Head problem. Valves or timing, help please ?

[johnoo]

Hi
have just finished pulling the head off. had no compression in the #2 cylinder.
Its a 1.6 nubira A16dms engine
The question is - did i take off the head for no reason, did having the intake cam out by 1 tooth cause the #2 cylinder to loose pressure, wouldnt they all loose pressure ?
can a valve be slightly bent if it got touched by the piston when trying to get off the pulley bolt- and show no damage,on piston or valve.
if it is slightly bent would it stick or be a little slower when closing that it shows no compression but seeems fine on first inspection.

There was some oil in the number 2 cylinder (probably happened when taking head off), would a leaky head gasket give absolutely no pressure. If it is the head gasket i find it unusual as all cylinders had good pressure a few months ago and the car was running fine up to this repair.
the metal rings on the head gasket and the block surface look ok.

originally this repair was for leaky water pump.
thought i had probs with the timing due to an incorrectly lined up timing belt- when trying to start the engine it was running rough - it was hard to get going, even though the marks were lined up..
so yesterday i decided to see what happens if i kept the exhaust cam gear as it was, but keeping the intake in the position were there was no resistance, so it was out by a tooth, (originally when lining up the cam gears, intake was at 3 o clock and exhaust gear 9 o clock ) had to use a spanner to move the intake gear a tooth as there was resistance- didnt know if this was normal.
did not start the car, and decided to do a compression test.
wouldnt you know it, there was no pressure in the number 2 cylinder.
Now im starting to think i have taken the head off for no reason except my own stupidity of shifting the belt a tooth.
the only time that i may have hit a valve was when trying to get off the pulley bolt. By placing bricks in front of the wheels putting it in 4th gear, then when trying to loosen the bolt it slipped a few notches of the timing belt.
Did not get the bolt off, but i rotated the crank a little either direction and was not hitting the valves.
But later had turned the crank slowly (to get it in a safe position for the next attempt ) and came across resistance and probably hit a valve, i did not use much force as i was aware the belt sliped a few teeth. could this slightly bend a valve ?

[PrecisionBoost]

Sounds odd that your intake was at 3 o clock and your exhaust was at 9 o clock.... I thought the timing belt alignment marks were usually located at 12 o clock for both pulleys.

Almost sounds like your exactly 180 degrees off on one pulley.... I don't have pictures on this computer so I can't see the procedure and the one put into our how to section is also missing pictures...

http://www.daewootech.com/forum/viewtop ... =19&t=2746

To me.... it sounds like a misalignment and if you did a compression test by turning the motor over with the starter then that is more than enough to bend the valve.

Perhaps someone with the diagrams can confirm the correct alignment when reinstalling the timing belt.

[johnoo]

Checked it out properly, had bent the 2 inlet valves just a touch - took a while to notice it while turning the inlet cam. It just slightly jumps down as it lands on the seat.
The timing marks for the 1.6 litre a16dms engine is as i stated, and this is how it was shown in the manual. both marks face each other.
the valves were slightly bent when i was taking out the pulley bolt and the belt jumped a few teeth.
It was when i turned the pulley left and right to get it in a safe position for the next attempt of taking out the bolt, that it had hit the valve.


nubira 1.6.jpg[/attachment]

[MMamdouh]

Sounds odd that your intake was at 3 o clock and your exhaust was at 9 o clock.... I thought the timing belt alignment marks were usually located at 12 o clock for both pulleys.

this is the correct setup on the 2.0 and 2.2 engines... on the 1.5 and 1.6 DOHC the cam gears should have their marks facing each other... that's the 3 & 9 O'clock setup mentioned above.

Almost sounds like your exactly 180 degrees off on one pulley.... I don't have pictures on this computer so I can't see the procedure and the one put into our how to section is also missing pictures...

http://www.daewootech.com/forum/viewtop ... =19&t=2746

DAMN... since the php upgrade all pics that were originally in the forum's photo album are lost... now this post of mine is practically worthless

MMamdouh

[PrecisionBoost]

Sounds odd that your intake was at 3 o clock and your exhaust was at 9 o clock.... I thought the timing belt alignment marks were usually located at 12 o clock for both pulleys.

this is the correct setup on the 2.0 and 2.2 engines... on the 1.5 and 1.6 DOHC the cam gears should have their marks facing each other... that's the 3 & 9 O'clock setup mentioned above.

