OT- Is there such a thing as "engine rot" from old coolant in iron block jacket ?

[Milacron]

People seem to be dancing around your question...I will say 'probably' there is 'some particle' of truth to engine rot.

If coolant was used? No. But if someone used straight water or even worse something that contained the right chemicals? I think so.

I had a friend with a '02 3.8L Ford van that had been run for some years on what we surmise was straight water (prior to his owning it). We could NEVER get that think to stop rusting up the coolant. We did many system flushes but still the coolant would turn rusty, even to the point that the heater core clogged up.

We replaced the water pump due to low flow - when we removed the old one there were absolutely no vanes left at all as they had rusted away.

We'd flush it all out, and it would run fine with a fresh 50/50 Prestone/ distilled water mix but over a year or so it would get all rusty again. You could always tell because it would run hot and/or the heater core would clog up.

New radiator (old one was 1/3 clogged solid with rust) and the engine ran fine then started rusting up and running hot.

By 'running hot' I mean it would run cool fine then all of a sudden the temp gauge would start climbing to 'damn hot'. You'd pull over fast and it would usually just as suddenly cool down and start the hot/cool cycle all over. It was like a bunch of rust was slugging up then breaking free. He bought a new vehicle for other reasons and the van got sidelined before we ran it all down. One thing's for sure - every time we'd pull the lower radiator hose it would dump rust all over. I'm guessing that iron block must have cylinder walls that are paper thin cuz all that rust has to come from someplace.

But even in your extreme case the rusty water, other than perhaps the engine running hotter, never actually hurt anything important did it ? In my case, the engines run perfect temperature wise...and I mean perfect, exactly as they should on 6 hour + trips...and that was on the previous coolant, which was of unknown age....might have been changed a few months before I bought it (April 2015), might not have been changed since 1998...just don't know, and can't trust the previous owner to know as he was so hands off. I could try his "consierige service" in Naples, FL I suppose but they wouldn't be too thrilled to investigate it.

 

[Ziggy2]

1993 vintage Detroit diesel 12V71TA's (TA's are fresh water cooled, as opposed to older Detroit TI which is salt water cooled)
in a boat where both engines were totally rebuilt about 5 and 7 years ago, 300 and 320 hours ago. Coolant was changed about two months ago (not flushed, just drained and changed) but supposedly showing higher than normal levels of rust particulates still after just 2 hour sea trial.

Age of coolant at time of change unknown but as I recall it still appeared green looking at it.

Now get word from yard mechanic that it must be "engine rust rot" and once it starts, pretty much nothing you can do about it and will eventually invade head bolts and maybe even cylinder liners !

My BS meter is hitting the red zone on this, so I ask one of our most knowledgable PM members (he can identify himself if he wishes...hope he does actually) who rebuilds antique race car engines for a living. He tells me it makes no sense to him either, especially considering he has rebuilt 30+ year old engines that had just water in there for 30+ years and they were fine ! (water only because an engine will run slightly cooler that way and the track folks don't want any chance of slippery coolant leaking on the track)

Admitedly most race car engines have aluminum blocks but he has dealt with many cast iron as well.

So, I ask (in person) another marine yard owner who seems very knowledgable about everything marine, and he tells me, yes 100% bullshit....just needs acid flush and keep up with year coolant changes and will be fine....engines will die of some other cause waaaay before the jackets rust too much.

And if you think about it, there is no "protection" in the cored iron jackets from the day they are made...just raw cast iron in there. Also I Googled "engine rot" and came up with pretty much no one talking about the subject.

Also, think of all the tens of thousands of ancient "barn find" cars that have been sitting around for decades with old coolant in their engine...engines that are of pitiful construction compared to a military grade Detroit diesel, but with a coolant flush, are fine from there on out.

So, can you guys confirm the BS nature of this, or does this guy have even a tiny bit of reality on this subject with regards to a fresh water cooled marine diesel ?

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As an aside, I also find out they almost certainly used the wrong kind of coolant for a marine diesel when they changed it out two months ago. What they used (judging from a couple of leftover full jugs in the engine room) is NAPA green antifreeze coolant, formulated for use in automobiles and light duty trucks ! I don't think a turbocharged 12 cylinder 2 stroke diesel engine in a 90,000 lb yacht is "light duty"...do you ? (can post photos of the coolant jug label if you need all the details) Pretty much the polar opposite of light duty IMHO.

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Aside no. 2 is this engine guy may not be ignorant on this subject but rather flat out lying about it. I say this because the boat is for sale and is under contract....and the potential new owners are likely to spend way more with this yard on repairs and upgrades than I am. So they have some inspiration to make me "worry" about the boat and therefore reduce the price enough to ensure the buyers go thru with the deal. But then again, the coolant change was done way before these buyers were in the picture, so his use of "light duty truck" coolant makes one lean toward ignorance. Could be a little of both, but you guys tell me.

