92 90 Johnson VRO ran HOT for a minute then OK in tank

tfbrown1270

Petty Officer 1st Class
Joined
Sep 5, 2003
Messages
202
The shop I purchased this o/b from was demonstaring the engine in a big tank at the rear of the building to show me the "no start" condition was fixed (new powerpack was required).
They had backed the boat/motor/trailer to the tank and lowered it in with the tilt. It was running pretty good so the tech put it in gear and reved it up to about 3500-4000 and got the tank pretty churned up (the tank is about 4 feet wide, 12 feet long and pretty deep.
Anyway a small rooster tail of water started out the top vent of the tank and at the same time the tell tale stopped pumping water and the overheat alarm started.
The tech reacted by saying...the water gets too turbulent in the tank and eddies near the leg are pulling water away from the intake so he let it fast idle in neutral...the alarm continued for about 15 - 20 seconds and then it pumped HOT water, I mean boiling hot for 20 -30 seconds before the alarm went off and it started pumping cool water again.
I was pizzed off thinking he had roasted the impellor or worse but he insisted there was no harm done. However I noticed that the pee stream appeared to be weaker than before the incident (worn impellor from abuse?)...he said NO.
With some misgivings I took it home but before dragging in 250 km to the lake I ran it on the muffs and noted the left bank (V4) was cool (90 degrees f) while the right bank was hot (137 degrees f)...
I called and told them what I found and was told they had replaced one of the thermostats because it was running hot, they didn't say which one though.
My question is, should I insist they replace the water pump AND both thermostats on their dime or has there been no harm done.
It is going back today (Monday) to deal with the thermostat problem anyway.
 

hoeser

Petty Officer 1st Class
Joined
Jun 18, 2006
Messages
253
Re: 92 90 Johnson VRO ran HOT for a minute then OK in tank

137F is operating temperature. Your 90F bank has a stuck open thermostat. it's your choice if you want to keep running it like this. Cold temperatures can cause rough running and excessive carbon buildup. I've heard of shops just replacing one thermostat and personally I think it's ridiculous - I would be pissed.

As for the impeller, I doubt it was starved for water long enough to do any damage, but it's possible... especially at the rpms he was running it at.

Your thermostats will not likely take damage from an overheat condition.

I would be honestly more concerned with the health of the top end after an overheat. You should be able to argue an impeller and thermostats out of them though. I would.
 

redtech

Seaman Apprentice
Joined
Jun 23, 2007
Messages
45
Re: 92 90 Johnson VRO ran HOT for a minute then OK in tank

water pump most likey fine, 90f to cold, 3500-4000rpm in test take with test prop just not smart, if showing you no start was fixed no need to run an engine at that high of rpm
 

tfbrown1270

Petty Officer 1st Class
Joined
Sep 5, 2003
Messages
202
Re: 92 90 Johnson VRO ran HOT for a minute then OK in tank

They had the regular prop on not a test prop!...they had run it on the dynometer prior to my getting there...does that make a differance?
 
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