Cleaning water jackets

[WillieOne]

I have a 1991 90 HP. At top RPMs it reverts to idle speed and the hot horn comes on. It runs fine at medium RPMs all day. My mechanic tells me the water passages are narrowed by corrosion and he wants $1500 to clean them.

My neighborhood, part-time mechanic tells me that this can be cured by flushing a weak acid solution through the system.

Can anybody tell me if this is a valid solution and how it should be performed?

Thanks.

[jb123]

have you replaced waterpump,thermostats and prv parts ?

[slim]

lets say all your thermostats and water pump is good. you will never get the corrosion out with any mild acid solution. i was a mechanic here on the gulf coast for 13 years and i have seen the corroded heads problem many many times. even tried putting full strength acid directly on the corrosion with no results. to do this correctly, this is the procedure you need to follow. remove head and all gasket material. pull cover off of head and remove that gasket material also. bead blast the head and cover gasket and thermo cover gasket making sure you remove all corrosion even if you have to scrape with a pocket knife. wash parts with dawn detergent and rinse. heat with a torch to evaporate any water soaked into the alum. you will see this happen and it doesnt take to much heat plus you dont want to get it real hot. spray all internal areas with zinc cromate primer. replace with new gaskets and torque. you should be good to go after this.

[WillieOne]

Slim, I appreciate your answer. I guess that's why the mechanic wants $1500.

I sure wish somebody would disagree with you.

[slim]

well to be honest 1500 is way to high for this job. heck i would do it here at my house for 500. to bad you live so far away.

[sandflyer]

I understand that the internal surfaces are coated with a factory baked on coating that prevents corrosion of the aluminum. Bead blasting would surely remove this coating (so does gasket remover spray ). Zinc cromate is the replacement coating? I tried CLR on some smaller components (stat housings) and it removed the crust without removing the coating but I'am chicken/reluctent to use it on surfaces I can't see. The factory coating is yellow I believe.

[Ken]

sandflyer,
I'm with you - I don't want to remove the factory protective coating .
Seems like "Hamfisted" some time back recommended a spray-down with WD-40 and allowing to soak over nite. Then take a high pressure water hose to the mineral deposit buildup and remove as best you can.
Anyway, this is what I am going to try this winter with the heads off my C115 - will post the results.
Good luck [img]smile.gif[/img] ,
Ken K

[slim]

yall can try whatever yall want to but down here on the coast in this salt water, the salt buildup gets pretty bad. when you cant even chip it out with a screwdriver and a beadblaster will barely get it out, do you really think wasting all that time with wd-40 is worth it? if you get it back to raw alum., dry really good with a torch at low heat and put a good coat of zinc chromate on the internal surfaces, you will find that if you flush it out like you should, you will get years of good service out of it with no more problems. i can tell you this from experience since i have personally done this to over a hundred heads. if muriatic acid dont get it out, i doubt wd-40 will.

[richardr]

hi guy

i like what you said where or who would have a beed blaster??
Richard r

[richardr]

Salt Away

ANYBODY use that salt away????
my heads are clarged up i wound if that will help it???
rich

[cyrillefrenchy]

cleaning water jacket

hello
i had good result with "lime away" when i cleaned up my water jackets on v4 yamahas with heads removed.
soak the heads and the inside of the block with lime away, let it set for 1 hour or so, and rinse off with water and scrape with a screw driver or a pocket knife and a little wire brush .lime away will soften the corrosion build up and will come off easier.not a miracle stuff but help a lot and it's gelly so it stay longer on vertical surfaces.
good luck
frenchy