Closed Cooling System on Port Engine Running Hot(ter)

[alldodge]

You should be in the 150 for new motor, they appear to be getting tired as you say.

 

[tpenfield]

You should be in the 150 for new motor, they appear to be getting tired as you say.

Pushing about 900 hours on these motors. I do remember a couple of years ago, I did a de-carb with seafoam and water and it brought the numbers up pretty good.

 

[alldodge]

Ya know I hear ever now and then about motors doing more then 900 hours, some say over 1200, but never seen one on great shape with those hours

 

[tpenfield]

Ya know I hear ever now and then about motors doing more then 900 hours, some say over 1200, but never seen one on great shape with those hours

As long as they run . . . I'll probably keep running them It would be quite a process to rebuild these engines.

 

[alldodge]

As long as they run . . . I'll probably keep running them It would be quite a process to rebuild these engines.

Come on Ted, it would be fun. You could do like me a spend twice what the boat is worth doing it :facepalm: but boy what power you could pull out of those motors

 

[tpenfield]

Come on Ted, it would be fun. You could do like me and spend twice what the boat is worth doing it :facepalm: but boy what power you could pull out of those motors

Yes, wicked fun . . . not sure I'm ready for that much 'fun'. Maybe in a couple of years. When I bought the boat, the engines had about 740 hours and I figured that they would probably go to the 1000-1200 hour range before they needed a tear-down. So, that was going to be about 7-9 years of boating.

Of course, once you take the engines out . . . then there is a whole bunch of stuff to check out in the engine bay and transom. Maybe I should retire first, so I will have enough time on my hands

 

[tpenfield]

FWIW - and because I like graphs, here is a graph of the compression data since 2012.
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My nomenclature is: "SL1" = 'Starboard engine' , 'Left Side', 'Cylinder #1'

I think the surveyor rounded 'up' to the nearest 5 psi, which is probably a standard practice. I try to be a bit more precise.

The De-carb in 2014 brought the numbers up a bit, although the progression over the 4 years is quite obvious.

Engines should be 150 psi when new.

 

[HT32BSX115]

The De-carb in 2014 brought the numbers up a bit, although the progression over the 4 years is quite obvious.

Engines should be 150 psi when new.

De-carbonizing is more effective in a 2-stroke engine (that has deposits from 2-stroke oil-mix) I suspect that "decarbing" a 4 stroke engine is more of a placebo than actually doing anything.

The most accurate compression reading is probably going to be obtained immediately after a few WOT runs (and maybe an oil fogging!!)

 

[tpenfield]

I bet I could get a few more psi out of them if/when I remove the outdrives.

 

[HT32BSX115]

I bet I could get a few more psi out of them if/when I remove the outdrives.

I don't think 900+ hours on an engine would necessarily be a guarantee of poor compression. My 66 150 Mercruiser had similar numbers in 2005, and the hour meter had over 1500hours on it (and it broke in the mid 80's)

 

[tpenfield]

Cooling System Flush Update:

Today was the day to do the iron flush of the cooling system. I drained the coolant and did a fresh water flush of the various parts of the engine. I pulled the fittings (plug and fitting) on the engine blocks, pulled the lower hose on the exhaust and the lower hose on the recirc pump, so that everything would drain.

Then I mixed about 20 oz. of Oxalic Acid powder with about 5 gallons of water. The directions said to do about 12 oz / 4 gallons of water, but I wanted to make the concentration a bit higher.

So, I filled the cooling systems (both engines) with the acid and topped them off with H2O. I ran the engines for about 15 mins and then again for about 5 mins. an hour later. My plan is to let the flush sit in the cooling system overnight and then run the engines some more tomorrow. Then I will drain, neutralize, flush and then load the cooling systems back up with AF.

An interesting Tidbit for everyone. . . The last time that I ran the engines, (about a week ago), I did a compression test and disconnected the coil wire at the distributors. Well for today, I had forgotten to re-attached the wire on the port engine. It was just lying on top of the distributor. Unknowingly, I went to start the port engine . . . it started up . . . after the idle settled, it ran like craap and eventually stalled :grumpy:. I started it back up again and it still ran poorly and rough. So, I turned the engine off to take a look . . . The coil wire was just sitting there about 1/2" away from the center post on the distributor. :facepalm:

I was in total shock that the engine started and actually ran. :faint2:

 

[HT32BSX115]

The coil wire was just sitting there about 1/2" away from the center post on the distributor. :facepalm:

I was in total shock that the engine started and actually ran. :faint2:

Isn't that a T-bird-5? That's a pretty hot spark!

 

[tpenfield]

Isn't that a T-bird-5? That's a pretty hot spark!

Thunderbolt-5 I suppose . . . probably 70K volts :noidea:

I kept the Oxalic Acid in the engines over night and then ran them some more this morning, then drained. The stuff went in the engine as a clear liquid yesterday . . . it came out the color of coffee (or stout beer) today., as shown in the pic below. I assume that is the iron held in suspension.



I did a water flush and then a baking soda flush to neutralize the acid. Got to fill the engines back up with AF.

This weekend will be winterizing, so I'll get a chance to look inside the outdrive water duct, etc. for any blockages.

 

[tpenfield]

The Iron Flush is done. Not sure how much it will help, but it is probably something I should have done before adding the closed cooling. The was a fair amount of iron 'dust' that came out of the engines.

Once the acid solution was neutralized the iron dropped right out and you can see it on the pavement below the boat.






Iron 'clouds' at the bottom of the water puddles.

OK, so the iron is flushed. On to the outdrive and intake line.

 

[alldodge]

That is a lot of stuff

 

[tpenfield]

That is a lot of stuff

Yes, quite a bit . . . I was surprised when I saw the color of the liquid coming out of the engine. The engine block drains were fairly clear when I opened them initially . . . now they are really clear. I didn't realize that the iron would settle out once the solution was neutralized, but I guess it makes sense, since the acid holds the rust in solution.

 

[alldodge]

Hey we could use you as the poster child as to why you should not add closed cooling unless it is thoroughly cleaned prior

 

[HT32BSX115]

Hey we could use you as the poster child as to why you should not add closed cooling unless it is thoroughly cleaned prior

My 454 had about 120 hrs since new when I installed the same closed cooling system. I flushed a LOT of debris (rust and sand) out if before I did the install.

I had the core plugs out and scraped out all the "stuff" I could reach. There was a lot of "caked" sand/rust in the bottom the cooling sys passages that did not flush out readily with flowing water by itself..

 

[tpenfield]

Hey we could use you as the poster child as to why you should not add closed cooling unless it is thoroughly cleaned prior

Yes, we could. But perhaps the acid flush is a good preparation step, prior to adding closed cooling. I don't think an engine that has been run in salt water would do so well. Still got to be fresh water run.

 

[Lou C]

Very interesting. I had always wondered how much internal corrosion interfered with heat transfer in a raw water cooled engine. I think all inboards should be closed cooled from the factory, since that is how GM designed the engines to start with, but I guess raw water cooling works OK in fresh water at least for a long time. Salt water, well you can get a good 15 years but after that you're on borrowed time. As I found out on mine with water in cyl # 2 at the end of this season (about 15 years in salt before that the boat was in the midwest in fresh water). I got the water out, changed the oil 2x, fogged it well and am starting to take it apart. Odd thing was the normal compression test readings (155-185).