Overheat after elbow change, possible coolant issue?

Hi guys. Hopefully a simple problem. 2010 6.0L. Just changed both elbows after four years, one had a crack and dumped a lot of coolant. Mechanic tested the boat in the workshop after the change and it ran for a while but then gave a high exhaust temperature code. On water testing today the boat was running cold on the gauge, around the 140 mark where it usually runs dead on 175. However the new elbows felt hotter than usual and after a little while the check engine light came on. When we plugged in the diagnostics it gave an exhaust temperature code again. The odd thing is that the boat doesn't have the exhaust elbow sensors so I am not sure which sensor is picking that up? During this test idle was fine, oil pressure, power etc.

My concerns are:

Was enough coolant added to the system? I had this issue before and seem to remember the boat took around 20 litres (5.2 gallons) of coolant. He didn't mention how much was added to refill but I am concerned that it was too little and possible the system was not purged of air.

Could this be thermostat related? The mechanic opened the thermostat housing after the testing but said there was nothing there, only one thermostat in the heat exchanger. Is that correct for this model?

My feeling is that the system is either blocked, causing the gauge (coolant temperature) to stay low as it is not circulating through the hotter parts of the exhaust and as a result the elbows are getting hot and causing the error code. OR that the amount of coolant is insufficient meaning it is not circulating, not getting to correct temperature and not cooling the elbows.

Does anyone know the coolant capacity for this engine?

I hope that makes sense, I am no mechanic. Appreciate any input.

You can get a lot of info from the owners manual and the parts manual - both from the crusader www site.

the cooling system needs to be purged after any service work....some installations may need a couple hot-cold cycles....

The exhaust manifolds are usually in the 'closed' side of the cooling system where the elbows always get raw water....I'd suggest getting an IR temp gun and making some measurements...

Thanks Mark. I have the manual and it states to fill the coolant until I reads full, doesn't give a capacity. However I found on another thread that it should be 21 litres.

Unfortunately the boat is in a workshop a few hours from me and I am not doing the work myself. At the last point of testing it was giving the above mentioned high exhaust temperature, not specifying which side. Since the elbows don't have the sensors (non CES version) where do you think that sensor would be located? I couldn't find it in the manual.

I am told they are busy trying to purge the system and look for any blockages at the moment. Haven't heard any other updates. Could air trapped in the system account for low coolant temperature and high exhaust temp?

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NautiqueTom said:

.................. Just changed both elbows after four years, one had a crack and dumped a lot of coolant.
Marine exhaust elbows are always Raw Water Cooled. In other words, they should not be dumping any coolant (as in ethylene glycol/h2o mixture).

Mechanic tested the boat in the workshop after the change and it ran for a while but then gave a high exhaust temperature code. On water testing today the boat was running cold on the gauge, around the 140 mark where it usually runs dead on 175.
140 is too cold unless completely Raw Water Cooled and in Ocean water.

However the new elbows felt hotter than usual and after a little while the check engine light came on. When we plugged in the diagnostics it gave an exhaust temperature code again. The odd thing is that the boat doesn't have the exhaust elbow sensors so I am not sure which sensor is picking that up? During this test idle was fine, oil pressure, power etc.

My concerns are:

Was enough coolant added to the system? I had this issue before and seem to remember the boat took around 20 litres (5.2 gallons) of coolant. He didn't mention how much was added to refill but I am concerned that it was too little and possible the system was not purged of air.

Could this be thermostat related?
The thermostat should have a small "air bleed" hole in it's flange!

The mechanic opened the thermostat housing after the testing but said there was nothing there, only one thermostat in the heat exchanger. Is that correct for this model?
Normally the thermostat is housed within the T-stat housing.
Does Crusader do this differently?