Absolute BS.
The 71 series Detroits are a dry liner engine. The water cooling jacket does not come in contact with the liners and there are no o-rings on the liner to leak into crankcase.

Now if this was a 53 series or a 92 series, then you should be worried if you have a lot of rust in the coolant. These engines were wet liner engines and the sleeves would perforate from cavitation ( possibly the engine rot reference)causing the liners to develop pin hole leaks into combustion area and crankcase.

All things considered, I think they are trying to mislead you.

As far as the wrong antifreeze, the 71 series of Detroits were not as picky about the antifreeze. The 53 and 82 series had specific anti-corrosion inhibitor requirements to protect the wet sleeve liners from perforation.

For the 12V71TA, it is probably alright until the next time you change it. It will not be the source of the existing rust. I would suspect that the previous owner was not servicing the coolant properly and allowed the coolant to degrade.

 

[Milacron]

I'd say he's full of shit.

Selling the boat already?

Trying to.....wife's health blew our "sell the house, live on a boat" plans to Hell. Actually didn't intend to buy one this large...wanted to max out at 58 feet but this one was just sooooo nice for the money. And yet still turned out to be a total mistake due to unforeseen circumstances.....not to mention the hurricane. But in a way I'm actually kinda glad about the hurricane damage as it forced me to take a really nice trip to the yard and much of it has been fun, amazingly enough. SWMBO was well enough back then to help out and she enjoyed it too. But now....uh boy...don't ask...

 

[Milacron]

Absolute BS.
The 71 series Detroits are a dry liner engine. The water cooling jacket does not come in contact with the liners and there are no o-rings on the liner to leak into crankcase.

Now if this was a 53 series or a 92 series, then you should be worried if you have a lot of rust in the coolant. These engines were wet liner engines and the sleeves would perforate from cavitation ( possibly the engine rot reference)causing the liners to develop pin hole leaks into combustion area and crankcase.

All things considered, I think they are trying to mislead you.

As far as the wrong antifreeze, the 71 series of Detroits were not as picky about the antifreeze. The 53 and 82 series had specific anti-corrosion inhibitor requirements to protect the wet sleeve liners from perforation.

For the 12V71TA, it is probably alright until the next time you change it. It will not be the source of the existing rust. I would suspect that the previous owner was not servicing the coolant properly and allowed the coolant to degrade.

Yes ! Finally a straight answer ! And great to know they are dry liner as well....the other marine yard guy I mentioned asked me that first thing and I didn't know the answer...but he said the whole 'engine rot' thing was total absolute 100 % bullshit either way, but especially if they are dry liner type.

 

[Monarchist]

Trying to.....wife's health blew our "sell the house, live on a boat" plans to Hell. Actually didn't intend to buy one this large...wanted to max out at 58 feet but this one was just sooooo nice for the money. And yet still turned out to be a total mistake due to unforeseen circumstances.

You are far from the first.

Most of those I know - all too-many, given Hong Kong's islands are, by definition, surrounded by water - tried the liveaboard life due to lack of choices after divorces. Sometimes more than one.

If that sort of deal can eat a Cathay Pacific 'heavy' left-seater's lunch, it is seldom the dream folks would wish it to be.

Hope you both get the chance to try it again in future.

Highly recommend sail, Diesel augmented, not power-only, if you still expect to eat, reglar-like, after the fuel bills for a few hours even at best-economy cruise add-up, even for a 'displacement hull', not pushed up to planing.

Chesapeake Bay and tributaries are a good base for that. Very much so. Works best even so, if there is a shore residence of some sort in the package, even if sort of early Hemingway'ish. Humidity thing, and cost of wintering on the water, mostly.

 

[Scottl]

Never heard of "engine rot" so if it exists it must be rare. I've seen badly neglected engines choked with rust work just fine after proper flushing. The major problem with neglected automotive engines is rust out of the core plugs, which people mistakenly call "freeze plugs".

I would definitely be suspicious of that diagnosis and seek a proper flush and fill elsewhere.

 

[CarbideBob]

Marine mechanic and repair shops are interesting.
Some differing problems but very much higher paying clients.
You are correct to call BS but they do not care, do not know any better and you get labeled as a whiner.
I'm sure your "mechanic" is 100% sure he is right.
Now I'm going to conventional finish cut some aluminum parts since my screws have backlash on the B-port.

 

[Monarchist]

Never heard of "engine rot" so if it exists it must be rare. I've seen badly neglected engines choked with rust work just fine after proper flushing. The major problem with neglected automotive engines is rust out of the core plugs, which people mistakenly call "freeze plugs".

I would definitely be suspicious of that diagnosis and seek a proper flush and fill elsewhere.

