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Chrysler 360 overheating issue

TPGG

Contributing Member
I'm stumped.

FWC motors.

1 runs at 150-160 idle, risers are around 105/110

Other Would slowly just climb up and up and up.
I pulled the thermostat and ran it sans thermo now it runs 150-160ish

The odd part is the risers on the hot motor were about 5-10 degrees warmer with the port riser spiking between 115 and 130 (vs the other motors 110 pretty steady). pulled the side plugs and they look a bit munged up, but not complete passage blockage (i would have to split them to check but that would require ordering new gaskets) i don't think.

Thoughts?
 
Check raw water pump impeller. If it's hard and stiff (don't get excited :p) replace it. If it's torn, remove heat exchanger and have rubber bits cleaned out-usually done by reputable radiator shop- side covers sweated off/tubes cleaned/resoldered together. Good luck.
 
Raw water pump on the hot (starboard) engine has a bit of wobble while the port engine runs true. Gonna bring the pump home when it cools down a bit outside and tear it down.
 
Wobble?? May indicate warn pump bearings. Consider full rebuild or replacement. Keep eye on those bits of rubber that may have broke loose from impeller. If impeller is not whole and you don't find them all, your problem will not be solved. They clog tubes in heat exchanger, resulting in overheat.
 
Thanks, I had that before with my other boat (350 chevy) that ended up having to dig the chunks out of the oil cooler. The Chrysler is a little easier being that they would be at the heat exchanger and you can take the end plates off. :)
 
Took apart the pump, impeller is fine (apparently replaced before winterized) and the pump is tight still. Wobble could be the belt being a little loose?
Onto back flushing the oil cooler to see if its starving there.
Also the hose between the oil cooler and the raw water pump was pretty beat, I barely had to back off the hose clamp to take it off.
 
some basic questions.

is there sufficient coolant on fresh water side of cooling system?

Is system a full fresh-water (block + manifolds) or partial (block only)? if full, some engines have bleeders near risers to evacuate air in manifolds-this can cause over heat if not properly bled.

Assume belt for pump was not slipping, the noise would have alerted you, plus the rubber dust from slipping belt.

Is raw water pump oriented correctly for rotation of engine? (likely impeller would be shot by now if incorrect)

Was raw water pump cam replaced at winterization when new impeller installed (is the cam in the pump?)

"Also the hose between the oil cooler and the raw water pump was pretty beat, I barely had to back off the hose clamp to take it off." System could be sucking air>> make sure all clamps are tight!

Good luck.
 
Full fresh water

Nope, no slipping, I had that with my other inboard CC that the entire console (under console engine) was covered in black dust.

Raw water pump is pumping into the heat exchanger. Will double check when I put it back. :)

I'm going to guess the cam wasn't replaced as its never mentioned. Yes the cam is in there.

On the hose, I'm pulling it later and straight up replacing it with new hose to eliminate it.
 
Replaced thermostat, had a starter issue, that's fixed now, replaced beat up hose between oil cooler and raw water pump, ran it in the slip, 160 all day long. No jump when i run it up to 2k for a bit then bang it back to idle like it used to. Run maybe this afternoon!
 
Almost there but thank you. ;)

Got a chance to run it (have another Mako so took a break, yes, that's an inboard also) and it still creeps up in temp (does anyone have an average temp for closed cooling engines? both at idle and with load???? the p/o clearly knew things were up because he won't respond to texts) BUT now it comes back down when you back down on the throttle. I think its the elbows/risers as when I pulled the plug on the side of one it was super caked with rust, and on startup i get a small cloud of dust out the exhaust. I have the gaskets to split them and take a look, that's today or tomorrow. :)
 
Well that didnt fix it. Same issue.
Start up, goes up to 170 comes back down to 160-165. Spooled up it creeps up to 200 before I back it off and temp comes down.
 
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