Argg :mad:

[Pomorza]

Hello all

So I bought a 280z (1976) back in August. Since that day I've had random ticking coming from the engine bay when driving for an hour or more. So like everyone advised I went and had my valves adjusted to the specs. Sound didn't go away. So I took it in again and they found that the exhaust manifold was loose and tightened it down. This made the sound slightly less audible but still there.

So here's my concern. The best and only way I can think of describing this sound is its injector tick but really loud. By loud I mean LOUD. At 85mph with the windows open I can still make it out over the engine and other sounds.

I ask this as this past Friday I drove down to Tombstone to visit. The drive took about 2.5 hours through the winding mountain roads of s. Arizona. Temp today was about 70 or so where I was. The engine temp needle never even reached the midway mark. To be exact it sat 3/4 of the way between 120 and the midway mark. (so like 170 maybe?). Anyhow about an hour into the drive the ticking begins. Its fairly constant and increases/decreases with engine RPM.

So here is my question to you all. What exactly can cause this sound? I mean it sounds like very loud injectors so can the injectors just be very loud due to engine heat or something? I'm at a loss here and it very agitating to drive with this ticking noise. (as I have no radio)

Any advise would be great.

Jan

[Mr Camouflage]

Hello all

So I bought a 280z (1976) back in August. Since that day I've had random ticking coming from the engine bay when driving for an hour or more. So like everyone advised I went and had my valves adjusted to the specs. Sound didn't go away. So I took it in again and they found that the exhaust manifold was loose and tightened it down. This made the sound slightly less audible but still there.

So here is my question to you all. What exactly can cause this sound? I mean it sounds like very loud injectors so can the injectors just be very loud due to engine heat or something? I'm at a loss here and it very agitating to drive with this ticking noise. (as I have no radio)

Any advise would be great.

Jan

Exhaust gasket leak at the head. They tightened the nuts up which may have cured it temporarily, but the leak may have damaged the gasket. The hot exhaust gasses may have burnt it away some. I had the same problem on a Turbo Z31.

Have the gasket replaced with a new one.

[IdahoKidd]

I'd concur it is an exhaust leak. Check the manifold for a crack. As it gets hotter, the crack expands. Also look at the exhaust manifold bolt closest to the firewall (where the rear engine lift would be). That bolt is broken on three of my cars and one of them leaks there. Look for a black exhaust soot sort of mark. Here in Idaho I just run studded tires and you can't hear the exhaust leak anymore

[Pomorza]

Ok thank you guys. Now to ask, other than causing the ticking noise can these leaks lead to any problem such as warping or anything? I mean I want to get it fixed but money is a bit...tight at the moment as I just fixed the drive shaft and tranny mount.

Jan

[IdahoKidd]

Probably nothing serious. It is always a good idea to have the manifold trued when you reisntall it so that if fits flat, but beyond that, just irritating. Keep in mind it could be something else, but my bet is on a crack or a loose bolt, a hole in the exhaust gasket (something exhaust related)

[JimmyZ]

Have you had a mechanic with a trained ear listen to it? I could tell you in a few seconds if it was a spun con-rod or main bearing... I'm in Florida though. The sound they make is more on the "thud" end of the spectrum rather than "tick". Con rods are a lttle more "tickey" and tick at twice engine speed. Pulling up to an engine rebuild shop and having one of them listen would be the ticket.

If the leak is an exhaust issue then you should be able to place your hands near the exhaust and feel the air pulsations. Just rev it a bit and do it when the engine is cold so you don't burn your hand(s). Exhaust leak sounds are more like an anoying popping/whiffing sound rather than a "tick".

You have verified that the coolant is filled to the proper level right? Z's temp guages can be deceiving when you have low coolant. Ask me how I know these things. The engine noise increases when coolant is low.

Jim

Edited December 19, 2009 by JimmyZ

[Pomorza]

Jimmy.

The coolant level is great. Its actually a bit higher than it should. (as its above the "full" line). As for the sound. From all my snooping around with a stethoscope it is most definitely coming from the injector side of the engine. I haven't had a mechanic hear it but to be really honest to you it literally sounds like an injector "tick" but about twice the amplitude. The sound also "tends" to match the pulsating in the fuel rail. (or that is what it really seems like)

I'm leaning on an exhaust leak of some kind or injector(s) problems as I'm pretty sure that a spun bearing or connecting rod problem would occur at all engine temperature wouldn't it and not after driving for nearly an hour? I just drove the car to pick up a friend (drove for about twenty minutes) and no ticking at all could be heard unless you pop the hood and get close to the injectors.

I'm trying to be as descriptive as possible but its a bit hard over the net. But I hope this helps with the diagnosis.

Jan

[oldhemi]

I am thouroughly unfamiliar with fuel injection, so take what I say with a grain of salt. How about pulling the spark plug wire on the suspected cylinder that is ticking? I would think that a no-fire condition would lessen or eliminate exhaust noise thus indicating an exhaust leak rather than an injector tick. If the ticking does not go away, try the nearest plug also. I am not sure if you could also try disconnecting the injector electrically because I know nothing about this fuel injection system. I would try this once the ticking really starts going. Should not hurt anything if you are only doing this for a short time.

[FastWoman]

Yeah, I agree that it's a broken exhaust manifold stud or a blown out piece of exhaust gasket material. That happened to the 318 in our boat. It sounded like a valve problem, and my immediate thought was "Oh no, I'm going to have to rebuild a head." (It really sounded bad.) However, a bit of poking around quickly revealed the problem. The sound was apparently from the manifold tapping against the head with each exhaust stroke. Obviously it got louder as the engine was put under load.

If you do have an exhaust leak, it can erode material from the head and manifold over time, and if you let the leak get bad enough, you'll have a possible carbon monoxide or fire risk.

[JimmyZ]

I am thouroughly unfamiliar with fuel injection, so take what I say with a grain of salt. How about pulling the spark plug wire on the suspected cylinder that is ticking? I would think that a no-fire condition would lessen or eliminate exhaust noise thus indicating an exhaust leak rather than an injector tick. If the ticking does not go away, try the nearest plug also. I am not sure if you could also try disconnecting the injector electrically because I know nothing about this fuel injection system. I would try this once the ticking really starts going. Should not hurt anything if you are only doing this for a short time.

I have a 240 but I believe that on a 280Z there is risk of damaging the ECU if you try unplugging spark plugs while running. One 280Z owner told me this and I think I may have read it in the manual.

I'm sure SBlake would know.

[Pomorza]

Ok here is a bit of an update. I drove the Z in the mountains again this past Saturday. The drive took about 45 minutes. About half way there the ticking started. (). But as advised I just drove on my happy way ignoring it. Parked the car and left for oh five hours or so. Came back and did the same drive (exactly just up hill) and long and behold no ticking...none nada.

So upon arriving home I popped the hood and began to inspect around the exhaust manifold. There "seems" to be a bit of a brownish haze along and above where the manifold meets the head. Didn't get to touch it as the engine is still hot. Did notice that the valve cover gasket it saturated with oil, weird, its new.

A number of reason why I'm leaning on an exhaust leak. (please feel free to advise on these). First when driving there is a fairly constant smell of exhaust when cold. Secondly when, say I'm going 55 (or any speed above 40) and I release the throttle for a few seconds and then reapply the throttle a fairly nasty smell of exhaust fills the cabin momentarily.

Let me know if this helps in you diagnosis.

Jan

[FastWoman]

Well, if it walks like a duck, acts like a duck, and quacks like a duck....