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Timing belt? i think so.


bsb1957
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I have a 91 that quit on me today while on the middle of a one lane bridge. Initially i was thinking fuel issue (pump,filter) but once i got it home and started thinking more i thought timing belt. Pulled off distibutor cap and cranked and rotor did not move. Anyone care to comment or confirm? Thanks

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How many miles on the truck? When was the last belt replaced? The rotor is spun by the cam so if it's not moving then the cam is not spinning. Looks like you may have made valve soup. Can you pull the upper timing belt cover and check it out?

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Im doing that now and from what i see so far the belt dosnt look like it totally snapped. I can see and feel that it still has tension at the centre point between the cams.Ive just taken out the top bolts and pryed the cover back a bit to get a peek. Thanks for the quick reply Tungsten.

Edited by bsb1957
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Got the upper cover totally off and the T-belt seems ok, tension is fine, no visible damage. I cranked it over, belt dosent budge. I dont know....cam bearing? Are they prone to seizing? Any ideas?

Thanks

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Hmm... you say you crank it but the timing belt doesn't move? :scratchhead: All I can think of in that case is that it's chunked out the belt teeth around the crank, which is now spinning on its own.

 

Or, the key for the crankshaft sprocket failed/escaped.

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I recall that someones cam walked on them whe one of the retainers failed. Maybe yours did that and isn't driving the dizzy?

I would pull the #1 plug (front passenger, easy to get to) and see of you get piston movement when the belt doesn't move. If so, I'd tear it all apart and look at the crank snout...

 

B

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Are you saying that the belt has tension but the engine cranks over without the belt moving? Your crankshaft might have snapped in half so only the back end of it is cranking. If that's the case, it is the first time I have heard of this happening. It's believable though as the crankshafts are just about the weakest part of the VG30E engines.

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Hmm... you say you crank it but the timing belt doesn't move? :scratchhead: All I can think of in that case is that it's chunked out the belt teeth around the crank, which is now spinning on its own.

 

Or, the key for the crankshaft sprocket failed/escaped.

I was thinking that also.

Are you saying that the belt has tension but the engine cranks over without the belt moving? Your crankshaft might have snapped in half so only the back end of it is cranking. If that's the case, it is the first time I have heard of this happening. It's believable though as the crankshafts are just about the weakest part of the VG30E engines.

Holy Sh#t

I'm sure you will find the problem when you tear it down because no matter what caused it you have some bent valves now! Time for VG33.

James

So its safe to there is no doubt that major damage was done. My own fault as i have been thinking about gettng that belt done for a long time now (if infact it was a belt malfunction). There has to be significant damage as ive turned the engine over a couple of times so some valves and pistons have had to have interfered with each other.

 

Thanks for your time.....ill keep you posted. There may be a parts giveaway coming up.

Edited by bsb1957
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How much of the timing belt can you actually see? If you can see the 2 cam gears and when you crank it that section of the belt does not move, does the crank pulley move???

 

If the crank pulley is turning possibly the timing belt broke but is keeping tension between the two cam gears???

 

If a valve is stuck open the engine will most likely not turn over completely, that is what happened on the engine that was in my pf when I bought it, and I was trying to turn it over by hand, it would get to a point and you couldn't turn the crank any more.

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http://www.mgaguru.c...es/odyssey4.htm

 

Yes, it can happen!

 

crank2pc.jpg

I've seen this happen too but they usually still run. They make so much noise that they make people run too!

 

The point I was making above was the VG30 is an interference motor. It doesn't matter if it was the belt or the key way slipping, if the crank is turning and the cams are not it will bend any valves that are open. The worst thing that can happen is some of the teeth strip off of the belt and it stops turning then bends some valves. Then when you try to restart it, it starts turning again out of time and bends the rest of them. I've seen this happen on an 88 sentra. You know your in trouble when even with a new belt the engine spins over with no compression at all.

James

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I've seen this happen too but they usually still run. They make so much noise that they make people run too!

 

The point I was making above was the VG30 is an interference motor. It doesn't matter if it was the belt or the key way slipping, if the crank is turning and the cams are not it will bend any valves that are open. The worst thing that can happen is some of the teeth strip off of the belt and it stops turning then bends some valves. Then when you try to restart it, it starts turning again out of time and bends the rest of them. I've seen this happen on an 88 sentra. You know your in trouble when even with a new belt the engine spins over with no compression at all.

