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 !

 

[awreneau]

Thank you all!

Follow up question but in the same vein

The bubbler hole has lots of exhaust coming out. At idle water barely bubbles at the foot. If I cover the hole with my finger it comes out of the foot. I suppose it’s the path of least resistance and the water pressure makes the bubbler an easier path.

I suspect this is normal as the thermostat is not installed. But it seems at idle very little water is bubbling up/out. If I throttle up obviously more water comes out it’s just very little water at idle.

Thoughts?

 

[Crosbyman]

I think you need to determine if the engine runs hot or not ... qualifying the volume of water out of the " bubbler" isn't all that improtant if it does spit out water .& . if the water is not boiling hot (should be luke warm)

most of the water goes out the prop anyway. a typical samll ob willcool the cyl. jackets by openning the thermostat while the rest of the watyer goes down the exhaust path via the prop .

bottom line ... if it runs good if it is "touchable" and an IR scan says it is not HOT then don'T worry about it.

 

[awreneau]

I think you need to determine if the engine runs hot or not ... qualifying the volume of water out of the " bubbler" isn't all that improtant if it does spit out water .& . if the water is not boiling hot (should be luke warm)

most of the water goes out the prop anyway. a typical samll ob willcool the cyl. jackets by openning the thermostat while the rest of the watyer goes down the exhaust path via the prop .

bottom line ... if it runs good if it is "touchable" and an IR scan says it is not HOT then don'T worry about it.

Water out if hole is warm. Not hot.

The engine is hot to the touch. But I do t have a scanner

 

[flyingscott]

The water out of the holes will warm. It takes a wide open run with the correct thermostat to get above warm. Especially in cold water. How do you know the thermostat is not installed?

 

[saltchuckmatt]

140 or so is hot but doesn't sizzle the skin. Your hand up on top (head to block connection) you can carefully touch it and keep it there for a sec or two, with no injury.

 

[tphoyt]

Agreed with above. IR guns are dirt cheap and give you a good pice of mind. I have a $60 Kline and $8 harbor freight IR gun and they both read the same.

 

[awreneau]

The water out of the holes will warm. It takes a wide open run with the correct thermostat to get above warm. Especially in cold water. How do you know the thermostat is not installed?

I opened it up few weeks back. Wasn’t there. I’ve got OEM ready to
Install now.