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Cooling Issues

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My 08 Murci LP640 has been running hot since I bought it in January. I'm seeing coolant temps of 100-105ish. My oil temp is normal at 120-130. I had dealership replace the coolant and it made no difference. Accessory drive belt was also replaced as it was original and due for a change also. I also replaced the expansion tank cap even though there didn't seem to be an issue with it. I've ordered a new thermostat but it won't be here for another 2 weeks. I was concerned I possibly had a combustion leak so I performed a chemical check for co2 in the coolant system and it came back clear and also sent in an oil sample for analysis and there is no coolant in the oil, so at least that was good. I noticed some sediment on top of the expansion tank fill level mark. I'm wondering if anyone else has had this issue and how they fixed it? At this point I'm thinking either the thermostat is bad or my cooling system/radiators needs to be thoroughly flushed/cleaned. Blasting the heat in the car brings it back down to normal temp ~90c.

 

 

sediment.jpg

sediment2.jpg

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I can't really see the sediment in those pics. Can you describe that sediment a little more? Do you think someone could have added a stop leak product? If so, depending on what they added, and how much, they could have semi-clogged one or both of the radiators. Don't put it past someone selling a used car to drop some of that in instead of fixing a small leak.

The fact that turning on the heater brings down the temp means that adding more cooling capacity solves the issue, so I am betting the new thermostat won't solve your problem. If the thermostat was opening at the wrong temp, it would keep the engine at that wrong temp despite using the heater for extra cooling.

You might also check that nothing got sucked into the air intakes that could be reducing your airflow across the radiators, like a plastic shopping bag. Probably not the problem, but worth an easy check.

It's good that you don't have a head gasket issue. An engine can also create more heat if it's running lean, the ignition timing is off, or if the valve timing or valve clearances are off.

How many miles on your engine?

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I just meant the brown stuff on top of the metal tab, not sure if that's normal. I've read that G12 + Redline Water Wetter can create some sort of brown build up so that was one thing I was thinking. I'm at 19,500 miles. Fans seem strong and nothing blocking the radiators.

Are you sure the fact that turning on heat bringing it down to 90c eliminates the thermostat as a culprit? I was thinking if it's not fully opening that would be restricting flow to the rear radiators, but turning on the heater is basically like adding another radiator outside the thermostat loop or am I thinking about it wrong?

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24 minutes ago, sprite said:

I just meant the brown stuff on top of the metal tab, not sure if that's normal. I've read that G12 + Redline Water Wetter can create some sort of brown build up so that was one thing I was thinking. I'm at 19,500 miles. Fans seem strong and nothing blocking the radiators.

Are you sure the fact that turning on heat bringing it down to 90c eliminates the thermostat as a culprit? I was thinking if it's not fully opening that would be restricting flow to the rear radiators, but turning on the heater is basically like adding another radiator outside the thermostat loop or am I thinking about it wrong?

Well, if you use the heater core to reduce the temp of coolant flowing through the engine, the thermostat would be exposed to that lower temp coolant and then restrict more of the coolant from circulating through the main radiators to bring the temp back up to whatever temperature the thermostat is set at. The heater core wouldn't be able to keep the engine at 90degC without the help of the main radiators in Atlanta summers.

So if I had to wager money, I don't see replacing the thermostat as solving your problem based on the symptoms you described.

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6 minutes ago, Stimpy said:

Well, if you use the heater core to reduce the temp of coolant flowing through the engine, the thermostat would be exposed to that lower temp coolant and then restrict more of the coolant from circulating through the main radiators to bring the temp back up to whatever temperature the thermostat is set at. The heater core wouldn't be able to keep the engine at 90degC without the help of the main radiators in Atlanta summers.

So if I had to wager money, I don't see replacing the thermostat as solving your problem based on the symptoms you described.

Yeah that does make sense, unless the thermostat just partially opens and never fully opens.  Lamborghini manual says thermostat starts opening at 75C and is fully open at 90-95C. So I guess only way thermostat could be a culprit if it never reaches fully open position for some reason. I was going to wait for new thermostat to come in before doing anything, but maybe I will just take it to dealer now and have them thoroughly flush the whole system and clean the radiators. Super annoying issue.

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If the heater core reduces temperature then that indicates your main radiators or fans are not functioning as designed or lack of airflow.

I would look closely at the fans, expansion tank cap, ducting, blades, stuck thermostat, and finally radiators.  You should also pressure test the system to see if it holds pressure.

