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Older Honda 8hp cooling question

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pfduffy
Captain

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USA
317 Posts

Initially Posted - 09/05/2011 : 09:34:09

I have an older Honda 8hp motor (with the squared motor cover.) It has what I consider a weak stream from the water outlet. I changed the impeller, but the stream did not improve. I also blew out the outlet hole. Where do I look next?

Pat Duffy
1984 SK/SR #4113
Slàinte

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Stinkpotter
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Djibouti
9075 Posts

Response Posted - 09/05/2011 : 09:47:24

There's a hose from the block to the hole, generally held on with a couple of wire clips... Try removing and clearing that, and stick a piece of wire into the block where it connects--there could be some rusty stuff blocking the flow there. Just make sure you reattach the hose securely--if it pops off, things can get ugly in there--especially in salt water. Don't ask......

(Don't worry "Voyager"--it was a different motor.)

Edited by - on

Voyager
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5352 Posts

Response Posted - 09/05/2011 : 09:50:43

Pat,
Have you checked the inlet area at the bottom?
I have a ~2000-ish Honda engine where the intake section has a screen. Could that area be plugged or blocked?
I believe you should be able to remove a few screws to look inside this area (careful not to drop them in the water).

Dumb question but, when you finish sailing, do you tilt the engine up out of the water, or do you leave it in?
Could be some build-up of algae or slime inside the water intake area as a result.

There's also a fresh water flush valve under the engine cover on the port side. On mine, there is a screw-on receptacle for a brass fitting, and inside the receptacle there's a ball valve that's held in place by a spring.
You may have a leak in this area. Do you notice water inside the cover area?

Edited by - on

GaryB
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4302 Posts

Response Posted - 09/05/2011 : 10:30:22

I just had the same problem on my '89 Suzuki last week. Finaly fighured out the thermostat was sticking shut. I removed it and the water poured out of the outlet. I still need to order a new one but at least I can use the boat for the time being.

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Stinkpotter
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Djibouti
9075 Posts

Response Posted - 09/05/2011 : 12:24:15

In salt water, I've replaced the thermostat every year on every engine (except my Honda 2, which is air-cooled). Cheap insurance.

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TakeFive
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2272 Posts

Response Posted - 09/05/2011 : 12:39:24

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by GaryB
 I just had the same problem on my '89 Suzuki last week. Finaly fighured out the thermostat was sticking shut. I removed it and the water poured out of the outlet. I still need to order a new one but at least I can use the boat for the time being.
<hr height="1" noshade id="quote"></blockquote id="quote">
Gary - I had meant to post a comment on this on the other thread, but hurricane preps distracted me. Your engine may run fine without a thermostat for the time being, but running below the design temperature for an extended time will cause excessive carbon buildup due to incomplete combustion, and that buildup could eventually lead to scoring of the pistons. So you really should order the replacement ASAP. There are also simple tests that you can do to see if your thermostat is working properly. Typically they involve clipping a thin string or fishing line on the plunger, immersing it in a pot of warming water on your stove, and recording the temperature that the string releases, which should be at about the target temperature (typically 120 or 130F).

I recently replaced the thermostat on my Force 50 (after 20 years of strictly freshwater use with the original). Prior to replacing it, the motor was running too cool (the opposite of your problem). The new thermostat made a huge difference in the low speed performance and reducing carbon buildup.

Edited by - TakeFive on 09/05/2011 13:20:47

TakeFive
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2272 Posts

Response Posted - 09/05/2011 : 12:57:34

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by pfduffy
 ...I also blew out the outlet hole. Where do I look next?
<hr height="1" noshade id="quote"></blockquote id="quote">
Exactly how did you blow out the outlet hole?

If you took a wire or rod and pushed in or blew in without removing the plastic outlet clip, you may have just pushed the obstruction back in the hose, only to return and block it again. That's exactly what happened to me.

My fix was to remove the hose from the outlet (as Dave mentioned), and carefully remove the plastic outlet clip from the engine housing, then clear it. When I did this and blew hard through the clip, a big chunk of stuff came out. When I just poked at it it went back in the tube as I described above.

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islander
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4018 Posts

Response Posted - 09/05/2011 : 13:58:58

Pat, Fist do what Dave said above, I take it your in salt water and I just had to clear my Honda on Saturday. I usually can clear it by sticking a toothpick in the hole when the engine is running then covering the hole with your finger on and off a few times. Repeat this 3-4 times. If this doesn't work the clog is farther up the line and the lines will need to be removed and cleared. The salt water crystallizes in the hoses when you turn the engine off and the heat dries up the water. If you clear the lines back to the thermostat and it still has a slow stream then I would look at the thermostat as the culprit.

Edited by - islander on 09/05/2011 14:01:20

pfduffy
Captain

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USA
317 Posts

Response Posted - 09/05/2011 : 16:01:17

Is thermostat replacement a DIY job on this motor? It looks like you have to take off the inlet manifold. I'm fearful that going in there will leave me with a big pile of critical parts for which I don't have a home.

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Downbucket
Navigator

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USA
188 Posts

Response Posted - 09/05/2011 : 16:05:28

Pat:

I have a 2001 Honda 8 hp and had the same problem at the beginning of this season. I replaced the thermostat and the issue was resolved. Water exiting outlet is now very strong.

Will

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Sloop Smitten
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1181 Posts

Response Posted - 09/06/2011 : 09:00:50

To replace the thermostat you need to remove a cover that also contains water passages that the flow indicator stream passes through. At places these passages are only an 1/8th inch wide and have 90 degree bends. They can clog easily especially in a salt water environment. Mine were completely blocked. A little work with a dremel tool can readily clean them up.

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GaryB
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4302 Posts

Response Posted - 09/06/2011 : 20:37:23

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by RhythmDoctor
 <blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by GaryB
 I just had the same problem on my '89 Suzuki last week. Finally figured out the thermostat was sticking shut. I removed it and the water poured out of the outlet. I still need to order a new one but at least I can use the boat for the time being.
<hr height="1" noshade id="quote"></blockquote id="quote">
Gary - I had meant to post a comment on this on the other thread, but hurricane preps distracted me. Your engine may run fine without a thermostat for the time being, but running below the design temperature for an extended time will cause excessive carbon buildup due to incomplete combustion, and that buildup could eventually lead to scoring of the pistons. So you really should order the replacement ASAP. There are also simple tests that you can do to see if your thermostat is working properly. Typically they involve clipping a thin string or fishing line on the plunger, immersing it in a pot of warming water on your stove, and recording the temperature that the string releases, which should be at about the target temperature (typically 120 or 130F).

I recently replaced the thermostat on my Force 50 (after 20 years of strictly freshwater use with the original). Prior to replacing it, the motor was running too cool (the opposite of your problem). The new thermostat made a huge difference in the low speed performance and reducing carbon buildup.
<hr height="1" noshade id="quote"></blockquote id="quote">

I figured there had to be something bad that would come if I didn't replace it. Thanks for the information! I will get the thermostat ordered in the next couple of days.

I noticed today that the motor was running smoother than it has in a while.

After removing my thermostat there was no need to test it. As I mentioned in my other post, hitting it with a hammer would not budge the plunger but your suggestion above is a good one. Works on a car thermostat too!

Edited by - on

Frank Law
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USA
159 Posts

Response Posted - 09/08/2011 : 08:58:35

I had a similar condition no water coming out of outlet port.. tried wire up port , no luck ,, removed cover , removed outlet hose and forced wire completely thru hose and a big chunk of gunk came out. A straight wire will pass thru the stoppage without clearing it
Frank law
ABOUT TIME
1983 3519
sr swk

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