense. There is a small amount of oil residue on top of the intake which points towards the pcv valve theory. I was wondering about the different metals and how they would mate. It actually ran pretty decent at low rpms and the first time out I put 5 hours on it no problem. But as soon as it warmed up I started noticing something wasn't right. After it cooled down sitting t the dock while I worked on adjusting the new trailer for a couple hours it fired right up with about 20 lbs oil pressure. Idled back to the ramp but it didn't have enough power to push it all the way on the trailer. I think Im going to go back to a cast iron intake but I didn't think it was a Vortec engine. Its not the original motor. There is a 'Jasper' tag on the block. My old employer in Va. had the motor rebuilt for me as a bonus and that guy said it was already bored 60 over. He honed the block and put in oversize rings. At least that's what I was told. Put the old crank and cam back in. New bearings, seals and he said he welded the oil pump in for some weird reason. Never heard that one before either. So do I buy a non vortec cast intake or what would you recommend?? Also, should I go ahead and have the head gaskets replaced while hes in there??  I definitely appreciate all your help. I was wondering if I should waste any money on this motor or just save up and buy a complete new one. Ive been working on this boat for 10 years now, would like to get some run time out of it before Im too old to enjoy it. (I did get 5 summers on it in Va. before I moved back here to Ohio.) Was hoping to get it up to Erie for some walleye fishing but I wont do that until im sure this motor is reliable so again I Thank You sir!!!!

Bachelordude

Bachelordude

Heres a pic of the motor after rebuild stored in my garage.

Bachelordude

MERCRUISER CHEVY HI PERFORMANCE IRON INTAKE MANIFOLD 1987-95 305 5.0 350 5.7. I found this one on ebay for about $350.00

Bachelordude

Bachelordude

So after re-reading your post Im thinking this is NOT the right manifold due to the angled center mounting holes correct??

Bachelordude

This may be the right one. NEW Cast Iron 5.7L/V8 Marine 4bbl Intake Manifold, Volvo/OMC/Merc 1969-95. ($205.00)

Universal intake bolt pattern for 1969 - 1995 applications 

• 4 Barrel Universal Carburetor mounting

• 15 degree carburator flange

• Must use electric choke

• All required mounting and accessories holes are tapped

• Superior runner finish for increased air flow

• CNC machined for exact fit and bolt hole location

• Manufactured of the highest grade of cast iron. Resists salt water corrosion that aluminum intakes experience & corrosion caused by natural gas and other dry fuels

Bachelordude

Bachelordude

Bachelordude

Bachelordude

Hopefully this is the right one. I think Im going to start by replacing the intake like you said once I find the correct one. This I can do myself. I don't want to do the head gaskets myself because I have a bad back and that would be too much for me to mess with. So how often should I check the torque on a cast iron intake??

Bachelordude

Also, I think I should remove the valve covers and clean the milky crap out, change the oil and run it after the new intake has been installed. May take a couple oil changes to get the water out fully correct?? A lot of questions I know and I appreciate the help. Ive been out of the mechanic seen for a while and would like to get this project completed before winter hits. 

PickleRick

Lots of vehicles have aluminum intakes and cast iron heads.  My inboard diesel and VW both have them.   Proper grade bolts, torque value and sequence need to be observed along with good grade gaskets, i have not looked into sbc builds in a while but felpro comes to mind

NASCAR ran it for decades for 500 miles at sustained rpms boats will. Never see.
Most big go fast boats have aluminum intakes. 
I wouldn't run one unelss closed loop cooled personally.  Many have and do.  

For water
Lots of oil changes with cheap oil, cheap filters.  Plan on 3 to 5 with running time up to normal operating temps the last few times.

I flushed mine with diesel/k1 between changes when i had a quart or two of water enter.  Wasn't any need to pull valve covers.

Bachelordude

Thank you Rick. I was just thinking since we are changing the intake not that much more to pull the valve covers. I can see a considerable amount of milky oil through the fill cap when removed so I thought I would get as much out with a small shop vac as I can. 

212rowboat

@PickleRick most cars don't have aluminum intake manifolds atop iron blocks running WOT of 4800RPM with less than 170* water pulsing through the jackets... ever heard of a phenolic spacer (intake manifold-to-heads, not TB or carb spacers) ?  THIS is a condition that would greatly benefit from them.  it's also a reason you don't see plastic/composite intake manifolds on boat engines though they are ridiculously cheaper to produce. 

re: water flushing
yeah, change the oil until you don't see it.. K1 flushing is an old and reliable trick to... 

matching right parts:  I don't know what engine you have... the vortec heads will mount on SBC's, but so will older heads- which will dictate your intake manifold... we gotta identify the heads first.  vortec heads have a sawtooth casting on the front of the head.  

the one on the right:


but you have vortec heads... the eight bolts give it away (eight instead of 12).  they sit at 70* instead of straight up and down, which means it's the later ones.  they are designed for a gasket of a certain flavor- it's plastic with rubber lined passages for the ports and water jacket.. they are torqued lightly... 11ft#'s IIRC... IF you're using the right bolts, they bottom out to prevent over torquing- you know what happens if they're over torqued?  the same thing they'll do not torqued enough... they'll leak.  hence, the 'vortec intake manifold warp' wives tale.... it's not that they warp- it's that folks think they warp because they don't use the proper gasket.  the proper gasket (plastic and rubber) is damaged by over-torquing.  

re-head gaskets: 
did you get hot?  you said it was running well prior... this is a close call to decide if you need head gaskets.... i'd almost (almost) say go with what you got, but i'd be worried about water infiltrating the cylinder and the gaskets blowing... so... do a compression test followed by a leak down test... do it with the valve covers off so you can ensure the valves are well closed on the compression stroke... but don't pull those head bolts until you've do this... if you unseat them then you're certain to need to check them.  most head gaskets don't like being disturbed after initial crush. 