My feeling is that the system is either blocked, causing the gauge (coolant temperature) to stay low as it is not circulating through the hotter parts of the exhaust and as a result the elbows are getting hot and causing the error code. OR that the amount of coolant is insufficient meaning it is not circulating, not getting to correct temperature and not cooling the elbows.
OK.... even if the E/G side of the system needs to be purged, it will not affect the "spent seawater" flow to and out of the elbows.
In order for that to be an issue, you would have developed a restriction somewhere within the seawater side of your cooling system.

Does anyone know the coolant capacity for this engine?

I hope that makes sense, I am no mechanic. Appreciate any input.

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NautiqueTom said:

Thanks Mark. I have the manual and it states to fill the coolant until I reads full,
That would be indicated by the lines on the cooling system recovery reservoir (i.e., plastic return/recovery system bottle).
The system must be operated to temp, then allowed to purge any air, and then be allowed to expand and contract before this reading would be accurate.
In other words...... you would check this on an engine that had been run and then allowed to cool down!

doesn't give a capacity. However I found on another thread that it should be 21 litres.

Unfortunately the boat is in a workshop a few hours from me and I am not doing the work myself. At the last point of testing it was giving the above mentioned high exhaust temperature, not specifying which side. Since the elbows don't have the sensors (non CES version) where do you think that sensor would be located? I couldn't find it in the manual.

I am told they are busy trying to purge the system and look for any blockages at the moment. Haven't heard any other updates. Could air trapped in the system account for low coolant temperature and high exhaust temp?
May we assume that you have a Full Closed Cooling system????
(full system includes the exhaust manifolds...... half system would be cylinder block/heads only)

Click to expand...

Hi Ricardo, thanks for your detailed reply.

The engine is completely closed, from the cooling diagram it appears that the raw water only flows through the ends of the elbows. The previous elbow failed from corrosion right before the outflow, behind the welch plug. The diagram in the manual shows the coolant entering at the front of the manifold and exiting at the top exit of the elbow. The raw water enters through the other pipe into the elbow and out of the exhaust. My concern is that the coolant flow is not sufficient through the elbow. There seemed to be a good flow of raw water out of the exhaust.

With regard to the thermostat I read that this model has the thermostat in the heat exchanger and not in the regular location. That was the mechanic's finding and I verified that through a Nautique owner's forum.

I am going to speak to them on Monday morning and see if they have made any more progress.

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NautiqueTom said:

Hi Ricardo, thanks for your detailed reply.

The engine is completely closed, from the cooling diagram it appears that the raw water only flows through the ends of the elbows.

The previous elbow failed from corrosion right before the outflow, behind the welch plug. The diagram in the manual shows the coolant entering at the front of the manifold and exiting at the top exit of the elbow.
Elbows are typically Raw Water cooled only. I'm thinking that Crusader's must be different.
Can you post a few photos of your elbows? The raw water enters through the other pipe into the elbow and out of the exhaust. My concern is that the coolant flow is not sufficient through the elbow. There seemed to be a good flow of raw water out of the exhaust.
OK.... let's get on the same page.
With a closed cooling system, E/G is referred to as "coolant".
Once seawater (river/lake/ocean) enters the system, it can also be refereed to as "coolant".

To help me.... let's use the terms Raw Water and E/G coolant.

With regard to the thermostat I read that this model has the thermostat in the heat exchanger and not in the regular location. That was the mechanic's finding and I verified that through a Nautique owner's forum.
OK..... but the same should apply in that the thermostat should have a small air bleed hole in it.
The air bleed hole may be open, or it may have a small brass restrictor installed in it.



I am going to speak to them on Monday morning and see if they have made any more progress.

Click to expand...

NautiqueTom said:

Thanks Mark. I have the manual and it states to fill the coolant until I reads full, doesn't give a capacity. However I found on another thread that it should be 21 litres.

Unfortunately the boat is in a workshop a few hours from me and I am not doing the work myself. At the last point of testing it was giving the above mentioned high exhaust temperature, not specifying which side. Since the elbows don't have the sensors (non CES version) where do you think that sensor would be located? I couldn't find it in the manual.

