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Jeff G.
Jeff G., Marine Mechanic
Category: Boat
Satisfied Customers: 4716
Experience:  42 years experience, Certified Master Technician, All Major Outboards, Sterndrives, Hi-Performance
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I am working on a 4 stroke 70 hp Johnson, model J70FTLEC.

Customer Question

I am working on a 4 stroke 70 hp Johnson, model J70FTLEC. The systems check gauge gives a check engine light and warning horn. The code is 15, which as I understand is for the exhaust manifold temp sender. However this engine does not have an exhaust temp
sender. The engine ran perfectly ok with this for about a year. Now it stalls when coming out of gear and will not restart. After a few hours it seems to start and run on muffs. Good spark on all cylinders, good compression, good fuel pressure. Any suggestions
what could be going on? By the way I tried a different systems check gauge and had the same results.
Submitted: 1 year ago.
Category: Boat
Expert:  Jeff G. replied 1 year ago.
Code 15 is for any number of things all related to overheating. This can be anything from a water pump failure, stuck thermostat, air in system, failed sensor, failed pressure relief valve etc. Some of the later motors used an exhaust temp sensor as well.Check your thermostat it should open at 122*, check in hot water and a thermometer.Check the pressure relief valve is in good shape and installed correctly.Are you getting a good flow from the water indicator?Start the engine and briefly remove the flushing plug from the midsection, you should get a lot of water, if not, replace the water pump/ impeller.Use a non contact IR thermometer and verify the block temperature on both sides of the thermostat.Check the temp sensor make sure it isn't shorted to ground.You have a cooling problem, just need to find which component. Post back what you find.Thanks
Customer: replied 1 year ago.
Thanks, I'll check those things out. I have already replaced the impeller, and have good water flow.I'll let you know any further findingsJeff
Driftwood Marine,LLC
Expert:  Jeff G. replied 1 year ago.
You may want to get the 4 stroke Software for the engine along with the harness, not too expensive. The Suzuki deal works on it as well as the engine is a rebadged Suzuki.
Customer: replied 1 year ago.
Yes, I realized it was a suziki, Thank you again for the help.. will follow your help and let you know the results. Tell me more about the software and where to get it.
Expert:  Jeff G. replied 1 year ago.
You can get it from any Evinrude dealer or sites such as e-bay motors. It sells with the software and cable to connect to your laptop.
Customer: replied 1 year ago.
I have checked the items you mentioned. I am getting good flow from the water pump. Have a good telltail stream. However the exhaust manifold is getting extremely hot (over 200+ degrees) in just minutes. With the hose from the thermostat housing and from the pressure relief valve housing I am not getting and water flow from either location. I am getting cold water through the prop exhaust. Engine block heated to 154 degrees and thermostat housing to 134 before I shut it off.
Expert:  Jeff G. replied 1 year ago.
The water flow cones up through the adapter plate under the powerhead there it splits with some water going directly into the block, the other water goes into the exhaust manifold. The water for the thermostat comes through the block , then the thermostat, down through the hose to the pressure valve, and top of the exhaust manifold and then dumps into the exhaust.If you are not getting water through the thermostat housing then you have a restriction at the entrance to the block or in the block. If the exhaust manifold is getting hot you have a restriction in the exhaust manifold. Usually in this case the problem is right at the adapter plats with poor water from the tell tale.In your situation I would recommend pulling the powerhead as you have poor water in two places and the only common joining is the adapter plate.Is this a salt water engine? You could have a build up in both areas or corrosion around the adapter plate.
Customer: replied 1 year ago.
Just as I thought. ThoughtI might try to back flush first, but I doubt if that will do anything. By the way, it is a fresh water engine.
Customer: replied 1 year ago.
let you know what I find.
Expert:  Jeff G. replied 1 year ago.
Is it used in muddy water, sat at a sandbar?
Customer: replied 1 year ago.
Neither
Expert:  Jeff G. replied 1 year ago.
Pull the pressure relief valve out and see what kind of water you get there.
Customer: replied 1 year ago.
none
Expert:  Jeff G. replied 1 year ago.
You need to pull the powerhead.
Customer: replied 1 year ago.
I know. will do that monday
Expert:  Jeff G. replied 1 year ago.
Let me know how it goes.Thanks
Customer: replied 1 year ago.
I have removed the powerhead and adapter plate. No blockage is present. Noted what appears to be a small amount of water in the oil (ie café au lait colored) Rechecked the waterpump and the impeller is good. from what I can visualize on the block I see no blockage.
Customer: replied 1 year ago.
also, forgot to mention, water tube from adapter plate to the water pump is clear
Expert:  Jeff G. replied 1 year ago.
If you are not filling the block something is wrong and a blockage. Remove the thermostat and see if you are getting water, just run for a few seconds, you won't overheat in 20 seconds. The adapter plate didn't have any erosion between the water cavity and exhaust area?
Customer: replied 1 year ago.
I was thinking possibly back pressure from exhaust or maybe cylinder/head. I saw no corrosion between the exhaust and water area. No blockage. No evidence of exhaust leak, I have done a compression test and all were 180 to 190 psi. I have not done a leak down test which I think I will do next. Unfortunately, I can run the engine at this time since it is in pieces. Before tearing down I had no water at the thermostat nor in the exhaust manifold.
Expert:  Jeff G. replied 1 year ago.
Leak down test won't help us with the water problem. When you inspected the pump did you remove the impeller and see if it was slipping on it's hub and that the key was still in place?
Customer: replied 1 year ago.
YES
Customer: replied 1 year ago.
