Overheating ?

[lwyatt]

Hello all I am new to the forum and have done my best to try and find answer before I posted but could not.

I have a 89 Evinrude 110hp have removed the vro pump about 1 year ago
lately the warning buzzer is going off I have verified oil tank line disconnected and not grounding

thought it might be impeller so I replaced that, water pressure guage has about 5 to 8 psi at idle
and about 20 -25 psi at 4000 rpm
the oil/overheat buzzer goes off, shut engine down wait 3 to 4 min cranks and runs fine,
next time left motor at fast idle about 2500 rpm felt the telltale and water was cool, after approx. 1 to 2 min the buzzer
stopped and motor seems fine as long as I run at around 3500 rpm or less does not overheat( I am guessing this is what is happening )

do I need to remove/replace thermostats ? does it need the thermostats ? or can someone point me in the right direction

thanks for any help

 

[racerone]

Re: Overheating ?

Inspection of thermostats and poppit valves should be done and requires 2 small gaskets.---------Bit of a pain to get at but it can be done.------Perhaps the water deflectors / guides are blocking proper waterflow in the block.----These are rubber tubes pushed into the block.----Water does not go through these tubes, but they guide water for proper cooling.---------Cylinder heads must be taken off to inspect these parts.-------Salt water motor ?

 

[emdsapmgr]

Re: Overheating ?

From your post, I'm not sure which buzzer you are getting. Your comment alludes that the oil/overheat buzzer are the same. Actually, there are 3 horn warnings on a V4 VRO: The oil, overheat, (low) oil tank buzzers are not the same. The oil pump buzzer is intermittent. One second on, one second off. An overheat buzzer is constant. A low oil tank warning is on for a second, then off for 20 seconds. Which buzzer are you hearing? Regarding an overheat: You can have a strong impeller, a strong telltale, strong gauge water pressure, yet still overheat at idle-if one/both thermostats are stuck closed. If you rev the engine up to maybe 2000 or more, that can mask a closed/stuck thermostat problem. Once the impeller water pressure rises enough, it can open the pressure relief (bypass) valves in the thermostat housing-flooding the block with extra cooling. Maybe that's why it won't overheat when it's running slightly above idle. Stuck thermostats will usually/eventually cause an overheat on one/both heads at idle. Your observed water pressure readings are very normal for a new impeller.

 

[lwyatt]

Re: Overheating ?

From your post, I'm not sure which buzzer you are getting. Your comment alludes that the oil/overheat buzzer are the same. Actually, there are 3 horn warnings on a V4 VRO: The oil, overheat, (low) oil tank buzzers are not the same. The oil pump buzzer is intermittent. One second on, one second off. An overheat buzzer is constant. A low oil tank warning is on for a second, then off for 20 seconds. Which buzzer are you hearing? Regarding an overheat: You can have a strong impeller, a strong telltale, strong gauge water pressure, yet still overheat at idle-if one/both thermostats are stuck closed. If you rev the engine up to maybe 2000 or more, that can mask a closed/stuck thermostat problem. Once the impeller water pressure rises enough, it can open the pressure relief (bypass) valves in the thermostat housing-flooding the block with extra cooling. Maybe that's why it won't overheat when it's running slightly above idle. Stuck thermostats will usually/eventually cause an overheat on one/both heads at idle. Your observed water pressure readings are very normal for a new impeller.

thanks for the info still trying to figure it out


buzzer is constant,
does not overheat at idle or up to 3500 rpm but does overheat at wot
does this sound like the thermostats ?

also the telltale stream is cool even when overheat buzzer is sounding

 

[Daviet]

Re: Overheating ?

Just a thought.
I have also seen a defective head gasket cause that type of problem. At higher RPM,s a defective head gasket can allow compression into the block and pressurize the cooling system so that the water will not circulate properly. When the RPM slows down the water pump pressure will be strong enough to circulate the water properly and cool the engine.

 

[boobie]

Re: Overheating ?

Lwyatt, you have a PM.