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2003 Toyota Sequoia Engine issues

Has anyone heard of engine issues with the 4.7L 8 cyl. engine on this car? We bought one new in 2003. Well-maintained by excellent mechanic the whole time, including checkout a few weeks ago. While heading out for a vacation a week ago the engine started making a horrible loud knocking sound going uphill on an interstate. We slowed way down & got off at the next exit. Still made the sound, even when idling. After a tow the mechanic who checked it out said it sounded like “internal engine damage.” Towed it to my mechanic’s who came up with the same diagnosis a few days later. We have been using synthetic oil for the life of the car & oil was full when the engine blew. No leaks or other fluids lost. Any owners or mechnics encountere this before? Any ideas what would cause this?

How many miles on the car? If it has 90,000 or more, it was due for a timing belt change. According to Gates, a major timing belt manufacturer, your car has an interference engine which means that if the timing belt breaks, major engine damage will result.

The engine couldn’t be idling with a broken timing belt.When the belt breaks everything stops,for good or bad.

Good point, thanks. I didn’t read the post carefully.

The timing belt doesn’t usually, actually, break. It can jump teeth, or rip teeth off. It can still run, though badly, or very badly. It can, but, may not run. Depends on the amount of mis-time.
The mechanic should check the timing of the camshaft to the crankshaft. A quick way to do this is to remove #1 spark plug, stick a straw into the spark plug hole to touch the top of the piston. Rotate, by hand, the engine to the 0 degree mark on the crankshaft pulley while watching the straw rise. The straw should rise to its maximum as the 0 degrees is reached on the crankshaft. If they do both of these things together, the engine is in time, or, exactly 180 degrees out of time, which is unlikely.

“Rotate, by hand, the engine to the 0 degree mark on the crankshaft pulley while watching the straw rise. The straw should rise to its maximum as the 0 degrees is reached on the crankshaft. If they do both of these things together, the engine is in time, or, exactly 180 degrees out of time, which is unlikely.”

This is the second time you’ve posted this. It makes no sense. The timing belt times the CAMshaft to the CRANKSshaft. The pistons, on the other hand, are directly connected to the crankshaft.

The timing mark you’re refering to is on the crankshaft pulley. There is no way for the crankshaft to be out of time with the pistons without the connecting rods being broken. The timing belt has nothing whatever to do with the piston/crankshaft relationship.

Well turns out you are all wrong thanks for the replies but 3 weeks after the event I got my Sequoia back $5200 later. Would have been worse but my great mechanic found a used engine with 53,000 miles on it to get it going again and TRADE IN SOON. Anyway, they analyzed the old engine before pulling it, plus some more Internet research, and found out something that all you Toyotaheads should know. Toyota plant in MEXICO is making most of the larger truck engine for Toyota SUVs not just trucks. Wrist pins are apparently defective and faulty (note NO acknowledgment from Toyota on this), we think one blew at 75 mph on the Interstate then quickly with the stress & imbalance on the crankshaft at over 3000 rpm several more popped before I could even pull over. So much for Toyota quality! Wasn’t timing chain as suggested as you could still start the engine & it would run (with terrible noises of course) even after I towed to the mechanic. Funny because at 87K miles you would hink you could trust Toyota quality & reliability. Final irony: I drove a 1990 Jeep Cherokee from brand new to 194K miles until last March, after 18 years had original engine & tranny, no major or unusual repairs in the life of the car just stuff you would expect to wear out. I hope this is helpful to others out there.

JMHO here, but I’m having a very impossible time of buying into this broken, cheaply made wrist pins diagnosis. It’s an utter crock IMO.

Diagnosed without pulling engine? “We think one blew…”?

OP, let me ask this. Did you actually SEE these allegedly broken wrist pins?

Sorry, I ain’t buyin’ it.

Glad it is back in order.

Toyota is not infalliable nor Honda like the kool-aid drinkers think. I think ALL makers have problems in each area. Depends on sheer luck or lack thereof whether you hit problems. Yes part of that too is driving style and maintenance/care too but luck is the greater factor.

I with you on the impossible “wrist pin blew” explaniation,I have seen the pistons broken and the wrist pin stuck in the block but still intact, in fact wrist pins were a favorite tool to leave by the press for pushing bushings and such. Anyone know the technical description of the steel used to make a wrist pin? some tough stuff,and think about the direction the load is put on the pin. maybe the situation is that the clip holding the pin in came out (like air colled VW’s,seen that) or are the pins installed like a small block (pressed in)

What is probably going on is a communication problem,from mechanic to the OP,then the OP to us,something is getting mixed up

I think hellokit is being misinterpreted a bit and think what he is referring to is the fact that if a wrist pin is broken the piston is not going to be where it’s supposed to be during the timing process.

The wrist pins are hardened tool steel basically and virtually impossible to break, although they may destroy everything around them. For hoots, I’ve tried in the past to see if I could cut one with a high dollar hacksaw blade (no way) and even with tool steel and carbide bits on my metal lathe (also a no way).

Here’s where I have an issue with this wrist pin diagnosis.
We’re supposed to believe that not one, but mulitiple, wrist pin failures occurred and yet:

  1. The vehicle continued to run; “although we slowed way down”.
  2. The vehicle continued on “got off at the next exit”. (How far was that?)
  3. The engine was still idling. (It would idle with at least 3 (their count) broken wrist pins/pin gouged cylinder walls, etc.?

Someone would have to show me the damage before I would buy into this diagnosis and from what I’ve read so far, I have seen no mention of the old engine being torn down at all; only a diagnosis of an in-car engine noise and some internet searching.
A search I did on this alleged cheap Mexican wrist pin problem provided no returns at all.

And an equally important question. Why in the world spend 5200 dollars on a used engine just to turn around and trade the vehicle off?