Mercruiser Woes-What Next?

[abl1111]

I pulled my boat a week or so ago as I always do before opening day of deer season. Weirdest bass season I can remember. The bass here on the southshore never entered the Great South Bay - they all have been in the ocean, caught on jigs. A lot of schoolies. I'm a live bait guy and target bigger fish, so I thought, "well, this season sucked"... But, I do hear it's still on !

Anyway, sorry to hear about your engine, and you're right, it could have been out in a bad place, snotty seas, COLD! etc.

Damn! I'm all about preventive maintenance and I know the job should be done, but it's a tough one to do when all seems perfect ! Your story, however has me freaked out !

Where did you buy your manifolds and set-up and what did it set you back ?

How was the labor, any tricks / shortcuts I should watch for ? How long of labor for each side ? I have done a lot of peripheral mechanical stuff on this engine; fuel injection cooler ( BITCH of a job ), new water ciculator/pump, exhaust bellows, heat exchanger, etc. plus all the seasonal maintenance.

My motor is very clean and well cared for - better than a mechanic would do - I guess anyone on this site has to be fairly meticulous or they would let other people work on or repair their boats... But, a 'clean' looking engine does not tell the inside story...

What'cha think ?

[oldfielder]

If you asked me a week ago, I'd say wait em out, but my manifold failed internally with no signs of decreased performance/overheating. If I could do it again, I would be pro-active. i think you're on borrowed time. If you post the question over on boater ed forums you will basically get shouted at that you are about 3 years overdue.
You certainly can roll the dice, but it's been a crappy end to my season. Good thing I like fishing the surf.
By the way, my buddy had nice fish the last few days in FI inlet on spot and herring-up to 30 lbs.
I got the exhaust from lighthouse in r-head-they go by partman online. Very cool guys and a big operation. All of my research on aftermarket led me to the oscos, which come with all the mounting hardware and the gaskets. Merc is making a low end product now, as well.
You could def. handle the job, but an extra set of hands would surely help. Manifolds are heavy beasts.
If you have any other questions, let me know. I'm hoping I dodged a bullet here.
Maybe we can hook up and do a N.Shore/S.Shore thing in the spring. The fluke bite gets pretty fiery just outside of my homeport in june.
Doug

[pelican]

if you're smart,you're gonna replace the engine with a complete new engine-too many horror stories !
it's gonna cost more,but,in my opinion(i own a marine repair shop) it's the best option-it's also the only way i repair problems like this.
using a "long block" that's reman'd is a crap shoot at best.

manifolds and risers-5yrs max-flushing has no bearing here.overheating isn't a factor either-the water passages will erode away,allowing the water to enter the cylinders via the exhaust valves-eroding the valves and causing a low,or,no cmpression situaton.remember,we're talking about sea water-this is where the cooling water is expelled.sea water in an engine isn't a good thing-think about the dissimilar metals here...
if you're engine "locked up" due to hydro locking-you would've had a few tell tale signs to alert you to a potential poblem-"steam" from the crankcase vents- breather tube,where it goes to the flame arrester,salt residue may be present as well.you may have noticed a drop in max rpm too...
getting into the habit of a yearly compression test is usefull-it gives you the opportunty to inspect the plugs-look for plugs with either a rust stain,or,plugs that are snow white-steam cleaned-this is another tell tale-this shows there's water entering the cylinders...

trust me,the advice i gave is the best...

[abl1111]

Fishing - heard about the spot but $5 a pc a is stiff. Not much bunker this year - a weird run... Maybe next year will hook-up with fishing... I never fish the north shore...

As for manifolds - did a little reading tonight. Mercruiser makes the ceramic coated manifolds - pricey ! I wonder if it matters which you use - OEM or aftermarket.

Pelican - you have an opinion here ?

Old - did you R/R elbows too ?

Also, did you torque them down or just tighten by estimate ?

[Fr. Frank]

if you're smart,you're gonna replace the engine with a complete new engine...
manifolds and risers-5yrs max-flushing has no bearing here.
trust me,the advice i gave is the best...

I agree with everything here but the issue of flushing. Flushing your engine can save your from early failure, but failure will still come. Regular motor flushing can extend manifold life to 7 years IF it is done without the motor ever cooling with salt water still in the manifolds.
the problem is many/most people shut the motor down while drifting or anchored, or fail to flush after use until they trailer the boat home, allowing the motor to cool and then reheat with high quantities of sodium still in the manifold.

Replace the motor if you plan on keeping the boat for more than two more years. Replace the motor with a closed cooling system and heat exchanger, and STILL change the manifolds and risers every 5-7 years.

[lost2a6]

I agree with everything here but the issue of flushing. Flushing your engine can save your from early failure, but failure will still come. Regular motor flushing can extend manifold life to 7 years IF it is done without the motor ever cooling with salt water still in the manifolds.
the problem is many/most people shut the motor down while drifting or anchored, or fail to flush after use until they trailer the boat home, allowing the motor to cool and then reheat with high quantities of sodium still in the manifold.

