jdanielca

Ok guys if you guys follow my threads you will know that my engine was disassembled leading me to be very jittery about problems or potential issues with it.
So one potential problem I was watching for was head gasket leak, i.e leaking coolant into the engine.

So I do not get any constant sweet smell from the tail pipes. But I MIGHT have a puff when i first start up, hard to be sure, I will need someone to monitor with me. I filled the coolant to the full line, when cold about I would say no less than 2 weeks ago, maybe 3. This morning when I checked the level it was AT or a bit above the low line, so I filled it up again to full. Is the system supposed to use up any coolant and if so is this sort of usage normal? I do not have other signs of a head gasket leak, the coolant tank is clear, no murkyness, the oil is also how oil should looks. But this does not exclude a small and slow leak right?

jrmckinley

Let me preface by saying I've read a decent number of your posts and know you are a DIY - I am the exact opposite - I'm not mechanically inclined at all. However, I chased a potential coolant leak for about 2-3 months - Lexus dealer said they saw coolant at the "valley plate" of my engine and told me I had a leak. They used a bore-o-scope to see all the way at the bottom of the engine and took a pic showing me a pool of coolant. I took it to a Toyota mechanic for a 2nd opinion and he said he saw the coolant at valley plate as well (using scope) but wouldn't be comfortable doing the repair. Took it to a high end indy mechanic who said there was no leak and Lexus was trying to rip me off. I was confused and decided to monitor it for a while. Here's a summary of what I found:

- My coolant level was always at the "Low" line. I'd check it after 5 mile trips and 50 mile trips and it never changed.
- My temp gauge has never waivered - it always is pinned right in the middle (once the car has warmed up obviously)
- I had no signs of a leak that I could see on my garage floor, or anywhere in the engine.
- I would frequently fill my coolant to the "full" line, only to find it back to the "low" level after a very short drive (5 miles or less).
- Determined to see the leak happen in action, I filled it to the full line, left the hood open as I started the car, and by the time I could get to the engine (less than 5 seconds), it was back at "low". I was convinced I had a leak and was going to pay Lexus the $1,500 to fix it. Luckily I tried one last thing. I switched the order of starting the car and filling the reservoir.
- I started the car in the morning (had been sitting 12 hours) - immediately opened the coolant cap and poured the coolant in so I could watch what was happening as the car was running. The coolant began pouring out of a black tube (behind the reservoir) as quickly as I was pouring it in.

I came to the conclusion that my car "likes" the coolant level at the "low" mark - as any time it gets above that the car pushes it out. This would explain why I'd fill it up only to find it back at the low level on a 3-5 mile trip. It also likely explains Lexus seeing coolant at the valley plate - at every oil change when my fluids get topped off, the excess coolant would just pour out of the tube. I check it about every 2-3 weeks just to be safe and it remains at the "low" level. The only thing I'm noticing (and I believe you are as well) is I feel like my car is slightly different at idle than it used to be. I posted about this - asking how the car feels in "D" vs. "N" and "R". I read in here a few weeks ago someone commenting that one of the things the ECU monitors is coolant temperature when the car is in "D" and it makes me wonder if something is slightly off and the ECU is trying to compensate. It isn't enough to bother me, but having owned a 400, 430, and now this 460 for almost 3 years, I know what the car normally feels like when in "D" at a stop light. Something feels slightly different and my brain is tying it to a slightly low coolant level...

I hope this helps and am curious for your feedback.

jdanielca

I really appreciate that you take the time to write your detailed observations.

To clarify I am not really DIY lol I live in an apartment here and I just recently have access to a covered parking spot in a multi storey parking building that is open on the sides. So I cannot really work on the car like heated parking back in Ottawa...I tend to focus on very simple things that I can deal with engine filter change, cleaning the air boxes.. attempting to clean the throttle body etc.. simple things i can do with my 10mm socket wrench haha. IF I was in Canada or US I would probably do more work myself like brake and oil changes etc because what they charge there is robbery, but even at the fancy "indy" shop here it is not really indy it is just an arm of a company that also owns skoda and suzuki but this arm deals with multi brands jaguar range rover merc etc.. I am probably the only lexus there BUT there is no better place to go in this city unfortuntely... long story short their hourly rate is only 400 uah which is 16 bucks... why would I bother to change my own brakes when it only cost 16 bucks in labour to do rears for example haha...

Oh and i think i posted on your thread about my feelings with the D N R etc the revs are all different..

Anyways back to topic... I know this overflow tube you speak of, how are you filling the coolant? just pour or funnel? when i used a jerry riged funnel (top of plastic bottle) the thing barely fit inside the mouth of the "hole" so when I start pouring essentially everything will gush out of the tube because the tube is located on the neck of the tank or just below it.. cant really remember right now. So the only way to fill it properlly is to get a funnel with a small enough neck that fits past the neck of the plastic tank.

It is super dark today no way to muck around and check for leaks in the engine bay, but I filled up in the morning, drove for a bit, back parked and before i drove to the car wash just now I checked and the thing is still at full. So I will continue to monitor and see how it is.

How old is your car? I am thinking of changing out the coolant temperature sensor, but especially in your case where the effect is so immediate, for you it means the coolant is expanding or boiling over and exiting the tube, that cannot be good.. in my estimation anyways. What coolant are you using? I am using some cheap coolant for the moment, and I will get it flushed in the next month together with the oil change once i get everything tested out... pressure test etc.

In the US you have access to Aisin brand coolant, it is cheap like real cheap https://www.rockauto.com/en/moreinfo...434552&jsn=338

and the thermostat https://www.rockauto.com/en/moreinfo...434552&jsn=359 cheap and easy enough for peace of mind I think.

And yes I think the car idles different when the coolant tank is full and when it is not, but it hard to compare unless the outside temperature is the same when i feel the roughness and when I do not... So lets see it is at full now and I will monitor daily. See what happens.

What you mentioned about filling up the coolant right after turning on the engine has logic behind it i was just discussing with a friend the other day, he though that it might have been low because when you drive at certain temperatures certain parts of the engine supposedly open up and coolant flows to cool more of these crevices or so he says... so i assume when you turn on the engine some other parts open up and the coolant flows to fill up more spaces compared to engine off... someone correct me if I am wrong..

jrmckinley

I filled my reservoir using a flimsy paper cup - intentionally chose that because I didn't have a funnel but could modify the top of the cup to pour very accurately without spilling. For coolant, I read my manual and then went to my Toyota Service Advisor and bought the Toyota coolant (can't remember the name of it - Long Life Coolant or something like that). I think it was around $25. My car is a very late production 2010 and has 100k miles.

I'm due for an oil change in about 1,000 miles so I will tell my Toyota mechanic what's happening and see if he's concerned. I've gone 4,000 miles since Lexus claimed I had a leak (even though they didn't do a pressure test to confirm an actual leak) and have had 0 symptoms. One of my mechanically inclined buddies said I should ask Toyota to drain my oil and put it into a clear container to make sure no coolant is getting mixed with the oil.