180 or 160 thermostats? South Florida...

[Captned]

Greetings all,

I'm pulling my starboard engines t-stats at the moment. I've been overheating some on that side this winter and I know that summer water temps will make the engine even hotter. I have never changed them so I was wondering, being in South Florida, should I install lower temperature thermostats? I have never had a problem running too cool, always too warm.

Also, my heat exchanger looks CLEAN/CLEAN and both zincs came out intact.
Impeller appears in good condition. Good water flow when running. Any reason to pull the exchanger if it looks clean? Could it be fouled on the coolant side? I've been using the proper coollant and additives.

FWIW- when I was chasing my port engines overheating problem last year, the cure was when I replaced the t-stats (180 I believe) AND the fresh water recerculating pump...(so I don't know if it was the t-stats or the pump)

Suggestions?

Thanks, Captned

78 46 CONV
8V71 TI's

 

[Chapeaux!]

FWIW- when I was chasing my port engines overheating problem last year, the cure was when I replaced the t-stats (180 I believe) AND the fresh water recerculating pump...(so I don't know if it was the t-stats or the pump)

Suggestions?

Thanks, Captned

78 46 CONV
8V71 TI's

Captned, I'm sure you've probably already been there, but have you looked at your intercoolers? They sit right in the raw water stream before everything else. Reason I mention it is that I have long term elevated temp problem on port eng that only occurs if I run at 2100 rpm or above for more than 20-30 mins. Then the temp starts to creep up. I've never had it outright overheat, but it will get to 200+ deg, and once set off the high water temp alarm. I've had it suggested that I should look to the intercoolers, since the added load of compressed air temp to the cooling system may be pushing the temp over the edge. Just a thought...

 

[Genesis]

Go with stock marine T-stats.

They should be fully open @ 180-185. If you're getting there, you're out of cooling system capacity. You either have a problem with water flow or heat transfer. If you've got intercoolers (salt water) check them, check the gear coolers, check the ENTIRE raw water path. You'll find the problem - but you can't omit ANY part of it.

Putting in lower-temp thermostats will not solve the problem.

 

[REBrueckner]

Genesis is right on...Water pump impeller parts and zinc pieces stick in the intercoolers of turbo engines...my stbd ones are off right now to check for that very problem. And I found what looked like a salt water ooze ..I gave it to my mechanic to pressure test for me..sure enough leaked confirmed!!!! This can result in a very unhappy captain if left unattended!!!


Start with the easy stuff you can see: On the raw water pump, a tired impeller or missing or cracked blades, worn faceplate or worn/irregular grating (can't think of the right word) can all cause a slight loss of raw water flow....check raw water hull inlet and external/internal strainers of course....

If the engines are naturals, the input side of the heater exchanger is the collection point for impeller and zincs pieces and maybe seaweed ... Just because the HE looks clean, scale on the raw water side or particles may be hidden inside....follow Genesis FAQ on HE cleaning here on Sams...If the engine is turbo/intercooled, raw water impeller and zinc pieces collect at the intercoolers...

I haven't heard of stuff collecting at the shower heads...where raw water enters the exhaust system for discharge...but I guess these can get clogged sooner or later as well. I'd check that last.

These cooling systems are not robust with plenty of spare cooling capacity...they need to be near perfect for high RPM cooling.

 

[Genesis]

The original design of the H/Es was for NATURALS in virtually all Detroit configs out there.

There are some exceptions - the DDECs have a different plate design (and god help you if you have to take it apart!) but believe me - if the system is not essentially PERFECT you will have overheating problems with turbo Detroits.

 

[Boss Lady]

If you don't do any other maintenance on your boat, do the cooling system. Karl is right on this, there is no excess cooling capacity on a high performance Detroit. With very high cost of engine replacement (labor), this is one area where we can really head off potential problems and this does not require a paid mechanic if you have a tool box. Since the 92 series are overheat intolerant, this is an area to pay extra attention to and just do preventative maintenance and not wait until you have a problem. A little problem can become a big, expensive problem. Now I just have to remind myself to take my own advice. LOL