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Coolant leak Challenge?!?!


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I am looking for some help with regards to a coolant leak. I got a red blinking temperature gauge warning. The 996 overheated. The coolant leak is on the top of the engine near where the transmission and the block bolt together. The leak appears to dominate towards the passenger side of the 996. When I start the 996, coolant streams out from the area as I mentioned. Reference graphic for a better picture.

Has anyone experienced this same leak or is familiar with what would cause this leak? Durametric does not give any faults or warnings.

Any Ideas?

Thanks,

Ken

post-25004-0-21879500-1375642183_thumb.j

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I am looking for some help with regards to a coolant leak. I got a red blinking temperature gauge warning. The 996 overheated. The coolant leak is on the top of the engine near where the transmission and the block bolt together. The leak appears to dominate towards the passenger side of the 996. When I start the 996, coolant streams out from the area as I mentioned. Reference graphic for a better picture.

Has anyone experienced this same leak or is familiar with what would cause this leak? Durametric does not give any faults or warnings.

Any Ideas?

Thanks,

Ken

Your red circle is at the base of the oil cooler, which is an oil to water system connected to your cooling loop. While extremely effective, these coolers do develop leaks, often from the O-rings at the base where they attach to the engine case. Sometimes the cooler itself goes bad. In any case, they are simple to remove (four bolts) and are not that expensive (around $200 or so) if you need a new one. If you are going to remove it, you need to drain the cooling system first, undo the four bolts and lift the unit very slightly while sliding a plastic bag under it (they retain a fair amount of coolant in them, and when removed from the engine and tilted, the coolant runs out all over the place, often into the now exposed oil passages for the cooler, and you end up having to flush your oil system out as well. The plastic bag is there just to catch this coolant.) before trying to lift it out of the engine bay. Always replace the four O-rings (two different sizes) when removing the cooler, they are single use seals and cannot be reused.

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That is reassuring. I appreciate the quick response. The price isn't that bad and being a DIY, enthusiast mechanic I'll save the $$$ in labor. The 996 has about 120K miles so it is probably due for a new oil cooler - the leak proves it. I am in the process of removing the top half of the engine (removed the airbox so far) I'm guessing this is the easiest approach to getting access to the oil cooler?

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That is reassuring. I appreciate the quick response. The price isn't that bad and being a DIY, enthusiast mechanic I'll save the $$$ in labor. The 996 has about 120K miles so it is probably due for a new oil cooler - the leak proves it. I am in the process of removing the top half of the engine (removed the airbox so far) I'm guessing this is the easiest approach to getting access to the oil cooler?

There is a bit stuff in the way (if you have access to the Bentley 996 manual, there are several pages of detailed instructions with pictures starting on page 17-6). After draining the coolant, you need to move the power steering reservoir and pump (siphon out the fluid first), disconnect the battery and move the B+ junction box, and then unbolt the AC compressor (no need to vent the gas) and move it aside, and then remove the right side intake manifold. You should now be able to look down at the cooler and see the four small bolts holding the cooler in place.

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Thanks JPF. I don't have the manual but I'll see if I can find an online version. Otherwise I'll move out smartly and start the right side procedures. Thanks again for your help! May be time for me to write up a DIY tutorial. I cant do much else right now except removing the stuff.

Ken

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Thanks JPF. I don't have the manual but I'll see if I can find an online version. Otherwise I'll move out smartly and start the right side procedures. Thanks again for your help! May be time for me to write up a DIY tutorial. I cant do much else right now except removing the stuff.

Ken

Not sure the Bentley is online anywhere, but it is a worthwhile purchase for the DIY'er. You will also need a low range torque wrench to reassemble everything, the oil cooler bolts are a mere 7 ft. lb. (use some mid strength thread locker on them). An inch pound wrench would be ideal.

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By chance are there any other common fixes that might be worthy to tackle while replacing the oil cooler? I would hate to have this open and could have done something else in the same area.

