Healthy motor with no compression?

[RickHaleParker]

I know head is solid as all new valves and seals were installed and no interference when hand cranked and checked timing a dozen times.

The symptoms indicate the head is warped. Did anybody check for warpage when the head was off?

[abscate]

Th head has to come off again and the botched valve/ gasket job redone.

No one likes being the bearer of bad news but there probably 496 ways to mess up a head job.

One thing to be careful of; a 2.5 liter 5 cylinder has 500 cc per cylinder. A 10:1 compression ration means a compressed volume of 50 cc. 50cc/ ml of oil will fill that completely and cause damage on the wet test

If the splines slipped 30 degrees , you would have 10 bent valves

[FREEBUSINESSES]

Thanks, I wanted to avoid this at all cost since it seems impossible to me to have damage to valves. The head was checked, and if warped, it would only effect a couple cylinders, not all, and that I have seen dozens of times, as with blown head gaskets. No cracks in head, and no leak down in each cylinder before I did head rebuild or after. I rotated crank manually several times with no interference, so I know valves have to be good at this point. I did see timing issue as there is no two dots on crank pully teeth, so the line on outside of pully edge was used as some suggested online in other videos. So could the two tooth out of time by previous setting cause no compression. I did the wet test, compression only came up to 15lb on 1 and 5. So last question, can the two tooth off timing at crank cause this near zero compression on all cylinder? I am about to reset timing differently from where it was marked by previous hack who screwed up something, so I am guessing he marked timing points wrong. I did use proper cam lock as I have done a half dozen head rebuilds over the years. Without the two dot marks, I was going on the pulley orientation where crank pully guide pin is up when timed correctly. All videos seem to indicate this same position which is close to where timing dots should be. Is it OK to use the raised line on outer pulley ridge???

One last question, with cams locked, is it safe to rotate crank by hand a full 360 degrees, I seem to be getting resistance point, and as the timing was off when I got it, I wanted to back up a couple teeth, but people always say only rotate crank clockwise. I know you can rotate cams while crank is on time, but I can't remember if I ever rotated crank with cams locked with no issue, that is what I seem to remember, but wanted to make sure first as memory is failing in my old age. lol

Thanks all,

[abscate]

No. you can't move crank with cams locked. It needs to stay on the mark during this process. There is no reason to move it.

You can't put the crank 180 out of phase, there is only one mark or set of marks. If you can't find the pulley marks, remove the harmonic balancer and use the large ridge in Braille on the crank end. Impossible to get wrong

The crank pulley pin needs to be about the one o'clock position to be correct, but that is NOT fine enough for timing. Use the ridge on the pulley mount and get it right.

[RickHaleParker]

For the lower end of the engine there is no difference between 0°, 360° and 720° in the four stroke cycle. When the crankshaft is aligned with the timing mark, the lower end is at 0°, 360° and 720° simultaneously. It is the camshafts positions that determines if the engine is at 0°/ 720° or 360°.

[jimmy57]

SO I think I undersand you had head off and now it has no compression? How did you time the cam gear hubs and locate came to put it back together? WHere did you place crankshaft?

[Chili58]

Old thread, but to help others: If all the cylinders have very low pressure e.g. less than 50% of the nominal 13 bar, you have camshaft installed wrong. That means that there is always and in every cylinder at least one valve opening too early to get the pressure inside the cylinder. And if you see the same in all cylinders, it means that the camshaft's timing is wrong - actually the sprocket at the camshaft is most obviously not correctly installed and its marking is used for timing purposes.

In case you lock the camshafts correct way during the installation and your crankshaft is at its timing mark, your markings at sprocket may show where ever, if those are not correctly installed. Its better to open the sprocket bolt while having cams locked decently - and rotate the sprocket to correct position; shoving to the correct marking settings.

I got a Volvo having 7 Bar pressure in all cylinders; The previous "mechanic" had messed with VVT-sprocket and did not know how to set its timing correctly. Had to replace the positions of both sprockets.

[duke1]

Amazing, no input in two months. I am stumped, I squirted oil in each cylinder and compression came up about 10 lbs now at 15 lbs in cylinder 1 and 5 and still zero in all the rest, barely a puff with rags stuck in spark plug holes. My question is how can one cylinder bleed over to another, even if ever so little??? I got air spark plug connector and it appears cylinders do not hold air, none even if I crank engine by hand which should present a closed intake and exhaust at some point, so how is this possible??? Could rings be that bad, I know head is solid as all new valves and seals were installed and no interference when hand cranked and checked timing a dozen times. Someone suggested crank pulley can strip and throw off timing by 30 degrees without damaging valves, is this possible??? I hate to pull it off, so is there another way to determine this possibility???

Thanks, Hope someone is out there reading this forum.

hi not experienced this myself but a friend had similar problem with a 94 855 and we found it had very little oil pressure after changing the oil filter and changing the oil (oil added hot by preheating on electric element as hot as poss) and armed with new filter fresh hot oil and a big slave battery it spun over a few times and fired up just fine,i reckon when they get old the hydraulic tappets get stuck open,add to this low oil pressure from either weak oil pump or blocked/clogged oil system and you have a spinning engine unable to retain compression as valves are being held open.
i often hear the tappets on mine for a sec or 2 when starting from cold but i never run it unless i am going to warm it up proper and keep oil and filter fit for purpose,worn gummed up piston rings are not unhear of but do you know how the car ran before current problems?ie was it firing on all 5 cyls?inc the slave battery is what makes the difference as engine spins faster so oil pressure goes up so tappets refill and work,and the hot oil trick,good luck

[scot850]

If you test the compression 'dry' (I.e. no added oil to the bores) and you get low compression or none, then you try again having added say a teaspoon of oil to each bore and there is no change then it is likely there is either a timing issue or you have bad valves.
Adding oil would also help with the 'lawnmower symptom' if it was a piston ring issue.

There is another possibility. When you cleaned the block/pistons and the top of the block, if you got a lot of grime into the gap between the cylinder bores and the piston you may end up with stuck piston rings. I do think this is less likely.

If you have a timing issue, then the valves may be open on the compression stroke so you are getting no reading.

Neil.