Mercruiser Life Span Question

[othelloears]

Just finished a full resto on a 1984 Wellcraft 200 Elite Bowrider which I documented on this site. The only thing I haven't done is the engine a mercruiser 228/305chevy. All the tags seem to say its original although I doubt it.

The engine runs perfectly (knock/knock) but I run it all season in saltwater and assume at a minimum it will need risers soon. I bought it 3 years ago with 950 hours and have put 100 hours each season.

My dilema is I hate to spend good money on risers on an engine that I can't imagine has many good years left.

Couple questions for you engine experts

1) is there anywhere on the block that will tell me what year it is?
2) What is life span of risers in saltwater (i heard 5 max)
3) What is lifespan of block run in saltwater (ive heard 10 max)
4) Would you guys recommend...

a) running the thing until it dies and replace engine and risers (my current plan) or
b) spend the money on this engine and replace the risers

I wil ldo the work myself if that changes anything. I assume the risers will run me 500$ in parts?

All input is greatly appreciated

 

[IES99]

Re: Mercruiser Life Span Question

Note my engine, but from my experience with a 3.0 in salt water for the past 23 years:

1. If you don't know how old the exhaust manifolds and risers are, replace them now and every 5 years.

2. The lower end of these engines seem to be tough as nails if treated right with nice fresh oil and filters. The block is usually the least or our problem.

3. Never replace a perfectly running engine

4. Knock on wood constantly that your engine is purring like a kitten.

 

[HT32BSX115]

Re: Mercruiser Life Span Question

I assume the risers will run me 500$ in parts?

Howdy,


You can usually buy a complete kit (manifolds & risers) for about $500-600.

If everything runs well, I would save my money and plan on a reman 350 & risers/man later and replace the whole mess.

Salt manifolds and risers if flushed can last 5-10 years I suppose......some people have said they pull the risers every 2-3 years to inspect and replace gaskets...... When they clog, it's time to replace. You hope they clog instead of leak!!

When raw water cooled risers and manifolds clog due to salt water corrosion, I start thinking about the block and heads!

When you repower it you should also consider closed cooling for the "new" engine. Then you'll only be replacing risers in the future and it'll run MUCH better!



Cheers,


Rick

 

[BAproject]

Re: Mercruiser Life Span Question

Serial number can be cross referenced for age I believe.

If you flush the engine after every use you will get, at max, 5 years out of the risers. Exhaust manifolds will last longer, but you need to keep an eye on them.

Just keep on flushin' and run her into the ground, $600 isn't bad even if you get another couple of seasons out of it, if you don't spend the cash you will be running a new engine in no time.

Minus a solved overheat issue this season, my 4.3 merc has been running for almost 20 years (with a few years off in there)...and it's solid, knock on wood!!!!!!

 

[LAC_STS]

Re: Mercruiser Life Span Question

You could buy the manifolds and risers and run them on your engine. Then if the engine dies in the next year or two use the manifolds and risers on tour new engine. If they still are in good shape that is.

I couldn't find the serial number on my new engine for nothing. I did find a casting number which told me the info on the block.

I forget where the block casting number is but I think it's on the back of the engine on the top.

 

[Brentathon]

Re: Mercruiser Life Span Question

My original saltwater cooled 5.7 Merc lasted 16 years, and was never flushed-out after each use.
The only reason why it finally died, was that I overheated......quite bad......oil was boiling out of crankcase vent tubes, and the hot exhaust actually killed the drive.
My friend's father's boat has same engine, doesn't flush-out after using, and his is original 1990.

I believe overheating is #1 killer of engines.

 

[jerryjerry05]

Re: Mercruiser Life Span Question

There are casting #s on the back of the block on top.Take them to a dealer they should be able to tell what you have.
The block itself can last 20 years or more.
The risers/manifolds can last 15 or more.
Air is the real enemy.If you drain the block/manifolds the rust starts.Water will slow the rust down.It will still rust but not anywhere like when in the air.

The thing is change your waterpump impeller yearly.Keep the oil clean.Ethanol is an ENEMY.Use good gas.
Flushing with fresh is good if the water is gonna drain out like an outboard.
Or it's gonna set a while.Water evaporates and leaves gobs of salt in the hard to reach places.
If you buy new manifolds/risers and then repower.Save them as they will last a long time.J

 

[Brentathon]

Re: Mercruiser Life Span Question

"The risers/manifolds can last 15 or more."???
15 years on risers (aka elbows) in a salt-water cooled engine........the owner would be "asking" for problems. I've never heard anyone make a 15 year claim on elbows
I replace manifolds every 6 years, and elbows 3 years........MUCH cheaper than the problems old manifolds/elbows will eventually cause.

 

[Lou C]

Re: Mercruiser Life Span Question

The risers/manifolds can last 15 or more.
Air is the real enemy.If you drain the block/manifolds the rust starts.Water will slow the rust down.It will still rust but not anywhere like when in the air.