Look over all the hoses exposed during this, vacuum lines in particular that run under the intake. If any look questionable, now would be the time to change them out. As the coolant is out of the car, and if your water pump is old (more than 40-50K on it), this would also be an excellent opportunity for a new OEM water pump and a 160F thermostat to help the car run cooler. I'd also take a good look at the cables on the B+ junction box for signs of corrosion; if they look bad, now would be the time.

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Thanks. I just replaced the water pump and thermostat not too long ago. I just about have the upper intake out. Bolts are out, but now comes a bit of finesse to get it out. By the way, I looked at the oil cooler. Upon inspection, I found a pool of coolant sitting on top of it.

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Thanks. I just replaced the water pump and thermostat not too long ago. I just about have the upper intake out. Bolts are out, but now comes a bit of finesse to get it out. By the way, I looked at the oil cooler. Upon inspection, I found a pool of coolant sitting on top of it.

Take a look at the coolant bleed hose that runs off the top of the oil cooler, make sure it has not failed. You might just get away cheap here...........

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Well, I think I found the culprit. looks like a trip to the auto store is all I need. though I'm still curious what might cause the 'blowout' look of the hose. perhaps being old is sufficient enough of an answer?

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Well, I think I found the culprit. looks like a trip to the auto store is all I need. though I'm still curious what might cause the 'blowout' look of the hose. perhaps being old is sufficient enough of an answer?

They get old and tired. Make sure you get enough hose to replace it (it goes all the way to the coolant tank) and is a very important component in keeping your cooling system air free. Also get screw type clamps for both ends to replace the factory spring clamps. You will also need to bleed your cooling system after recharging it with a 50/50mix of the OEM coolant (only) and distilled water if you do not have a vacuum filling setup.

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Thanks! I know about old and tired from personal experience. I was at the Porsche dealership yesterday and picked up their coolant. I don't have the vacuum filling system. I'll see if there is DIY on the net. I've never done it.

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Thanks! I know about old and tired from personal experience. I was at the Porsche dealership yesterday and picked up their coolant. I don't have the vacuum filling system. I'll see if there is DIY on the net. I've never done it.

You have to be careful to get all the air out of the system, air pockets are really bad for these alloy engine cases as they thermally stress components like cylinder heads and can cause them to crack. You might want to check your area PCA chapter to see if someone can help you out with the vacuum system, with one of these units refilling the system with no chance of air pockets is a 5 min. job.

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Follow-up. I replaced the coolant host going into the oil cooler. Changed the oil I went to start the car to begin flushing the system.

I had a rough idle afterwards. Is this an indication of air in the cooling system?

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Follow-up. I replaced the coolant host going into the oil cooler. Changed the oil I went to start the car to begin flushing the system.I had a rough idle afterwards. Is this an indication of air in the cooling system?

No, air in the cooling system will result in overheating, coolant dumps when steam pockets form, etc. The rough idle is coming from something else.

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Update: I took out the spark plugs and did a compression test on each of the cylinders. Each cylinder had 120 @ 5500 feet above sea level. All were well within 2% of each other. I checked the coils, all were good an I replaced plugs with NGK - R. I put it all back together and she starred up fine with an initial rough idle bit quickly settled into a nice running engine. The 996 is responsive and performs a bit better too.

My cooling problem is no longer a problem. I had a flashing temp indicator, but that was due to low coolant level. I cycled new coolant into the system and all seems well. My temp indicator is running about 190-195 but holding steady.

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Follow-up. I replaced the coolant host going into the oil cooler. Changed the oil I went to start the car to begin flushing the system.

I had a rough idle afterwards. Is this an indication of air in the cooling system?

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Follow-up. I replaced the coolant host going into the oil cooler. Changed the oil I went to start the car to begin flushing the system.I had a rough idle afterwards. Is this an indication of air in the cooling system?

No, a rough idle would not be caused by air in the cooling system.

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