Johnson 115 crossflow has hot spots after WOT runs.

[sutor623]

Hey guys,

I have a 1993 Johnson 115 crossflow motor. This was a salt water motor, but I have replaced the entire cooling system.
New stats, poppets, springs, water pump, cylinder head gaskets and water deflectors. I cleaned up the water jackets around the cylinder heads and made sure the passageways into the head were clear.

Anyways, she will idle all day and set in the 140-150 range. Telltale is pumping strong.

If I take a wide open throttle run and stop, she will be significantly hotter. The longest run that I have taken was about 4 miles and was running from 3/4 to WOT. I went to a dead stop and cut her off and took some temp readings. Below is what I found. I know that the circled area is about the last spot that the cooling water runs through before exiting the block at the bottom of the head, but it still seems too hot to me.

I thought these blocks should be in the 120 degree range once the poppets open? Is that head temp or block core temp? My block core temp was around 170, which Im not sure if that is too hot or not. Thanks guys!!

 

[89retta]

Did you clean the water tube that moves the water from the lower to the upper ?

 

[sutor623]

Are you talking about the area from the exhaust plate up to the powerhead?

Man I pulled this powerhead because it had an exhaust leak. I wish I spent more time inspecting, but from what I could see there was no debris in the water passage.

Do you suppose that I could run a toilet snake up the water tube and give her a good scrubbing?

How much hotter is this motor running than it should?

 

[flyingscott]

Try running salt away through it

 

[interalian]

The circled area isn't the last place the water goes, it's one of the first places. Water is pumped up, goes to the exhaust chest then into the block cavity between the banks. From there, it flows through the bottom wide hole under each lower cylinder, then up/around the cylinders as directed by the deflector rubbers. After making the circuit around the cylinders, it passes through the large hole in the head gasket, makes a trip around the head, then out the top of the head into the head cover, and down to exit the rubber hose to the thermostat.

Have you had the heads off? This looks more like a deflector issue than any salt buildup. This being said, having a hot spot there could be normal since your head temperature is correct. The temperature at the crank centerline seems normal since it gets no cooling aside from the passing fuel/air mix from the carbs.

 

[sutor623]

Scott, I will try some salt away.

Interalien, I have had the heads off twice. I just replaced the water deflectors with new BRP ones and put them exactly where they are in your pictures (your diagram makes it simple and easy to understand, and I actually used it when replacing the deflectors.)

That being said, the passageways are clear and look good. I even replaced the two rubber tubes from the heads to the stat body.

Does anyone know what temp the two temp sensors are supposed to trip at? I have checked my circuitry, and the alarm has not sounded, but I feel like it is DARN close to tripping.

IA, I posted a pic of where the hottest spot is. Its not the very last place that the water goes, but it is the last place just before entering the cylinder head itself. Only reason I know that is thanks to your diagram.

 

[interalian]

It's posible the 190 degree spot is an eddy in the water jacket, or there's salt buildup at that spot blocking waterflow. Otherwise the water coming out of the block to the head would be the same temperature or higher on the head/head water jacket.

 

[sutor623]

Yes I agree. Still very strange though. That spot is where the intake port cover is located. I guess the water really caters more to the exhaust side (understandable).

I know the waterpump is flowing well because the exhaust bubble is 110 degrees after a run. Maybe I am just overthinking all of this.

Do you happen to know at what temp the sensors trip?

 

[interalian]

No idea what the trip temperature is. The sensor is a 'klixon' with a bi-metal disc inside. I've always thought it was a dumb design having the sensor held in by the water cover and allllll those bolts.

 

[Rustywrench]

I believe the V-4 has a solid brown color sensor wire. It is designed to go off at 180* if my memory is correct. The sensor is pushed down into a pocket in the head. Pretty universal setup in the marine industry. I'm not sure you have a problem? Temps are usually taken in water flow areas around the block. Not crankcase areas. Have you checked your horn/alarm system to make sure it is working properly?

 

[Bosunsmate]

Thats the starboard side you have marked there, how a temps on the port side? (hopefully i havent missed you posting those)
And how is it running? Check that bottom right cylinder by visually inspecting and comparing sparkplug electrode and piston heads through spark plug hole, if its running lean itd heat up

 

[interalian]

I believe the V-4 has a solid brown color sensor wire. It is designed to go off at 180* if my memory is correct. The sensor is pushed down into a pocket in the head. Pretty universal setup in the marine industry. I'm not sure you have a problem? Temps are usually taken in water flow areas around the block. Not crankcase areas. Have you checked your horn/alarm system to make sure it is working properly?

Overheat is tan. I agree that crank case temps aren't applicable - you're only concerned with the swept areas of the cylinder areas and the heads.

 

[sutor623]

180 sounds about right for temp trip.

the port side is about the same temperature. The two banks are nearly identical in heat.

Boobie made a good point in my duplicate post. He asked what the temps were If i DONT shut the motor off. If I don't shut it off the temp drops pretty quickly. It raises if I turn the motor off.

i haven't tripped the alarm yet. When I pulled the heads to double check the deflectors the Pistons looked great. I do not believe that I have done any damage to the engine at this point. I just didn't want to make any super long runs until I talked to you guys.

 

[sutor623]

Checked compression on her just because. Still shootin' 120 outta all 4 holes.

 

[boobie]

Sutor, don't you realize if you shut a motor off after running it the temps always rise. Not very accurate to check engine temps. JMO !!!

 

[oldboat1]

https://forums.iboats.com/forum/engi...ors-and-alarms

I always trusted emdsapmgr's advice, and miss his posts -- said in the above post that 212F triggers the overheat alarm (in an '89 90, at least).

 

[sutor623]

Thanks old boat

boobie you are correct. I'll check her during a hard run with the temp gun out, bs after shutdown.

 

[boobie]

Keep us posted ??

 

[sutor623]

Sure will buddy. Thanks for all the input guys.

Oldboat, what happened to EMD???

 

[oldboat1]

EMD passed away about a year ago, sorry to say (https://forums.iboats.com/forum/othe...loss-of-friend )

Miss his advice/information.