150 Vmax over heating

[Dlowry]

I have a 2002 vmax 150. I have seen all the post on the over heating issues. I have a new poppet valve, new impeller and new thermostats. I have also had the water system filled and blown out several times. The mechanic drops the LU and has a rig to hook up to the system. one end fills it up with water the other end is hooked up to compressed air. 2 valves, fill with water then shut and open the air valve and it blows it all out. This has been done several times and still over heating. I think it will have to be taken apart and clean the screens to fix.
My question is has anyone ever put any products like lime away or something to clean the crud out?
I know when I took the thermostats out the inside had alot of crap in there. I can imagine the inside looks the same.
Thanks so much for any help.

[Southfork]

Mine turned up to build up in the water jackets. Had them pulled and cleaned out and issue went away. Tech did also replace the head gasket at the same time.

[Sigma]

Yes there was a good post about it some time back. The guy used a large plastic tub with water and muratic acid mix and then ran it for a bit. Then he flushed the system with just fresh water and was happy with the results.

There is also some stuff used in salt water locations sold at boat shops but dont remember the name.

MURATIC ACID does eat aluminum so do a search here for muratic acid and read........

Before you do all that could it be motor height? Hase it changed recently? What about blocking the top half of the water pickup on the LU?????

[Dlowry]

I said screens but I probably meant jackets. Yes that is what the tech said also. He just wants an arm and a leg to do it. I was just trying to see if they could be cleaned without taking it apart. Thanks for the reply.

[Dlowry]

Muratic acid. That kinda scares me lol. I'll have to do a search. I'm wondering what lime away would do? It really cleans pipes and shower nozels and stuff. I dont know if it would hurt the rubber impeller.
Nothing has changed on the motor height. It has been the same since 2006 when I bought it.
What gets me is the water psi is great. 5 to 10 at idle and 25 to 28 at any speed. I can run a couple of miles before the alarm goes off. Then I shut it down for a few minutes and I'm off again. I have not ran it over 40 miles an hour since this started. All winter I do alot of crappie fishing and only run short distances and it never goes off all day. Running in 41 degree water too.
Not sure but I kinda think I have faulty new thermostats or poppet valve.

[skyduck]

Did you have an old impeller fail? It's posible that there is part of it at the bottom motor and could scorch a cylinder if you continue to run it.

[Dlowry]

No. I have have a new impeller every 3 years or so and they always look great. I have it changed anyway just to be safe.

[Dlowry]

Does anyone know why I would have such high PSI, 25 to 28, and the water jackets be clogged? I can usually run a short distance without the alarm going off, but if I open it up it will go off in 10 seconds. Then the psi goes way down and takes a long time to come back up. Of course this is after I have waited 10 minutes or so to cool off and the alarm stops. I have not opened it up since it went off the first time. I just run a mile or so at a time and stay close to the take off.

[Sigma]

Did you add anything to the transome or LU recently?

[Sigma]

Did you add anything to the transom or LU recently?

Is it infact getting hot or do you have a faulty sensor.

[Dlowry]

No. No additions. I probably should change the sensor first to find out for sure. It does seen to bog down when the alarm was going off but not sure if it is supposed to( bog down ).

[Sigma]

Yes, I think the alarm puts it in fail safe mode. Are you sure it's not the oil alarm and the tank float is stuck????

[Dlowry]

Nope. It's definitely the over heat alarm. I'm going to call the tech tomorrow and see if I can get the sensor and change it out myself. Thanks so much for your help and I'll post if it fixes it.

[Sigma]

I boats .com should have them if you think the water jacket is fould try a tub with vinigar and some water but your going to need severl gallons or plug the bottom of the LU and fill it somehow and let it sit.

[Charlie206]

Has the motor ever been in saltwater, or do you run it in a high salinity freshwater lake? I would suspect corrosion in the water jacket of the heads. It is not that big of a job. Buy a repair manual if you have any ability with wrenches and pull the jacket covers and clean them out.

[Dlowry]

No salt water but I do run in a pretty sandy lake most of the time. I am going to change the sensor first and go from there. Thanks for all the help.

[gmn012]

My buddy was having a problem with his 150 overheating even after a new impeller. It turned out to be the metal housing that the impeller rides in was worn and would not withstand good water pressure.

[Dlowry]

I dont think I would have 25 to 28 psi at wot if it was bad. I have new thermo sensors coming in today. I will put them in and give it a try this weekend. If it doesnt fix it they will be taking it apart and clean the water jackets. Thanks for the info.

[cwilt]

brand new, i have never seen my wp at 25 psi

[Dlowry]

So your saying what? My gauge is wrong. How high has yours been? Mine has ran around 20 for 6 years until this last new impeller and now it runs 25 to 28 as soon as I get on plane. Then it will stay between 20 and 25.