2000 v6 150

[95GTSpeedDemon]

150TXRY

its my father n' law's boat. he has owned it since new.
recently it started turning the high temp buzzer on after about a 300yd wot run. pull the thermostats out and it does not go off again. he changed both t-stats and one buzzer, no dice.
yesterday we took a 55 gal bucket with the side cut out and allowed the engine to idle with the t-stats out, with 2 bottles of CLR, then flushed with clean water and then with salt-away. then ran the piss out of it. put the t-stats back in and the same ol buzzer came on. unplugged each buzzer one at a time, each set the alarm off independently. unplug them both and ran it about the same distance and no buzzer (checking for some other short circuit/malfunction).

i wanted to see if any one else has had this problem. the shop he brings the engine to said its likely scale buildup in the head/block. wants to remove the heads and clean it out, but if its in the block then its a much $$.

next step was going to be to flush it with muratic acid and change the wp afterwards.

is it possible its something other than buildup?

[rodbolt17]

before I started pulling heads I would change the water pump and water pressure control valve grommet.
I would NOT use muratic acid as it eats aluminium.

[ausnoelm]

Yep, agree with that one, use muriatic aid, then you might as well forget the water pump replacement, 'cause your motor will be eaten to bits.

[rodbolt17]

typically if the alarm is in fact due to a thermo switch and the heads actually got over 180*F it will take 10 to 20 minutes to cool down enough to shut off the audible alarm.

typically if its scale the alarm will shut off in a minute or so.
the only way to clean the scale is manually with the heads and water jackets removed.

[TownsendsFJR1300]

Should the above NOT pan out,

It's more time consuming to pull the heads and clean, but certainly a do-able project for the shade tree mechanic. (we just did my neighbors 200 HP V6). The cylinder sleeves/water passages are right there and very accessable.

You'll be very surprised, how much crap builds up in there. As noted above, you WILL BE literally digging hardened crap out. (I was amazed how well it ran with several coolant passages fully closed off with salt build up)

You will need a torque wrench and certain metric wrenches/sockets, etc. The head should have the torque sequence cast into it as well.

He was quoted a price of approx $700 at the shop. We did it for approx $150.00 in gaskets (already did WP, thermostats, etc). Ran great after that!

[95GTSpeedDemon]

the temp alarm literally stops within 10 seconds of the engine idling.

im a ford tech, so i have the tools. we were just trying to take the easy route, but looks as though the heads are coming off anyway.

how big are the passages; will i need small tools to dig away or will a medium screw driver fit?

[TownsendsFJR1300]

The deepest passage might be 4" deep.

A thin, flat head screw driver will work fine.

If you access to to a bead blaster (not sand), do the head and cover in that machine. You'll find just as much crap built up in there too. It'll take you as long to do the head/cover as it does the block... If not, a small brass tooth brush helps getting in the nooks and crannies ...

[rodbolt17]

does Ford have a mechanic in a can?
I didn't think so.
guess what?
Yamaha doesn't either.
however MOST auto techs get baffled by outboards cause the ONLY thing they really have in common is they burn gasoline.

outboards typically use whatever water they are running in to keep cool.
outboards typically have a radically different duty cycle than auto.

go to any automotive tech and ask them about a running issue after 10 minutes at 5000 RPM or above.
most give you a blank look cause they have never seen an auto engine run extended periods above 5000 PM.

so while the basics are the same, there are some critical differences.

the muratic acid trick, that's how we used to removed the AL transfer from a scuffed piston from the old mercs with chrome bores.
we did it because muratic acid EATS AL but not chrome.

however as your entire cooling system is AL I would not advise muratic acid in most outboards.

even certain freshwater areas have scale issues do to various minerals in the water

[99yam40]

do a web search on Rydlyme marine for info on descaling
I have read some good things on it in the past

Here is a thread on it I found
http://www.yamahaoutboardparts.com/f...g-th19434.html

[95GTSpeedDemon]

i know, the easy way out sometimes bites you in the ass and turns out to be the much longer route.

just waiting on the free time to help him out to pull the heads.


yes, outboards are different, i know enough to ask for help since i am not "versed" in this area. i have made enough mistakes along the way to realize what you dont know can and will hurt ya.

[99yam40]

did you read that thread I linked in my last post?
Looked like it did a good job from the pics he posted

[95GTSpeedDemon]

i just looked at it. i will let him know about it and see what he wants to do.

[95GTSpeedDemon]

He has decided to just pull the heads.
boats.net lists 64D-W0001-00-00 POWER HEAD GASKET KIT --- POWER HEAD GASKET KIT, but no part list.

will this kit have everything needed?

[rodbolt17]

you will only need 2 head gaskets, 2 water cover gaskets and possibly 2 thermostat cover gaskets.
no need for a kit.

like genuine ford stuff its rather pricey for what it is.
however over the years I tend not to like or use aftermarket stuff such as head gaskets.