Jeff, I just found a crack in the exhaust manifold. Filling the exhaust side with water, blowing air through water jacket, get large amt air from water jacket side to exhaust side. My guess this is the problem. Do you agree.
Expert:  Jeff G. replied 1 year ago.
Certainly, that would be your problem, the hot exhaust getting the cooling water hot and some letting the water flow out the exhaust.
Did it just crack or corrode.
Customer: replied 1 year ago.
CRACKED
Expert:  Jeff G. replied 1 year ago.
Probably got hot and thermally cracked. Can't find any service bulletins on it.Replace it and you should be fine. Not a common occurrence.
Customer: replied 1 year ago.
have one on order . will let you know the results
Expert:  Jeff G. replied 1 year ago.
Make sure you torque the bolts properly too.
Customer: replied 1 year ago.
Thanks, I always do. Won't have the parts till sometime next week
Expert:  Jeff G. replied 1 year ago.
See you then.
Customer: replied 1 year ago.
Jeff,
Just got my new manifold and installed it. Now cooling properly, but still getting check engine light and the the 15 code. How do I clear it to find if I have corrected the problem
Expert:  Jeff G. replied 1 year ago.
Once the problem is fixed, then start the engine and within 30 to 60 seconds the code should clear.
Customer: replied 1 year ago.
It did not
Customer: replied 1 year ago.
had already tried that, and it didn't clear
Expert:  Jeff G. replied 1 year ago.
Then the problem, at least as far as the EMM goes, isn't fixed. Test the Exhaust Manifold Temperature Sensor. the reading should be about 2.440K ohms +- 5%. Do this with a cool sensor. Check across the connector terminals. If way off replace the sensor.
Customer: replied 1 year ago.
This engine does not have an exhaust manifold temp sensor
Expert:  Jeff G. replied 1 year ago.
Had to go back and go over the earlier stuff. The EM sensor was added late 1998 and for all the 1999 and on engines. It shows up as a code 15. You're sure you aren't getting a 14?There could still be a problem with the cooling which may be what cracked the manifold in the first place.Did you replace the thermostat, check the cyl head temp sensor etc? Are you getting the proper water flow?
Customer: replied 1 year ago.
Yes to all of the above questions.
Expert:  Jeff G. replied 1 year ago.
Let me grab the diagnostic manual for that engine. it will be in the morning when I get back to the shop.
Expert:  Jeff G. replied 1 year ago.
Everything I have points to a cooling problem or the engine getting a cooling problem reading. In your case it could be the pressure relief valve, Water discharge hose blocked, damaged water pump, failed sensor or the wiring shorted to ground.Disconnect the cylinder head temp sensor, start engine and run for 30 seconds. Do you still get the code?What we want is to narrow down where the problem is. If you get another code when doing any of these don't worry about it, just make note.Check the cylinder head temp with a IR thermometer. Check on top of the thermostat housing should be 126* to 134* at idle. Run the engine to 5000 rpm, in gear in the water and the temp can not exceed 134*!
Customer: replied 1 year ago.
Finally had a chance to preform the tests you last suggested. Disconnected the block temp sensor, got a new code, 1 pause 4 pause, this repeated several times then got the good old 15 blinks, repeatedly. When I reconnected the block temp sensor, the new code disappeared. I can only run this engine in a test tank, so can not throttle up, but at idle, temp on top of thermostat was 132 +/- , the block temp was 144. Had very good water flow from both the temp sensor housing and the pressure relief valve. Strong tell tail stream. Both pressure relief valve and block temp sensor are new.However, the warning horn and check engine light continues to come on and the 15 code continues. HELP!!Thanks for your help to this point, and be assured you will get top rating from me.Jeff
Driftwood Marine
Expert:  Jeff G. replied 1 year ago.
Block temp is too high. If you have the old thermostat then gut the thermostat and see how it runs. If you don't have one get a thin stainless steel washer with a 1/4" hole in it of the same diameter as the thermostat and swap them out and see what you get.14 and 15 are virtually the same, both overheat, on your engine the 14 is also saying there is a problem with the circuit which in your case was the sensor disconnected.Try this too. Leave the sensor connected but out of the head and see what you get.
Customer: replied 1 year ago.
Jeff,
I am wondering if I am interpreting the blinking code incorrectly. What I am calling a 15 code is 15 blinks, pause and repeats.
When I had disconnected the block temp sensor, I has a single blink followed by a pause and the 4 blinks. a pause and the sequence repeated several times then when to the 15 blinks without a pause, then a pause and this repeated.The 1-4 disappeared when I reconnected the block temp sensor. \
Is the 15 blinks really a 15 code?
Expert:  Jeff G. replied 1 year ago.
No it isn't. You have it correct with the 14 code, one blink pause 4 blinks pause then repeat 2 more times.You may have a check oil light. Pull the kill switch lanyardTurn the key ONWith the lanyard off pull the kill switch out 3 times in under 5 seconds.You should hear one beepTurn the key off the oil is reset.If this does it do an oil change and filter change.
Customer: replied 1 year ago.
what about the 15 blinks, then pause and then repeats several times. Again it is 15 blinks with no pause. The oil light is not on, the oil and filter are new. The horn comes on, 15 blinks, pause and repeat. After a period of time the horn stops, the blinking stops, but the check engine light remains on.This control box has the lanyard on the key switch itself, and works by allowing the key to shut off when pulled.Jeff
Expert:  Jeff G. replied 1 year ago.
OK got ya, that engine doesn't have the oil reset.To be honest I have never seen that occur. The only code 15 is overheat but your instance the blinking is not the same as a code 15 which is really one, five.You are going to have to have the diagnostic software put on the engine. Even there it may not tell you everything you need to know. If you can get another ECU to swap and see what it does. If it still alarms then a sensor is faulty, if it stops the ECU is faulty.

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