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BF175 cooling issue

R

RussellAU

New member
Hi All,
When I recently put the muffs on my 175 I noticed the tell tail was just dribbling instead of a good stream. I checked the pick up intake, all clear, ordered and replaced the pump housing and impeller, still no good, got a high temp alarm after a couple of minutes, shut it down.

Any ideas / thoughts most welcomed
 
There is probably some foreign matter obstructing the water flow.
Try some thick fishing line though the eater indication tube hole.
Or maybe it’s time for a vinegar and/or acid rinse.
 
Hi,
I like to use a test tank (trashcan) with water well above the vent plate to test for cooling/water flow issues. That gives you a better idea of what the pump and system is doing and eliminates the "variables" (fit, leakage and water pressure) associated with muffs).
Just my preference.
Good luck.
 
Do you operate in salt water?
Has the outboard been sitting for a while?

I'm not the expert you might need but I hang out here a lot and read most of the posts.

Two things I've seen reported with overheat issues and fixes are relief valves clogged...items 17, 18 and 9 in the link below :

Honda Outboard 175HP OEM Parts Diagram for Mount Case | Boats.net

Buy OEM Parts for Honda Outboard 175HP Mount Case Diagram
www.boats.net www.boats.net

And, there was a recent case where the guy found problems with the molded hoses at the ends of the exhaust manifolds.
Items 7 and 8 times two in the link below:

Honda Outboard 175HP OEM Parts Diagram for Exhaust Manifold + Thermostat | Boats.net

Buy OEM Parts for Honda Outboard 175HP Exhaust Manifold + Thermostat Diagram
www.boats.net www.boats.net

Old hoses with bends have a tendency to catch crud in the curves and can plug up on you.

Just a couple of ideas if nothing else jumps out at you.

Good luck.
 
To add to what JGMO wrote...

You could have two simultaneous problems - a clogged pisser hose or nipple AND a problem with the cooling system. To fix the first remove the pisser hose, make sure it is clear, and run a piece of monofilament down the pisser nipple. Weed-Wacker string works well in most cases.

These big Hondas will often overheat on muffs unless you have a very good seal and very good water pressure, and the pisser stream could be weak if not enough water is able to circulate. A test tank is much better.

Were there any missing pieces from the old impeller? If so, drop the lower end, remove the t-stats, and try to flush with as much fresh water pressure as you can get. Use a rag around the hose into the t-stat opening to get as good a seal as possible.

Next, are you absolutely sure beyond a shadow of a doubt that you installed the woodruff key correctly - the one that locks the impeller to the drive shaft? If not absolutely sure, drop the lower end and recheck.

Next, thoroughly check the hoses that JGMO pointed out.

Finally, pull the pressure relief valves on the mount case. When you look at them you will see three bolts. You only need to remove the two outer-most ones to remove the valve case. The third bolt just holds the valve case together. Take the relief valve out and apart and clean up everything. Reinstall and retest.
 
Thank you everyone for your helpful tips, I really appreciate it.
I've had this boat for about 2 years and never had an issue with using muffs, so thinking it might be a blockage or something to do with the thermostats as suggested. Don't get me wrong, I will absolutely try a drum of water on the weekend though.
Thank you again for your suggestions, really appreciate it :)
 
All fixed. Checked the thermostats, all clear, replaced them anyway.
Back flushed with the hose connection first (motor not running), proved the tell tail was clear with the garden hose only (it did splutter a bit before it was a clear stream, so the hose alone may have dislodged something in the cooling system).
Then dropped the leg into a container of water as per everyone's suggestion, and hey presto, looking great.

A sincere thank you to all who provided such helpful information :)

PXL_20230909_074234807.jpg
 
jgmo said:
Do you operate in salt water?
Has the outboard been sitting for a while?

I'm not the expert you might need but I hang out here a lot and read most of the posts.

Two things I've seen reported with overheat issues and fixes are relief valves clogged...items 17, 18 and 9 in the link below :

Honda Outboard 175HP OEM Parts Diagram for Mount Case | Boats.net

Buy OEM Parts for Honda Outboard 175HP Mount Case Diagram
www.boats.net www.boats.net

And, there was a recent case where the guy found problems with the molded hoses at the ends of the exhaust manifolds.
Items 7 and 8 times two in the link below:

Honda Outboard 175HP OEM Parts Diagram for Exhaust Manifold + Thermostat | Boats.net

Buy OEM Parts for Honda Outboard 175HP Exhaust Manifold + Thermostat Diagram
www.boats.net www.boats.net

Old hoses with bends have a tendency to catch crud in the curves and can plug up on you.

Just a couple of ideas if nothing else jumps out at you.

Good luck.


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Thank you, you made my weekend :) I appreciate you for your help.
 
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