Engine knock!!!

[anthony280z2+2]

I recently took my 78 280z for normal weekend drive from Los Angeles to Anaheim then back.it was about 40 miles back and forth. The car had no problems but once I exit the freeway I heard a knocking sound but wasn't sure we're it was coming from.when I got home I checked and the sound was coming from the engine,the sounds come from the last cylinder or by the timing chain.i always check my oil before any long drive, the car was fine before that and even with the knock I haven't notice any power loss or noticeable at least. How bad can this be? Haven't had time to open the valve cover but will as soon as I have a full day to work on it.Any ideas?

[grantf]

do you mean the first cylinder the one closest to the front of the car? I would at lest take off the valve cover and take a look just to see if every thing is in order. With the cams pointed up there should be some play. I would also check timing. The term knock sounds vague to me.

Edited July 9, 2012 by grantf

[d240zx2]

Is the "knock" more of a ticking sound or more gutteral?

[motorman7]

If it is internal to the motor, you will have a bit of work ahead of you. Could be a bad rod or crank bearing. You may want to check your water pump. Once thought I threw a rod bearing in my ‘70Z only to find out it was a bad water pump bearing.

[Gary in NJ]

Does it only happen under load or is it there all of the time?

Can you hear it on a train, can you hear it in a plane? (sorry, I just had a Dr. Susses moment)

[anthony280z2+2]

Opened the valve cover and found that the first valve spring(next to timing chain) was missing the valve keepers that go inside the retainer were missing. The pieces were next to the spring. How bad is this.

[grantf]

Well theres yer problem. Can you show pictures? If you are lucky you did not bend a valve. I am not an expert on the valve train. I wonder if there is a way to find out without pulling the head.

[anthony280z2+2]

I was trying to figure out how to fix this broken valve keeper without taking off the head and I came across a complete l28 engine that was recently rebuild. The guy wanted 350 for the engine but the engine from a 76 280z, and my car is a 78, would that matter if I swap it. The price seems great, but I'll ask questions about the engine before anything

[grantf]

350 for a rebuilt engine is a great price, BUT do you trust it and who rebuilt it? How well was you engine running before you lost the valve keeper? just a thought.

[anthony280z2+2]

My engine was running strong for the amount of miles it had. Just had my fuel pump

Replaced by mikeZ in Whittier, and he said my car was still real strong.

[Zed Head]

The 78 N47 cylinder has exhaust liners in round exhaust ports, but otherwise is essentially identical to the N42 head,with rectangular exhaust ports, on the 76 engine. All of your 76 pieces should bolt n to the 78 engine.

There are tricks to working on the valves without removing the head, involving hose or rope jammed in to the spark plug hole or compressed air to keep the valve from falling in to the cylinder. You'll need a valve spring compressor also. I've never done it but apparently it's not super difficult.

Are you sure it was the keepers and retainer that you found or was it the lash pad? Without the keepers I believe that the valve would fall in to the cylinder unless it was jammed closed from bending or binding.

[anthony280z2+2]

You're probably right, it's one of the keepers and the lash pad.is the lash pad were the lever sits on. Sorry don't know to

Much about the names.im gonna ask around my area of mechanics to see if anyone has ever done what zed mentioned.