Nissan 720 problem after fresh rebuild

[georgesutter]

Was doing a search online for a repair and seems a lot of good information is coming from this site. I have a 84 Nissan 720 4x4 that has me and two other mechanics scratching our heads. Going to throw this out into the wind and hope somebody has had a similar problem and found a solution. 

 

84 720 4x4. 

Stock z-24 motor with a webber 32/36 on it. 

Full rebuild on the motor less then 2000 miles ago. 

 

*I am loosing coolant at a fairly steady rate. (empty overflow reservoir at 250 miles).

*Filter on valve cover breather has a bunch of mayo type gel in it. Some on the dipstick above the oil line. Below that *it's honey colored and clean. Oil is at correct level (not over filled)

*Some of the same stuff on the oil cap.

*Compression test was good across all cylinders. 

*There is no bubbling or overflowing of coolant with radiator cap off and truck is running.

*Crank case breather is NOT capped off.

 

Pressure tested the cooling system and and there was a slight loss of pressure (not external). Changed the intake manifold gasket with high hopes. It looked to have been reused (cracked and in poor shape). New gasket seemed to fix the problem. 

 

Humidity here is typically in the mid 30's. There is sufficient time for the things to warm up with my daily driving.

 

Searched though the postings so as to not repeat a question/find and answer.

 

Any thoughts or ideas would be greatly appreciated. Have a few people here scratching our heads.

 

 

 

[datzenmike]

Next time the engine has sat over night and is cold, re-torque the head bolts. Do not loosen more than one bolt at a time. Loosen fully and then torque to 60 ft lbs, and only then move to the next bolt. You can do front to back side to side any order you like  BUT only one bolt at a time.

 

Check ALL hose clamps are snug. 

 

Inspect the rad cap rubber seal and the mating surface on the rad. This has to seal tight or it will evaporate the hot water. 

[georgesutter]

Datzenmike, thanks for the quick response!!

I re-torqued the head at the first oil change (250 miles) didn't put that in original posting. Give'er another shot?

Will check the cap and double check clamps.... 

The excessive mayo build up is what has me the most concerned.  Thanks again for the response. 

[datzenmike]

If a fresh build the head torque is good for a year at least. Normally the Z24 blows the HG at 100K miles. To prevent this, the bolts should be re-torqued every tune up but once a year is fine. I suggested it as a hail Mary.

 

That 'mayo' could be gas, oil and water vapor condensing. Are the plugs burning clean? Light tan color?

[flatcat19]

Fuck a compression test. Cylinder pressure differential test.

Compression testing really should only be used to condemn a bad set of rings or sell more diagnosis.

 

 

This will tell you if you have a cracked head/water jacket.

[Draker]

Pressure test the coolant system.. I bet you'll find where it's going pretty quick.

[flatcat19]

Pressure test the coolant system.. I bet you'll find where it's going pretty quick.

He said he did that. No external leakage.

[Draker]

Missed that part...

 

but if it's not leaking outside... well that leaves only one other place it could go. To heaven, clearly.

[flatcat19]

While the rest of the truck goes to hell.