1987 Mercury 70 HP oil injected outboard (STEAM from front top hole of cavitation plate)

Hello to all.
Ok, so not sure why i did this in the first place. I have a 1987 Mercury 70 HP oil injected 3 cylinder 2 stroke. Runs very good.
I've been flushing the motor after every use in salt water. For some reason, (Stupidity) the last (2) times i flushed it, i had the motor raised half way up, (Not in the upright position!) I let it idle on the ears for about 3-5 min. The last time i took it out on the water, i had steam coming from the front lower water hole ( not sure what the hole is for on this motor) but it has always had water coming out of it! Anyways, now when i run it on the ears, the water from the tell-tail is completely cold and the water that comes from that little rubber pipe at the top of the cavitation plate is very hot!! there is also a small hole that i had never seen before right next to that little pipe that has hot water also coming out of it. The water is very hot after about 2 minutes of running it on the ears. From what the book say's, ( the motor must be in the upright position during and after flushing. This prevents water from passing into the power head through the drive shaft housing and exhaust ports during the flushing procedure. It also eliminates the possibility of residual water being trapped in the drive shaft housing or other passageways. This is what i've done so far, removed the thermostat and poppet valve cover and checked for any corrosion and also tested the thermostat by boiling it to the correct temp. Going to replace it anyways while it is removed. I'm pretty sure i messed something up! Not sure how to fix or what to fix! Im pretty good at mechanics and have most tools needed. Any help would be appreciated. this sight has been good to me so far! Thanks, James

Do yourself a favorite and leave the t-stat out (along with the poppet valve--the dealers removed most of them). Next, find the water line that goes from the right side exhaust adapter (below the power head) to the fuel pump and block that off with a plug. (This motor needs all the cooling it can get, for the impeller is a bit small.)

Trust me on this--I run triples exclusively.

Jeff

The 1987 70hp is a looper, do not remove the poppet or t-stat. Which small pipe are you refering to? The water out pisser is allways cool as it comes off outer exhaust plate...

faztbullet said:

The 1987 70hp is a looper, do not remove the poppet or t-stat. Which small pipe are you refering to? The water out pisser is allways cool as it comes off outer exhaust plate...

Click to expand...

OK, Thats what i thought! I'm not a big fan of removing OEM parts anyways. The pisser/tell-tail is bellow the cowl suit-case cover. The 1/4" hole that is in the front of the motor on top of the cavitation plate is were im getting very hot water when i run it at home on the ear's. Plus, The last time i ran it in water, there was some steam coming from the front lower 1/4" hole. This has never happened before. Today i removed the lower unit and disassembled the Impeller. All looks good, i think it was changed out recently. Looks new! I've owned this boat for about a month and have used it several times and have never seen the steam before. I'm pretty cautious about looking at the motor, just making sure for the first couple of months that everything is good with the motor and hull. I need to take a temp reading on the head with a heat gun to get an idea of the temp when it does this (STEAM). Not even sure if its running hot! I maybe running the motor wide open for only about a minute> just to get were I'm going in the Harbor and just outside the Harbor. Fishing for Halibut mostly. So the motor doesn't even run long. 10 mile an hour speed limit! The thing is, ill run it on the ear's when i get home for about 2 minutes and the water from the tell-tail is cold but the water that comes from the front hole is very hot! This can't be right! i know I'm not explaining it very good and i hope you will understand. Thanks for the first help. Would you know whats going on with this?