Our Community is 940,000 Strong. Join Us.

Major Timing Prob Plz Help!!!

04-26-2008, 02:00 AM
Ok so my car 90 300zx n/a needed a new timing belt. so me and a buddy take everyting off spark plugs timing belt cover radiator fan, belts inlet tubes for the wp, etc down unto the timing belt itself. so we mark what we thought was tdc, later to find out its not. so we have to forget about the marks we made. to make matters worst we didnt mark the exhaust cam on the drivers side or the crank shaft. as we were taking off the belt the drivers side exhaust cam came to a rest....... pretty fast. i dont know if that hurt anything. so after two days of trial and error, we get the stock "marks" on all the cams and crank matched up with the back plate, and we get all the marks of the timing belt lined up spot on with the stock "marks" on the gears. made sure the the #1 cyl. was tdc put things back together and whamo, nothing notda. All it does is crank really really fast. It started for like maybe 3 seconds in which time i possibly set the new world record for the shortest celebration, but then it died. Im thinking that the fast cranking may be a sign of advanced timing??? i just dont understand. I checked out the tz dallas thing you guys gave me a ;link to, i actually printed it out and used that and the z manual but nothing, i have found out alot... but not enough to start the car... did i f*** it up??? please help!!! please!. pictures would help. We have the belt facing the right way all lines lined up tension is pretty tight. there any tricks???
please help!


04-27-2008, 06:04 PM
Start checking the basics: spark, fuel, connectors, etc.

04-27-2008, 11:02 PM
yeppers everything is tight. on connected i know how these cars can be about that.
on the crank pully i noticed a mark and the little ^^^^^ thing on the timing cover that has 0-30 on it what is that for? does the car need to be tdc on cam 1 for it to start??
i feel like a big idiot for doing this....
oh and does the car have like a natural reset thing?? will it put its self back in time if its slightly off?

04-30-2008, 06:12 PM
Unfortunately, it will not put itself back in time. . .

the little ^^^^^^ thing you are describing sounds like the timing marks for the ignition. (that's something else to look at-- is the ignition timing still correct)

Do a compression test on the engine-- it's possible you bent a valve or two (or 24) rearranging the crank and camshaft timing. Did you loosen the rockers before you moved the crank or the cam's and if you did, did you remember to tighten them back after the belt was installed?

05-01-2008, 03:05 PM
well when we first took off the belt we only marked the top two cam gears. like idiots we didnt mark anything else so that was our first problem. we didnt loosen the rockers and when we would rotate the crank we didnt rotate it hard and if it gave resistance we would stop. my worry is when we put the new belt on and things werent right i bent a valve. that would cause the car to not start right?? well we got everything lined up spot on and tried it. i smelt gas and we took the spark plugs out and they were covered with gas as well as in my intake. i got new plugs and tried it just a little bit ago with no luck. The marks above the crank that you said were the ignition marks what do they need set on?? im pretty sure its flooded and i took all the plugs off and intake tubes off and put a brick on the gas to let those air out. Im probably gonna have to tear the engine apart arent i? man that sucks. i think its in time now because it doesnt crank as fast as before, but that could be my battery dying. im so stupid to have even attempted this...:banghead:

05-03-2008, 10:01 PM
Don't go falling down the hole of beating yourself up and feeling bad, doesn't get you anywhere.

Pull the timing belt covers and re-check all of your timing marks. Bring the number one piston up on TDC and count the cogs. The marks on the belt won't be lined up any more because of the unequal distances between the pulleys but the number of cogs between the points will be the same. Do a compression and/or leak down test. Preferably leak down. You can usually rent the equipment from a local autoparts store. Double check all of the injectors, plugs and connections. If you can get it to idle, check the timing, base timing should be 15 degrees.

05-13-2008, 03:37 PM
well got some good news and bad i think.
We finally got it to start i dont know what we did differently then before but... Maybe if you take the belt off and put it on and all back together like 73 times it will start for you...
lol well anyway, the bad news is it started but sounds like sh*t. you can hear alot of chattering on the drivers side intake like the sound of valves. and the drivers side exhaust is crackly and it wants to stay at about 2000 rpms when i give it gas it cracks and sputters... are those signs of bent valves??

05-15-2008, 02:17 AM
Do/get a leak down test done, that will tell you if there has been valve damage. Did you make sure the timing belt tensioner is with in the specified range?

05-17-2008, 09:19 AM
it looked like it was right. it was opened about 4mm.
ok so on a leak test what exactly do i do?? i have never done one.

05-20-2008, 12:16 AM
It does take some equipment, if you can't rent it you'll have to get to a local shop that can do one. Compression tests have their place but for diagnosis purposes I prefer the leak down test.

Basically what you have is a tester unit and an air compressor. You put air into the cylinder and the tester measures how much leaks out. If you have a bad set of rings, a bent valve, torn up valve seat or whatever you'll see a big leak. And you'll be able to hear where it's leaking from, like air from the exhaust with a bent exhaust valve or out of the dip stick with some blown rings.

Here is some reading:


05-21-2008, 03:10 PM
Thanks n i will get on that as soon as i have a day off from work. And i will let you know!
youre awsome , and thank you for the help.

05-22-2008, 01:18 AM
I'm only trying to repay a terrible debt to society.

Add your comment to this topic!