louden11

My 86 max sheard the pin on the crank so I replaced it and the timing belt now it still won't start. could it have bent valves or busted a piston? I have not looked & I don't know alot about these motors.
Is this motor an interference motor?

MaxWgn

iTrader: (1)

By your description, I assume you mean the tensioner stud, that holds the tensioner to the block is what broke. If this is true, then yes, you very likely have some serious internal damage. Depending upon how fast the engine was running when the stud broke, you could have as little as some bent valves, requiring R/R of the heads, and a complete valve job, with new valves of course, all the way to cracked pistons, and/or damaged heads, requiring total head replacement, and new pistons.

The fact that it won't start could also be from not getting the timing belt properly installed, or not getting everything hooked back up from the timing belt change.

What does it sound like when you try and crank it? does it even try and turn over?

louden11

The timing belt is in time and it turns over very fast.
The pin that sheard is the one that holds the timing belt gear to the crank.

MaxWgn

iTrader: (1)

Ah, the Woodruff Key...yes, it still could have caused impact inside the engine. That key, of course, prevents the crank sprocket from freely spinning on the crank. If it sheers off while driving, the cams will slow down, while the crank continues to spin, allowing the valves to collide with the pistons.

Again, if the engine was running at a slow enough speed (ie, from idle to about 1000 to 1100 RPM) it's possible no damaged was done...

If the engine is turning over, check for spark, and fuel delivery.

louden11

It was running at about 35mph can't remember what rpm but was not being raced. Thank you for your help.

alllw86

Wow , that key sheared off! Usually a tight fit, wonder why?

I was getting on the freeway rounding an on-ramp going under 15mph when my T-belt broke some tooth. Cam seal was leaking oil onto it. Got 3 bended valves, but replaced them all. Did the work myself, good learning experience, ha.

Do a compression test of the engine since you say the work was done right.

Good Luck

Al (86se)

GundamWZero

Have any luck getting that cam off? I had a heck of a time triyng to fix that (Maxine and I are in a cease fire; I took a impact wrench to the bolt on the camshaft pulley and tightened it with that)! Don't do what I did, though! You will have to rent a bolt puller, a tap and die set, and but another pulley and Woodruff keys (I still got those keys) to do the job right. Once you drill into the old camshaft sprocket to tap and put in the bolt puller, it is no longer good. And a gear puller won't help either. The sprocket comes too close to the engine block.

dr.disc

I have seen harmonic balancers wallow out their keyway, and I have even seen the front end of VG30 crankshafts break off. Your woodruff keyway has to fit snug or you need another crankshaft.

You have to do a compression test to see if your valves were damaged.

I lost one timing belt at idle in the driveway on one Maxima (my first one I had only had for a couple of weeks) and I put a new belt on it, but it had bent a valve, so when I started it up, it ran terrible, broke off a bent valve and swallowed it, which thoroughly killed the engine. All in my driveway at idle. That is why I put a replacement engine in that car out of a 300ZX.

I have seen broken pistons, stretched rod cap bolts, and damaged cylinder head castings out of timing belt slips on VG30 engines. I buy cars from people who don't do preventative timing belt changes for $300-400 every now and then. It is a good source of bodies.