Headgasket replaced and failed shortly after? Do anything different next time?

Oil consumption and miles would be my number 1 engine or no engine decision factor. If I did a hg only it would be with a rebuilt head from a qualified machine shop. Of course any of the points your list would have to be done right in either case.

A lot depends on how long you will keep the car and how many miles per year. Fix it and sell in a couple of months? Or try to get two or more years out of it in a high mile per year usage case?

Even the replacement engine choice has two options. Rebuild or as is. For me "use as is" would have to be a low mile 2015-17 gen3 US engine. Otherwise rebuilt.

If I were in San Jose I would let Gasketmasters do it at their shop and get a guarantee. Nothing beats experience for doing it right. They can help you decide.

 

I watched one video where the guy (describes himself as a "master mechanic") said something along the lines of: "I'm not sure if it's necessary, but I like to put a few drops of oil on the new head bolt threads". Repair Manual says oil the threads, and the space between bolt head and washer*.

Anyway, Read up all you can. There's some repair manual excerpts linked in my signature, the "head gasket" ones.

Also linked is @The Critic's thread, if you haven't found it already.

* In "Cylinder Head Removal" pdf, linked in my siganature, under "head gasket...".

 

Though the head bolts should have oiled threads, and oil between washer and underside of head.

 

How much is the variation? Here's the spec (and more complete excerpt attached:


That last sentence; Toyota doesn't recommend machining?

 

Sorry, no hands on experience.

oh, linked in my signature, is @the Critic’s head gasket thread; there’s discussion of machine shop.

 

Absolutely take the head to a machine shop.

 

If one side of the straightedge shows it's flat and the other side shows a gap, which side do you believe?

 

That wouldn't surprise me since it came from Amazon. At a B&M store, you can hold one up against the shelving or anything else prior to purchasing. I always check levels before purchasing, as well. Hold it against anything stable and check the position of the bubble, then spin it, flip it and check again. If the bubble changes position, it isn't level!

 

I think he meant hydrolock type of thing. Not the oiling of bolt threads

 

If it doesn't lie flat on the shelving, which do you conclude isn't straight?

 

I was looking at my assortment of levels, aluminum rails, slotted angles, thinking: if I just lay them out on a table, put some of them edge to edge and check for gaps with a feeler gauge, I should be able to sort out if one or two of them are pretty good.

 

That is "nice person"uming the table is straight...

Maybe lay some dental floss out and tie the ends to nail hammered in something to hold them firm.
And have some clean glass between them. Then lay the straight edge close to the floss and have
a light shining through. Then you could see if light shines through. Not exactly perfect, but at least
you would know the floss is straght, if it's tight.

 

I'm not sure the table is a factor, if it's just supporting to straight edges lying side by side. If you press two items gently together, then test with feeler gauge?



the slotted angle tested very straight btw: pressed against the long level 2/1000” feeler wouldn’t pass anywhere along its length.

 

I guess you could flip ends of one. And if there is no gap, I guess both of them would be straight.