Opinions Please !!

[kenmyfam]

Well here we are at the cottage on vacation. having a great time etc however I need some opinions on the following. My outfit is as my signature at the bottom. 1985 140hp Johnson V4 Looper running premix.

Running full out at 5,800 RPM then backing off to idle I noticed steam coming out of the motor. Tested again since with the hood off and does not do it.
Checked a few things out already.
Compression 125lb on all 4 cylinders and maintains 125lb if left for 5 minutes.
Head temperature both good (forgot my temp gun but the 3 to 4 second hand test on the heads is good)
Plugs all look alike in color and not "steam cleaned'
Tell tale seems to run a little slower at WOT but increases significantly as I back down to idle then runs O.K. at idle. Is the water being diverted to the motor over the tell tale at higher rpm ??
Impeller was replaced this spring.
Boat has actually never run better !!!!
Any thoughts ??
Thanks,
Ken.

 

[rolmops]

Re: Opinions Please !!

As for the tell tale,it is quite possible that the thermostat opens up when you run at WOT.This would decrease pressure in the cooling system and less water will come out of the tell tale.As for the steam,did you check to see whether you have a leak from the tell tale connections or hose? It might squirt water onto the hot engine

 

[ezeke]

Re: Opinions Please !!

Where was the steam; did it come out with the exhaust, out of the engine compartment, out with the exhaust relief or just where?

The properly functioning water control valve diverts water to the thermostat diaphrams at speeds below 2000 RPM and from the thermostat diaphrams to the overboard drain at speeds above 2000 RPM.

The water control valve is a specific feature of the looper cooling system used from 1985 through 1992; It was eliminated in 1993 models on.

 

[kenmyfam]

Re: Opinions Please !!

Where was the steam; did it come out with the exhaust, out of the engine compartment, out with the exhaust relief or just where?

Best guess from what i saw would be the exhaust relief.

 

[kenmyfam]

Re: Opinions Please !!

No leaks from water hoses spraying.

 

[wilde1j]

Re: Opinions Please !!

Possibly adapter gasket is leaking water into the exhaust.

 

[cougar1985]

Re: Opinions Please !!

had a older scow with my 90 rude on that when you backed off too fast the water would roll up over the exhaust hole causing about the same effect.i was worried at first till i saw what was actually happening and it never bothered me another second after that!ive since replaced the boat so problem solved,lol.

 

[kenmyfam]

Re: Opinions Please !!

had a older scow with my 90 rude on that when you backed off too fast the water would roll up over the exhaust hole causing about the same effect.i was worried at first till i saw what was actually happening and it never bothered me another second after that!ive since replaced the boat so problem solved,lol.

That could well be it. I will be checking that theory out first thing in the morning.
Thanks to all for the input so far. Keep it coming please.

 

[Lion hunter]

Re: Opinions Please !!

If the thermostat works like Ezeke says, then it closes when you go to idle, there would no water to cool the exhaust and the residual water would burn off as steam. Just guessing here.

 

[cougar1985]

Re: Opinions Please !!

That could well be it. I will be checking that theory out first thing in the morning.
Thanks to all for the input so far. Keep it coming please.

ive actually had it happen on a couple of boats!i noticed it because i went to the back of the old boat and i heard the exhaust holes go underwater so i knew right away what was up after that.hope thats all it is for you ,weve had a brutal summer so far and we cant be wasting it on anykind of troubles,lol.

heres the new woodie!

 

[tashasdaddy]

Re: Opinions Please !!

no idea of the temperature or humidity there, but i like the back wash idea. we get that a lot here in the winter.

 

[ezeke]

Re: Opinions Please !!

If the thermostat works like Ezeke says, then it closes when you go to idle, there would no water to cool the exhaust and the residual water would burn off as steam. Just guessing here.

The water control valve is a specific feature of the loopers from 1985 through most 1992 models. It was eliminated in the 1993 and later models. It changes the circulation pattern of the water flowing through the cooling system but does not effect the exhaust cooling at all. The valve may require occasional servicing and is sometimes removed in the process of upgrading to the 1993 system.

 

[jonesg]

Re: Opinions Please !!

Only Iboater's take their tools on vacation with them.
Can't wait for somethin to go wrong.!

I actually have my compression guage onboard.

 

[R.Johnson]

Re: Opinions Please !!

There are two thing's about this post. #1, it's a real rarity to find a multiple cylinder enine that will have exactly the same compression on all four cylinder's. There's a saying in mechanic's, " You can make one alike". #2, it would be impossible to have a cylinder hold #125 compression for 5 minute's. The ring gap just is not going to let that happen. With a leak down tester, you will find that pressure will bleed away in second's. My compression tester's will hold #125 pressure all day, until I push the pressure relief valve.

 

[kenmyfam]

Re: Opinions Please !!

There are two thing's about this post. #1, it's a real rarity to find a multiple cylinder enine that will have exactly the same compression on all four cylinder's. There's a saying in mechanic's, " You can make one alike".

Agree entirely with the "exact" compression on all 4 cylinders. I reported that to take any "it's the compression" out of the equation. reality is they were all between 125 and 132 psi.

Thanks to everyone for the responses. I have come to the conclusion that it is the back wash scenario. Boat has run fine all day today and only "steams" when I back off harshly and pretty much fully loaded. Just seems strange that I have never noticed it before !!!
Well, one more full day here before we have to head back to reality !!!
Thanks again everyone,
Ken.

 

[kenmyfam]

Re: Opinions Please !!

Well, back home now. Boat ran like a charm for the entire vacation. Wondering if the "steam" was actually 2 stroke smoke as well !!! Got my nose over the stern and found that it smelled of 2 stroke oil. Now I am premixing maybe it is getting too much oil when i throttle down. I also found out that my son added a 50 to 1 oil mix to an already premixed 5 gallon can that we put in. Maybe running a little rich right now ???

 

[kenmyfam]

Re: Opinions Please !!

Just to bump this up again. Motor has never run better than it has this season. Still get the steam thing, still have excellent head temperatures, still no other issues. I am firmly with the backwash thing when I come off plane in a hurry.