Vernatherm removal good or bad idea?

H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Hello all,

I have a 1977 Johnson 115 h.p. outboard model 115EL77S. I've never owned a Johnson outboard and noticed this thing has a thermostat (vernatherm). I was wondering if I could remove the thermostat and leave the check valve assembly in place so water is continuously pumping through. I also have the one wire temp switches on the back of the cylinder heads and would like to pull these out and replace them with temp sensors and hook them up to a temp gauge. Reason for this is that when I bought the outboard the control box was not included, therefore I am missing a warning horn. I feel a temp gauge is more useful for engine monitoring, but the temp sensors that are out there have two wires and not one. Where does the other wire go to? Any and all suggestions are greatly appreciated here. As I said, I have never owned a Johnson outboard, only mercury, and I have fixed or rebuilt every one I have ever owned. Thanks.
 
B

bonzoscott

Senior Chief Petty Officer
Joined
Jul 26, 2008
Messages
745
Re: Vernatherm removal good or bad idea?

Welcome to iboats. It's never a good idea to run with no thermostat. Why would you want to? Overheating issue?
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

Thermostats do nothing for a carbureted outboard like mine. In fact, I have seen outboards seize up out on the water because the thermostat either would not open or didn't open enough. If you have a fuel injected outboard that is another entity. Thermostats ensure the best fuel economy. If I'm not mistaken, non of the earlier outboards were equipped with thermostats, so I don't understand why I have to have one. I am ensuring myself that my outboard won't overheat because there is no thermostat to go bad.
 
Chinewalker

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: Vernatherm removal good or bad idea?

Your motor was designed to have thermostats. To say they "do nothing" is really untrue. In addition to increasing fuel economy, they help reduce wear as internals were designed with certain tolerances which are affected by metal expansion, etc . Related to temp. Leave 'em in.
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

Ok, that's fine. I'll take the chance and just replace the vernatherm with a new one. But seeing as how I am lacking an overheat warning buzzer, can I replace the temp switches with temp sensors so I can at least monitor the engine temp on a temp gauge? These motors were not equipped with the "tell tale" hole to see if water is actually going through the motor. I'd rather not overheat and lose my motor because of something this ridiculous.
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

Forgot to ask how I get better fuel economy with thermostats when I have fixed jet carbs. The same amount of fuel will be siphoned through the jets - it doesn't matter if the engine is cold or hot. Not trying to be a jerk here, just trying to get some schooling on this.
 
stylesabu

stylesabu

Master Chief Petty Officer
Joined
Aug 2, 2009
Messages
849
Re: Vernatherm removal good or bad idea?

why do car have t-stats? warm fuel vaporizes better, so better fuel economy.
 
B

boobie

Supreme Mariner
Joined
Nov 5, 2009
Messages
20,826
Re: Vernatherm removal good or bad idea?

Ridiculous ?? I guess the engineers at OMC were all stupid for putting them in there. Oh' well it's you mtr but it will last longer with thermos in it .Good luck.
 
Bob_VT

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,077
Re: Vernatherm removal good or bad idea?

hotwheels1975 said:
Forgot to ask how I get better fuel economy with thermostats when I have fixed jet carbs. The same amount of fuel will be siphoned through the jets - it doesn't matter if the engine is cold or hot. Not trying to be a jerk here, just trying to get some schooling on this.
Click to expand...

Because the optimum feul economy and power does not come from a too cold or too hot engine...... similar to Little Red Riding Hood the temperature needs to be just right.

In your first post you alluded to the point that previous mercury motor's did not have thermostats and that is not true. Here is a listing for the mercury ones Mercury Thermostats - iboats and a listing for the Johnson ones Johnson Thermostat Kits - iboats There are no outboards listed on either list that do not contain thermostats.

If you are really concerned about overheating you can use a temperature gauge AMEGA GAUGE KIT-WATER TEMP O/B - Teleflex Marine 58862P - iboats or go with my favorite for an outboard which is "T" fitted to a hole you must tap and 0-30 lbs is plenty for an outboard Water Pressure Gauge Kit, 30 PSI, Aluminum - Faria 13108 - iboats

A water pressure gauge will let you know if you have a blockage in the water pick up too. I do not like audible alarms because I do not wear my hearing aid while I boat.

Fresh impeller, good thermostats, clean water passages and water deflectors are the secret.
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

To boobie:

I'm not calling anyone stupid on here - but there are things that I felt I should question. Bob, thank you for your post. But the mercury engines I fixed or rebuilt had no thermostats. This includes a couple of inline 6's (the tower of power), a 1976 70 h.p. 3 cylinder, and a 1977 85 h.p. 4 banger. None of them had thermostats. They had the traditional tell tale hole where you could see the water being pumped out. I can't do that with this one. I'm not complaining either, I finally have a motor that doesn't need work. I agree with the alarms, I feel that would be more of an irritation than anything. I have the temp gauge, I just need to find the right temp senders for the back of the cylinder heads.
 
Bob_VT

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,077
Re: Vernatherm removal good or bad idea?

Tap the head for a tell tale .......... it's been done many times and actually an easy job since it is aluminum
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

Thanks again Bob - did not even dawn on me to do this. What size npt fitting should I use? I know on Mercury outboards they have a 5/16 hose but it is reduced at the end to keep water in the water jacket. I'm assuming even a 1/8" hose will suffice for the task but I'm seriously considering the water pressure gauge instead. I would also assume that with the pressure gauge setup no pressure detects a water pump problem and too much indicates a thermostat problem?
 
V

Vintin

Petty Officer 1st Class
Joined
Oct 12, 2011
Messages
223
Re: Vernatherm removal good or bad idea?

Bob_VT said:
Tap the head for a tell tale .......... it's been done many times and actually an easy job since it is aluminum
Click to expand...
I seem to remember reading that a correctly position tapped head for a tell tale may also improve cooling by removing air that may be trapped in that line of motors.
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

A huge thanks to all of the helpful replies. I was a little lost on this and hopefully I can retrofit some temp sensors to help.
 
B

bonzoscott

Senior Chief Petty Officer
Joined
Jul 26, 2008
Messages
745
Re: Vernatherm removal good or bad idea?

The Mfgs spent millions on testing of the motors, and while both Merc and OMC used no thermostat at times, both had their problems which lead to the thermostat. They'd probably be fine at all times as long as you're WOT.
 
K

kodibass

Master Chief Petty Officer
Joined
Apr 10, 2010
Messages
865
Re: Vernatherm removal good or bad idea?

I have t-stats in all my motors that came with them, but I do have a 1975 40hp Jonny seahorse that has none and came factory that way' from what I have been lead to understand?
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

kodibass:

I went to marineengine.com and looked up the 75 40hp seahorse you have and neither the cylinder and crankcase section nor the exhaust housing section showed a thermostat.
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

kodibass:

I went to marineengine.com and looked up the 75 40hp seahorse you have and neither the cylinder and crankcase section nor the exhaust housing section showed a thermostat.
 
H

hotwheels1975

Cadet
Joined
Aug 9, 2013
Messages
20
Re: Vernatherm removal good or bad idea?

What I don't understand is if the t-stat is stuck in the closed position doesn't the water sit in the water jacket and boil? And would the back pressure ruin anything in the water pump area?
 
You must log in or register to reply here.
Top