1999 c60tlrx stuck thermostat bolt

[YammyMan]

Hello Yall,

I have been lurking and learning great information from you guys for a while. Well I havent seen this particular problem out there, so I registered and now here I am asking my question. I have the motor mentioned above in the title. I purchased this boat a few weeks ago from Charleston SC (saltwater). I said I would never purchase a used saltwater motor, but I lied to myself.
Ok, heres my problem. I love tinkering on 2 stroke outboards and couldnt wait to get into this one. It idled like a concrete vibrator, so I went through the carbs and now shes a singer sewing machine. Well I wanted to go a step further and and do the thermostat, water pump and clean some of the saltwater corrosion out of the jackets. I turned the first bolt on the t stat housing and it broke free no problem. Went over to the second bolt and its locked tight. I stopped before it broke, and now I'm here for some advise.
Here is my brain storm and tell me what you guys think. Being the bolt is still in tact and the t stat is still in place I can t really get any penetrating oil to the threads. There is the thread jacket on top of the block(the housing that holds the t stat bolt). What do you guys think about drilling a small hole into that bolt housing, spraying penetrating oil in over a couple of days and using heat etc. And once I get the bolt to break free, just seal the hole back up? Anyone ever done this before?

[Capt. Barry]

Before you get the drill out...

I would start with penetrating oil dripped on the bolt (next to the block). Let is sit overnight then take a flat punch and gently tap the head of the bolt (not from the top or sides but in parallel to the bolt). If the bolt begins to move, use more penetrating oil and let it sit overnight again.

Good luck.

[YammyMan]

Thanks for your reply. I will give that a shot first. I have read many horror stories on here about rung off bolts. I dont want to end being one of those guys!

[rodbolt17]

penatrating oil is a waste of time and money.
oxy/acetylyne is what you need.
god I love salt water and ethanol.
most penatrating oils are designed to combat iron oxide not aluminimum oxide.
bleach actually works better.

[Capt. Barry]

Unlike steel which will turn orange to white before melting, aluminum will change from solid to liquid quickly without a color indication.

If you do wring off the bolt head the cover will pop off. If there is a stud left, you can again try the pentrating oil, file a flat on two sides of the bolt and use an adjustable wrench to turn the bolt.

If there is no stud left (the bolt is flush with the block) then the next trick is to drill the middle of the bolt with a small bit and use an easy-out to remove the stud.

[rodbolt17]

DO NOT attempt an easy out on a 6mm bolt.
if you do you will post about a broken easy out.
its just to easy to drill and either retap or heli-coil the hole.
the key is to use a good drill bit, I use dewalt bullit points or carbide.
then its keep the bit wet and patience.
thats why I use oxy/acetylyne first.
I have lived and worked on boats here in the salt pond most my life.
I hate the beach and detest the sound of the ocean.
I dont weld well but I have a friend that is good at welding nuts on broken easy outs for me so we can extract them.

[robert graham]

There's a product called Loctite Freeze and Release which uses extreme cold to shrink/loosen stuck bolts. I've not personally used it but might be worth a try...maybe that and the heat alternately would help improve your odds of getting the bolt out..Good Luck!

[YammyMan]

So no one likes the idea of drilling a small hole into the bolt housing to introduce some sort of penetrating oil? Today, I purchased some PB and sprayed it on all the bolts and including the one on the t stat housing. I tapped it will a counter sink and hammer and sprayed a little more. I put a little pressure on it and it did move about .5 mm. I will let it sit over night and try it again. But I really dont want to break that dang thing. One more thing, I am an electronics engineer ( I work on battery back up systems). I have a product called No Ox. Its a grease that we put on battery terminals to keep them from oxidizing. I have been cleaning any bolt I can get out of this thing and coating it with No OX. What do you guys think about that as far as preventing future seizures? Thanks for all of the ideas. Your experience is appreciated!

[robert graham]

I use a wire brush to clean the threads on all bolts and fasteners that I remove, then apply waterproof marine grease...some folks use anti-seize compound...

[Capt. Barry]

Sounds like it's working. You may want to move the bolt back and forth a bit (nice and easy) and spray some more.

Hopefully, once the bolt is out, measure for proper thread count and tap the hole to clean it out.

There are a few different kinds of anti-seize. Find one that works for aluminum.

[YammyMan]

Capt. Barry, I hope its working. Not sure if it moved or if the bolt neck just twisted a small bit. I'm going to take it nice and slow(maybe 4 or 5 days). I will repeat the process tomorrow and keep you guys updated. Thanks for the responses.

[99yam40]

penatrating oil is a waste of time and money.
oxy/acetylyne is what you need.
god I love salt water and ethanol.
most penatrating oils are designed to combat iron oxide not aluminimum oxide.
bleach actually works better.

Rodbolt17 knows his stuff guys, he is a Yamaha master tech and does this for a living and has for many years

I would try the heat and bleach as he said

[Capt. Barry]

YammyMan,

Yep, sometimes you think the bolt moved and it's just the head twisting.

I never said that heat will not help, you just have to be careful as to how much heat to apply. If you have never heated aluminum before, you may end up with a puddle.

As far as bleach is concerned, I have no opinion about it as I've never tried it.

[rodbolt17]

I typically dont rotate the bolt back and forth.
I find this increases the tendancy to cause the aluminimum to gald to the steel.
I aint scared of fire, nor a good drill bit.
careful using sealents and other products in saltwater.
certain greases and never sieze compounds contain metals that CAUSE corrosion when saltwater is added.
you can actually heat it a lot more than you think,your heating a heat sink.
key is keep the flame moving.

[Bilge Rat]

Heat works.

I use left hand drill bits, turn them counterclockwise. When a bit goes thru the backside it binds for a second. This binding will sometimes unscrew the bolt.
It works well on noncorroded bolts and sometimes on corroded ones.

A hand impact driver is another tool that works on tight bolts. You can control the torque and the impact of the hammer.
Do not use any air impacts on bolts in aluminum unless you want to break off bolts fast!

This is a great forum, real mechanics on here. Thanks for good advice on outboards.