79 merc 115i6.....think i got cooling sys correct??

[skeeterFever]

ok being its new to me- i went ahead and changed the water impeler and all gaskest....and the thermostat...

after starting in a 55 gallon drum of water-IT TAKES APROX 15 SECONDS TO SHOOT HEAVEY STREAM FROM WEE HOLE.

avg temp in a glass of water coming from wee hole with bakers thermometer reads 165 degrees------and quickly falls to 140 degrees......i guess im sensitive cause this hurts my hands-----pretty similar to my hott side tap faucet...

does this sound average to you pros---- im ready to take it to the lake-- but had to be sure first......i dont want a melt down...


you guys say you can put your hands on the head and it will be warm-to hott, but not scalled you....

i can to and it seems ok but rather hott to my touch......{DOESNT BURN ME}

SO AS LONG AS IT HAS A HEAVY STREAM- BETWEEN 140-165 DEGREES-- AM I SEMI SAFE TO GO RUN AND TEST IN THE LAKE...

ISTHE PEE HOLE STREAM A SURE FIRE EXAMPLE THAT ENGINE IS GETTING COOLANT FLOW??????? IT HAS STRONG FLOW AT IDLE- HEAVIER FLOW AT 2000 RPM.....MAX I WILL ALLOW AT HOME.

INTIAL STREAM AFTER STARTING HURTS MY HAND{15 SEONDS TO PEE} THEN QUICKLY DROPS TO 140 DEGREES


THANKS,,,SORRY FOR ALL MY LONG POST- BUT I TRY TO ADD AS MUCH INFO AS POSSIBLE IN OPENING POSTS...

 

[emckelvy]

Re: 79 merc 115i6.....think i got cooling sys correct??

There is no thermostat on any Inline Six Merc ever produced, what motor do you really have??

And no, temps of 140-165 degrees are NOT safe for operation. This motor should idle Stone Cold in a 55-gal drum of cold water. Even after a hard run, the exhaust manifold should typically be no more than lukewarm.

You could have some sort of water circulation problem, or maybe still have a problem with the water pump. Recommend pulling the lower unit and attach a supply of water to the copper water supply tube. Don't use real high pressure, 12 psi max.

If the block shows good circulation, take a hard look at the water pump stainless insert and pump plate. Replace them if they are worn. Check the grommet in the water pump cover, replace if it's bad. Check for any obstructions on the suction side of the pump. Water poured into the water pump base should flow freely out the side intakes in the gearcase.

HTH & let us know what you find........ed

p.s. if you do instead have a later-model 115hp 4-cyl, it does have a thermostat and slightly higher water discharge temps wouldn't be unusual (but 160 deg is still too hot). Make sure you have the correct thermostat (should be 120-125 deg if I recall, no more than that). The block will get warm but the exh. man. sidecover still should be cool/lukewarm at idle. Check the poppet relief valve for issues also.

 

[skeeterFever]

Re: 79 merc 115i6.....think i got cooling sys correct??

seriously scratching my head.....engine clapm tag numbers showed as 79 ...

115 i6........top of engine seems brand new--nowrench wearon any bolts...

i dont know whqat i have here now then.....i was asumed it was a 79 with a new power head etc..


back to the rest-- i cant fathom an engine running dead cold water through it..surley it would cold sieze------these things have to run around 140 degres for -proper running temp....

there is no wqy water can circulate around the heads and return out cold...

i think its fine now....but im going to do everything you said and re check the poppit valve---as im sure probly very wrong....i dont want to be the reason of destroying my engine before i have fun in it,,


thanks

 

[emckelvy]

Re: 79 merc 115i6.....think i got cooling sys correct??

DUDE! Inline Sixes DO NOT have a thermostat or poppet valve!

The exhaust manifold sees cold water, if you're idling in a 55 gal barrel there's very little load on the motor and the manifold will be COLD.

These motors DO NOT run at 140 deg unless there's something wrong with them.

I'm not saying that the water coming out of the head will be stone cold. It will definitely be warmer than what's going in. But 140 deg, I guarantee, is TOO HOT unless you're running in very hot water to begin with.

This is a very basic motor with no thermostat, no poppet valve, the only thing that regulates cooling is engine load and the amount of water circulating thru the powerhead.

Thus the previous recommendation to check water flow thru the powerhead. If you have adequate flow, something else is going on, such as problems with the pump. It's also possible for a leaking exhaust manifold gasket to cause water circulation problems, but in most cases you're also gonna see droplets of water on the spark plugs.

If you find you have poor water circulation thru the powerhead, there may be a physical problem such as silted-up block cooling passages (pull the cover at the back of the block in this case), or even an issue with the water tube upper grommet (which requires pulling the powerhead to repair).

Anyway, back to basics, the flow check I'm sure will tell you a lot about what's going on.

HTH.......ed

 

[Moody Blue]

Re: 79 merc 115i6.....think i got cooling sys correct??

As emckelvy says, the inlines run very cold. Not likely temps will exceed 100F even at WOT unless something is wrong or you are running in tropical water temps of 80*. I can run my motor for an hour full out and the temp gauge barely comes off the lower peg. There was the one time I picked up a bunch of weeds on the LU and the temps rose to about 110* before I noticed it.

Right now it seems we are on different pages as to what motor we are talking about. Can't be absolutely certain about any detail until we can agree on what the motor is.