Got it running... then BOOM, tick, tick, tick, tick,etc

[agent4573]

I've been building a sandrail for a while now and finally took it out for its maiden voyage. Ran great for a while then I got the rear end like 3 inches off the ground and as soon as i landed the motor started ticking really bad, had no power, and the vacuum gauge was reading zero with any pedal more than idle. The drivers side timing belt cover was cracked and the belt has a nice tear down the center of it. There are also some holes in it when you look at it from the inside out. This belt has about 30 miles on it, and maybe 45 minutes of total running time. I'm pulling the crank pulley off tomorrow and hopefully will find the culprit in the lower timing belt cover, but this just sucks. I may be in the market for a twin turbo complete setup soon.

[Ziggy1621]

Possibly, something fell in the crank cover and got sandwiched in at the oil pump. Sucks!

[t.mcginley.jr]

Agreed, it definitely looks like something let loose and then got wedged against the timing belt. I can't think of anything else that would come in contact with the belt normally

[agent4573]

Found this little guy pretty beaten up and sitting next to the crank pulley. I don't think I've ever seen it before. It also appears that the drivers side exhaust cam jumped a tooth, the other 3 still seem to be where they're supposed to be. I thought I had my old belt laying around and was going to re-time it and give it a compression check, but it looks like that's not an option right now. Can anyone tell me if having the exhaust cam off a tooth is a death sentence for the valves? It sure sounded like it, but I just want an idea before I spend more money on another belt. Thanks.


EDIT: The exhaust cam was retarded a tooth. The ticking I heard may have just been a huge "exhaust leak" but it may have been 3 bent exhaust valves as well.

[Ziggy1621]

That's a washer. I can't remember right off where it went, but there are 2 or 3 like that. Too early in the am to dig that deep in the brain

As far as the valves, better safe than sorry. Check them out

[J30tChumpCar]

Just toss the old belt on and start it up, any damage will be apparent at that point without all the hoopla of a compression test and such.

[agent4573]

Is there a way to check the valves without pulling the head?

I can't find the old belt or I would put it back on. I gave to order a new one to try. I'm just trying to avoid the cost of a new belt if the motor is shot. Its not worth fixing the head as replacing all the valves and machine work will be about as much as a running junkyard motor. If the valves are bent I'm just going to get a new motor

[J30tChumpCar]

Honestly the quickest way to asses a engines condition is to run it, you will need a new belt for whatever engine anyway, saying that, just re-time the damaged belt and run it for only a few minuts.

[agent4573]

You make a convincing point, even if I go with a junkyard motor, a new timing belt would be going on it. I'll order a new one now and post an upate in a few days when it gets here and gets installed.

[twinturbozxtacy]

if it only jumped a tooth youd be ok. i have had a few pulleys off a tooth before, even the crank pulley off by a tooth, valves were all good when i did the head gaskets. now if the crank jumped a tooth and the exh jumped a tooth then you might be in some trouble.

[t.mcginley.jr]

You can usually tell if there are bent valves using just a leak down test. Since you are basically filling the cylinder with compressed air, any bend valves will leak like mad. Assuming your engine had decent compression before this, then any leakage above 10-15% is probably from bent valves. They rent leak down testers at AutoZone I believe.

And for those who don't know what a leakdown test is, you basically just thread a piece of air hose into the spark plug hole, connect it to a set of gauges, then connect the gauges to your air compressor and like magic it tells you how much leakage that cylinder has. Under 10% leakage is great, 10-15% leakage is ehh OK, greater than 15% is usually pretty bad. Easy way to tell things like bent valves, bad/clogged valve seats, bad headgasket, etc. Also make sure the cylinder you're checking is at TDC using a long screwdriver or something.

[J30tChumpCar]

You potentially risk doing damage trying to turn things to tdc of each cyl while the belt is off, replacement of the belt with everything in time is when you can do testing, or just hit the key and see.

[t.mcginley.jr]

True, I didn't think about having to turn it lol. I'd imagine you could still do a leakdown test without turning each one to TDC but whatever you choose to do, let us know what happens

[agent4573]

I turned the motor over with a breaker bar to TDC before I removed the old belt. Its just easier that way for when the new belt comes in.

[agent4573]

New timing belt came in today. Fired it up and everything sounds good. I'm so freaking stoked it didn't tear up the entire head. I did manage to install the crank pulley at a 30 degree angle and didn't realize it. Made some interesting noise until I figured that out. It somehow got caught up on the keystock and tightened down at an angle. Anyway, it seems to be all good to go now.

[nissanfreak12]

If you have the belt off and all the valves are closed, you will have zero issues moving the crank to get the piston TDC, it will cause no damage. This I just wanted to put for future reference in case someone saw this and and was looking for an answer.

Agent4573- glad you got it all sorted out, I bet its a blast in a sandrail, even more fun if you can get a TT setup in there.

[J30tChumpCar]

Sweet

Nissanfreak, at no point are all the valves closed unless one was to remove all 4 camshafts, never rotate a assembled VG30DE without a timing belt!

[nissanfreak12]

Sweet

Nissanfreak, at no point are all the valves closed unless one was to remove all 4 camshafts, never rotate a assembled VG30DE without a timing belt!

You sure about this? I have been able to a few times with the timing belt with ill effect. Think about it, when you have the belt off and accidentally the cam gear snaps back out of time and you have to wrestle it back into place? Before you put it back into place it should have a a very slight movement where there is no resistance on the shaft, that is because there is no valve is pushing on it. That is when all the valves close for that camshaft. Does it mean its in time, not at all. But its safe to rotate with out the belt, there is nothing that it can hurt AS LONG AS WHEN YOU FEEL RESISTANCE DO NOT PUSH THROUGH. That is all, if you don't feel this is true, then don't do it. Use your judgement. If you force anything it will cause damage.

[J30tChumpCar]

You are correct, it takes a understanding of what is going on and going to happen if one were to push a little too hard or perhaps accidentally hit the key when out of time, damage free rotation is possible but not recommended for those with less experience.

Saying that, there is no point where ALL valves are closed.

[twinturbozxtacy]

You are correct, it takes a understanding of what is going on and going to happen if one were to push a little too hard or perhaps accidentally hit the key when out of time, damage free rotation is possible but not recommended for those with less experience.

Saying that, there is no point where ALL valves are closed.

yes not all valves are ever closed, if you have pulled a head you know. that being said they are not open that much either, in fact probably just enough to sneak past a rotation by sitting in the valve cuts in the pistons...