2004 V-6 Coolant noises when stopped

Many posts about overheating on the forum, but my question has to do with engine noises after shut down. I am trying to find out if these noises are normal for a Freelander V-6...I do not think it should be making clunking noise or percolating in the expansion tank via the bleed hose.

It does not loose coolant, and it does not "overheat". The gauge never goes above normal. I connect a scan tool and the coolant temperature, while driving, is from 204-238F. I have replace the thermostat several times...2 used and 1 new, and swapped out the radiator. The heater blows hot air, I have bled the system via the heater inlet screw, and after a couple of heat and cool cycles the coolant level stabilizes. The fans have come on only once after a long uphill climb at slow speeds, but the scan tool never showed above 238. The expansion tank and cap are new, aftermarket. I have not pressure tested the system, yet, but if I remove the cap while hot it does vent pressure.

The hose to the top of the radiator gets hot, but the bottom seems to remain cool. The small hose that runs the auxiliary coolant circuit gets hot and seems to be doing as it should. The little bleed hose from the top of the intake manifold and radiator squirts water at a reasonable rate.

Water pump is new, with a metal impeller. Hoses look fine. There is a valve in one of the hoses that I suspect, but I think has to do with the hose to the top of the radiator.

So, back to the original question: is the boiling after engine shutdown, given the above, normal for a Freelander?

Thanks for you help.

Hello
Please pop to the front page of the forum, then community then introduce yourself.
Gives us a warm fuzzy feeling inside.
And you'll get a lot more answers

Cheers
Mike

Hi Mike,

Is done as you suggest, and thanks for taking time to respond.

Regards,

Denis

Cheers
Unfortunately I'm useless with the v6.
Hopefully Nodgev6 or teddywood1 will be able to give you an answer.
Mike

238F is 114C. 204F is 94C

That is a bit on the high side 114C/238F. How do you describe the noises? Can you record a video/audio sound to hear?

Did you do a combustion gas leak test ? a tiny tiny hole in the head gasket might leak gases into the cooling system and make noises?

When you use your code reader, do you see the the temperature of the bottom radiator hose change when the thermostat opens? (the NAS V6 has a temperature sensor in that hose)

There has been comments of gurgle sound when there is air left in the heater core as well.

I agree the temperature seems high, but the temperature gauge holds rock steady at normal. I am getting the readings from engine coolant temperature, which I assume is the on the top of the block under the intake manifolds.

The noises are clunking, like boiling water starting to boil in a deep pan. While you can hear them from inside; they are much louder when the bonnet is open. The coolant also percolates into the expansion tank from the bleed hose, with the engine off. I do not think it is normal, but this is the first Freelander I have owned.

The engine is from a salvage yard, and was not supposed to run, however I put it in my Freelander and got it running, with clouds of white smoke. I checked it for combustion gases in the coolant and there was, so I replaced the head gaskets. I did not recheck for combustion gases, which would seem like the proper thing to do, and I will tonight. I initially figured it was probably a bad thermostat and swapped out the one from the old engine and there was no change. Drove it for a month and never lost a drop of coolant. Still the noise persisted and I bought and installed a new thermostat...no change. Next on the list, due to the original engine failing with oil in the coolant, was the radiator. Frugal Yankee I am, so I got a 2004 Freelander from a auto parts recycler, and at the same time I decided to do the water pump, just incase the impeller was the culprit. Impeller was OK, but changed the water pump anyway.

Now it is getting a little warmer here, so I began monitoring the coolant temp with the scan tool. Again, no loss of coolant and no indication from the temperature gauge that the engine is running hot.

I do not think my scan tool shows the lower temp sensor. I have a Max Mentor and I will take a closer look to see if there is a second coolant sensor....I just thought the one in the lower hose was a dumb sensor connected directly to the fans.

I am not confident the water is circulating properly. In the cold weather the heater probably was removing enough heat to keep the noise minimal on shutdown, but I did not monitor the temp until recently. There are lots of hoses and a couple of t-fittings, one in the supply hose to the radiator, which I think has some sort of spring loaded ball valve, and one in the lower radiator return hose, but that one is just an open fitting.

I thought I would ask some other V-6 Freelander owners if this was normal to avoid trying to fix something that did not need fixing.

Thanks for your post.

oldyankee

oldyankee said:

I agree the temperature seems high, but the temperature gauge holds rock steady at normal. I am getting the readings from engine coolant temperature, which I assume is the on the top of the block under the intake manifolds.

