Tell tale or bubbler what’s normal w/o a thermostat

[awreneau]

I have a 1974 15 hp Johnson 15r74g that does not have a thermostat installed. Bought it without one.

I put new water pump and rubber grommet at inlet where it meets the power head.

Is this a normal amount of water w/o a thermostat installed? If it sits and runs for a while the water will warm up. Never too hot but warm.

Not sure what normal is. Thx for help.

 

[saltchuckmatt]

Were you going to send a video or something?

 

[awreneau]

Were you going to send a video or something?

Geez… Ive tried twice to attach the video. 3rd times the charm?

In case not here is the YouTube link

 

[tphoyt]

Looks okay.
Are you going to get yourself a thermostat?
They do keep to motor run as it was designed to.

 

[saltchuckmatt]

Yes....normal.

 

[Texasmark]

Water needs to be above the impeller, amount depends on the engine being tested. Yours looks OK. You are dumping exhaust into the water so expect it to warm up. Engine thermostats of which I am familiar are in the range of 125-145*F. An engine without a tstat will just run a few degrees above the adjacent water ambient. Agree that if designed for a tstat, put one in. Consult your engine specs for required temp. Some V engines are said to have problems with the upper cylinders getting too hot due to low water level with no stats.

 

[chrisgt]

Without a thermostat you'll have a hard time getting it to idle right in cold water, if you do a lot of low speed trolling you'll foul up spark plugs and carbon up your engine without one.

If you always run above like 3000rpms or whenever the poppet valve opens you won't notice a difference. I see no reason not to install a thermostat with the spring, cup washer, all the stuff that belongs in there.

Do you know WHY the thermostat was removed? If you have a blown headgasket getting exhaust into the cooling jackets you'll have cooling issues until the thermostat opens so people just remove them.

 

[cyclops222]

Post # 7 gives you all the reasons to install ALL the thermostat parts. In the correct sequence / order in the engine.

 

[awreneau]

Looks okay.
Are you going to get yourself a thermostat?
They do keep to motor run as it was designed to.

Yes I’ve got it on my bench. I just wanted to be sure things were in working order before I took that plate off. It’s not easy getting that lower bolt off/on.

Thx!

 

[awreneau]

Without a thermostat you'll have a hard time getting it to idle right in cold water, if you do a lot of low speed trolling you'll foul up spark plugs and carbon up your engine without one.

If you always run above like 3000rpms or whenever the poppet valve opens you won't notice a difference. I see no reason not to install a thermostat with the spring, cup washer, all the stuff that belongs in there.

Do you know WHY the thermostat was removed? If you have a blown headgasket getting exhaust into the cooling jackets you'll have cooling issues until the thermostat opens so people just remove them.

No idea why it was removed. I’ll add it and run it a bit. See what shakes out.
Thx!

 

[awreneau]

Looks okay.
Are you going to get yourself a thermostat?
They do keep to motor run as it was designed to.

Yes. Installing this weekend. Thx!

 

[awreneau]

Without a thermostat you'll have a hard time getting it to idle right in cold water, if you do a lot of low speed trolling you'll foul up spark plugs and carbon up your engine without one.

If you always run above like 3000rpms or whenever the poppet valve opens you won't notice a difference. I see no reason not to install a thermostat with the spring, cup washer, all the stuff that belongs in there.

Do you know WHY the thermostat was removed? If you have a blown headgasket getting exhaust into the cooling jackets you'll have cooling issues until the thermostat opens so people just remove them.

Good to know! Doubt we use it in chilly temps too often but installing it just the same.
Thx!

 

[racerone]

Years ago I had a fellow come in complaining that his 15 Johnson would not idle properly.----Had the fuel pump in pieces in a plastic tub.-----I looked at the pump and re-assembled it as there was nothing wrong.-----Found that his thermostat was stuck open and in 4 degree C (39 F ) his motor simply was running way too cold !