James

When it initially died my first reaction was...it stalled....try to restart. When it turned over my first thought was that it was turning over a little quicker than normal. Like it had less compression.

Funny thing is the day before my daughter and i drove into the USA for some cross border shopping and we were running around those Minneapolis freeways and just flogging the truck. When it died i was actually in a slow line of traffic on a single lane bridge near town crossing at basically idle speed.

Anyway im going back out to try to investigate some more.

Thanks for the responses guys, I like the sense that im not alone on this one.

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Start looking for a wrecked R50 Pathfinder or a WD22 Xterra. The 3.3 is a great upgrade and you can do it with the factory ECU. All the parts that you need for conversion can be acquired quite cheaply too.

 

VG30E

Bore: 87mm or 3.43in

Stroke: 83mm or 3.27in

 

VG33E

Bore: 91.5mm or 3.6in

Stroke: 83mm or 3.3in

 

The bigger bore block also has thicker walls, a better oil pump, a better oil filter location, a better oil filler neck, a beefier crankshaft, and better head castings. The only thing you want to do is swap the VG30E camshafts over to the VG33E.

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I think I've seen your truck before.

 

But back on topic you could look for a used engine and just replace it with another vg if the frame is solid.

 

I know a guy that has a '91 model that was stolen and rolled into a river. He let it site the entire summer and I believe winter before he started working on it and he acutally had it running with a load of water in the cylinders. He finally pulled the plugs and shoot all the water out. Thetruck still runs (with 280k) but is used as a wood truck now.

 

If you keep up on the oil changes vg's will live a long time.

 

Just too make sure, your positive the starter is engauging the flywheel? Its hard not too notice the valves bending since they make a hell of a lot of noise, along with a crank breaking.

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Yes, a nice oily, coolant soaked mess. Im guessing bent valves are a for sure thing.Can only blame my neglect. What do do next is the question. The body is showing its age,frame a bit too, still had a few years left in her i beleive but i cant see pouring serious money into it. Im not a mechanic by any stretch of the imagination nor do i have a decent garage and to get someone to rebuild or replace the engine may not be worth it.I guess ill sleep on it.

Edited by bsb1957
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100_2114.jpg100_2115.jpg

 

Good old square tooth belts! The teeth get stripped clean off with the square tooth sprockets. I see this happen quite often on square tooth belts. They are extremely sensitive to tension and once the belt stretches out a little the teeth on the sprockets just remove the teeth on the belt clean off. Usually takes a while but this is the reason the square tooth belts have a lower interval than round tooth ones. Although the round teeth are not resistant to being stripped off either! They just last a little bit longer.

 

You can actually upgrade to round teeth if you get another square tooth block:

 

555394_10150932530249075_1499542683_n.jpg

 

251842_10150932529769075_119174551_n.jpg

Edited by Tungsten
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I wouldn't consider bent valves a major repair...or even a hard repair to complete...i broke a TB when i was 18 or 19...bent 3 valves...I replaced the belt originally BC my mechanic friend has seen several folks get lucky and not bend anything but it is extremely rare....I rebuilt the top end with the gf at the times dad in 3 days, including waiting on parts...we dumped like $300 in parts/tools...engine stayed in the truck and really wasn't bad...intimidating yes but pretty easy

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When it initially died my first reaction was...it stalled....try to restart.

 

Don't worry about that, it’s the first thing everyone does. My wife's quest broke the belt at 118k because I was too lazy to change it at 106k like the manual said. When I went look at it the first thing I did was hit the key. You never know till you try!

 

I agree with unccpathfinder, if you don't want to spend much just replace the valves yourself. You can probably find some used valves either here or on ebay. Lap them to the seat with a drill and you'll be good to go.

James

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Well, ive decded to to give this repair a shot. I dont see any thread here on a procedure so if anyone can direct me to one or give me basic idea of where to start and maybe some steps for the procedure it woul be appreciated. For whatever reason dont want to let this truck go . Im figuring that while im doing the repair that i can also do the transcooler bypass with a bigger external. any suggestions as to brands of parts,sources,etc would help. Ive never dealt with Rock auto but i see a lot of there name being mentioned here. Anyway the suns up and im out the door to start. Ill keep posting and if anyone has any comments,suggestions feel free to chime in.

Im figuring first off that ill pull the rad and clean things up.

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