2013 Coolant conundrum (SOLVED. spoiler: it was the valley plate leak) (3 Viewers)

[elcie200]

Looking for suggestions on next steps, things to pay attention to, etc

2013 LC 104k

• Got the truck in May 2018, no issues/problems observed
• June 2021: replaced the radiator due to the beginnings of the radiator crack at "shop1"
• No issues/problems observed at that time.
• No overheating etc.
• Starting approx May 2023 (2 years later), observed low/empty coolant in the reservoir. Filled, to F, drove, it dropped to L, or slightly below L. Over the course of a week, had added approx 1/2 gallon of coolant. It intermittently drops to L (after filling about half way up) Sometimes it holds for a day or more, sometimes it drops between two trips on the same day. Kinda random.
• Feared the Valley Plate Leak; No visible leak ("shop2" confirms this is not valley plate)
• May 23, 2023 had coolant system tested at "shop2", 15psi; passed test. <-- good small Toyota shop reco by friend who takes his Tundra there
  • Shop suspects could be head gasket and recommends leak down test to confirm/isolate
• May 31, 2023 coolant system re-tested: passed; block test: passed. at "shop3" <-- good known toyota shop; used to take my 4runner there back in the day.
  • Leak down not conducted as block test passed
  • Shop put the truck on an incline, heater running, system "burped" (found air pocket); added coolant to F line

Currently, shop says there are no apparent problems (engine and cooling system checks out a-ok). It was probably the air pocket? Shop advises to monitor coolant level at this time.

On the one hand, I feel like I dodged a bullet (or two): valley plate, head gasket.
On the other, I'm paranoid if I should be more concerned about this apparent "air pocket"

Any advice, things to follow up on, monitor, look in to etc from the great Mud hive mind?

Thanks!

 

[goldwater58]

Cracked coolant overflow tank?

 

[linuxgod]

Air in the cooling system after a radiator replacement is not uncommon. It took a little while for my truck to burp out all the air. I think every time the reservoir gets empty you potentially may suck air into the system during a heating/cooling cycle, and then that air bubble gets pushed around into some high spot in the system, so if you weren't really watching the reservoir previously then this may have been ongoing for a while.

TBH I don't totally understand the air pocket issue, but if you can't see any pink residue anywhere and if you're not seeing any evidence of coolant on your dipstick or sludge on your oil cap then I would keep the reservoir topped up to F and watch it for a few weeks.

 

[bloc]

TBH I don't totally understand the air pocket issue, but if you can't see any pink residue anywhere and if you're not seeing any evidence of coolant on your dipstick or sludge on your oil cap then I would keep the reservoir topped up to F and watch it for a few weeks.

Seconded.

 

[elcie200]

Aha. I think I found something! Since having the block and radiator tested, I’ve been monitoring the coolant. It’s been mostly stable, slowly dropped the last couple of days.

Got a small endoscope camera to poke around more. Today, going in thru the front of the engine, there appears to be a little suspicious pink residue on the driverside.

BUT!!! when you turn the camera toward the passenger side right at the front when you get past the foam THERES A BIG THING OF FRESH RED/PINK CRUST.

 

[elcie200]

To conclude this thread… tl;dr: IT WAS THE VALLEY PLATE LEAK!!!

Went back to shop3, asked them to pull the intake manifold to inspect/advise per the endoscope pictures. They initially just pressure tested again and said “no problems found”.

Sent and reviewed the images with them and we agreed it would be worth it to actually pull the intake manifold. They found the heat exchanger plate leaking in the front and rear; are resealing.

Interestingly, both shop2 and shop3 were initially very confident this was not the valley plate leak; saying the pressure test would have revealed the leak. My current understanding is that the system held 15psi for over 20 mins during three tests; but obviously there was a leak?

Anyways. Hopefully this concludes this episode of “where’d that coolant go?”