Since I bought this car (1990 GXL N/A rebuilt engine - 2500 miles), I've noticed a ticking noise - more of a peck - coming from under the hood when the car is idling. Clutch engagement does not affect the noise; it is definitely coming from the engine compartment. I can only detect it when the car is idling at rest, otherwise, the road noise and engine rev interferes.

What is this noise? Because I'm very inexperienced with rotaries, things like this make me a little nervous - always hearing 'worst case scenario' horror stories from 'Prideful Piston Soothsayers'. I must say, the sound reminds me a lot of a pecking valve in a piston engine - peck-peck-peck (3/4 times per second). I've searched the archives and can't find anything that makes me feel better about this. Any bumps would be great. Thanks in advance...

 

Fuel injectors maybe?

 

I read that in another post... I also read something about TPS, loose plug wires, bad spark plugs, solenoids, etc. - a host of electrical issues... Then, there was an injector idea. Something about injectors clicking, some normal, depending on the brand, and others when they were about to fail. Like I said, I'm blind on this stuff at this point. I'm trying to learn. If it is the injectors, how might I test that hypothesis?

 

its your fuel injectors...you should be able to hear them but it shouldnt be TOO loud...it shouldnt sound like bad lifters in a piston motor...just a soft patterned ticking

 

The FSM has you listen to the "clicking" sounds with a stethiscope-type device to verify correct injector operation, I hear mine every now & then

 

does it do it constantly? if so, go stick your head under the hood when the car is idling and find out where it comes from.

 

I'd say he's got a loose or damaged plug wire...

 

That's a pretty good guess.. but pretty uncommon. Make sure the wires are on tight- spark plug arcs make a surprising noise!!

Take all the belts off (or just loosen them enough so that they are just hanging loose) and start it up again. BUT DO NOT LEAVE IT RUNNING FOR MORE THAN 10-20 SECONDS, since the water pump will be disconnnected.
See if it still clicks, at least you can rule out the most common causes- the accessories that turn....and the belts that drive them.

 

Does it tick when the car isn't on?
Something on the passenger side of mine ticks when the cars not on. And also when it is on, I think...

 

run the car in the dark with the hood open, if it's a spark-ark, you'll enjoy the show

 

No sparks in the dark... And no ticking while the car isn't on... It was a bit warmer during the day here today, so I drove home from work with the window down and payed extra close attention to the noise. The sound was very noticable, but it wasn't exactly loud. Analyzing it deeper, I watched the second hand on my watch, and i counted 4 pulses per second. And, if it helps, the sound didn't strike me as much as a tick or a peck today... More like a lack. That may 'sound' silly (no pun intended), but I have very sensitive ears with pitch. Good for recognizing good music and timbre, but terrible for dealing with everyday, annoying sounds. I just can't imagine a 'lack, lack, lack, lack' every second being an electrical spark or arc. The sound has a 'tinny' component - maybe like metal on alloy or alloy on alloy. It really sounds like it's coming from a pump that needs lubricating. Does that make any sense with a rotary?

Just thought I'd send out an update on my observations to see if any of you guys can think of anything else... Thanks again in advance for any help.

 

does the frequency of the "lacking" get faster/ slower with wheel speed or engine rpm's?

 

My rebuilt motor does it too - tap tap tap, sort of like a old 6-cylinder Chevy. I wenty crazy looking for it, including taking off the accessory belts, switching injectors, making a blank gasket for the ACV, new plug wires, checking all the intake gaskets, blah blah.

According to some of the biggest minds on this forum, nothing in this engine should be making that noise. I'm told its probably the 5&6 ports rattling around, but I have my doubts. It doesn't affect anything else tho, so I do my best to just ignore it.

 

Dude... you are about as paranoid as I am.... if it isn't the spark plugs and the car is idling right... its the injectors..... poke your beak under the hood, and rev her up very slowly by tuning the throttle yoke where the throttle line hooks up to the throttle body.. if the tapping increases as you rev the engine.. its the injectors...

The primary injectors are down on the engine block on the passenger side of the engine.. you could take a length of heavy vaccume hose and stick one end to your ear and try and pin point the sound.

I don't know why.. but some injectors are LOUD... i used to be able to hear the ones in my GTU outside the garage!!

 

My injectors tick, no big deal.

 

Well, I know I'm paranoid about this stuff. However, I'm trying to learn about this car in the most humble way I know how - by asking questions.

I'm checking the TPS tomorrow for another issue, so I'll be sure to listen for the noise picking up with more idle.

Thanks again to all...

 

Alright... Someone is probably gonna chew me out for this, but for some reason, I think the noise is coming from the OMP. Does the pump have oil injectors? If so, could one of them be going bad and be causing the noise? I can hear the fuel injectors tap, but they aren't that loud (sewing machine sounding). However, the lack, lack, lack is still persisting and not getting any quieter. Anyone know how to rule out OMP failure/wear in this case?

 

heres another thing you may be overlooking...an exhaust leak!! this can sound like a mechanical tick and may be at your manifold or just a gasket that is a tad worn at an edge. keep in mind, most tapping on a piston engine is a bad lifter which we don't have.

 

could be an exhaust leak at the manifold possibly?

 

how loud is it? can u hear it from inside the car?

 

Yeah... I can hear it from inside the car when it first starts up for sure -and other times if I'm listening for it. It is pretty loud. I've ruled out the injector thing. PM'd a pretty good rotary mechanic on this site, and without full details, he said that six port actuator rods could sometimes get a little noisy after a rebuild??? What do you guys think about that?

 

Thinking about reforming this question and resurrecting it as I was PM'd a few days ago by someone else with the same engine sound. I'm starting to get worried because of that sound coupled with a groaning vibration that likes to occur at start up when idling about 1500 RPM's.

The "lack, lack, lack" is still as persistant as ever. The dude that PM'd me was concerned about the eccentric shaft moving around inside the engine (on the gears of the rotors). I don't know, I just hate to have something like this ruin a good rebuild if I ignore it until something really bad happens... If anyone can relate and can offer some direction - please respond.

The noise seems to be more centralized lower in the engine with a passenger side focus.

 

Wouldn't hurt to check your timing aswell... If its over advanced at idle it could make a very similar sound....

 

Timing... I hear that a lot, but how could my car be running fine other than some strange sound... and the timing be off???

I'm familiar with the timing on a piston engine, with respect to the fact that if they aren't timed they totally run like hell. I didn't know a rotary could not be timed right and still seem to run fine...

Is that right, or am I misunderstanding?

 

No, because it doesn't need to be that much too far advanced to tick at idle...
So it will still run fine..
a mate who has a 13b with a 12a turbo distributer has this same 'problem' under boost it's fine, but it advances too far at normal idle..

Similar thing could be happening here.