48' Sedan Bridge Running Hot - 195/200

S

Sjspooner

New Member
May 31, 2013
8
Mystic, CT
Boat Info
2000 48' Sedan Bridge
Engines
CAT 3196
Hello forum folk....I'm a new 48 DB owner, year 2000, cat 3196's. Love the boat and getting ready to go out for a 1 week trip. That being said, the boat is running Hot. At cruise, master gauges in the bilge are showing appx. 200 -- right up against the red line, in calm seas, appx. 1900rpm. I've just installed new impellers, and boiled out (cleaned) the fuel exchangers....and it's still running at the same temp. When I come back to idle, it does cool a bit to 185/190'ish. Regardless, 200 seems to HOT to me.....and ideas? I don't know when the coolant was last changed..thats my next step. Any help is greatly appreciated! Best,Steve
 
both motors are at 200? seacocks open, strainers clean, thru-hull intakes not clogged? check and clear obstructions such as impeller vanes in hoses & heat exchanger? should be seeing 195-197 temps. were temps ever in this range since you've had the boat or did this just start happening? i'd think with your lower water temps in CT you'd be seeing same range. you're alarm goes off at 210.

I had same problem on one motor recently. impeller installed less than year ago missing a couple vanes, caused port to steam and gage reading ~199. new impeller, no steam, back to 195.
 
Last edited:
Thanks Tim. The strainers are clear, thru hulls clear, brand new impellers - and pushing a lot of water. Are you saying that 195-197 is normal operating temp? My engines are running appx. 200 in calm seas, water temp is probably 70. I haven't checked anything in the heat exchangers yet? Is that complicated -- tough to do?
 
200 is on the high end of normal 3196 operating temp. If it creeps up much more you need to find out what's going on especially since you're running in colder water temps. I remember Frank once saying to pull the inlet hose off the trans cooler and see what it looks like as it tends to catch everything. Probably the easiest way to see if there's something unusual going on. When was the last time the cooling system was flushed? probably time to drain the coolers and everything, flush and put in new Cat ELC. I have a maintenance guide somewhere. I'll see if I can find it.
 
Besides all the basic items, I guess the next obvious question is when was the last time the heat exchangers and aftercoolers were serviced? If you don't have the records on this I'd say it could be a good time to call the Pros to do the service.

New impellers is not the answer to overheating engines, just b/c there's more to preventive maintenance. As Tim pointed out, there could be lost vanes blocking the water flow. There could be just growth in the components like aftercoolers.
 
Thanks everyone for the intel.

I've recently completed a coolant change, new regualros (thermostats), transmission cooler removal and cleaning, and alas -- it still is running 195-200. Basically I'm down to doing a complete flush to clean the heat exchangers, and aftercoolers.

Some say just run it at this temp - but I am concerned because the guage shows it basically up against the red line.

Anyone know the normal operating temp for these motors?

Thoughts? What exactly does CAT do when they "service" the aftercoolers?

Thanks -- again, just bought this machine in May. Love the boat just trying to get an idea of what is "normal". Can't stand looking at my guages up against the red line.....just doesn't seem normal
 
If it is running hotter than expected, but evenly on both engines it would seem less likely to me to be a single bad impellor or thermostats on a single side. More likely to be evenly plugged strainers, evenly restricted coolers, etc. and most likely to be additional load (bottom fouling, overpropped?), or both resulting in poor fuel burn.

Also in your original post you mentioned 1900rpm which on my 410 is struggling, pushing a big bow wave and not yet on plane.

Q: What would happen if you ran the boat for 15 minutes at your target cruise RPM (in my case 2300-2400rpms) ??? Would it overheat, or would your temperatures moderate?
 
Last edited:
Have you confirmed the temperature readings using the EMS on the bridge for comparison numbers? You can use the scroll buttons and change to the engine temp to get a digital reading rather than the gauges.. Just another idea..
 
It seems as though you have rules out almost everything except the heat exchangers. Cat's cooling systems have a lot of capacity so this isn't something you should face as frequently as Cummins owners do, but

1. if you don't know the service history of the boat and have no idea when or if t he heat exchangers were cleaned and,

2. if your temps continue to rise as you increase load (rpm's) after they stabilize at normal operating temps.

then you probably need to have the heat exchangers and transmission oil coolers cleaned. The boat is 13 years old and it is likely that the heat exchangers have never been serviced.



There are 2 ways to approach this. One is with a portable flushing pump where the mechanics removes the inlet hose and transmission cooler outlet hose then pumps/recycles a cleaning solution (mild acid) thru the sea water side of both coolers. This takes 4-5 hours per engine. The other approach involves removing the transmission oil coolers and taking the heat exchanger apart to remove the tube bundle from the inside. THe oil cooler and the tube bundle are then manually cleaned in acid and a wooden dowel, much like rodding out a car radiator. If t he tube bundle can be removed between the engines so the heat exchanger body can remain in place on the engines, then this is about a days job for an experienced mechanic. The doog thing about the second method is that the mechanic can see inside the heat exchanger and retrieve anything that is foreign to the sea water system like broken impeller blades and broken zinc anodes.

The one thing you don't want to do is to fix something that isn't broken. Your engines probably have 195˚ thermostats in them so what you are seeing could be entirely normal. Caterpillar uses some pretty hot thermostats to reduce emissions and get more complete burning of the fuel charge. To test it the cooling system capacity, look at the engine mounted on the engines or ECM driven temperature gauge....for purposed here, ignore the Teleflex analog gauges on the panel- if they are within 15 degrees of right, you are lucky.......and see if the temps rise past 200˚ as you increase loads. Keep applying power/rpms and see if you can make the engine temps rise. If the temps rise up to about 210˚, the come out of the throttles and gradually but immediately slow down to a good fast idle. like about 1200 rpm and hold it there. If the heat exchangers are clogged up, the temperatures will drop almost as fast as they rose when you accelerated.

For Cat engines, 195˚ is good; 200˚ means "hey there Mr. Temp, I've got to watch you"; 205˚ is "now you are worrying me", 210˚ is "uh-oh....time to back out of the throttle" .......never, ever under any circumstances exceed 212˚. It is one hell of a lot more expensive to fix an overheated diesel than it is to pay SeaTow.

Hope that helps, and good luck with it..........
 
Last edited:
I help on a 2001 Cruisers Yachts 5000 Sedan in Charleston and it has the 3196's from 2003. When the survey was done during purchase port ran at 200 F and Starboard at 205 F at max throttle in cold (55 F) water. During this past summer both engines started hitting the alarms at 212 F at cruise 1950 rpm and we would have to back off to idle to get them back to 189 - 193 F.

We asked around and were told to do the Rydlyme flush of the raw water cooling system and coolers. This did the trick as there was much barnacle growth etc in the lines. I believe the technician let them cycle through with the acid for 6 hours.

She then ran right at 200 F and 202 F maximum at cruise and WOT (2310 rpm). These engines run near 200 F so I would not be so worried at this level.

After new bottom paint we hit 34 mph in this beast with no current with the CAT's spinning 2310 rpm, temperatures right at 201 F.

Hope this helps.

Kendall
 
Any final outcome. Have 1 running 196 and 1 running 184. Maybe the 184 is the issue and not the 196
 
I seem to run right at 199. If I am heavy into the throttles (2100 rpm), I will climb up to 201 sometimes, but once I reduce the RPMs to normal operating range, the temp drops right back to 199.
 
You must log in or register to reply here.

Forum statistics

Threads
113,253
Messages
1,429,373
Members
61,133
Latest member
Willbeckett
Back
Top