08' Honda 150hp 4-stroke Heat Alarm

[frustratedboater]

My 150hp Honda has a steady alarm at about 3-4min at idle. I did notice white scale flakes coming out and an intermittent stream and had to keep clearing it.. I did get mix communication that the motor may have sat a few seasons when I purchased it.
I pulled the unit off to check the impeller and the pump looks new, the water pickup flows out through the bottom of the pump plate and no visible clogs. The T-Stats look new (ish) and had no crud in or around them and I boil-water tested them and they both opened. I did force water through the thermostat housing and out came more scale out the pickup tube. I also ran water up that pickup tube in 15 sec. shots and let it drain out and got a little more of that scale stuff. I did this 6-8 times..

I ran it and alarm sounded at about the same length of time. I disconnected the T-stat housing, removed the stats and started the motor to see if I'd see any water out the T-stat housing (lg. blk hose) for 15 sec and did not. I did not see water running up the T-stat holes aw well and thought I'd see something. I re-assembled, then scratched my head.. Is there a passageway crud could collect restricting flow I'm missing?

 

[Sea Rider]

Make a long flush with Salt Away with removed thermostat and motor ON to flush/clean the whole powerhead. Assume that motor was run in saltwater over the years ?

Happy Boating​

 

[frustratedboater]

You are correct. The motor was sitting in upper Chesapeake kinda brackish, but 'salty'. If I may ask, how is the flush setup since I use ears/hose, how do I administer it into the system?

 

[Sea Rider]

You are correct. The motor was sitting in upper Chesapeake kinda brackish, but 'salty'. If I may ask, how is the flush setup since I use ears/hose, how do I administer it into the system?

Can use a large water bucket with product dumped in there, use as directed by the manufacturer. The peeing water must be discharged inside the bucket to avoid product loss outside the bucket. There are other methods, check at YouTube : https://www.youtube.com/results?search_query=salt+away+engine+flush

Happy Boating​

 

[dingbat]

Is it over heating in the water or on muffs?

Buddy has one that fine on muffs. The other overheats on muffs

 

[frustratedboater]

Can use a large water bucket with product dumped in there, use as directed by the manufacturer. The peeing water must be discharged inside the bucket to avoid product loss outside the bucket. There are other methods, check at YouTube : https://www.youtube.com/results?search_query=salt+away+engine+flush

Happy Boating​

of course, containment! I have a barrel I can stick under it.

 

[Sea Rider]

of course, containment! I have a barrel I can stick under it.

Don't forget to remove the thermo(s) from the head, bolt cap(s) back on, flush the motor for at least 20 minutes, put thermos back in with bolted caps and report if Salt Away did its Magic as advertised. Good Luck!!

Happy Boating​

 

[Faztbullet]

You need to replace impeller also

 

[MattFL]

From what I have read, Salt Away isn't the most efficient at clearing major scale. If the motor is that clogged up, I would personally try something a little stronger. I recently tried this with my 21 yr old Honda, the results at the link below. Just be aware that chemicals that are excellent at removing scale can also be hard on the metal. It's like chemo, use enough to kill the problem but not so much that you kill the patient.

Descaling flush, motor that stops peeing

This is to share the results of a little experiment. Backstory; my 99' Honda 50 has lots of hours and gets year round use in salt. It has built up enough crumbs of sediment that the pee tube frequently gets clogged and the stream slows to a dribble or stops. The rest of the motor is flowing...

forums.iboats.com

 

[Sea Rider]

West Marine has a good descaler solution intended for outboards run in saltedwater compared to using other industrial descaler products which are more aggressive with metals..

Happy Boating​

 

[frustratedboater]

Don't forget to remove the thermo(s) from the head, bolt cap(s) back on, flush the motor for at least 20 minutes, put thermos back in with bolted caps and report if Salt Away did its Magic as advertised. Good Luck!!

Happy Boating​

Sorry, been aways for a few days.., I do appreciate the step-by-step. I will have to get that salt-away and do the steps suggested and see the results. I'm assuming I'd see some junk pass through exhaust?

 

[frustratedboater]

From what I have read, Salt Away isn't the most efficient at clearing major scale. If the motor is that clogged up, I would personally try something a little stronger. I recently tried this with my 21 yr old Honda, the results at the link below. Just be aware that chemicals that are excellent at removing scale can also be hard on the metal. It's like chemo, use enough to kill the problem but not so much that you kill the patient.