Click to expand...

Unfortunately the needle stays at normal for any temperature range from 95c to 115c (sorry not good in degrees F, Canada is mostly metric) Thus I would monitor the temperature via the scan tool. That needle is almost useless in my opinion.

oldyankee said:

The noises are clunking, like boiling water starting to boil in a deep pan. While you can hear them from inside; they are much louder when the bonnet is open. The coolant also percolates into the expansion tank from the bleed hose, with the engine off. I do not think it is normal, but this is the first Freelander I have owned.

Click to expand...

I would pressure test the expansion tank cap, to confirm it is venting at the proper temperature. Seen many of these caps (on Ford F150 as well) have manufacturing defect.

oldyankee said:

I do not think my scan tool shows the lower temp sensor. I have a Max Mentor and I will take a closer look to see if there is a second coolant sensor....I just thought the one in the lower hose was a dumb sensor connected directly to the fans.

Click to expand...

I use a plain odb2 scanner, and it has both PID for water temperature (one sensor is in between the intake manifolds in the V, the other on the bottom hose.

oldyankee said:

I am not confident the water is circulating properly. In the cold weather the heater probably was removing enough heat to keep the noise minimal on shutdown, but I did not monitor the temp until recently. There are lots of hoses and a couple of t-fittings, one in the supply hose to the radiator, which I think has some sort of spring loaded ball valve, and one in the lower radiator return hose, but that one is just an open fitting.

Click to expand...

Does the upper hose get warm after the thermostat opens (should be around 82 to 89 degrees C) There has been a few report of fairly new thermostat failing open. Mine failed closed (not fun) FYI the Rover 75 uses the same KV6 engine and automatic transmission, the forums there have a lot of engine related posting too.

This is my favorite one, can spend many hours reading there:
Technical Help Forum - The 75 and ZT Owners Club Forums


Well done on the job of engine transplant!!

The bubbling noise is the coolant boiling. It's caused by loss of pressure in the coolant system. The cooling system needs to build up pressure as it gets hot to stop this happening. When the engine is hot the pipes should pressurise. When you squeeze them you will notice the difference when comparing it to when it was cold. The pipes should be more difficult to squeeze when hot. I have witnessed a similar situation when a coolant reservoir cap was removed on a hot v6 which was running. Coolant reservoir level started to rise and bubble as the coolant in the engine started to boil, when the cap was removed and the system lost pressure. Are your pipes still pressurised 5 minutes after switching off the hot engine?

Hi. The sound is localised boiling as Hippo said. Under normal running, there is no way the engine should run at 238°F (114.4°C). This is just below the hot threshold on the gauge.
This boiling is I suspect is caused by a temperature rise after shut down. With the running temperature you are getting, you cooling fans should be running at full speed. From memory the fans should be at full speed from 234°F (112°C). Unless you're rad is clogged or air locked, there is no way the engine should run that hot with the fans running. With the fans off, the symptoms you are getting are what I'd expect.
You need to check the cooling fans or its controller.
The fans should start to run slow speed from 222.3°F (106°C). This would increase to full speed at 234°F (112°C)
The can controller is told what speed to run the fans via a control signal from the engine ECU.

Spent yesterday trying to sort out the problem, and thanks for the guidance.

Yes, as mentioned, the noise is coolant boiling. I made a basic assumption that the new coolant recovery tank with a new cap would have pressurized the system to the required 16lbs...it did not. I do not know what pressure it was providing but the hoses were more ridged when hot, but not as hard as when at 16lbs. Long story, but I did manage to pressure check the cooing system to prove that there were no leaks with a loaner tool from an auto parts chain. It took me two 30 mile trips to get a tool that was not broken or missing parts, and in the end there were no included adapters that fit the threads on the tank or cap. I used a universal rubber adapter and was able to pressurize the system to 10lbs and it held without drifting down...I could not get anywhere near 16lbs as the adapter would blow out of the coolant tank. I bought a Stant cap and drove the 15 miles home while monitoring the temp and it did not go above 226F and when I stopped the engine the hoses were ridged and the coolant was not boiling...idle temp just after the drive, lots of hills, was 217F.

Thanks for the suggestions and help. Next task is to get the AC working and see what that does to the running temperatures.

At those running temps your cooling fans should be running, if not that's the place to look.

