Third

Guys, New one on me...

No recent work or problems before this point.
03 lx470 187k miles all services performed since 10k when purchased.
Driving down the road about 70 today. Heard a noise and thought just something in the road. Couple miles later notice the VSC track, VSC off and CE light are all on. Scan the dash to see what is going on. Temp was maxed out HOT. Pulled over let car cool and then drove to the house only 2 miles from this point.
Things I did, check coolant and very low, checked oil, filled overflow, nothing leaking under the car. Let cool drove to Parts store to scan.,,, Dash lights went off on the way and decided to scan anyway, no codes stored and clean scan. On the way to the parts store the truck temp shot up again, this time I noticed a rushing water sound when it reached hot, after the sound the temp dropped back to normal. I can idle with no problems, and no codes but driving the truck over heats, rushing water, cools back down, then starts this process all over. Can't seem to find anything leaking, no spray under hood. Scanned hoses, pump and thermostat area and everything seems dry. The parts store is only 1.5 miles away and when I get back to the house the overflow is totally empty. Still nothing dripping under the truck but I can def. hear something releasing pressure once it gets hot. Sounds like it is behind the NAV screen.

Any ideas would be great, the wife is headed out of town this weekend and need this one going.

TIA

hankinid

The only coolant-related thing behind the dash is the heater core. The heater core has continuous coolant flow through it...temp you feel is controlled by doors under the dash that direct heat (or no heat) where you want it via the climate control.

Are you smelling hot coolant while you're sitting in the truck??

I'm thinking a stuck thermostat perhaps.

While you're at it, if you have not changed the heater hose T's (back of engine under the hood), NOW is the time to do it. More than a few reports on Mud of T's breaking over time as they're plastic. About $7 each at your dealer.

hth

Steve

Third

Thanks for the reply Hankinid

I do not smell any coolant inside the truck and only at times outside the truck. I pulled the plates off of the bottom fo the truck about 10 minutes ago. The only spot with coolant on it is what looks like a sensor plug about an inch from the oil filter on the passenger side of it to be more precise. I already have a thermostat here to replace it with but that still doesn't explain where my coolant is going because there is nothing blowing out of the overflow or radiator cap. Any ideas??

TIA

hankinid

PM inbound

Jacket

What was the condition of the oil when you checked it? Any milky colors or indication of possible contamination? Any white smoke coming from the exhaust?

I don't want to be overly dramatic, but it could be a head gasket leak. If it's leaking into the cylinder chamber and then burning off, that could explain the coolant loss without external signs.

The rushing water should could be the coolant bubbling/boiling due to the excessive temps. The one thing I WOULD NOT do is take it out of town or do any excessive driving until you figure it out. The high temps could cause a lot of damage if not fixed.

hankinid

Another pm inbound.

Third

jacket,

Oil was normal and not milky in any way. This is what Hankinid and I discussed as well was possible head gasket. I in the past had one blow on a chevy with milky oil coolant and white smoke. I don't have access to a pressure test kit and that is my next step. Had a shop close by with one so I trailered the truck up there and they will test it later today. I did run it this morning with the skids off of the bottom end and finally got some drips but with a hour or so of time, flashlight in my mouth and phone trying to video it from different points to examine more slowly later I had zero luck trying to see where is was coming from. I have changed countless water pumps in my life although never on this truck. It does not seem to be the pump but could be. I will update the forum when I get the pressure results back. Thanks again

Third

Shop could not explain the noise nor could they replicate it. Go figure on that one. Said water pump was leaking and seemed to leak just down the front although I never had anything on the ground. Can't explain that one either. Quoted 1550.00 for pump and TB change. I am not a mechanic but pretty handy with the wrench. I will be doing the change myself this weekend.
Thank for your replys and glad it is not the heads.

bbrowncods

That is a pretty big leak there. you are probably not seeing liquid because it is coming out as steam. Let it cool and put pressure on it and watch where it is coming out. You are hearing air in the heater core as the coolant gets low.

hankinid

I'm glad you found and are going to fix the issue.

What was wrong with the throttle body...or did I miss something??

Steve