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I have 3208 NA's. One is a new CAT reman engine. While idling the temp on that motor runs up to 170+ F fast, but levels when T-stats open I think. The port engine will idle all day @ 135 F. I switched raw water pumps and checked the intakes. No change, the heat exchangers were cleaned last year,less than 20 hours on engine. Am I just paranoid? or is there something wrong? Should I just run it and see it runs hot?

Thanks
Frank

Sounds like the motor running 135 is the one that is the problem - sounds like thermostat is not working right. You really should come up to temperature on that motor even at idle in the summer months.

Check the accuracy of the temp gagues with an IR gun...the one running up to 170 at idle sounds off....my Cummins will idle all day, even in our 90 degree water and never get over 135.

UV

Definitely check thermostat with an IR gun (Harbor Freight $30 or so) and point red dot on the brass sending unit on the engine block.

You have to start there before anything else, then you will know what the ACTUAL numbers are. Ruling out bad sender, bad gauge etc...

If the numbers jive with gauge readings I would check the thermostat on the one reading lower.

If the thermostat is easy to get at I would change both of them and see what happens.

If you have good pumps and the heat exchangers are good as well then it starts pointing towards thermostats, could be something else though, but start with these basics to get started.

Keep us updated!

Frank

therm on the 135 is stuck open... thats a smoking problem.. I had that too..
Wayne

The thermostates are new last year. Are a real pain in the a** to change.
I have check block with IR gauge is correct. When runing the 130 runs up to 170 while running. But was afraid that the other would run hot. will check tonight if it stops raining.

I'm with Vic on this. I've never seen a marine diesel that would come up to operating temperature at idle, even in warm water.

Mine sure as hell don't. And drop back down when trolling.

I just checked my engines with the IR gun. One was running at 190 the other 185 cruising. That was by the guages.

The IR gun says both were running the same temp.....170 degrees.
Idling along, they went down to 150 degrees.
Run it Frank, and maybe no problem. I have the same engines as you do.
bob k

Now you know the gauges are working properly. It is time to run the engines and cruise and then keep an eye on what they do.

If one gets hot, shut it down, if not then see how close they are at operating temperature. If they are close run the boat at an upper RPM to see if they stay close to each other.

I would not worry what they do at idle (unless overheating of course), it only matters when you are under load.

Thermostats can be not calibrated to perfection.

Run the boat, I bet it will operate fine.

OK, I swapped raw water pumps and the heat issue went with it. Ran the boat port now running warmer @ 178 and IR its with in 5 degrees. WOT it goes up to 180+. The port exhaust has less volume of water then the port now and you can see the steam coming out. Exhuast temps port 125 and starbord 90. The water pump is about 1 1/2 years old and new impella. Blew a motor last year, so no hours on pump. So is there a cam, shim or something in the pump that could be wrong? Jabsco pump.

Never over heated just running warm. I have had the bout for over 16 years so this is not normal.

Frank

If you can switch them, you can easily take them apart. 1. the impeller. Check that out. 2. the cam. One screw holds it on. Look to see/feel a smooth transition from the inside of the pump. Any sharp edges or broken looking edges, replace. 3.side plate. flip it. Put the outside on the inside. Since its flat and has had no wear on the outside, it often works. 4. the gaskets, paper and o-ring. Just replace. Put it back together and see of your temperatures come closer to each other. Good luck.

If the pump is only a year and a half old I'd check the cam and plate as you will be there anyway but I'd place my money on the impellor...

they say to change yearly...but I have found impellors usually last longer...however running dry for a real short time will dramatically reduce their life. Dry or Airbound...I've traveled across a tugs wash making the pump airbound...had to replace. Some people have pulled a bag and had similar issues...needed to replace impellor.

OK, I emailed ITT (Jabsco) about my flow issue. With in three hour I get a email back from a Associate Product Manager he tells me something I and the last two CAT techs missed. The cams are different in the two pumps. So just by changing the cam I will be able to increase the volume by 20 GPM and both pumps will be the same flow. Parts should be here thursday, install on Friday will report back.

Frank