PickleRick

 The guys putting the LS motors in the go fast boats, are they ditching the composite intakes?  Ive not looked into their builds other stupid priced exhaust manifold and riser kits.

212rowboat

they're using phenolic spacers, which are a part of the intake manifold gasket on those things.  fel-pro for composite intakes: 



looks like a regular old gasket...... almost.  blending the temperature is a big deal especially with the composite intakes. 

and, those high dollar go fast guys tear those things down all the time- just like the nascar guys... we don't.  we run the dog mess out of them and then park them for a week and expect it to happen again the next weekend without complaint.  how many heat cycles does a nascar engine endure?  how many heat cycles do the go fast off shore boats endure between tear downs?  why is is far more popular to run BBC's in those folks 'recreate' on? 

there are more problems with that eddy intake than just the material, anyway.  it's not a low end grunt intake- it's a mid to high range where developing the inertia of the mass (air- hence runner differences) isn't as important as it is at low range... there is a reason merc intake manifolds are popular in off road builds, as a for instance, as the off idle flows superbly and follows right up to the around 5kRPM... it falls off dramatically over 5k, which is outside the design envelope of the merc engines but right at the beginning of true performance engines range.  

PickleRick

Is the intake manifold in question a marine specific aluminum intake or automotive?   I also didn't follow the question on the off shore BBC choice.  When researching my bayliner the 454 vs the 350 was a near 1000 drop in rpm for a cruising speed when the BBC was used and I think 5 or so more mph top end, maybe more.  Less rpm, not much weight gain, not really a bad trade off to go BBC.  Big displacement torque to move big displacement boats.  

Speaking of edelbrock manifolds, what's the  rpm range on the performer rpm vs the high rise torque manifold?  Isn't the performer more for street vehicles, more low/mid range rpm perfomance?

Bachelordude

SO the intake that's on the now is a Marine eddy aluminum. Im going to replace it with a cast iron intake to start with. It seems 212rowboat nailed it. Sure is making sense. The intake is a 12 bolt so the was it sounds its not a Vortec intake. I dont have the saw tooth on the front of these heads so they are not Vortec. I found a manifold I think is the one that will work.  Item# 174379632814 on ebay. $205.00. 

Universal intake bolt pattern for 1969 - 1995 applications 

• 4 Barrel Universal Carburetor mounting

• 15 degree carburator flange

• Must use electric choke

• All required mounting and accessories holes are tapped

• Superior runner finish for increased air flow

• CNC machined for exact fit and bolt hole location

• Manufactured of the highest grade of cast iron. Resists salt water corrosion that aluminum intakes experience & corrosion caused by natural gas and other dry fuels

Hopefully this is the correct one so I can get it ordered asap.

Thanks Guys!!! You ROCK

Bachelordude

Should I get the Felpro gaskets with the phenolic spacers?? I havent located them for a Mercruiser so do I just get them for a 350 SBC???

212rowboat

Nah... dont need them of you're using cast to cast iron.  Regular ol gaskets and youre golden. 

PickleRick

You wont have the different heat expansion rates using cast iron on cast iron so no need for special gaskets although i still wouldnt use cheap ones.

@212rowboat would you flow match the intake gaskets if needed? Cutting off any gasket material that overlaps into the runners?
I think that's called flow or port matching.

212rowboat

yeah i would... its a good little trick and helps with flow beyond doubt... i don't think i've not done it since i learned about it.  

except on vortec heads it's a great thing... the vortec heads NEED that specific style of gasket (not the phenolic spacer but the ones that fit and clamp with the lessor bolts), and that eliminates opportunity to port match... but vortec heads and manifolds breath good no matter- really well, actually.  so long as the cam isn't too aggressive, say under 430 lift.. the flow capability on OE vortec heads and intakes is better than most after-market anything on the old 'double humpers'.  which is why they respond so well to headers and increased (a little) ratio rockers... those two little things offer a lot more gain than doing the same thing to a ford modular or 289/302... because those vortecs have the capability to flow as is... 

Bachelordude

Sweet. You guys are awesome. Probably saved me a lot of money. Did anybody look up that ebay item number I posted for the manifold? Pretty sure it the right one. Ive always bought mercruiser parts with the exception of the intake and carb. I will buy mercruiser manifold gasket if its available. Once the manifold is confirmed I will order it and get it installed in the next couple weeks. I will also make sure the gasket is flow matched as mentioned. Thanks to all of you!! Great forum. We gotta stick together right??