480db raw water flow issue

[creik]

i recently had starboard overheating problem on my cat 3176's, so i looked at entire system, checked everything, and changed impellers. when all was done, i noticed apparently much less flow from starboard pipe than port pipe. boat runs fine, no temperature issues.
my local cat rep tells me that he has heard that on some sea ray models, and as long as the temps are the same, not to worry.
anyone with similar experience? what should i do?

 

[Four Suns]

i recently had starboard overheating problem on my cat 3176's, so i looked at entire system, checked everything, and changed impellers. when all was done, i noticed apparently much less flow from starboard pipe than port pipe. boat runs fine, no temperature issues.
my local cat rep tells me that he has heard that on some sea ray models, and as long as the temps are the same, not to worry.
anyone with similar experience? what should i do?

So... other than your "starboard overheating problem", you have "no temperature issues" ?

 

[BonBini]

When you say "so i looked at entire system, checked everything". Did that include heat exchangers and coolers?

 

[creik]

correct.
i was on a crossing from muskegon, mi to milwaukee wi, and within a period of 30 seconds, the stbd temp gauge went from 188-192 (normal temp for me), above 230, and the coolant temp and water pressure alarm sounded. i shut down immediately, checked the bilge, nothing obvious, sea strainer was clean, secured the shaft and proceeded home on one screw.
began search the next day as previously described, including change of impellers, and now it appears to be back to normal, with the exception of the apparent lesser raw water flow stbd vs port.
btw, to be honest, i am not sure if it was even prior to this event......
chris

 

[creik]

i have looked at:
thruhull, sea strainer, free flow through intake to sea strainer, with strainer out and seacock opened, changed impeller.
there is belt to check since my water pump is gear driven.
i also checked that there was not a furry creature living in my exhaust, which is unlikely.
i have not torn into the heat exchanger side of things, and know i need to do that.

 

[osd9]

When you changed the impeller, was the old impeller in one piece or were there pieces missing?

 

[BonBini]

"i have not torn into the heat exchanger side of things, and know i need to do that". I was thinking 10 yr old boat... If heat exchangers haven’t been cleaned ever, may be something to get done on a maintenance level.

 

[MaddyDean]

Had a simular issue with my twin 5.7's. I went to WM and got Salt-Away and had the boat hauled for a couple of hours and flushed the system.

warmed the engines with water only then applied the salt away and I could visually see the water flow increase out the exhaust.

dropped her back in the water and has not over heated since.

 

[MaddyDean]

BTW: in regards to the heat exchanger. When i got back to port I had a beer with a dock neighbor and was telling him the story. he mentioned that he did the same thing--having the same issue--and also had the Exchanger removed and chemically washed. he said hit has not over heated since.

 

[osd9]

The OP had an accute overtemp issue. He shut down the motor and then the only thing he did was change impellers and the temps were back to his normal.

If the impellers were the problem, then I would think that they were in shot. If the impellers were still in good condition, then something else caused the problem.

 

[creik]

impellers were not in good shape, but on side of temp issue, only a piece about 1 inch by 1/4 inch was missing.
other thing: this is a fresh water boat, has never left lake michigan in its entire existence.

 

[BonBini]

The thing about fresh water is it's hard water. In the heat exchanger lake Michigan scale will get left behind. The same stuff that fouls our bottoms. You had a marginal impeller failure that sounds like was your heating issue. Now your wondering about a little less water flow. As these heat exchangers slowly become plugged over the years, they will slowly restrict the flow of water more and more. The end bonnets come off so you can rod out the cores. Get some new coolant in there too while your there. There is most likely a trans cooler too. If it's sea water cooled, clean that too. You've already heated up the fire rings in your head gasket once pretty good. Heating them too much weakens them. Cat has revised the gasket and procedure a couple times all ready. You don't want to be an unhappy boater with a blown head gasket. If your running cool now, perhaps they can wait till winter lay up. It's just around the corner.

