76 Johnson 115 V4, no water flow (cooling system)

afkrinkledub

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Jul 14, 2011
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17
i was running my motor on muffs, no water flow... then ran in tank, still no flow.... then i checked the water pump, everything looked good so i put it back together..... motor is running, but overheating after a few minutes and now i am at a stand still. what else can be stopping the water flow to the heads/thermostat.. please help!!:confused:
 

emdsapmgr

Supreme Mariner
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Dec 9, 2005
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11,551
Re: 76 Johnson 115 V4, no water flow (cooling system)

That engine does not have the telltale feature. That came out on the 1978 models. You can test for water flow. After you start the engine when cold, hold you hand right behind the two exhaust relief ports at the top of the midsection. About a minute after the engine starts, you should see water droplets form your palm. That indicates the stat has opened. If it does not open, you will get an overheat, even if you have a new impeller. If both the impeller and stat are new, I'd probably pull a head cover off a head. Check for debris accumulation inside the cooling passages. With the head cover off, briefly start the engine. You should almost immediately get water flow out of the head. Quickly shut down the engine. Replace that head cover and check the one on the other side the same way.
 

afkrinkledub

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Re: 76 Johnson 115 V4, no water flow (cooling system)

emd,
i have no water/mist coming from the two exhaust relief ports, but i do have what looks like smoke coming out of there instead. the water flows from the stat to the heads correct? if this is the case, sounds like my stat could be stuck closed, correct? i will check the heads and cooling passages for debris this afternoon and post results.... thanks for the input.
 

Bob_VT

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Re: 76 Johnson 115 V4, no water flow (cooling system)

Thermostats and water deflectors probably need to be changed. I would go the extra and do the whole group. If the delectors are allowing blow by and the thermostat is not working your motor will cook
 

afkrinkledub

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Re: 76 Johnson 115 V4, no water flow (cooling system)

where are these deflectors located? i'll change whatever i need to in order to get this motor running right, thanks for the info!!
 

Bob_VT

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Re: 76 Johnson 115 V4, no water flow (cooling system)

Do a search here on iboats. They are located under the head gaskets in the block itself. Check shopeveinrude.com for a diagram

You will need head gaskets, deflectors and I would strongly recommend a thermostat
 

afkrinkledub

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Re: 76 Johnson 115 V4, no water flow (cooling system)

Bob,
I found where they are/go, thanks again! Buying head gaskets, deflectors and a vernatherm tonight, thanks for the assistance, hopefully I find and fix the problem!
 

apollothesun

Petty Officer 3rd Class
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Nov 3, 2010
Messages
79
Re: 76 Johnson 115 V4, no water flow (cooling system)

Check the exhaust outer cover, i had small chunks of water impellar stuck in the passages when i rebuilt my motor
 

crestlinermusky

Petty Officer 2nd Class
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May 9, 2010
Messages
110
Re: 76 Johnson 115 V4, no water flow (cooling system)

Make sure that when you reinstalled the water pump that the keyway has not dislodged or fallen out as the impeller wont do its job then.
 

my05hammer

Seaman Apprentice
Joined
May 21, 2011
Messages
36
Re: 76 Johnson 115 V4, no water flow (cooling system)

I just had the same issue with my 115. Mine is a 115ETL77 but it does have a tell tail on the #1 cyl (replacement engine I guess). I tore open the thermostat housing and found that someone had put the check in backward. I can see how it might be easy to do because the drawings in the Johnson manual can be a little misleading. Anyway, I re installed the check and before I put the thermostat back in I checked it in a pot of water on the stove. Once I put it all back together I had great water flow.
 

afkrinkledub

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Jul 14, 2011
Messages
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Re: 76 Johnson 115 V4, no water flow (cooling system)

ok, so i took off the head covers, cleaned all the crap out of them... only the left one (looking from behind motor) was really bad, the right one wasn't too bad. it looked like calcium build-up or something, anyways they are clean now. ran motor for a few seconds, still no water.... i removed thermostat housing, i have a vernatherm in this motor but nothing looked out of the ordinary (to me). i'm starting to run out of things to look at.. or where to look at?? any other suggestions?? how high does the water have to be in a run tank to ensure i have water available to water pump? do i go ahead and remove the heads to look at deflectors now, check out the passages...... please, someone help !!
 

afkrinkledub

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Jul 14, 2011
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Re: 76 Johnson 115 V4, no water flow (cooling system)

so after putting more water in the water tank, everything is working now!!! that calcium buildup was the culprit... thanks everyone for all the help with this!!
 

my05hammer

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May 21, 2011
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Re: 76 Johnson 115 V4, no water flow (cooling system)

Good job! Glad to hear it was a fairly easy fix.
 

emdsapmgr

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11,551
Re: 76 Johnson 115 V4, no water flow (cooling system)

Since you indicated that you had calcium buildup inside the powerhead, you may want to dig a little deeper. What's inside the powerhead is probably inside the heads. You may want to pull the head covers off the heads and inspect them for debris also. (you don't have to pull the actual head.) Restrictions inside those covers can/will slow water flow thru the whole powerhead.
 
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