I am told they are busy trying to purge the system and look for any blockages at the moment. Haven't heard any other updates. Could air trapped in the system account for low coolant temperature and high exhaust temp?

Click to expand...

23 quarts is in the owners manual....using the search function in acrobat usually covers all entries.

As a rule, air in the system will rise and not cool.....with the ECT up high, air won't cause a low temperature reading. high exhaust temp is almost always due to insufficient raw water flow.....and its always best to measure a parameter than to provide a WAG.

As far as the CEL being on due to a sensor you don't have, its possible the scan tool isn't configured correctly....the newer CANBus ECU's provide a lot of detailed data and it can easily be misinterpreted if the scantool doesn't have the appropriate s/w in it.

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Just a bit of an update. The mechanic checked all the pathways on the raw water and E/G systems and found no blockages. He believes that all of the air has now been purged from the system and there is a good flow of raw water out of the exhaust when running on the trailer.

The problem now seems to be that the engine is still throwing up the SPN 173 'high exhaust temperature' code even after 5 minutes at idle from a cold start. This engine does not have the optional exhaust temperature sensors although it does have the wiring for them on the harness. The only temperature sensor is the one that measures the E/G temperature which reads on the dash. This hasn't moved by the time the exhaust code is lighting up. Any ideas on what could cause a sensor that is absent on the engine model to throw up a specific code on the computer?

Most systems are configured to send an alarm code if/when the sensor is missing or disconnected.

I looked thru the sampling of 'modern' ECU I've collected and can't find a SPN-173....were there any FMI values with the SPN?

The earlier CANBus ECU's had provision for an overheat SWITCH input vs a sensor....but the code for that isn't close to a 173.

I don't remember any more detail about the code. I spent quite a lot of time searching for this code online and only found one other mention of it, a guy with the same engine in a similar boat with the same problem. His engine did however have the exhaust sensors but he found one of them to be faulty. The manufacturer (PCM) told him they were non-essential sensors and he ended up cutting the wires and taping them off. The code went away. I am having trouble finding a detailed wiring diagram for this engine online. Its a 2010 6.0L MPI.

I checked with a buddy - he said SPN-173 only associates with DTC-2428 and provided this procedure:

DTC 2428 EGT Temperature High - ECM detects a ground or low level at ECM pin 41. The EGT switch closes at 248°
(+/- 5° F) applying a ground signal to the ECM. Verify the Cooling System operation. Verify no short to ground in the
wiring, connections at EGT and ECM - repair as required.
Replace EGT.
The Buzzer, if equipped, will sound for one second every

So, if there is no switch, I'd say the next step would be to check to voltage on Pin 41 of the ECU connector....

Thanks for that Mark. Very useful indeed, couldn't find much information about that 173 code anywhere. Mechanic was able to trace the pin you mentioned and has since remedied the fault. No more lcheck engine light. Just got to get a water test done and should be good to go. Really appreciate all of the input above.

Glad to help.....did the mechanic every specify what was done to remedy the issue?

Sorry for the delay. I believe he put a resistor on the wire. It seems to be working.

On another note, boat is running at temperature on the gauge but I feel like the new elbows are too hot. Mechanic measured them at 175 on an IR gun but to the touch I remember them being a fair bit cooler. All hoses etc were checked. Does that sound too hot for the 6.0L with the full closed system?

NautiqueTom said:

.... I believe he put a resistor on the wire.....

Click to expand...

Resistors have two leads so that's maybe half the story.....

temp of the elbow will vary alot depending upon where it is measured....I was taught the best place to check was "on top" - but that was in the day when elbows were 'fully cooled' with the raw water. I think the newer engines (ie, the 6.0) have the bulk of the elbow in the "'closed loop'.....that means they will run about as hot as the exhaust manifold..... The newer elbow design is readily identified by the two hose connections on the outlet side it its 'hump'...