 

[tobnpr]

I'd listen to Ron- service the heat exchangers. They're long overdue...
I was thinking that something as simple as sucking up a plastic bag over the intake strainer would cause a sudden overheat like you experienced. Shutting down (and eliminating the suction) would release the obstruction and the overheat "problem" would not recur and remain a mystery. That still wouldn't explain the reduced raw water flow- which is where the heat exchangers come in.

If you want to try a "shortcut" first, use Rydlyme Marine, or some guys use muriatic acid, to flush the raw water side.

 

[Four Suns]

I curious how you know you have reduced water flow... the pipes on your boat, I assume, are the same as mine and when the tanks are full, they are underwater and when they are empty, they are about half underwater... and the gases from the engines move the water as much as the water pumps.

I would agree you need to clean the raw water system...

This is a fuel cooler from my boat at 4 years old:

and

I flush the engines with Rydlyme now every 2 years and the raw water cooling circuit stays very clean:

and

No scale....

I sucked up some sea grass in my starboard engine this summer on my way to New Jersey and the temp rose a few degrees. The result after running 5 more hours, however, was an impeller (that was 7 days old) being shot along along with the plastic cam being busted up:

I had to pull the water pump off the starboard engine (in Atlantic City no less) to get the old impeller out... You can see from this picture of my water pump (with shiny new impeller and cam from my spares box) the scale on the lower bronze hose connection:

I had to get a wire brush and dremel tool to clean all the scale deposits off the outer part of the bronze fitting before I put it back to get a good hose seal... it's been about 2 years since I've flushed the raw water circuit... Skip and I are having a Rydlyme flushing party at Port Kinsale this labor day weekend. Beer + flush kit + Rydlyme + burned chicken will be a hoot.

Scale is scale... I don't think salt water has a lock on holding more non-NaCl minerals that fresh water... I remember growing up in Michigan and hard water was a real problem and they sucked our drinking water out of Lake Huron about a mile offshore.

 

[douglee25]

I'm surprised they don't make that cam out of broze instead of plastic?

Is there any upgrade to that?

Doug

 

[Boatingfool]

Another options (but not sure if I am sold on this yet) -

Three of my friends have Crusiers with the Cat diesels(3116 or 3126). All three started overheating this summer (running 10-20deg warmer than normal). They had a Cat Tech come out to take a look. He said this is what he'd do (but not to tell his boss...lol). Instead of paying all the labor to take the aftercoolers apart which is the normal procedure, simply force muriatic acid through the system (same stuff you use to clean the aftercoolers when it is all apart). Let sit for three hours. Rinse through (by starting the engine back up), then install new zinks if needed.

All three did this, and all three had a lot of scale come out. All three are also back to normal operating temperatures, and have been running strong ever sense.

Further, my father A/C units started not cooling as well this year. Reading through the A/C Crusair directions it said to periodically clean through the raw water strainer with 20% mixture of muriatic acid. This worked and restored his A/C air to normal cooling.

Still not sold on these processes, but it works successful for those people. Has anyone else tried this?

 

[douglee25]

That's basically the rydlyme technique althought they tend to circulate it through from a buck/reservoir.

Doug

 

[tobnpr]

Mike, same idea as what we're talking about with the Rydlyme. I don't know enough about the proper concentration of muriatic acid to use, and Rydlyme is "safe" for the metals (except the zincs).

Basically you make a "loop" through the raw water circuit- on my 3208's it was from the raw water pump outlet (that became the flush inlet) and the hose right before the turbo before getting dumped into the exhaust.

I used an old freshwater pressure pump, grabbed proper size pvc bushings to fit the engine hoses and 5/8" hose barb fittings for them to attach to the water pump, and a bucket of Rydlyme. You pump the solution from the bucket, through the "loop", then back into the bucket for a few hours. You'll be amazed at what comes out of there. Simple to do, and the results are well worth the minimal effort. You need to replace all zincs after, or pull them first if they're worth saving and put the empty plugs in for flushing.