overheating question

[nickmo]

Hi I was chasing an overheat problem on my saltwater RWC 5.0. I changed the impeller first then mainfolds and risers ( they were 7 years old so needed them anyway ) then thermostat no help. Did a bunch of tests and finally went back to the impeller. I bought a new kit that included the housing. With that kit, I received the bottom plate with the rubber gaskets already attached. After installing that kit, I was good to go. No more overheat. I run a 160 stat BTW. The housing was a bit grooved so don't know if it was that or the paper gasket sucking air on the bottom plate.

 

[brian4321]

Well what I couldn't figure out was why one side was cool but the other side was hot..I assumed if the impeller or circulating pump was bad both sides would be hot

 

[brian4321]

A little update ...so I pulled the boat out today and installed a new temp sender, sierra part #18-5897...got it fired up and let it warm up for 5-10 minutes and the dash gauge showed @ 200* but my infared temp gauge showed @ 90* on the t-stat housing and the risers and t-stat housing were barely warm to touch...did I get the wrong temp sender or is it a gauge/wiring issue?

 

[nateo]

on mine there were actually two parts there in the engine that have something to do with the temp gauge. (they were both named sending unit or something similar) I never did fix my gauge because I didn't know which one was bad and didn't want to spend the money on replacing a good part.

Perhaps there's another part on yours as well.

 

[Grub54891]

Chasing ghosts...Sometimes it gets interesting. If you can't find the issue, It could be a restriction someplace on the hot side. Even could be an exhaust shutter that broke off and is slowing the cooling water down enough to make that side run hotter.

 

[Outsider]

One sender is for the computer, one sender if for the gauge. If you couldn't put your hand on one riser, your gauge and gauge sender were probably OK. Not every sender works accurately with every gauge ...

 

[NHGuy]

I just ran your serial #, comes back efi, right? In that case you want the correct temp sender which may be 160 so the efi gets the right signal temp.
BUT, your dash keeps giving you high readings. So before going further get a volt ohm meter.
Make sure you are replacing the right sender, does that design have one for the display and a separate one for the efi? I think it does.
Go to the gauge page in the manual and look up how to test the gauge and sensor. I forget the exact test, but it's in there.It's not too hard.
For the gauge you jump across terminals with a wire on an alligator clip, or with slide on terminals. Both of which you can make up from hardware store parts. For the sender you read ohms at the device.
If the guage is correct you can test the sent resistance in ohms at the helm with the meter and compare that to the ohms at the sender. That will verify your wiring is OK. If it's bad run a replacement wire to the helm.
When you check the temps with your IR gun shoot right at the sender, not at the front of the thermostat housing. In fact shoot all over, you'll be educated about the running temps that way.

 

[brian4321]

I've been working a lot lately and haven't had a chance to work on the boat ... NHguy , it's a carbureted motor and and both sending units are new ... I'm convinced it's not overheating, but it's a gauge issue... When I have time I'll try to test the gauge and wiring... Thanks