2016 Mercruiser 6.2L ECT DTS Axius Cooling System Issue

[Scott Danforth]

Pull the PS cooler, clean the intake side and back flush the line out. You can do it with a beer and your transom shower hose

 

[drewm3i]

Alright Ted, time to get the Formula with big blocks back

 

[alldodge]

Alright Ted, time to get the Formula with big blocks back

Formula yes, BB ah no

 

[dubs283]

Formula with big blocks

There's a few

Some good

Some okay

All squirrely

 

[Scott Danforth]

Ooohhhh ...... twin 632BBCs with twin 871s and twin 1150s

 

[tpenfield]

Formula with Big Blocks . . .

We looked at a Formula 330 CBR, but it had 350 MAG SeaCore @ 300HP each IIRC. Seller wanted 20% more than what we were looking at for the CY 338 boats. The Admiral did not like the cabin access door design.

I do miss BBC Gen6 rollers that were on the Formula 330 SS.

I ordered an impeller kit, just in case I find any impeller bits..
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It seems that Mickey Mouse has a job in Mercury's design department . . .
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Anyway, I got a few things to check out today. I might pull the boat on Tuesday for a look at the outdrives.

 

[tpenfield]

Quick update. . .
The P/S cooler is hopelessly buried under other hoses and the Popeye valve. So, that may be a project for another day.

As a work-around solution, I tied the 2 cooling systems together using the engine flush feeds. White hose in the picture below ( but don’t tell anyone that I did that )
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This worked out OK, as it has taken about 3 psi from the port engine and given it to the starboard engine at cruising speeds ( 3500 - 3800 RPM). At lower engine speeds the starboard engine gives a couple psi to the port engine.
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Hopefully, it will suffice for the next couple of weeks as we have family coming. I’d rather take the boat out afterward.

 

[alldodge]

That's thinking out of the box

 

[nola mike]

Did it bring down the exhaust temps?

 

[tpenfield]

That's thinking out of the box

Morning coffee epiphany. The flush line is only 3/4” ID, so it is a bit restrictive, but it seems to help.

With this - the bets on the ‘shell stuck at the bell housing’ are looking good.

 

[tpenfield]

Did it bring down the exhaust temps?

Don’t know, I didn’t have the computer with me. Maybe this week I can do a computer recording.

I ran it for a couple of mins at 3800 and no Guardian mode. I bet if I went WOT it would go Guardian

 

[Lou C]

One thing I wished they would have incorporated into outdrives is removable water intake screens; in my experience with salt water boating most restrictions are in the water intake area. I never found anything past there with pulling the outdrive every season. Some outboards have these but I/Os moored in salt water need them even more…

 

[tpenfield]

One thing I wished they would have incorporated into outdrives is removable water intake screens; in my experience with salt water boating most restrictions are in the water intake area. I never found anything past there with pulling the outdrive every season. Some outboards have these but I/Os moored in salt water need them even more…

That is why I have the sea water strainers. I my area, it seems that stuff grows inside the outdrive water duct, dies over the winter, then detaches from the water duct the next season, where it blocks the intake line at the bell housing fitting. I've had this happen twice. Once was the infamous 'shell' and another was a barnacle that I caught during pre-season prep.

Some folks put a thru-hull water pick-up as a remedy. I try to spray the anti-fouling paint inside the the water duct as best I can, but it still can be a problem.

 

[tpenfield]

Here are some before & after 'tying' the cooling systems together . . .

1,000 RPM . . .
2+ psi difference with Stbd higher.

less than 1 psi difference, stbd still higher

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1800 RPM
Stbd still higher by 2+ psi

Stbd & port about even . . .

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The stbd engine psi max'es out at 15-16 psi, while the port continues to rise, although not as high as before the workaround was installed.

Rain/thunder storms for the next couple of days, so I am not sure what additional testing I'll do. I'd like to get another Diacom recording in to see what the exhaust temperatures look like.

 

[Lou C]

I wonder if you could back flush your raw water intake line from the impellers back with the outdrives off to really clean it out.
I had such a problem with barnacles growing on that water intake screen in the lower unit I removed it about 10 years ago. After that I could easily rod out the 4 water intake holes with it tilted up on the mooring.

 

[tpenfield]

I wonder if you could back flush your raw water intake line from the impellers back with the outdrives off to really clean it out.
I had such a problem with barnacles growing on that water intake screen in the lower unit I removed it about 10 years ago. After that I could easily rod out the 4 water intake holes with it tilted up on the mooring.

Yes, when I pull the boat, I should be able to take the drives off, clean out any debris and backflush everything. If I have enough time, I might do the poor man's fix on the delayed shift.

 

[tpenfield]

Today was a nice flat day out in the bay, so I took the boat out for some test runs of the cooling system. The starboard engine raw water intake is typically running about 5 psi less that the port engine - not always, as at the beginning of the holiday weekend they were both the same. Yesterday and today, not so much.

Today, I was able to get about 4 minutes of Diacom recording on each engine. Below are the graphs comparing the exhaust cooling water temperature to the engine speed and then the raw water pressure.

Starboard Engine . . .

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The temperature steadily rises as the boat is accelerated from idle speeds to cruising speeds.

Port Engine . . .

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By contrast on the port engine, having higher water pressure, the exhaust cooling water temperature goes down and then rises.

I got to do some more studying of the data. Each run of the engine was abut 4 minutes. The starboard engine was run after idling out into the bay . . . the engines were up to temperature by then.

The port engine run was done immediately after the starboard engine, so that may be why the temps started out as high as they were.

I did not run the engine up to the 4,000+ RPM range, because I'm pretty sure the starboard would have gone into Guardian mode.

I'll run a few more comparisons of various elements of the data, but I'm thinking my next steps would be to get both engines to be about the same psi, then re-run the tests.

 

[tpenfield]

A couple more graphs of the engine coolant temperature (ECT) and the exhaust manifold (riser) cooling (sea water) temperature

PORT ENGINE

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STARBOARD ENGINE

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Just kind of shows the starboard engine is running at a 'marginal' cooling situation.

 

[tpenfield]

On the port engine, the port/left side exhaust is hotter than the stbd/right side exhaust.

On the starboard engine it is the opposite.