D21 vg30i 1986 timing belt moves one tooth

[josuetrejoreal]

I bought a Nissan d21 vg30i 1986 4x4, manual transmission and only include the cylinder head but all ready refurbished (I don't know if they do it correctly). So I bought another vg30e 1995 engine autom. Transmission at a junkyard. send the engine block to the machine shop whit new set of Pistons and rings, to be honest I buy all the autoparts from ebay, valve lifters, ceramic clutch kit, engine gaskets kit, water pump , timing belt kit, and many other parts....


Changing the belt tensioner, the water pump, and the timing belt, and getting it in perfect condition was no problem. The real nightmare began when I manually moved the crankshaft pulley to make sure everything was in order. I manually rotated the crankshaft pulley a full cycle. At this point, when I aligned the belt marks with the pulleys, they had shifted one tooth on both pulleys. I performed another cycle with the same result. Then I completed another cycle in reverse, giving the same results: the marks had now shifted one tooth on both pulleys. I was able to verify that not only was the belt moving, but the engine was also out of sync with the timing belt, as the belt shifted one tooth each time it completed its revolution.


I updated the timing belt and the pulley set and the crankshaft pulley, from the square to the circular ones. The result was the same.


I confess I'm at a crossroads due to what were probably bad decisions on my part. I didn't use the valve head from the VG30E engine because when I disassembled the engine, I could see it was in very poor condition. What must have been oil at one point was a completely hardened black sludge that couldn't be easily removed. It was clear there was serious wear from overheating on the valves and camshaft. Without hesitation, I opted for the valve head (VG30i) that came with the pickup truck. I don't know if the machining shop that took the valve block that came with the pickup, may have planed it outside of its maximum tolerance and reduced it excessively and that caused the band to become out of phase, honestly the timing belt was always adjusted according to the standards of the maintenance manual, at no time did the belt jump or be loose enough to jump from one tooth to another, all of this is very confusing and frustrating to me. I don't know whether to buy another valve head or buy another complete engine and this time not separate anything, any idea what could be happening?



Cambie el tensor de la banda, la bomba del agua, la banda del tiempo, sincromizar la banda y ponerla a punto no fue problema, en donde realmente empezó la pesadilla fue al momento de mover manualmente la polea del cigüeñal para ver qué todo estuviera en orden. Gire un ciclo completo manualmente con el maneral, llegado este punto, al momento de alinear las marcas de la banda con las poleas, se habían recorrido un diente en ambas poleas, realize otra vuelta con el mismo resultado, después complete otro ciclo pero de manera inversa, dando los mismos resultados, las marcas ahora habían regresado un diente en ambas poleas. Pude comprobar que no solo la banda se movía, el motor también se desfasaba del tiempo, conforme la banda se desplasaba un diente cada que completaba su ciclo de vuelta.


Actualize la banda del tiempo y el juego de poleas del bloque de válvulas y la polea del cigüeñal, de la forma cuadrada por las circulares. Dando el mismo resultado.


Confieso que me encuentro en una encrucijada debido a lo que problamente fueronalas deciciones malas de mi parte.


No use la culata de valvulas del motor vg30e ya que al desarmar el motor, pude ver qué se encontraba en muy mal estado, lo que en algún momento debió de ser aceite era una sedimento negro completamente endurecido que no se podía quitar, de manera sencilla, resultaba claro un serio desgaste por sobre calentamiento en las válvulas y el árbol de levas. Sin dudarlo opte por user la culata de valvulas (vg30i) que venía incluido con la compra del pick up.


No sé si el taller de maquinado al que fue llevado el bloque del válvulas que venía con el pickup , habrá cepillado fuera de su tolerancia máxima y lo haya reducido excesivamente y eso haga que se desface la banda, honestamente la banda del tiempo siempre estuvo ajustada conforme a los estándares del manual de mantenimiento, en ningún momento la banda brincaba o quedaba floja como para poder brincar de un diente a otro, todo esto me resulta muy confuso y frustrante.. no se si comprar otra culata del válvulas o comprar otro motor completo y está vez no separar nada., alguna idea de que pudiera estar sucediendo..

[Slartibartfast]

Do you feel/hear the belt jumping? Unless there's debris between the belt and the crank sprocket, I doubt it's actually slipping. I've turned a VG over on a stand with the belt barely tensioned at all, without issue. And if it was loose enough to slip, I doubt it would be polite enough to only slip a single tooth at a time.

 

Are you looking at the paint marks on the belt? Those marks are for inital setup only, and they are not meant to line up again afterwards. I don't remember offhand how many teeth are on the belt, but I suspect it would have to go around quite a few times before the paint marks lined up with the sprocket dimples again.

 

The important measurement is the tooth count between the cam and crank dimples. If you're at 40 between cam dimples, 43 between the driver's cam and the crank, and you turn the crankshaft two full revolutions, and you're still at 40 and 43, then you're golden.