Reviving a 270K mile Highlander Hybrid

[Drifter]

[Piotrsko]

Generally I have found on aluminum blocks that when you get a leak somewhere (unless you're really paranoid about topping off coolant level) you start the head gasket failure routine.

The warpage of heads is a heating then rapid cooling process which mimics a stress relieving procedure which machine shops do between "billet" machining steps.

Air bubbles in the coolant do not promote even cooling.

[Drifter]

Front cylinders. Lots of carbon build-up, clearly these cylinders were not taking on water even though the headgasket looked a bit rough (prior post).





Rear head gasket:



That head gasket didn't look bad to me (the coating hadn't eaten away from cylinder to coolant jacket like the front head gasket), but one of the back cylinders had much less carbon build-up than the others:



I'm guessing it was weeping when cold and sealing when warm - causing the rough cold starts but smooth warm driving.

Heads & block were flat within 0.001" so minimal warpage and still within spec.
Exhaust ports (valves) held water on the front head:


But most of the intake ports dribbled. The back head dribbled from both intake and exhaust.



This gave me pause. These piston markings don't look like the Toyota markings from the 80s & 90s engines I rebuilt in my youth:


They look like this photo from an advertisement of DNJ 0.045" over pistons:


...But the bore is the stock 92mm... So maybe it is just a photo of a stock piston? Dunno. My friends are goading me to pull the block and tear it down too. I'm reluctant - I'm hoping the valves will seal when I clean up the carbon (or, if not, after having a machine shop do a valve job).

Of course I am willing to disconnect the motor mounts in order to raise the engine enough to be able to remove & install a new control arm. The bushings aren't the worst I've seen, but the part is cheap and the 12-hour book time job will be much easier now


Pulling the engine wouldn't be that much extra. Tearing it down, on the other hand... And the garage already has been overwhelmed by HiHy parts I hope to keep track of:

[redpoint5]

Hybrid Highlander just entered my radar after Xist made a CMAX comment, which lead me to fueleconomy.gov, which lead me to looking at what the most fuel efficient vehicle with 3 row seating is.

[Drifter]

The 3.3 isn't great on fuel, but it is acceptable. The later 3.5 running the Atkinson cycle is a bit better, but they command a much larger price premium here.

Personally I wish we got the 3-row Prius V like the rest of the world.

[redpoint5]

Wait, what! How did I not know there was a 3-row Prius option? I suppose that's because 3 row wasn't on my mind until recently.

The latest gen Hy Hi has my attention, but of course it will be a few years before used ones are a reasonable price to me.

[Drifter]

[cRiPpLe_rOoStEr]

Originally Posted by Drifter

Personally I wish we got the 3-row Prius V like the rest of the world.

NHTSA might be the one to blame...

[Drifter]

All the (reputable) local machine shops are backed up 4-6 weeks so with a small amount of hope I decided to try and clean up the carbon from the valves & seats and lightly - lightly - lap the valves to see if they would seal. To save time in case it didn't work, I went straight to the worst chamber (middle cylinder on back head) which leaked water from every valve - prodigiously so from the exhaust side.

Each exhaust valve had a fair amount of build-up and the sealing edge looked a bit pitted - a bad sign for shade-tree mechanic sealing methods:


The combustion chamber before - intake seats didn't look too bad - I was confident they would seal with a little elbow grease:


Intake valve looked decent - only a couple rough spots:

The intake valves after soaking in solvent & a little elbow grease. Still a few rough spots, but probably lappable:


I forgot to take after pictures of the exhaust valves, but the sealing edge was still quite pitted. Lapping helped a little, but it really looked like they were going to need a proper grind. Anxious to test them, I popped them back in to see if they would hold water:


They barely weeped, so I'll still have to have a machine shop to a proper job. I hope if I clean & prep the head and bring it to them disassembled they might be able to get it back to me in a week.

The good news is the 4 valves I checked were within spec for length, stem thickness, etc. I don't have a tool to check the valve guides, but I'd feel comfortable running these valves in those guides for another 100,000 miles.

[me and my metro]

Back 20 years ago when my used car dealer friend was selling a lot of Chrysler minivans, the rear head was always worse than the front head. The 3.0 Mitsubishi engine was a hemi and the exhaust seals got baked and these engines smoked and burned oil. Sometimes the exhaust guides even slid in the head. Usually just replacing all the valve seals made a nice van out of a smoker, rarely did we have to go deeper. The rest of the engine was really bulletproof. If you are going to grind the valves I would replace the rings. Valve jobs alone usually create oil burners. Since you found the steam cleaned cylinder But the gasket looked good I would have that head pressure checked for cracks.