If the dance-card sez it must be sold, then yes, anything that doesn't cost the Earth to set right and adds 'comfort' to the survey of a buyer does help with how SOON it sells - which can be just as important as how much it brings.

Larger hulls can take a longish time to move, and it beggars prediction, save that the longer they sit, the harder it gets, and the less they bring.

 

[gnorbury]

Green coolant ok in iron engines - 2yr life. Orange (extended life) coolant in mixed/aluminum engines - 5yr life. Both include corrosion inhibiters.
Drain, flush and refill (incl water heater) with new coolant properly diluted with distilled water.
Go boating.

 

[snowman]

Trying to.....wife's health blew our "sell the house, live on a boat" plans to Hell. Actually didn't intend to buy one this large...wanted to max out at 58 feet but this one was just sooooo nice for the money. And yet still turned out to be a total mistake due to unforeseen circumstances.....not to mention the hurricane. But in a way I'm actually kinda glad about the hurricane damage as it forced me to take a really nice trip to the yard and much of it has been fun, amazingly enough. SWMBO was well enough back then to help out and she enjoyed it too. But now....uh boy...don't ask...

Eh shit...sorry to hear that. Dad's got the cancer...diagnosed a couple weeks after my grandma, who they were caring for, passed. Both him, and mostly my mom, while upset of course, were really looking forward to the freedom of having both sets of parents gone allows. Gives them the feeling that they get got when the kids finally moved out!

Hope you get to get back to that, even if it's not on a boat.

 

[SteveBausch]

Years ago, before the EPA, there was a Dupont No. 7 product (oxalic acid) for cleaning cooling systems.

NOT safe for aluminum.

Cleaning a Radiator - Technical - Antique Automobile Club of America - Discussion Forums

 

[Monarchist]

Years ago, before the EPA, there was a Dupont No. 7 product (oxalic acid) for cleaning cooling systems.

Still have some on the shelf, 1992 or so vintage.

Oxalic acid is still out there. Look for it at Big Box sold to remove Iron stains from marble or granite.

I have also used ignorant 'washing soda' and - before most of the TSP was removed, Tide laundry detergent powders, dishwashing powders, or TSP itself.

So long as one gets ALL of 'whatever' flushed the Hell OUT and HOT afterwards, not a lot of risk in any of those.

That said, I ALWAYS replaced the water pump, thermostat, and hoses before filling with fresh straight glycol.

Weakest players on the team, and first to fail, always at the worst of times, those three usually are. Now and then the radiator, too.

Costly?

Not compared to all the call-out and mileage fees of hook or roll-back I've mostly avoided, 1961 'til now.

Watercraft and potentially motive-power crippled far from shore - worse too CLOSE to it - in bad weather?

I'd be even more paranoid/careful.

Family were part owners of the downeaster "Henry B. Hyde" before de facto beneficial ownership was transferred to some ignorant ROCKS!

All that's left is an original in oils by a cousin, the late Gordon Ellis, Naval Architect by training, painter by profession.

 

[JHOLLAND1]

Detroit Diesel Block Rot

I refer to the official Detroit Diesel inline series 71 shop manual

"an improperly inhibited coolant can also become corrosive enough to
eat away coolant passages and seal ring grooves and cause coolant leaks"

if products of block oxidation are found in coolant --commercial heavy duty descaling process must be undertaken

cost of this service for a 12v71 marine in situ is $1000 ballpark

 

[Milacron]

I refer to the official Detroit Diesel inline series 71 shop manual

"an improperly inhibited coolant can also become corrosive enough to
eat away coolant passages and seal ring grooves and cause coolant leaks"

if products of block oxidation are found in coolant --commercial heavy duty descaling process must be undertaken

cost of this service for a 12v71 marine in situ is $1000 ballpark

Very good J. In order words, unlike actual "rot", there is something relatively inexpensive one can do about it that will cure the problem.

 

[JHOLLAND1]

well--$1000 per unit could be a cheap fix if it catalyzes sale of motor yacht

in situ engine descaling reminds me of chelation in humans--it does have application in circumstance of heavy metal poisoning but otherwise questionable

these folks in Tampa offer descaling--

24/7 Mobile Marine Repair Sarasota Bradenton St Petersburg Clearwater

 

[Ziggy2]

Very good J. In order words, unlike actual "rot", there is something relatively inexpensive one can do about it that will cure the problem.

Being that your engines run fine, are not over heating, and externally look very good and the fact that they were overhauled in not too many hours ago, you probably only need a really good flush.

One thing that is important before the flush is to take the boat out and run it hard for several hours to get everything suspended and then get the coolant dumped before the engine gets cold.

Then do the flush. All to often the coolant is dumped cold, the flush is only done in a minimal manner. All of the low point drains need to be opened and drained, the heat exchanger needs to be serviced.