77K 2016 Prius and Headgasket Failure

sorry to hear it!

3rd gen? is it a v, or 4th gen prius?

did art's have any clue to the cause?

are you losing any coolant?

 

OP states in title it's a 2016, so 4th Gen. Hmm, I wonder if the coolant pump or thermostat failed or some other contributing factor is involved?

Posted via the PriusChat mobile app.

 

4th gen has the coolant exhaust heat exchanger leak problem, leading to overheating and blown head gaskets.
but 2016 can be a 3rd gen v

 

Taking OP at his word, and where he’s posted, he’s got a 2016 Prius. Assuming that’s the case:

The exhaust heat recovery is a common cause of coolant loss with 4th gen Prius.

It could have caused overheating and head gasket failure.

There’s also a chance the shop jumped to conclusions, and it’s only coolant loss through the exhaust heat recovery system. It’s commonly misdiagnosed, worth double checking.

the latter is covered by Toyota, except replacement parts are on short supply.

 

The two most probable causes of head gasket failure are overheating (which can be prevented by insuring the coolant is in good condition, which is why the maintenance schedule requires it to be checked for condition (freeze point and additives) every 6 months or 5K miles) and pre ignition which is why Prius oil changes are so critical (the oil does a lot more than just lubricate the engine). So as long as you met the maintenance requirements, you might get lucky.
If it is the heat exchanger, then again it is possible Toyota will step up to the plate, assuming the coolant condition doesn’t reveal that it was neglected. With a 2016 you have the advantage that Toyota did redesign the heat exchanger because of some failures.

 

If the problem is actually in the exhaust gas heat exchanger; California Smog laws requires Toyota to fix it - free; See CARB laws.

Have the mechanic do a coolant pressure leak test on the heat exchanger; by itself - separated from the engine cooling system - BEFORE proceeding with a head gasket repair.

 

Did the car pass the cooling system pressure test? Was there a leak and now fast did the pressure drop? Just because there was no external leaks, doesn't automatically make it a head gasket problem. The heat exchanger leaks into the exhaust pipe and get blown out the back of the car; no coolant drips.

You would also get combustion chamber gases in your coolant from an exhaust gas heat exchanger leak. Easier and cheaper to do the extra test, than to rip the top end of your engine apart. There's been many people here that has paid for a replacement head gasket and found it didn't fix their problem. and a few grand lighter.

see my post above

 

the odd thing is that 77k is a lot sooner than most gen3.

maybe just a factory defect somewhere

 

Based on what?

 

yes, and there's plenty of evidence. there might even be a tsb iirc. unfortunately, toyota dealers are not very good at service.

 

The engine in a 4th Gen is NOT the same as the 3rd Gen Prius. They are both 1.8L engines, but the 3rd gen is rated at 134 HP and the revised engine for the 4th gen is rated at 147 HP.

What did the first shop find when they pulled the head. Did they show you the old head gasket? They may have misdiagnosed the exhaust gas exchanger problem as a bad head gasket.

Posted via the PriusChat mobile app.

 

Has the coolant ever been replaced on this car prior to this fiasco? While the maintenance schedule doesn’t call for replacing it until 100k miles/10 years, it does require it to be tested (and replaced if the condition calls for it) every 6 months/ or 5k. Depleted additives in the coolant WOULD lead to multiple failures in system components.
EDIT: Additional question: Where was the scheduled service done on this car for the last 7 years? If it was quick lube places then there’s a significant chance that the coolants were topped off with non-compatible coolants, which would dilute the coolant and cause loss of corrosion protection. You might want to have your inverter coolant system checked.

 

The closest item is "inspect and adjust all fluid levels", but there's nothing about testing of engine/inverter coolant condition.

 

Short answer is yes; but not directly - Which is why Toyota is thumbing their noses at that theory. The heat exchanger leak will cause a low coolant condition; which will run the motor abnormally hot. The temperature warning lamp trigger is set pretty high; so you can go weeks or months running your engine abnormally hot - thereby warping the head and causing a head gasket failure.
The only way to prevent this is to check your fluid levels at every fill-up. I always check mine before a trip over 100 miles. Just a quick visual, under the hood and a napkin to check oil level.

Hope this helps....

 

I draw your attention to that little number “1” beside the second bulleted item below (which is from the Gen 4 schedule. It refers to a footnote that says (in part)
“ Inspect engine and inverter (if equipped) coolant level/condition/freezing “

MAINTENANCE LOG
5,000 miles or 6 months
■ Check installation of driver’s floor mat
■ Inspect and adjust all fluid levels1
■ Inspect HV battery cooling intake filter5
■ Inspect wiper blades
■ Rotate tires
■ Visually inspect brake linings/drums
and brake pads/discs
Driving on dirt roads or dusty roads:
■ Inspect ball joints and dust covers
■ Inspect drive shaft boots
■ Inspect engine air filter
■ Inspect steering linkage and boots
■ Replace engine oil and oil filter2
■ Re-torque drive shaft nut (AWD)
■ Tighten nuts and bolts on chassis
and body
Driving while towing, using a car-top carrier, or heavy vehicle loading:6
■ Replace engine oil and oil filter2
■ Tighten nuts and bolts on chassis
and body
Repeated trips of less than five miles in temperatures below 32°F / 0°C:
■ Replace engine oil and oil filter2 Extensive idling and/or low speed driving for a long distance such as police, taxi or door-to-door delivery use:
■ Replace engine oil and oil filter2

 

Touché.