Is my OMC Cobra stern drive Model 5.0 Litre running hot?

[Megalotis]

Under normal operating conditions the engine temperature runs right around 170-175. I have been through all my manuals and can't find anything to indicate a proper running temp. Any help will be greatly appreciated.

 

[sw33ttooth]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

welcome to iboats!

wot my temp pushes 175 after about 2 minuites, then it takes its sweet time cooling down, cruising at 3k rpm it stays in the 150ish. when you say normal do you mean idling out the no wake zone or cruising? i would think just idling its high, cruising may be fine as long as it doesnt go much over.

not sure on your year [not stated] but if its the same outdrive as i have the early 90's cobra changing the impellor takes 2-3 minuites, might be good just to double check it.

 

[Megalotis]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

Thanks. It is a 94 and that is at 3k rpm give or take a few. I'll give the impeller a check as well. It was just that someone thought it might be running too hot and I wasn't sure what the correct running temperature was.

 

[Lou C]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

I have an 88 4.3 Cobra, I find that it ranges between about 165-170, never gets as hot as 175 unless I come off plane and then after a few minutes of idling it will cool down to 165-160 or so. I'd say not knowing how accurate the gauge you have is, your temps can be OK. More important, what is the temp of your exhaust risers and manifolds? That's even more important because if they run too hot, they can burn through the rubber exhaust hoses which is safety risk. I just got an laser temp gun, when my gauge was indicating between 165-170, the hottest part of the engine I found was the part of the intake manifold where the thermo housing bolts to it, that was at 155, the thermo housing and hoses were all cooler, like in the 120-115 range. Manifolds/risers were at 115 idling in the channel,to 135 after running on plane...

 

[Gold Dragon]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

I run right around 175 to 180, but I have put in a different thermostat after the suggestion from my local mech. We get winter run off into our lakes so the water is fairly cold at the start of the season. Later into the summer when it is very hot (110+) it still seems to hover around the 175 range still.
I agree with sw22ttooth about your impellar. If you dont know the condition you should probably replace it. Or at least take the 2 minutes to look at it. Good Luck

 

[bruceb58]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

You also don't know if your gauge is accurate or not. Measure the thermostat housing with an IR temp gun to see what it really is at.

 

[Lou C]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

One thing about using the ir gun, you are measuring the temp of the housing, whereas the sensor is measuring the actual water temp, I think there is a difference, my thermo housing was quite a bit lower than what the gauge said, more like 115-120, but I think the actual water temp is higher...if you know your thermo (from testing) opens at the correct (160) temp...

 

[Randy J]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

hmm thermostats are going to run at temps the stat is made for isnt it ??? 180 degree etc lolo

 

[Lou C]

Re: Is my OMC Cobra stern drive Model 5.0 Litre running hot?

Nope all raw water cooled OMCs I have seen, and most Volvos and later model Mercs, use a 160 stat. That means it should not run cooler than 160 and can range up to about 175 or so, but should not be more than 180...