Questions and Answers

Datsun 280-ZX Cylinder Head Q. Dear Vince, Here is another question. I have a 1983 Datsun 280-ZX with about 120,000 miles. It is a four speed stick with an in-line 6 engine. This is the 2753 cc six.

I have been told that the reason I have coolant in the oil is a leak in the cylinder head gasket or a cracked cylinder head or block. I am tearing it down to check the cylinder head and replace the gasket. While the cylinder head is off I thought I would have the valves done.

Two questions:
First, I am having difficulty breaking the bolt loose that holds the cam sprocket on. Is this a left or right hand thread. No one seems to know or where to look.

Second, I am interested in knowing if there are any other sources of coolant in the oil that I can check while the cylinder head is off. I appreciate your help sir.

Best wishes, Bill

A. Ahh... the L28E engine. Many a Nissan technician cried when they did away with that engine.

Anyway, I'm glad you got stuck with that bolt and came to me about it. If you took the cam gear off, you would have popped the chain tensioner and then you would have to tear the whole front of the engine off to fix it.

There is a special wedge that goes into the timing chain to hold it in place. You can make one easy enough.

Here's the general shape and dimensions. The angle on the one side should be about the same as the angle of the chain in the tensioner (right) side. I made several from ¾" oak. Put a sturdy piece of rope through the hole so you can pull the wedge out when you are done.

Now make sure you have the engine set up on the timing marks. I put a paint mark on the chain and gear so I am sure of proper alignment when it goes back together. When you are set, drive the wedge inside the timing chain. Make sure it is in good and tight. I give it a couple of taps with a hammer.

The bolt on the cam gear is a regular right hand thread. What I do when the wedge is in place is put a box end wrench on the bolt and bang the other end of the wrench with a hammer. That will break it loose. When you do this the engine will move so be sure to move it back and re-set the wedge in place.

The chances are real good that it is a blown head gasket, but I would send it out to be pressure tested and shaved. That's always a good idea when a head is off the car.