Manifolds Getting Hot Quick

[suprasam]

OK I had a similar issue.....I guess it was never fixed. I started my boat yesterday to run seafoam through and to get the oil changed. I had my water hose put right on the intake grate and it seemed to be sucking up water well and spitting water out the exhaust well to, or maybe I am just used to seeing that amount being pushed out. Anyway here are my thoughts, and let me know what your two cents are so I can try and eliminate any over heating next spring/summer. I am rebuilding my pump this winter, I already have the parts for it so I am hoping this is the issue along with a new impeller. Is there anything else you can think of I might want to take a look at while its winter? BTW these water pumps are STUPID STUPID expensive! My temp gauge isn't working so I need to get that fixed as well.....but it will be done. The portion of the manifold that connects to rubber exhaust is the part that got the hottest first.....then slowly creeped to the top of manifolds, very warm that I couldn't keep my hand on it more than a second or two. After that I shut the motor off, I know its not exact science to see if over heating at what temp......but its hot enough to know it should be that hot.

[Jetlink]

Did you use a fake-a-lake or just hold a hose up to the water intake? Your post right there is a little confusing to me with the wording.

[suprasam]

No not a fake lake, i took the hose that goes to the intake grate and use that so water can be sucked into the motor. So yes held hose up to the intake.
On a side note...... my motor mount rubber bushings seem to be dry rotting(not bad, but getting there), are these things easy to change? It's not that I don't have enough things to take care of this winter, or spend enough money on this boat....so i figured why not add more things to my "to do" boat list.

[wotan2525]

Is the supply side of your hose a bucket or your water supply? In other words -- is it generating pressure or is the pump doing all of the work?

If it has pressure, then the problem isn't your pump. If water is exiting the back of the boat, you should be providing enough flow to cool the engine and manifolds. Is it only 1 sid or both? 1 side could mean some blockage.

I would make getting a new temperature sender a priority. It is located in the top of the intake manifold and I would guess that if you pulled it and took it to NAPA, they'll be able to help you out. I'm sure you could also test it with a multimeter and a lighter and see that the resistance is changing or if it is staying the same.

The other option is to get an infrared thermometer (harbor freight has the cheap, or you may be able to borrow one.) We need to see what the actual manifold and block temperatures are reaching to tell if you actually have a problem.

[suprasam]

Wotan....your right. A buddy of mine said stop being a DUMB_ _ _, get the temp gauge issue fixed first to see what the temp is getting at and to see if its actually over heating or if I am just a panzy_ _ _ when it comes to heat. I know the manifolds are suppose to get hot....and maybe I was gun shy about the heat, I just don't want to over heat the motor. So I am taking the advice and getting the gauge/sender fixed before moving on. Yes both were getting warm, not just one side.

[Jetlink]

I know that both of my manifolds get hot to the point that I instinctively pull away if I touch them even after it has been shut down for awhile, like trailered home from the lake an hour and then cleaning up. As a point of reference, my temp gauge and sender are both good and only two seasons old and I never get above 160 degrees American when running.

[suprasam]

160 Degrees American? Well damn that might be my problem....Im Irish! I knew that would come back an screw me at some point! Although it does help me drink a few while working on the boat! Ok....so it is a new gauge and try to figure out how to wire it back to the sender! thanks guys

[Jetlink]

I did the math for you, 160 degrees American comes out to 71.1111111 degrees centigrade give or take a tenth of a degree. Hope that helps! Haha!

[docdrs]

Ok , I'm calling ya on this one :) . There is no 160 American. Its 160 fahrenheit which is closer in proximity to being Irish than American.

[Jetlink]

Ok , I'm calling ya on this one :) . There is no 160 American. Its 160 fahrenheit which is closer in proximity to being Irish than American.

Haha, fair enough, I gotta have fun somewhere... My work we use the metric system for all temperature readings and we joke that the "C" stands for Canadian and seeing as how we don't really fly anywhere outside of the North American continent, it works for now...:lol:

[lslsupra]

I'm having a similar but different issue. One manifold it getting hotter than the other. One side is reaching 210 F and the other stays around 110. The hot side melted the rubber hose. We used a thermal gun and looked at temps all over the engine. The only hot spot is the manifold. For process of elimination, I replaced the water pump and thermostat anyway. That was no help. I took the top of the manifold and took off the hoses to look for blockage, but I could not see anything. Any ideas?

[wotan2525]

I'd try to backflush it from the exhaust end through towards the water pump. Be sure to take off all the hoses and keep back flushing. You'll find some old impeller over there....

[lslsupra]

Great idea. Thank you.

[SquamInboards]

What engine do you have? What year?

At the very least, you probably need a new hose if you melted the current one. I had an issue with my exhaust hose collapsing around the manifold where it was supposed to be dumping water out into the hose. It looked ok but when it would get warm it would collapse internally and block the water passages. The hoses are only rated for about 200F, 250F intermittent. If you've had melting, it's time for new hoses anyway. It would be a good idea while the manifold is off the boat, to take the plug and elbow out of it, separate the riser and manifold, and flush them both really well in every direction with water. No doubt you'll see some accumulated rust and junk come out of it.


edit: didn't see the above post at first. Try that first, keep it simple. But I do think your hose may be damaged...

[lslsupra]

Thanks for the input. It is a 1987 Ford 351 Marine Tech with less than 400 original hours.