I decided to run it as it was and things were seeming OK until one of the heater core coolant hoses sprung a leak. I repaired the leak, etc and decided to drive it myself with my Mac Mentor scan tool hooked up. I monitored the temperature on my 30 mile commute and can confirm the running temperature is usually about 216 F. The range usually was between 208-226 and depended directly on engine load...up hill higher and the opposite on down hill runs. I could force the temperature down by dropping to a lower gear and high revs. On the rare occasion...no explanation why, the temp would drop to 196 F, hold there for 10-30 seconds, and then begin to climb. I tried restricting the secondary cooling water circuits and all sorts of combinations to get the temp down toward the 196, but nothing made much difference. Finally, I bought another new thermostat and installed that with the results no change. I cut open the tested thermostat and put it into a pan of water on the stove and it starts to open at 180F. All during these test the bottom radiator hose was usually cool, or cold. On my trip home in the evening I have several major hills to climb just before I reach home, and even then the bottom hose is barely warm, however the fans will come on and do vary speed. The engine does not overheat or loose coolant. The original clunking sounds I started this thread with were from, as others thought, coolant boiling, and I replaced the cap. The system pressurizes when it warms up.

I have spent a lot of time trying to understand the cooling system and think I have a reasonable understanding. I also noticed that there is a 5 degree difference if I check the scan tool coolant temperature and the outside air temperature shown on the Freelanders display, where the coolant is 5 degrees warmer, or at least that is what the scan tool reads.

I am wondering if the engine coolant temperature sensor is not sending the correct value to the engine control module. I have already swapped the sensor with one from a used engine, but the readings are the same.

I am thinking of buying a new sensor.

Anyone have any ideas why the lower radiator hose is usually cold, or is this normal. My outside temperatures here in western Massachusetts are in the 50's at night, and if anything it runs hotter when it is colder.

Thanks for the suggestions.

Denis

Sounds like it's ok to me. After extensive testing on the V6 cooling system, I found the bottom hose temperature was just a few degrees above ambient.
Over cooling can be forced by using low gears off load.
It doesn't sound like you have a problem with your Freelanders cooling system.

Thanks Nodge68. I bought the Freelander with a blown engine, so I have no experience as to what normal might be on a Freelander.

Still.....

I am wondering about the thermostat design. As I understand the system, the thermostat is fed normally by the circulating coolant through all the auxiliary heat exchangers- transmission cooler, heater, etc, with the thermostat outlet feeding the water pump through the connecting plastic tube. The water outlet from the block supplies part of the secondary circuit and feeds the top of the radiator. The thermostat opens to allow cool water from the bottom of the radiator to mix inside the thermostat and then to the water pump.

The part that confuses me is the outlet in the bottom of thermostat that inserts into the block. The block water outlet, the plastic curved pipe that connects to the top of the radiator, shares the same porting in the block. The thermostat has a spring loaded valve on this bottom thermostat outlet that stops the water from the block from entering the thermostat directly....additionally, if the thermostat opens the spring tension on this valve increases. I cannot understand what it does when it opens from pressure...seems to me it would just create back pressure. That brings me to the theory that the high revs on the engine actually make the cooling circuit behave as it should, or in other words the resistance of flow through the radiator cannot be overcome until the engine is around 2000 rpm. My "normal" cooling seems to use the secondary cooling system, and it appears that the heat loss from all the hoses and pipes in the secondary circuit are enough to keep the temp below 230 F. I used another generic scan tool and can read the thermostat sensor...one in the bottom radiator hose, and true to what you pointed out, the temperature of the return water is only a few degrees above ambient temperature.

Seems very strange to me. I keep thinking this system is not working correctly, but as you point out it is normal for Freelander. Instinct tells me the engine temperature should be near to the thermostat temperature rating, which I take to be 180F, 82C. OK, I understand that the thermostat is on the supply side to the water pump, and the ECT sensor is closer to the water outlet, which could account for a few degrees difference, or maybe the ECT sensor is just in an area with poor circulation. From my experience 196F /92C would be typical, so considering the position of the thermostat and the sensor it could explain why a 82C( or maybe it an 84C) thermostat is used. But 216F/102C seems way too high.

I think I will figure out a way to monitor the mechanical movement of the thermostat. I am curious to find out how much it is open when the scan tool reads 216F.

Thanks for you help and advice.