This is what I have been saying for some time in discussions on winterizing...people keep saying you don't need antifreeze for winterizing, air doesn't freeze...right....but air OXIDIZES...that's RUSTS in laymen's terms....it's the OXYGEN in either air or water that causes iron to oxidize (rust)...so if you fill the engine with no tox -100 AF with corrosion inhibitors, you reduce oxidation (rust)....doing this can make both raw water cooled blocks/heads and manifolds last longer....Just drain it manually and back fill....

Winterizing means not just protection against freezing, protection against corrosion too...why else to you fog the engine...why do you spray everything with Corrosion X or Boeshield....

I have seen raw water cooled blocks last as long as 20 years or longer around here....

 

[othelloears]

Re: Mercruiser Life Span Question

Wow. Thanks for all the input.

The basis of my plan was that the blocks rot/rust out. It sounds like that is not a big concern and that most enigines are trashed becuase of rotting manifolds/risers due to leakage or overheating. That changes things for me. I will do the compresion test when I pull it

The boat is in the water all summer and really can't flush.

My frustration is that the thing cools perfectly (knock knock) 140-145 all day long

BIG QUESTION...Would you still replace them if there are absolutely no signs of overheating?

 

[sasto]

Re: Mercruiser Life Span Question

The Admiral has a 1974 318 Chrysler with 1300 hrs and she still runs great.....today, don't know about tomorrow. Don't know about you, othelloears, but I'm gonna run her till she drops. Have Sea Tow will travel.

 

[HT32BSX115]

Re: Mercruiser Life Span Question

I believe overheating is #1 killer of engines.

The number 1 killer is lack of maintenance.

 

[6meter]

Re: Mercruiser Life Span Question

My '86 is all original 350/260 and an Alpha 1. There was several years I didn't use it though. Only put about 25 hours on it this year. Winterized with no antifreeze.

 

[Lou C]

Re: Mercruiser Life Span Question

Wow. Thanks for all the input.

The basis of my plan was that the blocks rot/rust out. It sounds like that is not a big concern and that most enigines are trashed becuase of rotting manifolds/risers due to leakage or overheating. That changes things for me. I will do the compresion test when I pull it

The boat is in the water all summer and really can't flush.

My frustration is that the thing cools perfectly (knock knock) 140-145 all day long

BIG QUESTION...Would you still replace them if there are absolutely no signs of overheating?

I 'd be looking more for flaking chunking rust...cast iron, when it really starts rusting bad, flakes off in big pieces...IMHO when you see that replace em even if it's not overheating...all that means is the rust chunks made it out the exhaust...and didn't clog it!

BTW I have heard of people starting their raw water cooled I/Os up in spring and seeing a lot of rust come out in the cooling water...I've never seen this on mine and I think filling it with the AF helps....

 

[Alpheus]

Re: Mercruiser Life Span Question

I believe overheating is #1 killer of engines.

And rust clogging up the water passages from not flushing your engine and regularly changing risers and manifolds is the #1 reason for over heating engines.

Maybe #2 after people not changing their impellers. But its up there on the list...

Maintenance is not just a word...

 

[zbnutcase]

Re: Mercruiser Life Span Question

The number 1 killer is lack of maintenance.

Freeze damage!

 

[Alpheus]

Re: Mercruiser Life Span Question

Freeze damage!

Thats a good one too...

 

[Kaplooi]

Re: Mercruiser Life Span Question

If conventional wisdom says you can expect around 1500 hrs from a gas stern drive engine then you're approaching that number. But that's all it is, an average number. If it was well taken care of prior to your owning it and still has good compression you might as well run it until it dies, replacing manifolds/risers as needed. The point is, either way, you're better off only replacing the long block and transplanting all your accessories and manifolds. So even if you do invest in new manifolds you're going to keep them if you get a new block and it's not money lost. Unless you have a good reason to replace the entire engine (upgrade HP or switch to EFI or something) I'd say stick to your current plan and replace the block when it finally quits because every day you use that tired old block is one less salty run on a new one .

 

[Riegfrghtl]

Re: Mercruiser Life Span Question

I have a 1972 Cruisers, Inc. with a Mercruiser 888 (ford 302) with just about 1200 hrs on it. I have been diligent with tune-ups, oil changes, and outdrive maintenance. Come spring will pull manifolds and rod out or replace if necessary along with risers. Motor runs like the day it was brand new. I'll keep my fingers crossed but I hope there is not a new motor in the future.

 

[Brentathon]

Re: Mercruiser Life Span Question

And rust clogging up the water passages from not flushing your engine and regularly changing risers and manifolds is the #1 reason for over heating engines.

Maybe #2 after people not changing their impellers. But its up there on the list...

Maintenance is not just a word...

Yes, I agree.......with above.......it's kinda like the "chicken or the egg"....impellers, manifolds, risers are top reasons that cause the top engine killer....overheating. That's my 2 cents.
I don't often hear of freeze damage, as I do overheating issues.