Overheating at idle

[shep247]

I have a 1981 150. When running at idle speed(no wake zones) for too long it tends to overheat. If I give it enough gas to start getting into illegal no wake zone speed(nose of bow begins to rise a little) it seems fine, and it always seems fine when bombing across the lake. I've replaced just about everything I can think of in the coolant are including water pump, impellor and thermostat. Well, I should say the mechanic replaced it all.

Any clues guys?

 

[HighTrim]

Re: Overheating at idle

Im no expert by any means shep, but by any chance is there anything blocking the exaust gas from exiting? The high speeds may help clear them and thats why it over heats at idle. Im sure others will help that are better informed, but that's just a guess. gl and happy boating

 

[jenoble01]

Re: Overheating at idle

just wanted to subscribe and follow the thread.

 

[jurgenscraft]

Re: Overheating at idle

Firstly check that the water flow inducator hole is showing a good stream of water (pee hole) if you can reach the water stream while the motor is running
feel the temperature and flow rate of the water being pumped through.
replace the thermo stat as well as the water pump impellor located above the gearbox, flush your motor after use,If used in salt water use a flushing agent that will remove sediment built up in the coling system.
Regards William Wright.

 

[emdsapmgr]

Re: Overheating at idle

Put an infrared heat gun on it. Find out just what is overheating. both heads, or just one...How hot does it get? Did you test the overheats sensors on each head? Could be that temp sensor, but they are not prone to failure..

 

[shep247]

Re: Overheating at idle

Thanks for all of the advice.

I don't have a temp gun. I should probably get one if this continues, and will try that out. It seems like something that would come in handy.

I check the pee hole pretty often. It always seems to be shooting a steady stream. Both times this has happened to me however, the buzzer startled me and I went into a panic trying and turned the motor off asap in order not to damage anything. I just forget to check the stream when the buzzer goes off.

I am interested in the flushing the engine thing though. How should I go about doing that? I live nowhere near salt water, so i don't think I'll need the cleaning solution, but should I still flush it after running in fresh water? A buddy suggested just starting the motor after pulling it out of the lake. Would that be sufficient? I'd really like to avoid trying to start this in my garage, as its usually about 8 or 9 pm when i get home to my home in a pretty compacted neighborhood.

Thanks again!

 

[OhWellcraft]

Re: Overheating at idle

shep,
I am not too sure what to tell you about the cooling problem, but (and im sure others will tell you this as well) DONT START IT OUT OF WATER even a few seconds dry on an outboard will fry the new water pump you just had put in, guaranteed. Don't mean to sound like a hard a** but you will never get your initial prob worked out if you run it dry. Unless the lakes you run in are real sandy or silty I would simply lower your motor for 5 min. while getting ready to leave then tilt back up and you should be fine, I have an 83 200 rude and run in some sandy waters but have always had good luck lowering to drain then back up for drive home. If you are real concerned get a set of muffs and let it run for a while on those, the next day or when ever you can just dont go over about 1200 rpm's on the muffs. Then you could simulate idel speed(rpm) and feel the tell tale then...

 

[iwombat]

Re: Overheating at idle

I'm guessing your buddy has a motor he wants to sell you.

Starting a motor dry is up in the top 5 of worst ideas ever. Probably right behind running it w/o oil.

 

[walleyehed]

Re: Overheating at idle

Sounds like you need to change out the water pump and if it were me, I'd change the housing too....I've had a half dozen do the same thing so far this year...and, as said above, NEVER run it out of water.

 

[shep247]

Re: Overheating at idle

Thanks guys,
I will DEFINITELY give my buddy a hard time about the starting out of water thing. He's always ran inboards though, I don't know if that makes a difference.

I'm looking over the bill from my recent mechanic visit trying to determine if he did replace this housing thing, and I see that the impeller and thermostat were not replaced (or at least I wasn't charged for them). It does have kit ay, water pump on it though. Could this mean he replaced the housing too? If not, could I do this with a socket/wrench set or does it take any special tools?

on a side note,now that i'm looking at this bill, why do marine mechanics cost so much in labor? Its even more expensive than a car mechanic. I assume its a supply and demand issue, as I'm in Phoenix AZ, and have only found 3 or 4 mechanics that work on Evinrude/Johnson, which are all about a 3 week wait to even look at the motor, but I figured I'd see if there was another reason. This is not meant to be insulting or a jab at anyone's profession, or even a complaint about the bill, I'm just curious.

 

[Solittle]

Re: Overheating at idle

If your mechanic installed a new kit it would include the housing. Yes this is a job tha most driveway wrenches can do WITH A SHOP MANUAL. Your first step would be to get a temp gun to verify that is is getting hot and where.