1980 datsun 4x4 z2.0 engine question

[1980datsun4x4]

i bought today a 1980 datsun 720 4x4 and im having oil issues im leaking excessive oil out of the bottom of the motor! On the valve cover, the hose going to the carb, fills the air cleaner with oil! there's such excessive pressure it blows my dip stick out of my motor and sprays oil when i plug the breather element hose! it runs good idles a little heavy! the manifold gasket is not blown, there's no oil in my radiator fliud and there's no water in my oil! if any one can think of what may be causing this issue please get back to me asap! Also what year did the first datsun 4x4 came out? thanks soo much crystal:):confused::D:cool::confused::confused::confused:

[datzenmike]

'80 was the first year for the Nissan 720 AND the first year that a 4X4 was available. It was also the last year that the L20B engine was used. '81 saw the introduction of the new Z22 NAPS motor. The Z20 wasn't used in the '80 truck but could have been swapped in. If the intake and exhaust are on the driver's side it's an L motor.

 

There was a dealer supplied 4X4 option for the earlier 620 using Jeep components, but it was not 'factory'.

 

It's possible that the crank case is over filled with oil, but more likely that the motor is suffering from extreme blow by. In other words the rings are not sealing in the combustion and huge amounts of exhaust are getting past and have to go somewhere. The hose to the air filter is meant to let air into the motor but in your case blow by reverses the flow and even pushes oil spray out too.

 

Does the exhaust smoke much?

[1980datsun4x4]

it doesn't burn oil or smoke oil from the exhaust pipe it only smokes because of the oil spraying out of the breather hose and dip stick hole. onto my manifold causing it to smoke from the oil hitting my exhaust headers. could the rings or seal issue be causing oil to apper in my air cleaner housing? it idles rough when first started and runs fine when at higher speeds my motor is out of a 84-86 z2.0 motor it should have been an L20B motor for that year? is that correct? i really appreciate all of your help! my man has a datsun! its a 78 bullet side hes got me hooked on them!

[datzenmike]

Wow. The Z20S was a Milage Option for those years. It had 9.5 compression, a knock sensor, and 3.365 rear gears. Not very impressive performance and people didn't care for them and so were discontinued.

 

Correct, the L20B should be in there. When the Z20 was put in the tranny would have had to be changed as well.

 

Perhaps a compression test would shed light on this. The #1 could be blown into the timing chain area and would explain the blow by.

[dat521gatherer]

i had smoke coming out of the breather and i mean it was like a exhaust pipe coming off my valve cover. people would be pointing at me as i drove down the road with smoke coming out of the tail pipe. on top of that i had massive oil in the radiator but no water in the oil. burned more oil and water than gas and it still ran like a champ. i'll be taking that l16 apart soon, probably has bad rings and a crack somewhere. good luck.

[1980datsun4x4]

upon pulling the head no blowen head gasket no cylinder damage either please help any ideas