Replace the motor if you plan on keeping the boat for more than two more years. Replace the motor with a closed cooling system and heat exchanger, and STILL change the manifolds and risers every 5-7 years.

Frank, read his first post carefully. He has the partial closed cooling system which means that his engine/block is fresh water cooled only however the manifolds/risers are not. That being said I would see what I had before I just spent a lot of $$$ on a new engine. What normally kills a inboard or I/O is most of them are completely raw water cooled and the salt eats up the block/heads etc. Another option would be to get a new long block from GM and install his marine cam and acc. from his other engine, being a 1999 it should be a roller cam, which is nothing wrong with re-using provided it looks good.

[pelican]

[QUOTE]
[QUOTE]

if you're smart,you're gonna replace the engine with a complete new engine...
manifolds and risers-5yrs max-flushing has no bearing here.
trust me,the advice i gave is the best...

in 20yrs,i've never seen an engine fail directly due to being raw water cooled

i've never seen an engine fail due to lack of flushing either...most engines fail due to exhaust manifolds an risers leaking.i've seen the engine block break-where the starter mounts-the hi torque starters will actually shear this area off,when the motor hydro locks...
i've seen many boat owners with the exact same prolem,some opted for the "reman long block"-when all was said and done,the money spent was almost the same as a new complete engine...just some good advice...

[abl1111]

Mercruiser makes the ceramic coated manifolds - pricey ! I wonder if it matters which you use - OEM or aftermarket.

Pelican - you have an opinion here ?

What should a set of manifolds and elbows cost for a 2001 350 MAG MPI - fresh water cooled ?

[pelican]

Mercruiser makes the ceramic coated manifolds - pricey ! I wonder if it matters which you use - OEM or aftermarket.

Pelican - you have an opinion here ?

What should a set of manifolds and elbows cost for a 2001 350 MAG MPI - fresh water cooled ?

not sure if the administrator here would appriciate me giving prices-it could be tuned into me soliciting biz...

i use "OEM" parts only-if it's a merc,it gets merc parts-same for volvo's-ect...

truth is,the exhaust system is the weak link-this is usually where problems begin.alot of owners cause their own problems.improper storage is one cause of problems-storing an engine"dry" is one thing that's common.when stored-an engine should be "fogged" and ran on non-toxic antifreeze.reason being,if the cooling passages are "wet",there's an absense of air-meaning,no oxidation-get what i'm saying ?
flushing-you can flush all you want,but,truth is,the exhaust system still has a usefull life of approx 5 years-raw water side.read that as,if the exhaust system is raw water.in a fresh water cooled exhaust system,the risers are the point of raw water expolsion-these are good for 5 yrs max-the manifolds will last longer-only problem comes in,at the riser gasket/block off plate-this point will fail.merc has a "dry joint" here...

if i were you,i would compression test the engine,then winterize it,then replace the exhaust system.during winterization,i preform,and recomend others to perform a compression test,at this time-it will alert you to potential problems in the engine.do not go by the old "water in the oil",when water shows in the oil,the damage has allready been done.an example of this is,rust on valve springs-if rust is present,the spring is gonna fail.this is why,when an engine has water in the oil-and it locked up,attempting to free it with pour in products is like peeing on a forest fire-the damage is done...

i have the same power in my sea craft-2002 5.7 mpi merc,with the horizon package-the boat was in storage for 3 seasons-this year,it's getting a new exhaust system...it's all about preventitive maintance-i practice what i preach,avoid a problem before it happens...

[lost2a6]

[QUOTE]
[QUOTE]

in 20yrs,i've never seen an engine fail directly due to being raw water cooled

i've never seen an engine fail due to lack of flushing either...most engines fail due to exhaust manifolds an risers leaking.i've seen the engine block break-where the starter mounts-the hi torque starters will actually shear this area off,when the motor hydro locks...
i've seen many boat owners with the exact same prolem,some opted for the "reman long block"-when all was said and done,the money spent was almost the same as a new complete engine...just some good advice...

Well if he had shut the engine down and stored it for the winter not knowing that he had a problem, then it would cause major problems with the cylinder sitting with water in it all winter long which in turn would probably warrant engine replacement. However this doesn't sound like the case, he has found the problem right when it happened which should pretty much be treated as if the boat had sunk (pickling, oil change water removal etc.) If the boat had sunk you wouldn't just automatically assume that the engine was bad and just replace it, you would get the water out and get it running. I'm not a parts changer, I like to be sure that the part that I'm changing is actually bad, just throwing parts at something is the easy thing to do and requires no skill. If you wrecked your truck and it was fixable you wouldn't just throw it away and buy a new one you would fix it. As far as corrosion goes, on a completely raw water-cooled engine, the engine is made from the same materials as the manifolds, which is cast iron. The manifolds go first due to heat and they are thinner than the block, then the heads will go next. Usually the water passages get ate up and are so large that the head gasket will no longer seal it. Ask me how I know this? My father use to own a Marina and use to work on boats. I have been turning wrenches with him since I was 10YRS old; I'm now 40. The last thing that he want's to do is winterize it with moisture still present, if that happens, then he most likely will need an engine replacement.