Coolant leak at 96K miles
 

Just had routine oil change and a transmission drain-and-fill today. Unfortunately, mechanic noticed a small coolant leak that has dripped onto the engine and transmission bell housing. It may be a long-standing issue since the time I bought the car at 70K last year because he had to top off coolant a few times during oil changes but we could never figure out where the coolant went. Hopefully it is just a hose and not a head gasket leak. It is a 5-hour labor job just to remove parts to get a better look. Before I spend $500 for a look-see I'm going to inspect it this weekend with my Dad first and use a wireless endoscope I found on Amazon for $30. The car has been running great for the 26K miles that I've had it. No other indications of issues, errors, odors, or anything (other than the occasional musty AC smell). Well, also the car wouldn't start after four days at the airport parking garage and I think that is related to a known TSB afflicting 2013 models, below (post #8):

2013 LS battery discharge issue requires ECU update

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Thanks, Doublebase. He is an honest and trustworthy mechanic, but I couldn't blindly approve that inspection service. My Dad had mentioned a mirror too and we will follow the rest of your suggestions. Crossing my fingers that it's just a hose or overfilled coolant reservoir. However, it is doubtful the reservoir is overflowing since my mechanic said it was slightly low. Odd to me that the reservoir is all the way in the front and yet the coolant trickled down to the transmission bell housing. My mechanic said he wanted to look beneath the intake manifold and that didn't make sense to me for a coolant leak to start there but I suppose that's the area directly above the transmission bell housing. In any case, it will be some quality time with my Dad this weekend. Cheers.

So I topped off the coolant four days ago on 10/10/2018 and today it is even lower than before and below the Low level! No leaks on the ground and no splatter on any engine parts. I don't see any leaks near the radiator or reservoir. Wondering if the cooling system is just low from the previous owner or when they may have replaced the water pump. I need to go back and review Lexus records to see if water pump was ever replaced. The car runs great and I do get some heat. The weather is still in the high 80s and so I'm not sure if I have any heater symptoms. Instead of noticing q lack of heat, I actually feel as if the AC works too well sometimes. I usually have it set at 72 for the Summer but sometimes it blows colder than expected and I dial it warmer to 74 or 76 even (outside temp 100+). If there is a leak, it doesnt appear to be head gasket since no oil contamination in the coolant reservoir ad no smoke out the exhaust nor any burning smells.

I topped the coolant back up and will check it again in a few days. I know there is some dried up coolant underneath near the transmission bell housing but it looks crusty and maybe old (from a long time ago?). I dont know what caused that to begin with. I wanted to clean off that area but my jack is too tall to place at the front center jack area. Anyone have any suggestions on where else to jack the LS up so I can clean off old coolant stains to see if coolant reappears?

I used a $30 wireless endoscope to get some of the underneath photos below. Excuse the bright pink halos as I think that's just from the LED lights. There is clearly quite a bit of dried up coolant but I don't know if tha is all new. I have read some other threads about low coolant and some folks have added coolant only to see it drop low and stay at the low level without getting worse. I just want to know where all the coolant is going and figure out if I have a leak somewhere but it is hard to get under the car to clean it up and confirm new splatter.

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Engine temp has always stayed pegged at the exact middle.

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Your "AC works too well" comment is related to the low coolant level. This is a problem in the winters that happens when sitting still at idle for an extended period of time. As soon as the car starts moving and you start working the engine, the low coolant starts moving and you get heat again.

Hmm, interesting. I do not recall any trouble warming the cabin last winter. When I notice the AC working too well it was still the peak of Summer. The reason it stood out to me during Summer is because the car would sit at work and I would leave for lunch and wonder why the car is trying to cool the interior so quickly...or at least quicker than typical. I know the LS has various sensors to detect passenger body temperature and adjust the climate system accordingly. Since the air was so cold I wondered if the LS thought I was burning up. Again, this is happening in the Summer. The air would be super cold during the lunch hour but then when I return to work the AC seemed to work normally instead of blasting super cold air. I never understood the inconsistency and never made the connection to low coolant. I am just learning now that the hot coolant goes through a heater core or heat exchanger to provide cabin heat (and presumably to help produce the desired air temperature). Where is the heat exchanger? I always thought heat exchanger was otherwise known as the radiator. :dunno:

Do you think I have a leak somewhere, 213374U? @roadfrog regularly tops his coolant off too and I don't think he had any leaks in his system. But where does the coolant disappear to?? I added 8 fluid ounces on 10/10/18 and 12 fluid ounces today, 10/14/18 to FULL.

Heater core in every other Japanese car I've worked on is behind the dash. A trick if your radiator fan quit working was to turn the heat on full blast; it would act as a radiator inside the cabin with the blower motor replacing the radiator fan.

I too have to top mine off every so often but have not found the leak either. Recently had to replace the radiator and bled the system fully at that time, I should bleed it once more just to see how much coolant it actually takes. Will report back if I do that.

Thank you, Doublebase. I emailed him today (on a Sunday) to ask if he'd be willing to put the LS on a lift for me so I can wipe off the coolant stains and see if new stains appear. He called me back on his day off and said he was willing to put the LS on a lift for me but felt it would be a waste of time. He was very nice about it though and I respect his diagnosis. He suspects it is leaking from the valley plate of the V8 and says he's seen it with the Lexus IS and V6s around 150K miles, and V8s around 100K. He is probably right and I plan to keep an eye on it until I can bring the car in for him to do the work in a few weeks. In the meantime, my plan is to remove one of the plastic underbody covers to see if something will drip onto the ground (as I now suspect it will).

Pretty scary to see the valley flooded with coolant on this IS:

https://www.clublexus.com/forums/showpost.php?p=8184588&postcount=10

That looks more like coolant IN then engine of the IS F rather than on the valley of the vee. Yikes!

https://cimg6.ibsrv.net/gimg/www.clu...ab01e5c814.png

On this other IS F, the coolant leak seems contained in the valley, but "outside" the engine:

https://cimg4.ibsrv.net/gimg/www.clu...0e4bd90afd.png


What is the middle section then? I thought the vee is empty space and I can't see any coolant puddles when trying to peek under the intake manifold on the LS. Shouldn't I be able to see this from above the engine of the LS?? And what part or seal is failing that causes this leak? Why is it common on the IS F?

On a side note, why doesn't my TPMS display like yours? Maybe someone was flushing the heater core and some coolant ran down the firewall onto the bell housing.

Thanks, sha4000, that is what I'm hoping, that it is just runoff from some prior service and not an actual leak. I didn't get a chance to remove the underbody cover yet. Once I do that it will confirm whether a leak drips on the floor or not.

As for the TPMS layout, they changed it on the 2013+ model years when the LS went through a mid-cycle facelift.

Yup, leak near the valley plate of the vee. The underbody covering must have been catching the drips and preventing puddles beneath the car. Mechanic says this is common in the IS cars and Lexus V8s at 100K miles and even ES/RX 330 at 150K miles. The factory seal wears down over time and needs to be redone. It is a 5-hour labor job. Initial estimate is $570...which I consider not too bad, although I am disappointed from the Lexus flagship. This issue is not present in the LS 430 because the material or design in the valley of the vee is different.

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Looks like the leak was in the rear as well as the front pipe. Normal for the coolant to be in the central chamber, but not normal to be present around the perimeter. Will be glad to get this finally fixed as it has been a mystery and difficult to diagnose.

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