timing gear spun??

[Djuhnk]

i have an 85 720 with a z24. this last weekend my truck was idling and then shut off, i tried to start it again and it wouldnt start. the starter makes kind of a faster winding noise now like there is no compression. i put my thumb up to cylinders 2 and 3 and there is no compression, although 1 seemed to have compression. then i thought it was a blown head gasket like a lot of other people deal with, so i proceded to strip it down and take the head off.. got the head off and there is no prob with the head gasket, but when i was in the process of taking the head off, the timing gear was suspiciously loose.. it barely took anything to loosen the nut. the cam gear doesnt have any splines so isnt there a pin that holds in on the right place?

[Djuhnk]

lots of help here in this forum...

bump for anyone who can answer this question.

where can i buy those pins that fit in the cam gear to lock it in place?

[PEZi]

i have no idea how something like this would even happen... maybe the tensioner broke?
as far as finding most things the pins to hold the cam gear in place, as much as i hate to say it i recommend the dealer. there's just really no other place that i would trust

[Djuhnk]

i have no idea how something like this would even happen... maybe the tensioner broke?
as far as finding most things the pins to hold the cam gear in place, as much as i hate to say it i recommend the dealer. there's just really no other place that i would trust

alright thanks for the help, im pretty sure the timing skipped because of the cam gear being loose and the pin coming out. probably the weirdest thing that has ever happened to me with cars..

[PEZi]

that would be a decent guess... but what made it come loose is what would concern me more

[Djuhnk]

that would be a decent guess... but what made it come loose is what would concern me more

the dude that rebuilt this engine did a s*** job, he overtightened 3 of the cam bolts and stripped said bolts out.. i gotta get a helicoil kit now.. great

and he also must not have tightened the cam gear bolt all the way up for some reason. cuz i am pretty sure that is the reason why the timing jumped.

[PEZi]

ah so its due to a s*** rebuild... gotcha

i was under the assumption the inside hadn't been touched and couldn't figure out why this would happen

[Djuhnk]

haha yeah, there is gasket sealer all over the place.. its a disaster

[Djuhnk]

how do i adjust my timing, ive done it before, but there isnt a tdc mark on the crank pully, or any marks on the cam shaft/chain, may have taken it apart a little hasty. i put it back together with piston one and 4 at tdc(or as close to it as possible) which valves need to be open and closed?

[PEZi]

if i recall correctly... you want cylinder 1 at TDC... and there should be little marks on the pulley, you sure oyu aren't overlooking those?

[Djuhnk]

well there is a little bracket that has marks on it, but there is no reference mark on the pulley to line up, so that does me no good, im not too concerned about that though, because i know it is very close to tdc, what i want to know is how to do the cam timing?

[PEZi]

there is some info here about that... let me know if it helps

[noface]

If the cam timing gear bolt worked it's way loose, the gear wobbled around and worked out the dowel pin... the pin is now in your oil pan.

there are marks on both the upper and lower gears. The chain will have TWO links on it that should be different color than the rest of the links... said marks line up with said colored links.

Get a new set now that you've got it torn down. I wouldn't waste my time with a set of unknown condition.

You'll likely have to get a whole cam, as a replacement dowel pin is likely NOT offered.

Or go to your local machine shop and ask for a dowel pin the same size. If they don't have it, they can turn you one out on a lathe. Should be cheap...

[Djuhnk]

the timing chain has very likely slipped past the crankshaft gear. this means i have to take my front cover off right?

knowing that it is at tdc, i could theoretically get the timing right just by putting the chain on when certain valves are open and closed correct?

[noface]

the timing chain has very likely slipped past the crankshaft gear. this means i have to take my front cover off right?

knowing that it is at tdc, i could theoretically get the timing right just by putting the chain on when certain valves are open and closed correct?

yes, you should and will have to remove the front timing cover.

If you KNOW it's at TDC, you might get lucky and get it close. One tooth off with your eyeballs looks good... but runs like crap. Do it right, and take the cover off.

Is the tensioner intact and corrct?

