I remember that when I started reading this forum, there was a lot of talk about failed head gaskets on the 3.0 motors.

If they fail, is there a spot that tends to be the most likely? IE - between certain cylinders?

My son is concerned that our old truck might be exhibiting signs of a problem.
He is not losing coolant to any extent so maybe not but he says it does not run well when cold. It lacks power and runs a bit rough until it warms up. Especially true if it sits for a day or two between uses. He is concerned that it might be ingesting some coolant and then burning it off before it runs better. He has pulled a couple of plugs to check and thinks they look too clean.
Any thoughts?

He is a licenced mechanic working in a shop, but no expert on Toyotas.

Randy

If he's a mechanic, then he should know about testing the coolant for exhaust gases next.

If he DOES go yanking the HG's, then make sure you print out the TSB for torquing the headbolts. I've got a link posted in the Toyota Tech archive section.

Go back to the index page, and you'll see the section down at the bottom. Might need to also open up the viewing time a little bit if you don't see the thread for it.

If the plugs are white or almost white, it is burning water.

Use only HG's from the dealer, they have done a lot of research on them.

Should quit driving it until it is fixed, could hydro-lock the engine which can bent rods or the crank.

Yhe head bolts are torque to yield bolts, one time use.

Check the decks of the block and the heads to make sure they are flat.

Now is the time to replace the water pump and timing belt and do a valve job.

My recollection is that one should never touch the knock sensor in the valley without replacing it too. The wiring gets brittle with time and it is likely to cause trouble afterwards.

No input on where it is most likely to go? I seem to recall that it was often one of the cylinders towards the back but I could be wrong.

Randy

Yep, swap it while you're in there.

Just to jog your memory, we have link to a 93 FSM in the sticky here, in addition to the TSB for the head bolts that I've mentioned.