cold engine

sunbird

Cadet
Joined
May 27, 2002
Messages
25
Sorry for the long post.<br /><br />Went out fishing yesterday, the water temp was 45 degrees. The quickstart feature on the engine would not cut out after letting the boat warm up for 10 minutes. I eventually just put the boat in gear and ran it out to my fishing spot. The temp guage never went past 100 degrees (bottom of guage). Even after running it the quickstart still didn't cut out. Finally when waiting to pull the boat out of the water the temp increased and the quickstart cut out. I just replaced the thermostats a month ago. I have a 1990 Johnson 120hp VRO. Anybody know why the engine wouldn't heat up and why the quickstart would not cut out. It ran fine last week and runs fine at WOT.<br /><br />Thanks in advance.
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: cold engine

Were they OEM T-Stats? I would check them to be sure they are'nt sticking open, even if they are new.
 

sunbird

Cadet
Joined
May 27, 2002
Messages
25
Re: cold engine

they were new OMC thermostats. Is there a way I can test them instead of replacing? They are about $30 each. Could the water just have been too cold? Do you think it could have been something else?
 

Beaux

Petty Officer 1st Class
Joined
Oct 30, 2002
Messages
390
Re: cold engine

Thermostats can be tested easily by placing in warm/hot water and determining whether they open fully and then cooled to check for proper closing again. In your case, I would think if the thermostat is the problem it would be sticking open. If it opens but doesn't close upon cooling, it is "stuck" and needs replacement. Thermostats are closed when cold and open to allow cooling when engine temp gets to specs. Hope that helps! <br /> Beaux
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: cold engine

sunbird did you remove and change old springs along with T/stat changeout?many of the earlier model spring ratings have been upgraded to newer.My 95 70 hp was.Different springs and cap.
 

sunbird

Cadet
Joined
May 27, 2002
Messages
25
Re: cold engine

there were no springs, just a black plastic thermostat that screws into a rubber diaphragm. Am I missing something? If the thermostats are sticking open, can I clean them or do I have to replace again?
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: cold engine

If your particular t/stat set-up had no springs then disregard above.I personally don't feel the ones you have now to be bad if that recently changed out.Would be worth looking under housings again to insure assembly is installed coorrectly.Dealer should have "microfish"(spelling?) drawing of t/stat assemblies.Were diaphragms changed as well?Don't know if your motor has pressure relief valves or not ,but if so ,could be stuck open.
 

Jack Shellac

Lieutenant Commander
Joined
Aug 7, 2002
Messages
1,661
Re: cold engine

I believe this motor has presssure valves in the thermostat housing alongside each thermostat. Were they inadvertantly left out? Should be a plastic plug with a spring under it.
 

sunbird

Cadet
Joined
May 27, 2002
Messages
25
Re: cold engine

I'm not sure about the pressure release valves. I will pull out the thermostats tomorrow and take a look.<br /><br />And yes, I did change the diaphragms when I chaned the thermostats.<br /><br />thanks for all the help.
 

sunbird

Cadet
Joined
May 27, 2002
Messages
25
Re: cold engine

I pulled the thermostats out last night. They were clean and they seemed to open when I put them in hot water (130 - 190 degres). How much should they open? All I was able to see was a little brass piston move about 1/4 of an inch. Does this mean it works? If so, why wouldn't the engine get hot and the quick start function cut out. Any ideas? I am hoping to avoid spending more money at my mechanic. thanks again.
 

sunbird

Cadet
Joined
May 27, 2002
Messages
25
Re: cold engine

I forgot to mention that the pressure relief valves were in place. If they are what I think they are, they look like a black rubber/plastic plug that are acutally in front of thermostats.<br /><br />Just another thought, could the engine not get hot because of a temperature sensor?<br /><br />thanks again.
 

Beaux

Petty Officer 1st Class
Joined
Oct 30, 2002
Messages
390
Re: cold engine

Sunbird, i am by no means an expert, but I am sure these guys can correct me if I am wrong. The cooling system for outboards(cool intake h20 flowing thru motor) controls temp by a thermostat(s) which is not controlled by anything except the temperature of its surroundings. That is why when you pulled and tested the thermostat it opened even when not connected to anything. Until temp gets high enough, h20 should not flow which allows for quicker heating of motor. Therefore, if you had a bad temp sensor it could(?) have possibly cause the quickstart feature to stay engaged but the motor would have still gotten to normal operating temp if the thermostat/relief valves were working properly. I know nothing about pressure relief valves but the concept sure does sound like it could be your problem. If you have them, and If they were stuck open, then h2o (coolant) flow would be constant from startup which would prevent proper warmup. I hope this long winded post makes sense. Good Luck
 
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