Frozen thermostat bolts...anyone encountered this before?

[mamm7215]

Maybe frozen isn't the right word, more likely corroded in place. I've sprayed the heads with seafoam creep. Is that as good as wd-40? I tried heat but not much. I'm only using a small 1/4" ratchet so it's not like breaker bar torque but these bolts shouldn't need much to come out. Keep heating/spraying? Is the thermostat body plastic or steel? It's painted and hard to tell. I'd hate melt and permanently damage something.
Thanks.

 

[mamm7215]

Re: Frozen thermostat bolts...anyone encountered this before?

Ugh, thought I was getting somewhere, little movement, sprayed more creep in, turned a little more-snap. Bolt head off. So I guess now I need to find out if the lower cowl comes off without removing the power head. Crap.

 

[1946Zephyr]

Re: Frozen thermostat bolts...anyone encountered this before?

Yes, this is common, if the motor has seen a lot of salt water use. Your head bolts are probably rusty too I bet.

What motor do you have there?

 

[mamm7215]

Re: Frozen thermostat bolts...anyone encountered this before?

'81 90hp Johnson v4. J90TLICM. I have the bolts out of the lower cowl but how the heck does that thing come off? Or does it? I can pry it down about an inch. And yeah, the middle bolt snapped. Fwiw, if I snap the other 3 bolt heads off, the housing will just slide off and I can then work on removing the bolt shafts with heat, wd-40 or seafoam creep or something. But first things first, how does that lower cowl come off?

 

[lowkee]

Re: Frozen thermostat bolts...anyone encountered this before?

Once the other bolt heads are snapped, the bolts will still be corroded in place, so the head will not likely "slide off", or move at all. I'd recommend spraying the bolts with PB Blaster (wd40 does nothing for corroded bolts), going to a garage, having them weld a nut onto the head of the snapped bolt and using an impact gun on them. Heating the bolts will actually make things worse, as the bolt will expand even more. What will help is spraying with PB Blaster, then heating the bolts the night before going to the garage, so that the bolt will expand, then contract again (as it cools), making some microscopic, but helpful, gaps. It may be possible to manually unscrew them after the heat treatment, but you may just snap off another head and be in worse shape.

 

[mamm7215]

Re: Frozen thermostat bolts...anyone encountered this before?

I'll definitely try the pb blaster stuff tomorrow. I didn't even know about it, seems to deal with corroded bolts good from reviews. Hopefully the 2 outside bolts will come off, very hard to get a socket or wrench on them ... thanks again, I really appreciate all the help.
fwiw, the leg to motor bolts have some surface rust but I was able to turn them so I'll back them out one at a time and never-sieze them all. That's something I do whenever I turn a bolt or nut.

ps, I researched a bit more and found crc freeze off is rated even higher than pb blaster so I'm getting BOTH tomorrow. Hope this helps. Thanks again, all!

 

[mamm7215]

Small victory, but new problem...

Small victory, but new problem...

Well I got the bolts out but it was ugly. Had to smash the plastic valve body and cut the bolts by hand with a hacksaw blade to get the t-stat housing off it was really rusted on there! 2 of 3 bolts are out with pb blast and channel locks. 3rd is
soaking in more pb blast. Bad news is I noticed a hole in the exhaust housing right at the lip where the gasket would sit with another good gouge right beside it. There's also a good gouge near the left bolt hole. PO mentioned a leak but said he didn't know where it was from. Now I know. Oh well, the motor was cheap and I bought it for the head but I'd hoped to not have to pull it off this motor and swap it for the one on the boat. Guess I will now. I wanted to just fix this 90 up and put it on and keep the other for parts, now it's a total mix and match. Pulling the head should just be a matter of a few bolts, no? The Seloc manual is a little vague on this. Do I need to disconnect the shift linkage for a power head removal?
Thanks.
pic of hole lower left of the center t-stat housing bolt hole...

 

[boobie]

Re: Frozen thermostat bolts...anyone encountered this before?

I have seen the gray Marine Tex do wonders in situations like this but all surfaceses have to be clean and shiney. Then a little filing, drilling and tapping.

 

[mamm7215]

Re: Frozen thermostat bolts...anyone encountered this before?

Thanks, I'll look into it. The marine tex page says it can withstand up to 200 deg F, 300-350F in spikes, so it should be good for the thermostat housing as long as it doesn't overheat.