Tfalley

Recently did the head gaskets and belt, pump etc on my 3VZE. Ran really well for a couple of weeks then lost torque, badly. Still starts and runs smoothly enough but makes no power. Two best guesses are (1) intake leak (2) timing belt slipped and valve timing is off. Hoses all look good, timing is set properly, ran around with starter fluid and propane and am leaning toward the timing belt. Vacuum Gauge reads a steady 8" HG at idle (low). Very slight spitting noise at the tail pipe. Plugs look normal.

thefreqofnature

My vote is timing belt

When I changed my belt, I cycled the engine a few times to make sure the belt was seated and correct. 3 times in a row it skipped a tooth. 4th time was the charm, belt seated buttoned her up and its been good ever since.

Just my 2 cents. Best of luck!!

Tfalley

Thanks: What is wierd is it ran really well for about two weeks. Now that I know how to take it apart, shouldn't take too long if it does come to that. Mostly hate draining and refilling the cooling system!

Tfalley

Will a compression test show a valve timing problem or not? Best place to hook up vacuum gauge? Currently using plugged spare tube on top of throttle body.

scope103

A compression test will show a valve timing problem if it's off far enough (the exhaust valve will open before TDC, or the intake valve will close before the cylinder reaches BDC).

The plugged "spare" tube on the throttle body is gated somehow (how, I don't know) as are the rest on the throttle body. So they give vacuum or not depending on throttle position. If you want to measure intake vacuum measure it at the intake; just pull off one of the lines on the "gas filter" (3-nipple black cylinder on the passenger side) that powers cruise control, or Fuel Pressure Up, or AC pressure up.

Yes, people (on this forum and elsewhere) talked about "timing belt slipped," but for my money, I don't think it's possible. It's a toothed belt and you'd have to do a terrific amount of damage to the belt to make it move. Unless, of course, your tensioner is off, in which case I doubt you could start the engine.

Tfalley

Amazing.... There is supposed to be a washer behind the tensioner adjustment idler. Without the washer the idler bound and stuck, allowing the camshafts (both) to equally jump about 15 deg off without damaging the belt. How can this be possible? The only think I can opine is that the slack occurred as the engine stopped.