In the old days when an engine ran hot we used to turn the heater on to reduce temps. This was in iron blocks as the sediment in the coolant would block the rad tubes. Once the rad was flushed all was well again. Radiator caps were also a problem.

Do the cheap stuff first to rule them out.

If all good I would then look at the radiators for reduced function. Overall they are not very big to begin with considering.

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2 hours ago, Old Guy Garage said:

If the heater core reduces temperature then that indicates your main radiators or fans are not functioning as designed or lack of airflow.

I would look closely at the fans, expansion tank cap, ducting, blades, stuck thermostat, and finally radiators.  You should also pressure test the system to see if it holds pressure.

In the old days when an engine ran hot we used to turn the heater on to reduce temps. This was in iron blocks as the sediment in the coolant would block the rad tubes. Once the rad was flushed all was well again. Radiator caps were also a problem.

Do the cheap stuff first to rule them out.

If all good I would then look at the radiators for reduced function. Overall they are not very big to begin with considering.

He already did the expansion tank cap, and we just discussed the thermostat.

Based on the info provided, either the engine is generating more heat than normal or the cooling system has less capacity than normal.

If the cooling system wasn't keeping pressure, he would be losing coolant and would really overheat as the coolant would boil without the pressure to raise the boiling point, so I don't see a coolant leak as the problem either.

It sounds like the fans are working because the coolant temps would drop at speed with the extra airflow if the fans weren't working properly. But it sounds like it's always running a little hot unless the heater is turned on. Plus a fan issue on either side of the car in Atlanta summer heat would cause major overheating. I will say it's possible to have corrosion in the connector for the fan that robs some of the power going to the fans. I know this, because I had that problem on my right radiator fan and had to replace the corroded connector. My left fan just quit working one day, so I have experienced that problem too. At freeway speeds, the coolant temps were good despite those fan problems.

Sprite, can you confirm that the coolant temps are still high even while driving at freeway speeds with the batwings open?

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2 hours ago, Stimpy said:

He already did the expansion tank cap, and we just discussed the thermostat.

Based on the info provided, either the engine is generating more heat than normal or the cooling system has less capacity than normal.

If the cooling system wasn't keeping pressure, he would be losing coolant and would really overheat as the coolant would boil without the pressure to raise the boiling point, so I don't see a coolant leak as the problem either.

It sounds like the fans are working because the coolant temps would drop at speed with the extra airflow if the fans weren't working properly. But it sounds like it's always running a little hot unless the heater is turned on. Plus a fan issue on either side of the car in Atlanta summer heat would cause major overheating. I will say it's possible to have corrosion in the connector for the fan that robs some of the power going to the fans. I know this, because I had that problem on my right radiator fan and had to replace the corroded connector. My left fan just quit working one day, so I have experienced that problem too. At freeway speeds, the coolant temps were good despite those fan problems.

Sprite, can you confirm that the coolant temps are still high even while driving at freeway speeds with the batwings open?

Temps seem to come down once I hit around 80-90mph, not 100% sure though,  but both fans come on. I will check the plugs for corrosion. If that's the case do you happen to know where to get/order the connector?

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Checked the fans. They both move freely with the same resistance on both sides. No corrosion on plugs and like mentioned previously they both seem to be running strong.

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15 hours ago, sprite said:

Checked the fans. They both move freely with the same resistance on both sides. No corrosion on plugs and like mentioned previously they both seem to be running strong.

That does not mean they are perhaps drawing too many amps, or not enough.  Could be an upstream connector or loose wiring elsewhere besides the connector. Also what about the thermo switches that turn the fans on? And finally, how do you know the temperature gauge or sender is accurate sincew the car is "new" to you and you don't have a baseline.

Going back to the original post though, increased cooling by turning the heater on, IMHO, that given that all other items have been checked and tested out, points towards perhaps scale which will reduce efficiency or solder bloom, if the radiators are not all aluminum and plastic, inside the radiators.

"Solder bloom is a reaction between the brass tanks, headers, the copper core, and the solder and is caused by the degradation of rust and leak inhibitors in antifreeze. "

Too bad you did not check the PH of the old coolant before dumping it. That would have been a good clue.

Lot's of causes, just have to keep eliminating them one by one.

 

I'll sit back now and wait to hear the result, which I hope you post when you get it sorted.

 

 

 

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Car is at dealer now. They said there is no air in the system, thinks it's possibly the thermostat, I got one on order so will swap in a new one when it comes in.

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