Question on overheating repair or replace

[Helmsman]

My starboard engine is running hotter than my port with some steam coming out, just as the recent post by RickieT . Both engines normally run 160. Crusader 6.0 mpi 2006 with 400 hours.

When I winterized, the starboard engine took a much longer time to empty the antifreeze from the bucket.

I haven’t checked anything yet. I plan to keep the boat. I am planning a trip down to Orange Beach Al from Chattanooga this spring. I will be in salt water for two weeks. I have to fix the problem before I leave. The problem could be an impeller issue, or it could be blockage somewhere. The raw water system has never been replaced on either engine.

Given the age, should I replace the oil cooler, trans cooler, heat exchanger, exhaust and elbows along with hoses as a maintenance item? Or should I get the Heat exchangers boiled out and pressure tested and go with the old, along with the new on other parts?

Should I find the problem, fix it, and replace the rest next fall instead of this spring? This will be the only time I will have the boat in salt water for the foreseeable future.

Qualitative discussion in part, but would like opinions. Thanks!

[bud37]

I think in your post you have the answer......low flow....change impeller and inspect for pieces, open up the heat exchanger and check for impeller bits and corrosion, backflush line from exchanger to pump and that looks like it would cover it for me.....thats where I would start anyway.There is more but a good start without replacing everything in sight.

[Cooler]

100% agree with bud37. Probably just a weak impeller, especially if you're talking 15-20 degrees. Crusader engines are known for top notch cooling systems, and 400 hours is nothing for them. You don't have to have missing pieces on the old impeller either. ( if there are missing pieces, try to locate them or they will cavitate the water, at the screens going into coolers. Backflush with LOW pressure, and those pieces normally come out real easy. Run the backflush water into a white pail. Don't be surprised if you see other junk like sand or seaweed pieces ) The impeller fins may just be bent to the point where they do not produce enough suction through the pump. Traditional impellers only last a season or two. The run dry impellers last a little longer, but not worth the extra expense. I had one impeller last less than 1 hour for me. ( The tech admitted he put it in backwards )

Relative to the post by RickieT, his main issue was a plastic bag sucked up into his water intake. That was discovered by a diver he hired to clean his bottom. He did a number of things before that was found, but that's OK. Apparently his heat exchanger was 40% plugged also. Having said that, if I had a nickel for every plastic bag I pulled out of our marina or middle of the bay, I would have a lot of nickels!

Finally, if you are inclined to replace all those parts, I would wait till after the salt water experience. Salt water is hell on engines. It will introduce/enhance corrosion to parts at an unbelievable rate. Good luck. Your problem is minor.

[Helmsman]

Ok. That is the way i will approach it. I will back flush the hoses.

The sides of the heat exchanger are somewhat covered up by the exhaust hoses. Will make it almost impossible to address it in place. Would you guys unbolt the HE from the engine, pull the HE free then work on it, or pull the two exhaust hoses on each side of the engine free from the elbows and then work on the heat exchanger?

Thanks for any advice you can give.

[tomschauer]

When you remove the old impeller, compare it to the new one and see how many pieces you need to find. Some of them are most likely in the out let of the pump housing and easily flushed out. Collect the pieces when flushing. Follow the pump outlet hose to the next heat exchanger. It is most likely your main exchanger for engine cooling (depending on engine brand). Pull the raw water outlet hose off and back flush with a garden hose into a container. You will most likely find the rest of the missing impeller and can put everything back together and be good to go.

[Helmsman]

Source of the post When you remove the old impeller, compare it to the new one and see how many pieces you need to find. Some of them are most likely in the out let of the pump housing and easily flushed out. Collect the pieces when flushing. Follow the pump outlet hose to the next heat exchanger. It is most likely your main exchanger for engine cooling (depending on engine brand). Pull the raw water outlet hose off and back flush with a garden hose into a container. You will most likely find the rest of the missing impeller and can put everything back together and be good to go.

Thanks Tom. The flow is from the sea clock to the oil cooler through something to do with fuel canister, then through the RWP and impeller, to the transmission cooler, the heat exchanger, then out the back. If I have a problem with the impeller it would almost have to be between the RWP and the transmission cooler.

I neglected to mention that the oil pressure runs a little higher on the starboard engine, also

[Cooler]

Slight oil pressure variance is normal. When you see the condition of your impeller, I think the discussion around removing the HE will be moot. If the impeller did come apart, the pieces are going to be in the hose between the water pump and what ever is downstream of water flow. I am almost sure there is a screen to catch debris, before it enters the downstream cooler. Remove the hose from the water pump on the down stream side to catch debris as it back flushes out. Any debris will not go back into the water pump, as it will just catch there. If the impeller is intact, just with cracks near the hub or flattened outer edges, then there may not be any debris in the water line. Unless, of course, a previous owner did leave some previous pieces in there. Still do a back flush with LOW pressure to make sure. Hope this makes sense. I am not a technical writer. How much hotter is the port engine running?

[Helmsman]

Source of the post Slight oil pressure variance is normal. When you see the condition of your impeller, I think the discussion around removing the HE will be moot. If the impeller did come apart, the pieces are going to be in the hose between the water pump and what ever is downstream of water flow. I am almost sure there is a screen to catch debris, before it enters the downstream cooler. Remove the hose from the water pump on the down stream side to catch debris as it back flushes out. Any debris will not go back into the water pump, as it will just catch there. If the impeller is intact, just with cracks near the hub or flattened outer edges, then there may not be any debris in the water line. Unless, of course, a previous owner did leave some previous pieces in there. Still do a back flush with LOW pressure to make sure. Hope this makes sense. I am not a technical writer. How much hotter is the port engine running?

Thank you. I have been changing the impellers annually for the last two years. Last year, one of them looked a little worn (can’t remember which). The problem began earlier this summer after replacing the fall before after several trips. I noticed it after the first couple of trips. I intend to look at the impeller, and search for small pieces in the hoses leading up to the screen on the trans cooler. I will probably replace that cooler and the two hoses anyway. The cooler on the other side started leaking in late 2016 and I replaced it. I expect to find the blockage at the transmission cooler. The antifreeze flow during winterizatiion suggests that will be the case.

What I am trying to do with the set of questions is to understand as much as possible what some things are to look for as I go through the process. I will have to re-winterize that engine, don’t want antifreeze in the bilge, and will probably reintroduce water during the “fix it” period. Therefore, I am trying to avoid minimizing the time to wait on parts while the boat sits in below freezing temps. Should be ok, and the help is very appreciated. I will let you guys know what I find.

Thanks for the tips!

Nate

The temp is about 10 degrees higher and the oil pressure is about 5 degrees higher.

[tomschauer]

Nate, you should be able to get a few years between impeller replacement. I replaced one last year that was only 18 years old!
If they are actually failing that quickly, unless you are running them dry, maybe the pump bearing or housing is out of tolerance and prematurely wearing the impellers?

[Helmsman]

Source of the post Nate, you should be able to get a few years between impeller replacement. I replaced one last year that was only 18 years old!
If they are actually failing that quickly, unless you are running them dry, maybe the pump bearing or housing is out of tolerance and prematurely wearing the impellers?

Tom, they aren’t failing. I just replace them annually as part maintenance. (Cheap insurance!) thanks, Nate