Cat with a fever..

[jim rosenthal]

I noticed recently that Cat #2, the stbd one, was running warm. Typically even with the water rather warm they will run at 175-180 degrees. Engine #2 was running warmer, about 195 and occasionally 200. The flow of seawater seems the same as the other side, the belt tension was right, and the impeller looked fine. (I use Globe blue impellers, I think they are sturdier than the Cat/Sherwood ones). The boat is out of the water 4mos/yr when she's winterized, and I flush the seawater circuit with the pink stuff before putting her away.
A call to T&S found that they felt the heat exchanger was probably clogged, with scale or mud or whatever (zinc pieces, impeller chunks, what have you). This evening I drained most of the AF out of the engine, shut the sea valve, drained the little seawater left out of the HE, and took the core out. I'm going to have it flushed at a radiator shop and then reassemble it. I also got a new thermostat with all the gaskets and seals that T&S sent me. And there's a zinc plug frozen in one of the end caps to the HE, so I'll try to do that too. Interestingly, the end caps are plastic. Now, is there any point to having zincs situated in the end caps in the seawater space, if they are plastic? Are they protecting anything?
If it isn't the heat exchanger, I'm in trouble, because it is either something inside the engine like a head gasket leak (don't think so) or the circulating pump is bad.
Interestingly, the port engine runs at its' normal temp. It is not as powerful as the stbd one, but evidently less temperamental. They definitely have slightly different throttle response time, although they max out at the same rpm with the same pitch and diameter. See what you would miss if you had a single-engine boat?

[Robert Trafford]

first thought, immediately...did you check the engines with a temp gun? if not available, did you try swapping guages and senders to see if the problem moves across the boat?

the work you're doing on the exchangers is excellent maintenance regardless of what you find, and don't be alarmed about the plastic plugs. they are designed to do the job properly. mine have always been brass, however.

throttle response could well be found in the fuel pump, but if it isn't a true problem, let it rest for now. sounds like you're investing enough for the time being.

best of luck.

[GCombos]

from my recent experience, has gotten much simpler with the use of the IR (non-contact) temp guns. I bought one OTC for less than $100 from the local NAPA auto parts store.
Running the boat under a load, you can jot down periodic readings taken along the raw water side, then compare those measurements with readings on the engine that's running properly (twin engine advantage). This should reveal where the initial cooling inefficiencies are. You can even determine how effectively your HE are working by measuring the temp at each end. From there, you can work back to the fresh water side if you don't find anything obvious.

Those little guns are almost infinite in their use. I pointed the little red light at my battery terminals and confirmed one connection was at a higher temp (resistance) than the other battery connections I had just cleaned. Obviously, you can check for defective ice, beverage temps, crew fever, :o etc., etc.

My HE end caps are also plastic, a concept that took me a while to get used to. I have a spare on board, just in case.

[Captddis]

If you look at the inside flange of the cap, there should be a brass insert around one of the bolt holes. This insert makes contact with the expansion tank when assembeled. FWIW I always clean the Cat exchangers as routine maintenance every two years. It is not very difficult and guarentees a cool running engine. Put some grease on the o ring and install with even pressure to prevent slicing. Good Luck

[jim rosenthal]

..which I will follow. I have not done this particular job before. I spent most of today looking for muriatic acid to clean the tube bundle- maybe tomorrow at a plumbing supply shop. While I'm in there, as I said, I'll change out the thermostat. I do have an IR thermometer, but have been handicapped by the lack of a second person to check the engines while she's running. I'm satisfied that the stvd one is hotter, though.
Last year I did a routine coolant change and put a fitting on the bottom of the turbo water jacket, which has a flare-nut end on it. I have a hose with a flare fitting which I can put on it, and then pop the expansion tank cap. 5gals of AF drains out in about 20 minutes, which isn't all of it, but low enough for most of the things I need to do.
From what I can see, at least in theory you can drain the seawater side, remove the end caps, and "clean out" the heat exchanger with a wire or rod, without draining the AF. I don't think you can do as good a job though.
I'll keep you all posted on how this goes and what I find.

[Banshee36]

Jim,
You can get muriatic acid at home depot, or gomoljaks .It is used to clean masonary work.
good luck with your engines.btw, if the main circulating pump was bad it it just like one on a car it will leak.
good luck.
jw

[nick]

Jim,

Muriatic is also available at Ace and Sears hardware.
Keep in mind that the silicate drop out typically deposited on the core is NOT dissolved by acid. A small amount of silicate will tremendously effect heat transfer through the surface of the core or tubes. Let the radiator shop do the cleaning in alkaline bath.

[Surfdancer45]

Jim: I am sure you condidered it. The trans oil cooler could also have some blockage. You might want to take that to radiator shop also. Good luck. hope it is a minor problem. Bob

[jim rosenthal]

..the medical term for no longer having a fever. It was the thermostat, which was sticking. I did take the HE core to a radiator shop; I also replaced all the O-ring seals etc when I put it all together. And you grease everything to get it to go back together without tearing the brand-new O-rings...anyway, I sea-trialed it yesterday and she stayed nice and cool even at 2400 running into a head sea and 20kts of wind. I tested the old t-stat at home on the stove with a cooking thermometer and sure enough she was sluggish, only fully open at 205F.
The other one has never had a problem, however this winter I will drain down the engine and pull the HE and have it cleaned as well.
Last year, I changed the coolant (routine maintenance). It was a miserable enough business that I then got a double-male flare fitting which I screwed into the bottom of the turbo on each engine, and capped the outside end of it off. I have a mating female fitting on about two feet of 3/8" hose. Now I just screw the hose on, stick it in a bucket, and pop the header tank cap. The AF drains into the bucket. This made the recent service work pretty easy. Of course, if I have to drain the entire system I will have to find a lower point yet to drain the motor.

[Genesis]

Hint to all...

Find the lowpoints. On my engines its on the bottom of the H/E elbow going to the water pump, and on the bottom of the oil cooler.

Remove the drain cocks you find there (there should be draincocks at those points) and replace them with fittings and ball valves.

Remove the handles from said ball valves so you don't accidentally open them when underway, or wire the handles closed to prevent disasters.

If you put hose barbs on the exit end of the ball valves, you can now stick a hose on that, stick the other end in a bucket, and open the valves. Presto - the system is drained.