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More issues with datsun 521


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Smoke when going downhill or decelerating is worn intake guides. The high manifold vacuum sucks oil into the cylinder. Oil puffs on start-up or after long idling is exhaust guides. Exhaust pressure otherwise will push the oil out.

 

Oil clouds when accelerating or heavy throttle is from cylinder wear or damage.

 

"my radiator puked out all its water, out of the overflow tube"

 

The motor was severely over-heated. When the motor is shut down the water no longer circulates and the block temp will rise with nowhere to go. In this case high enough to boil up and blow the relief valve in the radiator cap which releases at 13PSI.

 

"the truck is smoking quite badly after not smoking much at all after the first few times I drove it."

 

This is an important clue. New pistons properly fitted have a skirt clearance of .001- .0015in. That's quite small. If a piston over expands, it has nowhere to go and will gall the skirts and score the cylinder walls. They will then collapse and make the motor run noisy from piston slap. The rings also can over expand and may break, distort, or collapse.

 

A simple test would be to remove the crankcase vent hoses from the manifold, plug the PCV valve and judge the amount of blow-by coming from the motor when running.

 

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"Smoke when going downhill or decelerating is worn intake guides. The high manifold vacuum sucks oil into the cylinder. Oil puffs on start-up or after long idling is exhaust guides. Exhaust pressure otherwise will push the oil out." This is kind of my issue, it smokes worst when it gets warm. If I start it up it might smoke a tad, but it picks up drastically when it gets warm. But unless guides go bad from sitting it shouldnt be that issue as the head has had very little miles on it since it was rebuilt it just sat for 10 years.

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"Smoke when going downhill or decelerating is worn intake guides. The high manifold vacuum sucks oil into the cylinder. Oil puffs on start-up or after long idling is exhaust guides. Exhaust pressure otherwise will push the oil out." This is kind of my issue, it smokes worst when it gets warm. If I start it up it might smoke a tad, but it picks up drastically when it gets warm. But unless guides go bad from sitting it shouldnt be that issue as the head has had very little miles on it since it was rebuilt it just sat for 10 years.

 

I am going to check if the intake coolant holes are lining up but I'm 99% sure they are.

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Ok I figured everything out the hard way. Ricks cylinder head wasnt very thorough on their check of the head and they missed some big problems and I had to have the head rebuilt (well mostly rebuilt). Anyway it is all together and running well (needs a rear seal must have been damaged on install).

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