'In water' cooling system maintenance . . .

[tpenfield]

My port engine is showing signs of a cooling system issue, so it looks like I have to do some maintenance while the boat is in the water, as pulling the boat and re-launching it is wicked expensive.

Some Info & Symptoms so far are:

Twin engines per my sig below . . . FULL closed cooling systems with sea water strainers before the sea water pumps.

1) When I come off plane and go to 'no wake' speed both engines rise in temp as expected, and then return to normal temp ranges. . . . lately, the port engine is rising higher and staying at elevated temp for several minutes, while the starboard engine returns to normal temp within a minute.

2) Cruising speeds - both engines run at their normal temp range (160-165)

3) Higher speeds - the port engine starts creeping up in temp to 170-175 while the starboard engine stays at 165.

4) Staying at idle speeds for a while, both engines go down to 150-155.

So, I am thinking that either the sea water strainer has become partially clogged with marine growth . . . or I may have an impeller failure in the making . . . and if so, it may have some impeller fragments partially blocking the water flow at the oil cooler.

I inspected both engine impellers during pre-season prep and they looked good . . . about 100 hours total on the impellers. Normally, I would replace them going into next season (150 hours)

This will be the first time I have done cooling system work while the boat is in the water, which may be 'very exciting' once I disconnect the hose to the sea water pump. The best that I can tell is that the intake hose is slightly below the water line, so water will probably come rushing in. I think I can raise the hose or plug it up while I do the work. We shall see. . . . :noidea:

T.I.A. for any words of experience or advice on this :thumb:

 

[alldodge]

sea water strainer has become partially clogged with marine growth

I'm thinking you actually don't have a "sea strainer" correct? From previous views it appears you only have outdrive water pickup holes.

With that, there should be no issue with just raising the intake hose up after removal. Have a line ready to tie the hose up. As you mention it will come gushing in when the hose is removed until it is raised up.

 

[tpenfield]

No I installed sea water strainers . Not std equipment, so I put them in because of the stuff that gets sucked in. It extendeI the life of the impellers quite a bit, since there is little solid matter ingested.

 

[alldodge]

I take it no ball valves then. If you don't think there is enough hose available to raise above the water line, have some 1 ID inch PVC pipe (about 1 1/4 OD) ready to push back in the hose to get it above the water line. Use the same hose clamp. Folks do it this way for in-water winterization

 

[tpenfield]

No ball valve . I just replace a section of the inlet hose with the water strainer. If I find that the strainer is pretty full of stuff, then I can clean it out. I have about 18" of hose that I can prop up to a higher position to prevent flooding.

My challenge is that the access is horrible so it may be tough to do things.

 

[alldodge]

My challenge is that the access is horrible so it may be tough to do things.

As a fellow Formula owner I empathize all to well, been hanging upside down on top the engine replacing my impeller more times then I care to think about. :facepalm: Hate working on it, love driving it

 

[tpenfield]

Yea, it seems that with the twin engine setup, they make them really close together (like 2") . . . not sure why.

Here is a picture of the starboard sea water strainer . . .


and here is the port engine strainer . . .


I sort of wish the starboard engine was the one that needed attention . . .

I also noticed that on the new series of Formula Sun Sports the center stringer is about 6" wide, so the engines are further apart.

 

[tpenfield]

I take it no ball valves then. If you don't think there is enough hose available to raise above the water line, have some 1 ID inch PVC pipe (about 1 1/4 OD) ready to push back in the hose to get it above the water line. Use the same hose clamp. Folks do it this way for in-water winterization

Yea, I am thinking either a hose that I can push into the inlet hose, or maybe just a wooden plug for the inlet hose. . . It looks like I will have limited access and movement of the inlet hose as I detach the sea water strainer.

 

[tpenfield]

UPDATE:

I took the intake hose and strainer out today to see if the strainer was clogged and take a look at the impeller. I forst tried to separate the strainer from the intake hose, but that was futile, so I just disconnected the hose at the transom assembly and jimmied the whole intake hose/strainer assembly out from between the 'big blocks'.


I just stuffed a rag into the transom fitting so the boat would not take on too much water. . .



I did find a serious clump of seaweed in the strainer, so I cleaned that out. I also took a look at the sea water impeller with the smart phone . . . looked OK, all vanes present. So, I put it all back together and will see how it goes over the next few outings.



Note to self though . . . remember to re-rig the v-belt onto the seawater pump pulley before you start the engine :facepalm: It is all good though, . . .

 

[tpenfield]

With a couple of outings this weekend and cruising for 20+ minutes, then coming off plane to an idle, it looks like the port engine temperature spike is about 170 degrees versus 180+ before I cleaned out the sea water strainer. The port engine still spikes more than the starboard engine, but the temperature of both engines come back down at the same rate.

I may still replace the impeller and back flush the oil cooler . . . that can be next weekend's project.

 

[alldodge]

Hope it isn't signs of trouble on the horizon. Fingers crossed

 

[tpenfield]

Hope it isn't signs of trouble on the horizon. Fingers crossed

I am hoping that too . . . Any specific ideas of other troubles ??? :noidea:

 

[alldodge]

With closed cooling as you have the engines should be fine. My thought is the salt may be taking its toll of the raw water side components. The heat rises are just now starting to show up and you take great care of your engines, but something is allow a reduction in water flow or air pockets to form somehow

 

[tpenfield]

With closed cooling as you have the engines should be fine. My thought is the salt may be taking its toll of the raw water side components. The heat rises are just now starting to show up and you take great care of your engines, but something is allow a reduction in water flow or air pockets to form somehow

The engines would always spike, just like other engines, just not as high as I was noticing on the port engine . . . 170 ish would be typical. I'll probably be more noticing of it going forward.

It seems with closed cooling, you have really 2 systems to be concerned with, the closed system and the sea water system. I have what I consider to be a nice setup. . . brand new exhaust manifolds which are part of the closed system (Full closed system) and the elbows , which are part of the sea water side, are stainless steel, so they do better with the salt water.

I have run the sea water strainers from the get-go, to avoid passing marine gunk through the heat exchanger. There is also the closed system side of the heat exchanger to consider. So, I could do some back flushing during the off season, just in case there is any sediment build up in either 'system'.

I'm going to replace the impellers (probably do both engines, since I have the parts on-board), and while things are apart, I'll back flush the oil coolers. I also can check the outdrive pick-up holes to see if anything is growing in there (happens once in a while)

Last time I had a cooling system issue was with my F-242 . . . it turned out a Barnacle had grown inside the outdrive water duct, dislodged and got stuck in the fitting at the bell housing. Of course, the symptoms then were opposite of what I am seeing now . . . on plane the temp would gradually and constantly rise, but at idle the temp would come right down (open system though).