00 Ranger 2.5 timing tdc = cyl #1?

[jorton]

Haynes manual states to set timing belt sprockets at tdc with the harmonic balancer key @ 12 o'clock. Does piston #1 have to be at the top of it's stroke(manual doesn't mention piston #1)?

Thanks!

 

[jorton]

Or is #1 piston at the top with both valves closed anytime the harmonic balancer key is @ 12 o'clock?

 

[mechanicx]

You need to line the crank pulley and the timing pulley to the mark to be at TDC with both vales closed. You could have just the crank pulley aligned but be at 180 degrees ATDC.

 

[OVERKILL]

#1 piston at TDC on compression stroke.

 

[jorton]

Originally Posted By: mechanicx
You could have just the crank pulley aligned but be at 180 degrees ATDC.


That's where my neighbors Ranger is right now. Do we have to pull the cam cover to get cyl #1 on the compression stroke?

 

[mechanicx]

You don't have to pull the timing cover and check that the cam sproket is at the mark, but that is one sure way. You can just take out the number 1 plug and tap the starter while watching the crank pulley mark come around with a finger over the plug hole you will feel compression stroke. Then you'll know the pulleys are at TDC.

 

[jorton]

OK thanks to all. Last w/e we didn't observe #1 piston when we set crank, cam and oil pump sprockets because there was no mention of #1 piston in the Haynes manual. Luckily engine is not interference type.

 

[mechtech2]

Any cam chain or belt that I have seen gets it's timing set with the piston of #1 cyl at TDC of the compression/firing stroke.

But having the key point in the right direction MAY have you 360 degrees away from correct!

You may be at TDC of #4 at the firing/compression stroke, instead of #1 [if a 4 cyl]

 

[mechanicx]

Originally Posted By: jorton
OK thanks to all. Last w/e we didn't observe #1 piston when we set crank, cam and oil pump sprockets because there was no mention of #1 piston in the Haynes manual. Luckily engine is not interference type.


They might not have mentioned it because as long as the the crank pulley is at its mark, piston #1 is at the top of its stroke(but could be at the top of the exhaust stroke, i.e. 180 BBDC iirc). And with a freewheeling engine you are free to rotate the cam sproket to the mark (making the engine set at TDC for #1).

 

[mechtech2]

180 BBDC? Never heard that term.

 

[mechanicx]

Well there's TDC, ATDC, BBDC, and BDC but whatever it is called at the top of the exhaust stoke as opposed to top of the compression stroke (TDC)

.

 

[jorton]

The cam and oil pump sprockets each have 2 timing marks. A diamond, and a triangle. The triangle is mark we used to fix the truck. When we used the diamond to set the sprockets, compression at #1 sparkplug hole was 90 degrees off.

When we got the truck started it sounded terrible because there was no oil pressure. Dipstick level registered 1/2" below the "add" line. I'm afraid there was no o/p when the timing belt broke. We added 2 bottles. The truck runs well but if I listen carefully there is a knock just audible over the turbine sound of the cooling fan. Now the pcm is re-learning settings and Roger's wife is delighted to have her Olds back!

 

[mechtech2]

Good work!

 

[jorton]

Muchos gracias Senor!