If the timing belt is immediately slipping off when you attempt to start the vehicle, that means that there is a camshaft problem, most likely the shaft bearings or clogged oil channels. If the belt stays on for a time then slips off, that means that the belt may be distorted, deformed, or otherwise defective.
wow, stayon to install, or stay on running do try to be clear. after all we are blind here. DO TELL>
stay on, what might that mean, SEEN THEM ALL< but do say.
I'm assuming you have a VG-30 engine. The timing gears have a small metal ring which is manufactured as part of the gear. It is poaaible to pot the gear(s) on backwards without a fitting problem.
The timing belt during rotation, has a tendancy to want to walk the belt forward towards the timing cover, that is why they manufacture a ring on the outer edge of the cam gear and that is why they put the large washer in front of the crank shaft gear. The rotational force of the engine turning clockwise has an effect which creates the reason the belt wants to walk to the front of the engine. NOTE. these are not free wheeling engines and if the belt comes of while the engine is rotating, they will bend valves. I road race Nissan 300Z'S and have never had a cam lock up on me. Even if some of the teeth were stripped off the timing belt, the belt would stay on. If a cam locked up, it would strip the teeth off the belt, but the belt would not walk off the cam gears or crank gear. One other thought does come to mind. The timing belt tensioner. If it is not applying enough tension, it could cause enough slack in the belt to possibly cause the belt to ride up over the cam gear and fall off. In the 31 years I have been in busness, the only situation I have ever run into where a belt rode over the cam gear was when the bolt that is used to tightenen the tensioner was over tightened and it snapped causeing tensioner to fall off and the belt to come off. There is a torque specification for this bolt. USE IT! If you have had the belt fall off while you have cranked the engine, put the cam gears on as I have described, the large washer in front of the front crank gear, set the proper tension on the belt and then crank the engine. Your belt will not fall off.. Just for grinns, do a compression test on all the cylinders, they should not vary more than 10% of each othe. If they do, you have a problem! One of these items I have described has to be the solution to your problem. I am takeing it for granted that you matched the belt up with the old one to make sure they were the same length. There is an old rule of thumb which was used in the old days (I'm in my 60's)to see if the belt tension was right. Take your thumb and forefinger, put it on the belt and in the center of the longest part of the belt between gears twist the belt, it should not be able to rotate more than 45 degrees. I haven't tried this on the VG-30 because I always put the belt tension to factory specifications and then tighten the belt. Your belt idler pulley should come with a spring on it. With about three plugs out of the motor to ease up the resistance, push the pulley back on the crank (PUT A LIGHT LUBRUCANT ON THE CRANK SO THE PULLEY SLIDES ON AND OFF EASILY.) With the belt in place, timing marks lined up properly the tensioner in place, leave the tensioner bolt slightly loose, just enough to where you an move it wih your hand, in one direction or the other(DON'T MOVE IT MUCH BECAUSE THE TENTIONER HAS ALREADY PUT TENTION ON THE BELT.) PUT THRE CRANK GEAR ON AND ROTATE THE MOTOR "SLIGHTLY" COUNTER CLOCKWISE, ABOUT 5 DEGREES SHOULD DO IT).lOCK THE TENSIONER DOWN AND TORQUE IT TO SPECS THIS WILL SEAT THE BELT JUST A LITTLE MORE INTO THE GEARS.). The timing belt during rotation has a tendancy to want towalk fordard towards the timing cover, if the cam gears are on backwards and that large washer is behind the crank gear, the belt WILL walk off.. I hope I have shed some light on the subject and maybe helped afew others along the way on this subject. If your engine is high mileage and you have bent valves, it may be cheaper to find an engine in a salvage yard with a lot lower milage. They usually will come with a 90 day warranty. Good luck.
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Because you didnt read the FSM. book?
on many engines, the cam gears, most DOHC engines.
must be locked,
and lots of other details most forget , ignore and Fail.
like how to get the tension right????????
is 300zx one engine.
here ill look, Most cars are never 1engine)
i drove a 240 for 1/2 million miles, pure love then.
it is.
VG30E or VG30ET?
my 240 was chain. no belts.
my Gates belts come with instructions, yours missing?
ok , im logged i to alldata.
so can you,.
see step?
11 steps, mine dont show locking the cams. most DOHC you do that.
the cams have bias on them from the valve springs, so not locking
the cams means you fight both cams. a real pain that.
my mazda, 1.8L has hex flats on the cam that i use 2 spanner on
then lock the spanner X crossed with huge vise grips locking both cam cogs to the mark. other engines have no cam hex flats. so must
use a generic cog clamp. (as most shops do)
before touching any DOHC ,i think.
1: all Nissan are interference so get it right 1st time never crank it until you are 100% sure, then check 1 more time. or BOOM.
2: how to lock that cam pair.
so are you saying you cant hold the above 4 marks aligned
as you install belt (you must)
or is it crank,? sparks not removed,? do so now.. why fight engine.
the #1 must be firing, or you will bend over all valves. I promise.
Please Let Me Know How You Make Out or If I Can Help In Any Other Way!
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