I was hoping someone with more experience with small block DOHC would jump in.... I am very familiar with the 1.5/1.6 SOHC and the 2.0/2.2 SOHC/DOHC but not the 1.6 DOHC.

Seems strange that being off one notch would cause interference.

DAMN... since the php upgrade all pics that were originally in the forum's photo album are lost... now this post of mine is practically worthless

MMamdouh

Yes.... it is a pain for me as well... I lost links to a pile of pictures...even my avatar is gone.... I have to talk to Efrain about it as there use to be a root directory accessable by FTP where all the images were stored.

That is to say the pictures still exist, it's just that the pointers to the files have changed.

I'm not exactly eager to spend countless hours trying to manually fix the thousand plus pictures, but I will see if there is some way to resurect the important picutres for the how to section and tech spec section.

[johnoo]

The engine wasnt out by one notch.
The problem occured when trying to take off the 17mm pulley bolt, Since i was loosening it anticlocwise the tensioner must have slackened off, and it jumped about 3 teeth. the timing marks where lined up at that stage.
But trying to loosen the bolt by placing bricks under the wheels,then placing it in gear would cause to much slack before there was tension, so the pulley had turned a fair bit.
Because it jumped 3 teeth and the pulley turned, i didnt know where the timing was anymore,
so i rotated the crank left and right to find the safest midway point before re-attempting to loosen the pulley bolt.
i didnt expect it to hit the valve so soon when doing this, and did not think this would bend the valve as i was slowly moving the crank clockwise and anticlockwise.
The other thing i didnt know was that by rotating the engine anticlockwise would slacken the timing belt tensioner, something i learned on this site, but a little too late.
Taking off the head was a good thing as it looks like the head gasket was on the way out around the number 4 cylinder.

[wolfsreign]

yea.. my head gasket broke apart on cyl #4, next to the coolant hole, and leaked in coolant.
on top of that, A cam can be off by a tooth at idle, but after ~2krpm the engine will start sputtering. and a CEL should come on list the mis fire.
just by some new valves from a junkyard or ebay, just make sure they are the right size, as some engines have been redone if you're not the original owner.
~wolf

[johnoo]

wolf,
yeh same spot on my gasket, must be a heating problem in the head, as my new gaket had 1 of the number 1 cylinder water holes blocked to supply more water to number 4.

got the engine running- but have a ? about setting up the belt tensioner.
I turned the water pump until the tensioner arrow was sitting on the notch, turned the crank pulley 2 rotations and timing marks lined up (though its a little tricky as a valve is either trying to open or close ) and the crank timing mark tries to overshoot the mark.
loosened the water pump then turned water pump anti clockwise so the tensioner arrow or pointer was lined up with the rear pointer.
tightened the water pump.
Problem is i was turning the crank and looking at the tensioner pulley and noticed the tensioner pointer move about 5mm towords the notch.
now when turning crank and it gets to a point where there is resistance due to opening the valves the tensioner pointer matches the rear pointer on the tensioner,
but when the is no resistance turning the crank the pointer moves up on the tensioner.
What is the correct position when adjusting the tensioner.
should it be done when there is no resistance turning the crank- or when there is resistance (valve opening ) .
when i adjusted it there was a little resistance when on the timing marks- (which i dont understand. im beggining to think the marks were placed in this position to make it a pain to work on ).
Also noticed when the 2 cam pulley marks are lined up, the crank timing mark is slightly out about 1/2 a tooth clockwise. is this just poor manufacturing ?
tried a tooth difference either side of the cam gears but the crank timing mark was worse. so i guess it would have to be correct.

johno

[johnoo]

Got her running, but pulsates on idle- but when air con is turned on she idles great , at the same rpm.
check engine light hasnt come on yet.
any clues.

john.

[MMamdouh]

Yes.... it is a pain for me as well... I lost links to a pile of pictures...even my avatar is gone.... I have to talk to Efrain about it as there use to be a root directory accessable by FTP where all the images were stored.

That is to say the pictures still exist, it's just that the pointers to the files have changed.

