TDC using compression tester

[lichen]

I am trying to find tdc by hand-cranking the engine but not getting any pressure. Cranking with the starter motor shows 90lbs. Maybe I don't have the pressure gauge seated properly? Or is there a better way to do it without lifting the engine? I need to replace the timing belt and camshaft seals. What if I paint a bunch of marks on the belt and just put the belt back on using those? And not worry about tdc? I know that's probably not a good idea. The half-tooth thing when I am putting on the new belt will probably get me in trouble. Any advice??

[lmdew]

What year and what engine?

 

Pretty basic, lots of good info here if you search timing belt and on you tube.

 

Pull the timing covers:

Crank gear has a tick mark in the back timing tooth that gets lined up with the tick mark on the engine block.  

The Cam Gear marks will be lined up with the tic marks in the plastic back cover of the timing belt cover and the head split line.

 

How many miles are on the T-Belt?  Most of the time you can still see the original marks on the belt and can use those when you put it back on.  If it's been over 80K, I'd replace the belt along with the seals, Oil pump rear cover screw and o-ring, and all of the idler pulleys.

[1 Lucky Texan]

tic/dash-line on the tab at rear of crank spocket is the correct mark for timing. But TDC is the triangle/arrow on the front of the sprocket.

 

sounds like you may have slipped timing? tell us why you are doing this test and give details as mentioned above. If you feel ANY resistance turning the crank, STOP - newer soobs are all interference engines.

[Fairtax4me]

You don't use TDC for timing on these. The cams are under load at TDC and you'll never get them to sit right while puttin the belt on.

 

Do some research on the proper timing marks to use. Dash marks on the cam sprockets and the dot or notch on the back edge of the crank sprocket.

Edited March 1, 2015 by Fairtax4me

[forester2002s]

Make marks on all of the toothed-pulleys, and on the engine block in line with these marks.

And then make marks on the old timing-belt, at the toothed-pulley marks.

And finally, take a photo of this set-up.

 

Then mark the new timing-belt with marks to match the old belt.

And away you go!

[keith3267]

Get a manual and do it the right way, as suggested above, but FYI, the most accurate way to find TDC for #1 is to pull out all the spark plugs and as #1 approaches TDC as determined by thumb pressure or wood pencil inserted in the #1 spark plug hole, then start checking the two cylinders where the pistons are about half way up, one ascending and one descending with the wood pencil.

 

When both of these pistons are at identical depths, the #1 piston is at TDC.  The reason this works is that if you are looking only at the piston that is TDC, moving the crank 10 degrees to either side barely moves the piston.  Five degrees to either side and you can't even perceive any piston movement at all.  But the pistons that are mid stroke are moving the most for every degree of crankshaft movement.  When they are matched in depth, the #1 is at TDC, dead on.

[Fairtax4me]

That method doesn't work on these.

When at TDC, pistons 1&4 will be at top dead, and 2&3 will be at bottom dead. All 4 pistons meet half stroke at exactly the same time. The proper crank timing mark sets all 4 pistons at half stroke.

[Crazyeights]

^^^ What he said! Setting up the valve timing on a Toyota Quad Cam 3VZ is the same in theory, as are many others.

Edited March 2, 2015 by Crazyeights

[lichen]

Actually I'm doing this initially to replace a can seal that sprung a leak. Its a '98, 2.5 Legacy Outback. I finally got the gauge to show pressure by cranking it more quickly and the previously made marks are all lined up now so I think I'm okay to proceed.

[lichen]

I have no clue how many miles on the belt. It looks pretty new.

[1 Lucky Texan]

in reading and only one personal experience, belts CAN look pretty good with time/miles. The idlers are what usually blow-up. On my WRX the toothed cog/idler was very rough and slightly wobbly after 8.5 years and less than 60k miles. One other idler was slightly rough.  i have seen pics posted of blow-out idler bearings and the belt looks OK.

 

that 2.5 is a bender - if the timing slips - you WILL have valve damage.

Edited March 3, 2015 by 1 Lucky Texan

[lichen]

Yep that's for sure.

[lichen]

Apparently, I got the timing wrong the first time because afterword, the engine lacked power and idled rough. So I'm trying it again. Book says use compression tester. Don't think there's time to to take out all that plugs today and I'm trying it again...can anyone phone me?

[idosubaru]

timing is easy.  print/look upt he online FSM, Subaru technical service bulletins showing detailed pictures of exactly how to line it up - lots of threads about it.

 

post pictures of your timing marks and we'll tell you what's wrong.

 

car ran and drove fine before the work?

 

compression tester?  they're almost useless for EJ engines, i wouldn't touch it, that's not what you need here unless you like running 25 miles to get to a place that's 2 blocks down the street.

[lichen]

I got it!!! It was so simple, I was trying to make it complex, and I was using the TDC notch on the crankshaft pulley and the zero mark on the cover, its amazing I didn't bend up the valves.