Descaling flush, motor that stops peeing

This is to share the results of a little experiment. Backstory; my 99' Honda 50 has lots of hours and gets year round use in salt. It has built up enough crumbs of sediment that the pee tube frequently gets clogged and the stream slows to a dribble or stops. The rest of the motor is flowing...

forums.iboats.com

I wonder, as a chef, using lime away product (used as a de-scaler in steamers/serving lines in restaurants..) would work the same? Curious if I'd be too harsh..

 

[frustratedboater]

From what I have read, Salt Away isn't the most efficient at clearing major scale. If the motor is that clogged up, I would personally try something a little stronger. I recently tried this with my 21 yr old Honda, the results at the link below. Just be aware that chemicals that are excellent at removing scale can also be hard on the metal. It's like chemo, use enough to kill the problem but not so much that you kill the patient.

Descaling flush, motor that stops peeing

This is to share the results of a little experiment. Backstory; my 99' Honda 50 has lots of hours and gets year round use in salt. It has built up enough crumbs of sediment that the pee tube frequently gets clogged and the stream slows to a dribble or stops. The rest of the motor is flowing...

forums.iboats.com

MattFL- thank for the thread lead, was an interesting read.

 

[frustratedboater]

1) Ran Salt-Away with the hose connector system one complete flush. Refilled with more and started up and w/ the stats out and the alarm sounded, about 15 min later, so I'm gonna run a lime-away product through for a short while.
2) Can anyone direct me to the jumper plug on this 08' Honda 150 4-stroke? I think I'm looking for a red plug I believe to jump the Lime & blk, just didn't see it in the front and don't want to dissamble any un-necessary stuff. I want to see what code its' throwing if any..
3) Should I, perhaps ohms test any temp sensors?

 

[MattFL]

Do some real homework on the chemicals. From my reading, Rydlyme seemed to me to be the safest to use that was also strong enough to actually work. I did look at the West Marine one above but I believe it had warnings about aluminum. Double check me. Acids will eat the scale, that's the easy part, but they also eat metals, especially sacrificial anodes and aluminum. Acids can be buffered with other chemicals to try to reduce their effects on metals like aluminum while remaining effective at removing scale, that's the hard part. I'm not a chemist so I encourage you to do your own homework, but it's going to take something fairly strong to remove built up scale. There are a lot of videos on youtube by private people that are sometimes informative. Also keep in mind that the raw water part of an inboards cooling system are made from different metals than an outboard, so when you see some chemicals used to flush the raw water side of an inboard that doesn't automatically mean that it's safe for an outboard.

 

[frustratedboater]

Update: So, I read about the manifold sensor and ohms tested it and got nothing. I pull it from the block and noticed something interesting. The sensor was chalky, meaning not getting water.. I ran this motor for 15 minutes until it sounded!

Is there any way to back flush through this sensor hole with water to force junk out? To your point, Rydlyme (Don't have any on hand..) seems to be the appropriate product in my case. I'm thinking pour some directly into this hole first and let it work. This maybe a separate issue, but what ohms readings should the sensor put out at rom temp? Mine has no reading at all.

 

[Sea Rider]

If you enlarge the small lower pic will see the astonishing large amount of salt, crap, filth whatever it's called already built there, now imagine what's going on on the entire OB internal water passages. Descalers are commercial grade ones used to clean machinery, water systems, boilers, etc. Could be used on OB's at your own risk.

The issue is if the OB counts with an internal anode located under the exhaust cover or any other internal water passage which has been excessively cloged such products won't do nothing as won't be able to soften and unclog a already hardened plug, crust, crap alredy built there.

One scenario is cleaning dirty unclogged water passages where the product used recirclulates through, other scenario is removing a highly obstructed water passages through a non recirculating water passage.

On such cases will need to remove the powerhead from the pan, remove the exhaust covers and cylinder head and manually scrape off the entire water passages to factory clean conditions as when out of the box, install new gaskets, torque them to factory specs and voila!! Will have a trouble free OB for years to come...

Happy Boating​

 

[frustratedboater]

Update:
SO after running a series of Salt-Away product through, I also brought home some De-scaler 'LimeAway product' from work and ran that through the flush connector at a 20% mix (pretty strong stuff) and then let it run and rinse with fresh water pretty well. I wanted to knock out some of that crud inside..
I had it running on muffs in the driveway well after the 15-18 minutes when the alarm would usually sound and this time it didn't!! Yipee! Sorry, if you knew all the frustrations i've gone through you'd understand.
I have a waterpump kit going in when it arrives. I'm going to check over all the zincs to see their condition due the the soft metal attack from the LimeAway. I'm also going to take it out and run it under normal load to be sure.

 

[MattFL]

Please let us know how the zincs look when you take them out, I'm curious to know how they held up to the descaler.