Missing thermostat

[blueyacht]

first time ever having overheating issues. thought to go directly to the thermostat and when i removed the housing....NO THERMOSTAT? So here the questions come in. Firstly is my search relatively over...install new one and things should be done, or is this just the beginning? I am still going to continue on and look at the pump and impellar. Secondly, is a motor able to function w/o a thermostat? Lastly, how does one determine if the pump is bad?
(1976 165 mercruiser inline-6)

 

[Hansolo99]

Re: Missing thermostat

A lot of guys remove them when they are having overheating issues. There was a reason why someone removed it (unless they did not have a job or dime in their pocket to replace it after they found out it was sticking). After replacing it you will have to pinpoint the problem........

 

[paultjohnson]

Re: Missing thermostat

Hmmmm How long have you had the boat ? how long has it been since the impellar has been replaced. I would suspect someone removed the thermostat because it was overheating. For sure put a new thermostat and impellar. Sure a boat can run without a t-stat. Put in a new one. Your boat might just run bettar, warm up faster and stuff. Hopefully the lack of t-stat wasnt hiding a more serious overheat problem. If the impellar is more then 2 -3 yrs old. It most definantly could be part of the prob. Soooooo new T-stat and impellar. $30.00 give or take + labor.. Then report back ! Good luck !!!

 

[blueyacht]

Re: Missing thermostat

I have owned and used this boat for about 3yrs without any cooling issues.

on my way to pick up the thermostat, but while i was taking off the circulating pump, I didnt notice what i was looking for ie. the "rubber" impeller. Instead the shaft seemed to go through the circulating pump housing and on the backside was a metal disc with blades. Is this an alternate version of the impellar, or does this piece im holding need to be dissected to get to the impeller? (that would make it one small impeller, approximately how big should this impeller be?)

 

[BAproject]

Re: Missing thermostat

The Impeller is in your outdrive, and feeds water up to the engine. The circulating pump forces the water through the engine when it gets there. Is your circ pump leaking or is the shaft loose (wiggle it). It sounds like there was an overheat issue or the t-stat would be in there. from what I have read, you should not run without a t-stat...
If you have not replaced the impeller in the O/D since you've had it, then it's time, and if you don't you will never fix the problem

 

[paultjohnson]

Re: Missing thermostat

Easy Cowboy... The metel pump on the engine [like a water pump on a car] IS NOT the impellar. The impellar is inbetween the lower and upper unit in the outdrive You need to split the drive upper and lower unit. The impellar is approx 3 in across and and a half or two tall. better do a little homework

 

[sethjon]

Re: Missing thermostat

first time ever having overheating issues. thought to go directly to the thermostat and when i removed the housing....NO THERMOSTAT? So here the questions come in. Firstly is my search relatively over...install new one and things should be done, or is this just the beginning? I am still going to continue on and look at the pump and impellar. Secondly, is a motor able to function w/o a thermostat? Lastly, how does one determine if the pump is bad?
(1976 165 mercruiser inline-6)

Your search should be over. The motor definitely needs the t stat. If the pump is bad it will leak but it will be too hard to tell. If you have any doubt replace it or pay the price.

 

[Eric 3.7LX Alpha 1]

Re: Missing thermostat

Here are a couple of youtube videos on how to do the job for your viewing pleasure

1st one is separating the upper and lower halves of the drive:
http://www.youtube.com/user/TcElectronicsMarine#p/u/7/kfpasFN_g8w

2nd is replacing the impeller:
http://www.youtube.com/user/TcElectronicsMarine#p/u/6/0QC6_j2_wmA

 

[blueyacht]

Re: Missing thermostat

What a confidence booster, those videos were. I got a quote from my mechanic and he wanted $200 to do the job. Called up Iboats and found the part for less than $50. Ill post back later.

 

[cr2k]

Re: Missing thermostat

A few things running without a thermostat can do.

1 water circulates too fast to absorb heat from the engine.
2 water circulates in a manor not proper for the plumbing of the system.
3 engine never fully heats up and burns moisture out of the oil, or runs lean enough for good performance.

You NEED the thermo. Then look for other problems. My guess is your impeller has been in there for at least 3 years, they get weak. 2 years is max life for impellers.

 

[wire2]

Re: Missing thermostat

first time ever having overheating issues. ......NO THERMOSTAT? .... Firstly is my search relatively over...install new one and things should be done, ....

The logic is wrong here. No thermo means the engine never gets up to proper operating temp. If it overheats without a thermo, you definitely have other issues.

You can easily test the impeller; put boat in the water (not on muffs), idle engine in neutral. Remove water supply hose going to the thermostat housing, let the water flow into a bucket.
2-3 gallons a minute? Or just a dribble?