Odd cooling problem on 2007 SN196

[Booze]

I already emailed Jody, but thought I'd run it by you guys...

 

For the 2007 196....

Just starting this spring (coming out of boat hibernation), I'm seeing when I leave the engine idling (worse when already warm) the temp rises abnormally. It's not super-quick, but after running hard and idling, it could hit 200 deg in a few minutes. Also, revving in neutral doesn't help. I have to plane off to bring temp back down.

Also, the heater stops circulating hot water (blows cool) as soon as I come off plane and idle. So there's a direct correlation between the engine water temp behavior and heater behavior.

I replaced the impeller (which appeared in good condition) and it made no difference in the problem.

Any suggestions?

 

Thanks,

Boozer

[skihacker]

does it have a seaweed separater? if that isnt sealed it will suck air.

[Gloersen]

Sounds like the t-stat is sticky or not fully opening at operating temp. Pretty sure under plane the raw water pickup permits the pump to generate more pressure and thereby force water past the sticking t-stat, which revving under idle may not.

 

The heater core will run cool if the t-stat is closed or partially open.

 

Assuming t-stat not replaced yet.

[Jody_Seal]

How is the o ring in water strainer?

[eleeski]

I had an impeller slip on its shaft. Everything looked good but the impeller wasn't turning properly. Same symptoms. Another new impeller cured it.

 

Is your raw water pump driven by a belt? Is that belt in good shape and properly tensioned? Maybe the belt is slipping.

 

Transmission coolers get plugged up as well. Worth checking.

 

Something was interfering with the raw water flow every time I've had symptoms like that.

 

Eric

[Lovell]

Agree that it could be the impeller not turning correctly

[Jody_Seal]

Over the last few years there has been some impellers with the hubs spinning inside the rubber compound. This was on the indmar pumps, however pcm had an issue where the impeller would twist itself into two parts.

Also with the 5.7 a few years back the circ pump had some issues where it's impeller that is steel would twist itself into two parts. This problem was with all marinaziers that offered that engine.

A general system inspection from bottom of boat to the manifolds should be performed, a volume test of the raw water pump, inspection of the thermostat and housing and a back flush of the system. If this does not reveal the problem then a tear down if the circ pump should be performed.

[skiinxs]

I agree with all of the above pointing to the raw water impeller. Whether it has lost vanes, is worn out, or the hub is spinning, or other issues with the raw water pump, your symptoms point to that. The water pickup on a 196 will ram enough water to keep it pretty cool while running at speed, even if the impeller is pretty much toast. That fact that it heats up when you slow down and reving the engine with the boat not moving doesn't help is consistent with this theory.

[Zoro957]

I had a similar problem with my '97 MC that had a seaweed filter on the main raw water intake. It took some time to diagnose, but it turn out to the cap for the seaweed filter was not seated properly. It was sucking some air when at idle, but on plane the water pressure was high enough to maintain normal temp.

[motoskier]

Could be a hole in the backing plate behind the impeller, happened to me but I think water leaked into the boat. Some times parts of the impeller can get stuck in the water ways.

[Booze]

Thanks for all the feedback. Won't be able to investigate until this weekend, so I'll report back.

[gmut]

my friend had a 2002 SN 196 and his did the same thing....he had put the pump on backwards...wrong side facing out.

[spicoli]

If you have play in the pulley shaft threw the pump and mech seal the impeller will suck or lose pressure there's 2 small bearings the shaft go threw the housing they wear causing the shaft to wiggle while it's idling you might see it ,it looks like your pulleys bent.

[Booze]

Solution:

1) Confirm strainer cup o-ring (actually its a seal, not an o-ring) is in place.

2) If it is not, dig around transmission mounts and bilge to find missing seal

3) Reassemble strainer using aforementioned seal

4) test it out and wonder how the he!! you missed it in the first place

5) Ski

6) Take girlfriend out on the "big lake" for mixers and cruising

[Jody_Seal]

yep!! called it first go around. Most of the time they end up out in the lake when the operator does not hold a finger over them when pouring out the cup!!

O-ring? / Seal? actually it is a gasket .

Tractor supply FIMCO part number 7771583. Get a spare and put it in the boat!!!