[Djuhnk]

k, wow did not intent to get this far into it.. i guess it is my fault in the first place.

the tensioner seems to be fine. and intact.

[noface]

we've all been there, done that...

well, at least I have anyway! LOL!

did you find a dowel pin?

[Djuhnk]

yeah, i had a spare head including the valvetrain so i just took the pin out of that.

this thing only costed 900 bucks so im tempted to fiddle with the timing.. but its not too much work to remove the front cover is it?

[PEZi]

removing the front cover can be hard... but its not intended to be... the problem is that to do it proerly you need to remove the fan, water pump etc. and i've even heard some people say they needed to remove the sway bar and such as well... don't know how true that is

[MetalFab]

Right there with ya, always get sucked into problems I never wanted to do. The best part though, is overcoming obstacles and coming out the smarter for it. So long as it doesn't squeeze your wallet too tight. >.<

[Djuhnk]

shoot, that sounds like a royal PITA, sounds necessary though. we'll see where i get this weekend...

[flinterman2000]

There is a half moon key that turns the cam shaft when the pulley turns. Getting the front cover off is not hard. To make it easier, remove the radiator, fan and crankshaft pulley. Then remove the bolts on the cover (there should be six bolts I'm not sure). There is one that is in the head to the front of the form around the pulley that also needs to be removed. If you have a clutch type fan then you will needs to remove the water pump also. Slackening the head would also help but is not necessary. Use a flathead screwdriver and pry off the cover. If its only the key thats cut go to a fastener store, it should be in the inventory. If not we'll need to know more to be of any assistance.

[Djuhnk]

well i decided to do it the old fashioned way and make an educated guess on the timing.. i wasnt right the first time but i managed to get it.
it runs, but not very well at all.. ive gone back and forth a tooth each direction on the cam gear and it doesnt get any better, i also tried adjusting the distributor but it only gets worse from where i have it. and last but not least, i tried turning the cam gear 180 degrees just on a hunch, and that didnt work either..

so now im at the point where its got to be something else. it sounds like its running on 2 or 3 cylinders... just replaced the head gasket so i know its not that. maybe its fouled plugs.. any ideas fellas?

[PEZi]

did you do anything with the distributor in the process to where that might be 180 off?

[Djuhnk]

no, i left the distributor where it is at right now. and where it is at right now is where it runs best on my current timing position.

i may have mixed some spark plugs up, and some plugs may have been fouled so i am going to go get some new ones right now.

[Djuhnk]

put the new plugs in, seems to run a little better... still not where it should be.

[flinterman2000]

Yeah. It sounds like an issue with the distributor. Can't be the modules, maybe the rotor or the gap for the laser lens.

[Djuhnk]

bent valves.. in the process of finding the timing the valves i must have f'ed them up. checked the compression before i tore the head off for the second time cylinder 1- 50 lbs, 2- 0 lbs 3- 25 lbs, 4- 25 lbs, i cant believe it was even running...

first of all, i took off the head and it wouldnt have taken a teenage girl to know that my valves were bent. there was a huge gap just looking though the intake and exhaust ports.. so i happen to have another head laying around with perfect valves as far as im concerned, switch out the valves and slap the head back on with the same timing where it was running before i took it off.. started it up and it didnt run that well. switched the timing around 1 tooth to the best running postion and checked the compression.. cylinder 1- 100 lbs, 2- 0 lbs, 3- 50 lbs, 4- 100 lbs. it runs and idles now, but not nearly as well as it should.... i am completely baffled because i know these new valves arent bent. its just so irritating. i even sprayed some starting fluid in the intake side ports just to check, and all the valves were water tight.

if anyone can help me at this point it would be very appreciated, otherwise i am just going to run it like this... i have spent over 40 hours on this thing and its pissing me off

[flinterman2000]

Lack of compression usually means two things. Head job or ring job. 100 is still too low for good performance. If there is no hole in the crown of the piston, then you will need to check the rings to see if they are stuck, work or broken. Hope this helps ya.