Motor too hot? small leak at t-stat cover

gnarbrah · Oct 14, 2007

Hello all - Still not sure if my 6 horse is running cool enough. Videos Below- I've changed the thermostat, impeller, lower unit oil and it seems to be pumping water good. There is a small leak at the thermostat cover (I'll get a new gasket soon) but the block seems awfully hot. I've read that I should be able to hold my finger on it for "a few" seconds. I tried but I don't think I can get past one second without burning my finger. What else could be wrong? When I had everything apart I blew compressed air poured water through all the cooling passages I could get to and everything seemed good. Is there anything else that could be wrong? I'm trying to post a video, if it doesn't work here I'll keep trying. Thanks!

bgbass.1 · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

remove thermostat and see if it cools better.

gnarbrah · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

http://www.youtube.com/watch?v=Ld77T97GaTA

The link above is where you can see the leak at the thermostat cover.

The link below is a video of it at idle where you can see the water pumping. I'm at a loss on how to keep her any cooler!!

http://www.youtube.com/watch?v=2vkXQd0uQCc

tashasdaddy · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

with it leaking that badly, i would not run it. possibly tstat in backwards, you need to find the cause, and new gasket before running. obviously the impeller is pumping.

bgbass.1 · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

thats more than a small leak dont run it

gnarbrah · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

Here's one more video of it throttled up.

http://www.youtube.com/watch?v=LXiowSwLx1s

Vic.S · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

I would not have thought that a leak that small would affect the cooling. It should be pumping loads more water than that little dribble.

Did you check/replace the rubber grommets at the top and bottom of the water tube?

Where you able to check that the water passages in the head where not blocked?

While the lower unit was off did you connect a hose to the water tube and confirm that you can get a good flow of water through the motor? Did you try that with the thermostat removed and the cover off and again with the cover on.

gnarbrah · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

It only actually drips maybe 2 or 3 times a minute, but I get that it shouldn't drip at all and a new gasket is next on my list. What do you mean t-stat in backwards? Do the "openings" need to be facing a certain way? Its bigger on the top so it can't be upside down.

Vic.S · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

Just seen the final video with it throttled up. There seems to be plenty of water coming out of the outlet down the leg. Suspect all is in fact OK but it would be as well to check the thermostat opens at the correct temperature.

gnarbrah · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

When I had the thermostat cover off I poured water in and it had no trouble finding its way out and when the lower unit was off I checked the grommets and they looked okay to me (granted I'm not a certified mechanic). I also blew compressed air up the water pickup tube and wherever I could when the thermostat was out. How can I be sure the passages are as clear as they need to be? Should I pull the lower unit again an force water up the tube? If so how do I get a hose to match up with that little tube to get any pressure through it?

samo_ott · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

Just to change the topic a tad here. I see you have your hose in the tank, probably running a tad to keep the water level up. Do you have an anti-siphoning valve on the hose? This is applicable to everyone that tries this. You should always have an anti siphoning vavle as there are certain conditions in a municipal water system that can cause negative pressure in the line and actually suck the water back into the potable system. Yes, it is possible to have your oily water in your drinking system doing this. I'm a home inspector and have heard of it happening. The same can happen if you do the same with pet water tanks or on farms etc. The valve is cheap and simple and just screws on the line at the tap. Easy to do. Just as an FYI for everyone reading this thread.

Vic.S · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

When I had the thermostat cover off I poured water in and it had no trouble finding its way out

Thats what i had in mind. Mine is an '84 model so its a bit different to yours and i can easily tell that water runs through the passages in the head by pouring it in with the thermostat cover removed. I guess you can with yours as well.

how do I get a hose to match up with that little tube to get any pressure through it

Improvisation is the answer. Bits of plastic or rubber tube, hose clamps, an adaptor maybe. If you take the thermostat out you wont need to develop much pressure anyway.

Samo-ott

Do you have an anti-siphoning valve on the hose?

Of course he does. We all do. We know what can happen without one.

gnarbrah · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

I'm definitely planning on replacing the thermostat gasket and I'll probably pull the lower unit again and see if I can get some "pressure" through the water pick up tube just to make sure. Is it a good idea to run it without the thermostat? Is it really necessary? I'm so close to being back on the water and having paid only $40 for the motor I'm very ready to go but I want to make sure its as good as it gets. I'd hate to burn it up! What would you do?

samo_ott · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

You can run without a thermostat and it should run cooler but I would not do it for long. You need to find the problem if there is one... Which leads me to the next point...

Are you sure it's too hot? As the video's look like all is good. Temp on the head can be subjective. I know my wife would say it's scalding while I could touch my head. The only way to be sure of the temp is to get an infrared thermometer and check the temp and compare it.

Another simple test is to spash a few drops of water on the top of the powerhead when it's at temp... does it sizzle? if so it could be too hot.

tashasdaddy · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

the would not have put it in if it weren't necessary, for the engine to run at the optimum temperature. without it the motor runs cold, and do damage over time, foul plugs, etc.

gnarbrah · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

My buddy has one of those cool laser beam thermometer things. Does anybody know what the "optimum temp" should be? Also, the place I am touching and planning to shoot with the laser thermometer is right in front of the spark plugs (see video), just want to make sure I'm in the right zone if you will. Also I'm okay in the pain threshhold, if I keep my finger on it for a count of 2-3 mississippi I will have a blister.

Vic.S · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

As said it is best not to run without a thermostat but there is no problem for test purposes (very small engines don't have thermostats anyway!) If all is well it will run a lot colder without the 'stat.

Some people will be able to withstand touching much hotter things than others. If you have hard tough skin from manual work or handling hot objects then you will be able to touch the block for much longer than you will if the roughest thing you handle is your keyboard or the hottest your girlfriend!

I think you are suggesting checking the temp on the cylinder head. That'll be the hottest place of all.

I am inclined to agree with samo_ott. It looks good in the video.

Give it a run. If you get loads of steam from the exhaust/water outlet then it is overheating. Also look at the cylinder head, if there is any discolouration of the paint then that is a sign of overheating.

Your question about the "optimum temperature" makes me realise I don't actually know temperature the thermostat should open. I have never noticed if it is marked even. I would guess that since it is supposed to be suitable for salt water it'll open in the range 140 to 170 F.

kenmyfam · Oct 14, 2007

Re: Motor too hot? small leak at t-stat cover

You can use temp sticks (crayon like things) to check the head temp.
I would fix the gasket immediately as it is not going to leak any less as time goes by. While you are doing this check the thermostat as well. I would ceretainly not recommend running without it. As said earlier, it is there for a reason. It would be cheaper to manufacture without it, consequently giving the manufacturer more profit. Therefore my opinion is that it needs it.

gnarbrah · Oct 15, 2007

Re: Motor too hot? small leak at t-stat cover

I've got the new thermostat cover gasket on order and I'll see what that does for me.

Where can I find these temperature stick (crayon things)? Or where can I find what temp. the motor should be running at?

samo_ott · Oct 15, 2007

Re: Motor too hot? small leak at t-stat cover

I asked at my local OMC dealer and they said they had not used the crayons in eons. So I use the infrared thermometer when needed.

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