Is 180 degrees too hot?

[Grice7]

I have 2 options for running my engine at home. I have not yet run in water. I can either hook my hose directly to the engine block, which does not allow the temp to even reach 100. Or fill a drum and lower the drive into it. When I did this the temperature reached 180 degrees in about 15 minutes. Is this too hot>? if not what is? I have a 1972 165 hp 250 ci mercruiser with I believe a pre alpha outdrive. Also my Idle is about 900 to 1000 rpms is this too high? This engine is eerily similar to a car engine in which case that would be fine. i just noticed on other posts an idle of about 400 rpms is recommended. Thanks for the advice guys! (And gals!)

 

[HT32BSX115]

Re: Is 180 degrees too hot?

Howdy,


180 is probably too hot for a raw water cooled engine running on a flush adapter. You may need to rebuild your raw water pump and ensure that your raw water circuit is clear of obstructions.


900 RPM is Way too high for ANY stern drive. You will eventually cause damage to the dog-clutch

It should be at around 600 RPM.


Regards,


Rick

 

[Bt Doctur]

Re: Is 180 degrees too hot?

The main impeller is in the lower unit ,so if you hooked to the engine and not the drive you fried the impeller already. 140-160 is the norm for temp. idle 650-750 ,in gear, in the water

 

[franktrav]

Re: Is 180 degrees too hot?

my 5.7L mercruiser was equipped with a 160 deg. thermostat-while 180 deg is a little bit warmer than what i am running, it doesnt sound dangerously high, put a cooler thermostat it it if you are concerned.
on the other hand the idle does seem a little high,mine is set around 650rpm, which is adjusted at the carb.the higher your idle, the more youre drive will get "beat up" when shifting into gear

 

[Grice7]

Re: Is 180 degrees too hot?

The impeller is fine. When I hook up to the block water circulates through the drive too. It porrs out of the prop and exhaust at great volumes. When in the drum i can feel the impeller sucking in water.

 

[Bt Doctur]

Re: Is 180 degrees too hot?

Nope, the impeller was fried if you had it hooked to the motor only.the impeller MUST ALWAYS have water with the engine running.

 

[Grice7]

Re: Is 180 degrees too hot?

Dude, I promise the impeller is fine. With my set up when I hook up the hose to the engine block water pours out of the drive. even with the engine off. I ran this way every time until I decided to check the impeller with the "bucket test". when I did the bucket test I can open the connection where I normally hook up the hose to the block and water flows through there like theres no tommorrow as well as the exhaust. I can feel the water being sucked into the drive by the impeller. If the impeller was bad I believe this wouldnt happen right?

 

[hawkf250]

Re: Is 180 degrees too hot?

Dude, I promise the impeller is fine. With my set up when I hook up the hose to the engine block water pours out of the drive. even with the engine off. I ran this way every time until I decided to check the impeller with the "bucket test". when I did the bucket test I can open the connection where I normally hook up the hose to the block and water flows through there like theres no tommorrow as well as the exhaust. I can feel the water being sucked into the drive by the impeller. If the impeller was bad I believe this wouldnt happen right?

Wrong... Your impeller may still be sucking water but probably not at the rate that it should be. The water that you see pouring out of the drive when hooked to the block is simply coming out of the exhaust, it cannot flow backwards and lubricate the impellar. The impellar housing is also sealed from the exaust side to prevent heat damage from heated water that has already flowed through the block. The impellars must always have water while the engine is running, it only taks 5 seconds of running dry to destroy it. it may still pump water but no where near the rate that it should be, when you disconnect the waterline at your motor from the outdrive and start the engine, it should shoot water half way across your yard. if not, time to change it. And since you have been running without water on it, I would change it just to be safe...$30 part vs $3000 engine.