I'm not exactly eager to spend countless hours trying to manually fix the thousand plus pictures, but I will see if there is some way to resurect the important picutres for the how to section and tech spec section.

i was lucky enough to find the timing belt topic in a MS word document with all pics on my work PC... extracted all pics and uploaded them to my photobucket account and updated the how to topic... also added pics for the special tools required and two pics for doing the job on a nubira/lacetti/forenza (front engine mount and drive belt differences)

MMamdouh

[johnoo]

just checked the ohms on the ignition leads, number 3 lead is broke, now i know why the idle was rough.
strange how these things happen, ran spot on b4 doing work on the engine- carefully pulled the leads out and back in, but somehow had broken !
tried finding an answer to setting up timing belt tension- as in a previous post above i still dont know if the pointer should match with the rear pointer when there is resistance due to cam opening a valve, or no resistance ( no valve open).
the pointer moves back and forth (up/down) about 5mm when rotating the crank. I dont think anyone has noticed this as i couldnt find an answer searching forums.
john.

[MMamdouh]

did you check the how to section article after adding the pics??

MMamdouh

[johnoo]

yeh, all it said was after placing belt and marks in right position- rotate water pump so pointer matches notch and tighten pump.
Rotate the crankshaft two full turns clockwise using the crankshaft pulley. (and i assume until timing marks are in right position as manual doesnt metion this).
loosen water pump-rotate pump anticlockwise until pointer matches pointer and retighten.
thats it,

my problem was double checking the tensioner after doing the above .and since there is no way to get consistant pressure on the right side of the belt when turning pulley to timing mark the results change.
I was thinkiing of jamming the inlet cam gear and using a torque wrench on the pulley- and at x amount of torque adjust the tensioner. But i now understand the original idea as in the manual.
I usually always double check things, and this is 1 case where double checking leads to confusion. I'm an idiot.
it was only when i realized the first step of overtightening the belt was to get rid of the slack in the belt, that it made sense.

i now know the first step tightens the belt to take out slack, and when doing second stage and turning water pump anticlockwise no mistake can be made,
i guess the only mistake that can be made is if you went past the pointer and then turned the pump clockwise again to match the pointer.
there could probably be a little slack on the right side of the belt which would give incorrect reading on the tensioner, so best to start over and go to the notch.

By the way- my timing was out by 1 tooth on the exhaust cam.
idles well now- but now have a ticking tappet. strange ! it wasnt ticking when timing was out.

still -when the cam marks are lined up, the crank is just slightly to the right of the notch mark of the rear plastic cover.
my guess is it was because the head had been machined, which i assume would change the timing if there were no shim installed.
If head was machined and no shim installed should the tensioer be adjusted a little more towards the notch.

john.

[Trey05Woo]

John what you are doing incorrectly is, your leaving the non tensioner side slack and this is causing your timing to be off.

The trick is to set your crank gear about 10 degrees or 1 tooth before top dead center. take some type of pliers (like grip pliers) and use it to lock your belt at the exhaust cam shaft, this prevents it from slack there, pass the belt taut to the idler, then loop it around your crank gear, use your hand to hold the belt in place at the crank gear and turn the crank pulley to the correct mark (#1 TDC) the crank gear will pull the belt taut on the non tensioner side. You will notice it tight from the idler to crankshaft. Afterwards you can adjust your tensioner to pick up the rest of the slack. This may take you several tries until you learn to read the travel required to taut the belt. It should be taut with all the marks lined up. Locking the belt to the exhaust cam will help keep the pulleys from moving while you do this too.

And yes never turn your engine counter clockwise (lefty) your tensioner will completely slack and engine damage will result.

The reason the manual tells you to adjust full right, then loosen and set to pointer is pre-load. Doing this sets the preload or spring effect of the tensioner . If you do not do this, and just set the tensioner to the mark and go, you will have little preload and your tensioner will eventually fail, and well you know what happens then. You can actually tell when the tensioner preload is incorrect. With the engine running you will see the pointer jumping left-right. It should actually point right at the mark and under accelaration pull right (preload) slightly

[wolfsreign]

i just rotated the pump alot so it was easy to be able to slip the belt on, from there, lined up cam timing, and my exhaust always wanted to jump up as the intake down, so i started with holding the exhaust with a big screwdriver against the valve body, not the cover as i didnt want to smash the gasket
then went around tensioner to the crank then up and around the pump, to the auto tensioner and to the intake cam. then rotated the pump alittle to hold the pulleys, took a look at the marks and liked it.
rotated the pump so the auto tensioner points matched, rotated the crank pully 3 times, and looked at the auto tensioner, little off, fixed it. then torqued the pump bolts.
((yes common sense i tightened the pump bolts before i tested slack and stuff, waste of time and lines to add it in every loosen and tighten.))
rotated the crank 3 more times to make sure. and it was looking sweet.
~wolf