No "how-to" head gasket posts for a Gen4?

You ask a good question- does it death rattle? Nothing death rattles like the gen 3- so no. Misfires reported only scanner app- yes.

As far as the coolant hoses that I bypassed- I have a picture up there. How else does the coolant enter the exhaust? I’m asking because I don’t know.

 

I appreciate everyone’s perspective and help- It’s not that I’m not doing those tests to rule out that it’s a head gasket -rather I keep trying to figure out how to do the head gasket if that’s my next step.

If the head exchanger has already been bypassed- what else could it be?

 

Hey Bill, thanks for asking. I really do appreciate the collaboration here. To me, it drives excellent. I get 53-60 miles to the gallon on a very easy 60 mph 100 mile round trip drive to work. I drove it about 1200 miles on a trip two months ago and I feel like that was when all of this started; could be wrong.

Big difference in gen 3 is, I don't notice a "rattle". Maybe once or twice; but usually I get in it, go in reverse out my drive way and then typically take off on a 50 mile drive. I might feel some misfiring around 1100 rpm as I exit the neighborhood

• Estimating (loses about 8 oz of coolant a day)
• Only really notice the white smoke if I start in maintenance mode (otherwise I'm driving). Haven't really noticed it from a start at a red light, etc.
• See a snotty, milky substance in the oil cap
• I think I spot some carbon in the coolant reservoir. See photo. I noticed this really bad in my last gen 3.
• Never a check engine light, I just use "Car Scanner App". I have had an occasional inactive misfire code, and an occasional P148F code.
• I bypassed the Heat Exchanger almost as soon as bought it 15,000 miles ago. I could smell and see coolant coming out the exhaust. I bypassed it at the bottom.

Not to act like we are solving a mystery here with abstract clues- but a little on the history of the car. Two owner car. Car fax reads that Toyota dealer did a "pre-delivery inspection" 10/2025. From 9/25 to 12/24 - it was driven 75,000 miles! Approx 270 miles per day for 279 days- wow! I believe the car was used for the dealership or some other fleet service, it was really only ever serviced at Toyota or a chain tire shop.

One might could guess, the heat exhanger was failing- perhaps it overheated during the long days of fleet service.

I bought this in Nashville, I live in Lexington. I did try to reach out to the dealer about the vehicle prior to buying it and emailed them the VIN,etc. All they said was "we'd love to do a prepurchase inspection with you- please bring the current owner and you to the dealership, and we will inspect it for $200 and give you a rundown of any recommended service".