Mercruiser 5.7L Thermostat Removal

[mike456]

winterizing my 1992 5.7L Mercruiser that I bought this year. After warming it I ran 5 gal anitfreeze through the muffs and out the exhaust. Just to be sure I pulled one of the engine block drains and straight water came out. I suspected a bad thermostat so I opened the housing and can't get the thermostat out. There is 1" long brass type sleeve inside the housing holding down the thermostat. Any tips on how to remove this sleeve (it's stuck)? Any tips on removing stuck hoses without destroying them (in case I have to remove the entire housing)? thanks

 

[crazy charlie]

Re: Mercruiser 5.7L Thermostat Removal

I use a thin razor knife to get in between the brass ring and the housing.Once you get the crap out of there you can tap a very small needle nose pliers in until you can get a grab on it.Look very closely because there is a spot with a tiny cut out to get the pliers where you need to.Dont worry about bending it,you can either bend it back to shape or get a new one.Once the clamps are removed from the hose ends,you will need to use a long pliers to get a grip on the end of the hose and then move it forward and back until it starts to slide on the fitting.It may benefit you to tap a flat screwdriver in between the hose and fitting to at least get it loosened a little.Try not to let the pliers slide too much on the hose or you will chew it up good.A trick I always do when drawing the 5 gals of AF in through the o/d is to make sure the af is not cold and I mix the 50/50 mixture with hot water.This mixture will assure you of the tstat opening and staying open unless the stat is bad.Don on this forum has mentioned many times that here is a possibility of not getting af in all the places it should be using the 5 gal container method.I have done it this way at least 15 times w/o a problem .Charlie

 

[Haut Medoc]

Re: Mercruiser 5.7L Thermostat Removal

Mike, if it doesn't over heat then I would say that the thermo-stat is OK......BTW...Air doesn't freeze....Forget the anti-freeze, and drain the block, and manifolds.....Remove & drain the hose that goes to the power steering cooler & the fat one @ the engine circulating pump...To loosen stuck hoses, I have a screwdriver that has been rounded off.... Gently pry the hose all around its circumference.....I use a pair of channel locks to apply side-ways pressure while doing this....Be patient & don't use anything sharp....I would use some penetrant (WD 40 or such) on the sleeve & let it soak for awhile....JK

 

[LANCLJ]

Re: Mercruiser 5.7L Thermostat Removal

I can see the point in using some care in removing the brass sleeve, but why worry about damaging it ? It's a $10. part. After it's out, clean up the thermostat housing with some emery paper, and the new sleeve will slip right in<br /><br /> Also, you may want to consider using a plastic sleeve instead of the brass next time. They are much easier to remove at the end of the season.

 

[mike456]

Re: Mercruiser 5.7L Thermostat Removal

Thanks to Crazy Charlie for the good advice. I got the sleeve out with little damange. Mercruiser dealer told me that the 140 degree stat that was in the engine is the wrong one and that a 160 degree stat should be in there. I plan to put everything back togather today get the boat shrink wrapped and as say goodby till Spring. <br />This forum is a GREAT service

 

[rodbolt]

Re: Mercruiser 5.7L Thermostat Removal

your t-stat was most likly good. thats why I say drain the block before installing the AF mix. I prefer to use the AF mix as it helps keep corrosion down, that casting will bleed water for weeks after draining. but even a warm engine will barely be warm enough to open the t-stat on the flush muffs and as soon as the engine is shut down the t-stat will cose and the incoming AF mix will mostly all go out the risers. good for risers bad for blocks. <br /> but everyone is different I just try to do the best I can for my customers.