81 evinrude 150 sport still overheating

[joerocket693]

Hey,
I'm new to iboats. I recently got an 81 150 sport. I have the manual, but what get's me is, is my outboard a crossflow? or a looped charged. It's the v-6 and it has SPORT on the outside. It's blue and silver. I'm having over heat problems. - oh yeah, We last used this boat 2 years ago to go water sking. It ran flawlessly. Now I have it, and it ran hot ( alarm went off) first time out. So i Let it cool and then took it in. Changed the completed water pump (kit). It pumps water now great. Went back on the water. Decided to check the engine after a short run. Port side cylinder bank was hot...water steamed when touched. Starboard side is running good and cool. Let the engine cool. Came in and assumed a stuck thermostat on port side. Pulled thermostat covers on both cylinder banks. NO thermostats found, only presure relief valves. I think previous owner took the stats out because they are not really needed down here in Southeast LA. Water never really gets cold. Anyway, ran the motor on the muffs with stat covers off. Water flowed fast and hard out the starboard, but little came out the port side. I'm thinking now that I have stuck parts of the old impeller in the cooling system on that side.
Questions:
1. How hard is it to get to the cooling system? Do i just remove the head covers and viola?
2. Is it possible to back flush by removing the lower unit and pumping water via a hose through the thermostat housing? Maybe this would dislodge any stuck particles.

Thanks for any replies.

 

[ob]

Re: 81 evinrude 150 sport still overheating

For peace of mind I'd recommend removing both head covers,particularly the hot running bank and inspect/replace the six water passage deflectors.Then I'd recommend reinstalling new T/stats to insure proper running temp and block pressure against the pressure relief valves.You'll need a new set of head cover gaskets as well.

 

[emdsapmgr]

Re: 81 evinrude 150 sport still overheating

You have a crossflow engine. The cooling water flows from the bottom of the head, up the outside head cover to the thermostat housing at the top, then runs down the inside of the block around the cylinders. Based on that flow, I'd follow OB's advice and pull the head cover (not the head) on the port side and check for water flow. Specifically, check the bottom of the head, for a large opening, that's the water inlet. That is where the incoming port water comes first, and if restricted, would show as low flow at the stat. I would also not run the engine without stats, as it can run too cool-causing other long term problems such as poor combustion and can promote carbon around the rings.

 

[HighTrim]

Re: 81 evinrude 150 sport still overheating

Welcome to iboats.

I always change my water pump and stats together, flushing the cooling circuit while I do it. This ensures adequate flow, and prevents you from doing a job twice. While the lower unit is down, to service the w/p, remove one of the t stats, run compressed air, or the garden hose, up the water line and ensure that it exits the t stat housing with sufficient pressure. Now backflush down from the housing to the water line. Replace stat. Remove second stat and follow procedure above.

This only takes minutes, yet prevents unnecessary troubleshooting after the fact. Good luck, hope you get it solved.

 

[joerocket693]

Re: 81 evinrude 150 sport still overheating

Thanks for the advice. It appears I can get to all the head cover bolts without pulling the powerhead. Now I will just need to convert in/lbs to foot/lbs in order to torge them back on correctly. Looks like I have a project for my day off. I will keep y'all posted on my progress.

 

[Dhadley]

Re: 81 evinrude 150 sport still overheating

It'd be a good idea to remove the heads and change the deflectors and head gaskets too, if you haven't already.

 

[HighTrim]

Re: 81 evinrude 150 sport still overheating

Torque the head bolts to 18 to 20 foot pounds (216 to 240 inch pounds)

Do this in stages, 1/2 the total torque first, then 3/4 of the value, then the total.

The pattern is important as well. Pretend the following numbers are bolts and torque as follows.

9............10
5.............6
1.............2
4.............3
8.............7

 

[Benny1963]

Re: 81 evinrude 150 sport still overheating

pull the heads and change deflectors ,change passage cover gaskets while your at it run stainless therm kits ,were we live here it is hard on regular thermos flush evey time out that water down that way is hell on blocks and bolts so ya may need a little heat on the cover bolts ,new head gaskets not the thick ones low comp torque to spec and in sequence .add pressure gauge and head temp gauge or gauges and you will have it beat,answered your pm .
fishing the mine this weekend

 

[Dhadley]

Re: 81 evinrude 150 sport still overheating

The preferred t-stat is the brass one with a V shaped bar across the top. The next best is the brass one with a pop up in the center and no bar. The ss one that looks like that is made differently internally and can actually cause problems in and/or after an overheat. The ss ones work correctly in normal conditions, just take extra care to make sure the motor never overheats.

 

[Benny1963]

Re: 81 evinrude 150 sport still overheating

didnt know that hadley i was runnin the brass brp stats went to the stainless because every time i pull em the look corroded .
after blowing my othr one from over heat i a liilte stupid on my cooling maint and carbs,will put my brass back in i pull them enough that it wont mater thanks

 

[lyncraft_mechanic]

Re: 81 evinrude 150 sport still overheating

here is a great website http://www.unitconversion.org/energy/foot-pounds-to-inch-pounds-conversion.html for the conversion of foot to inch pounds

 

[joerocket693]

Re: 81 evinrude 150 sport still overheating

Thanks for all the advise guys. I pulled the head cover, and voila.. what do i see. dry rot rubber particles pilled up agains two of those water deflectors. The deflectors have deformed and shifted toward the waterflow channels slowing down water flow and started collecting debri there. So, I pulled the deflectors out. They must be the originals, the are dryrot and flakey. Looks like i'll be getting new ones, Might as well do the other cylinder bank while i'm at it too. NOW only problem i've encountered is that the tip of the thermoswitch is stuck to the inside of the head cover. I guess a lil liquid wrench could persuade it out. Thanks again for all the input. I took pictures and will post them here soon showing the deflectors and the problems caused.

Benny, You talking about the sulfer mines out back of Larose?

 

[Benny1963]

Re: 81 evinrude 150 sport still overheating

yes back of larose fish there every winter, put in at bayou blue or sometimes
pointe auchin, glad ya got your prob fixed ,before ya put your heads back on
take a sheet of emery cloth and put it on glass or flat surface and swirl your heads in a figure 8 motion to true them up ,be sure to torque and use torque sequence
pm me if ya need something ive got lots of 150 parts got some real nice heads if ya need im ya can have any of it ya need .
catch ya later may pm ya when i head that way ,im in denham springs
but fish down that way when the fish are in the mines .haveing hard time finding out if there in the mines yet .if ya here something let me know

 

[mikesea]

Re: 81 evinrude 150 sport still overheating

If you are concerned about torque specf putting back the water passage covers,dont use a ft /lb torque wrench.Its going to be to powerful for the small in lb accuracy.You would be better off not torquing,make them all snug starting from middle out in circular pattern,when snug go back and give another 1/4 turn,use sealer on the gasket you should have no problems,the headbolts are a different story,240 in lb max,in incerments,on older engines with new gaskets I always stayed closer to 216,in/lb,the important is that they are equal,run the head over a piece of 80 grit on flat surface and give a nice even surface,be sure the block is clean,I like to spray the bolts with oil before installing

 

[joerocket693]

Re: 81 evinrude 150 sport still overheating

Wanted to follow up with everyone. I got her all back together. New water restrictors and all new gaskets. New Thermostat kits. although I did find that the motor was still running warm. I pulled the stats and she runs cool now. I'm kinda nervous to leave stats in when it's so dirty water down here in the marsh, with all the mud and grass. Anyway. She runs great. I even went ahead and pulled the air intake cover and wiped out the carb throats by hand with a lil foaming degreeser. Even vacuumed down inside the cowling. haha. Have to take pride in your work, you know. Now this ole rude is on the back of an old cajun bass boat. So few more tweeks to the actuall hull and i'll be out on the water. Thanks for all the help. happy wakes to you all.

 

[Dhadley]

Re: 81 evinrude 150 sport still overheating

If you insist on leaving the t-stats out, gut them and put them back. Without them (no restriction) the block may not fill all the way up. If you have a 35 amp stator you run the risk of damaging the water cooled regulator / rectifier.

 

[Benny1963]

Re: 81 evinrude 150 sport still overheating

glad to see ya got it going add temp gauge or buy one of the guns big piece of mind hope yall are well,i run my stats but have to maint them a lot this block when i got it had no thermos it was out of biloxi

 

[joerocket693]

Re: 81 evinrude 150 sport still overheating

Gut the therms...huh. How would I go about that exactly. Guess a dremel tool? This engine has248 hours on it...most without the therms. But for peice of mind and the great advise I've been getting, I'd gut them and put them back.

I assume local boat shop has temp guages....guess i'd mount one on each cylinder...maybe on the top where the less water and most heat would be located.
Have a great week guys. Thanks for all the input.