Crazy Intermittent engine tapping/ticking sound

[Black Panther]

Car's a Landrover Freelander 1.8L Petrol.

The tapping sound is quite loud - if you walk away from the car you'll quit hearing the engine but you'll keep hearing the ticking/tapping. It's like a strong "tock tock tock tock tock tock....."

It varies with engine revolution speed, and happens even when no gear's engaged.
At idle engine, it's between 3 and 5 taps per second.

It's not the valve tappets. Occasionally if it's in too high gear for the gradient of the road the tappets make a faint tapping noise, which is totally different (and more frequent than 3-5 per second) from this very loud tapping noise.

Changing the oil and filter and trying out different brands/grades made no improvement.

I've been googling this and this is the most informative info I found.

However there's a big "BUT"..

The tapping of my car is totally at random.
Sometimes it starts tapping on a cold start. Then quits.
Sometimes it doesn't tap at all on a cold start. Then it starts tapping 15 minutes into the journey...
Sometimes it goes for some days without tapping at all.
Other days it taps non-stop.
Other times it taps for 5 minutes, stops for another 5, resumes for another 5 minutes... etc etc...


It's frustrating... we went twice to the car mechanic, and as soon as we arrive the car puts on its best trollface and stops tapping!

One thing that was weird is that we removed the oil cap and there was air-pressure in there, it made a "pffffft" sound while the engine was still running (and tapping). We checked the breather, it isn't blocked.

Oh and it appeared to me that while it's tapping the exhaust is a tad whitish. The exhaust is colorless when it's not tocking/tapping.

Otherwise car runs fine, no problem with starting, engine runs strong and impeccable.

I've also been looking up videos on youtube, and it doesn't sound like rod-knock either.

This is somewhat what it sounds like, maybe the pitch of my "tock" is slightly higher... - I found a random youtube video of another engine...


But then bad lifters won't give intermittent tock-tocking??

[twilyth]

I'll let the car guys take this but it's hard to imagine it would be anything other than the rods and rocker arms - assuming you have that kind of setup. If you have an overhead cam, then I'm not sure, but that is classic rocker arm noise.

The reason for the differences you hear though is probably a dodgy oil pump. I can't remember if most cars have a screen in addition to the filter. If so, that could also be an issue. When the conditions are right for the pump to put out sufficient volume, the noise should abate, and vice-versa.

[Black Panther]

This sounds much more like my noise :

[1Kurgan1]

Yeah doubtful on rod knock, you would be down on power if it was that, big time. Does sound like a sticking lifter though. You could try checking the compression when the ticking is happening to see if all of your cylinders are about the same. If ones off, then looks like you found your culprit.

[Black Panther]

Thanks, I thought it's better to start 'excluding' culprits. Knowing the mechanics here, they'll try to change everything one by one till they find the right thing... and we'll be footing the bill!

The sound seems to come from the top of the engine and not from the bottom, and although the sound is strongish it isn't the big sound of something breaking. And yes, no loss of power at all whether engine is tocking or not.. In fact, this intermittent tocking's been going on since the end of last summer now...

[Flyordie]

Oh boy.. check oil pressure.

Go to a thinner oil or put in oil stabilizer like STP or w/e..


Hydraulic lifters love oil pressure. :-)

[Black Panther]

Originally Posted by Flyordie

Oh boy.. check oil pressure.

Go to a thinner oil or put in oil stabilizer like STP or w/e..


Hydraulic lifters love oil pressure. :-)

The more I google the more I think it's a lifter problem.

We've tried thinner oil though. No improvement.

We've had this SUV for ~ 5 years now, always gave it the same oil grade and brand... but this problem surfaced only a couple of months ago.

[TheMailMan]

Originally Posted by Black Panther

The more I google the more I think it's a lifter problem.

We've tried thinner oil though. No improvement.

We've had this SUV for ~ 5 years now, always gave it the same oil grade and brand... but this problem surfaced only a couple of months ago.

Thats an i4. What octane gas you using? Also when was the last time you had the plugs checked?

Also don't be messing around with the damn oil grades. You will end up having to flush the engine if you don't know what you are doing.

[erocker]

It's really hard to tell from a video. Try to isolate where the noise is coming from as it could be a variety of things. It could even be something as simple as a loose O/2 sensor, spark plug, etc.

[JC316]

What you are telling me sounds like what happens when a VVT engine has a VVT malfunction, but those cars don't have VVT technology. What is getting me is how random it is. It might be the lifters/lash adjusters effing up.

Air pressure in the crankcase means one of two things, either the PCV system isn't working right, or you have a good amount of blow by. Blow by and a tapping could be the piston rattling around.

[TheMailMan]

Originally Posted by erocker

It's really hard to tell from a video. Try to isolate where the noise is coming from as it could be a variety of things. It could even be something as simple as a loose O/2 sensor, spark plug, etc.

Thats kinda what I was getting at. Could be something VERY simple like low grade gas.

[Black Panther]

Our gas:
(We have a free market but only one company imports one type of gas)

[1Kurgan1]

The guys above have good points, can check their ideas, but mainly the random tapping is the weird thing. Another thing I have heard cause a tapping noise is AC Compressor, my friend 318 Dodge sounded like it had dropped a valve, sound wa coming from up top, when he fired it up and popped the hood I cringed. But then I realized the sound was coming from the front of the engine and narrowed it down to the AC compressor, we pulled the belt off and problem was solved (he didn't have working AC so it didn't matter much anyways).

Also not sure if that engine has a harmonic balancer (though that sound would be down lower), if it does it could be that as well.

But a tapping noise could come from something as simple as something hitting something else on the outside. Since you hear it up top that narrows it down, but a simple one (granted this is down below as well) is the heat shields on catalytic converts will have their cheap weld break on one side then it will rattle against your cat. Even a heat shield on a exhaust manifold could do something like that, but usually thats going to be a more tinny sound, not a deeper sound.

[Black Panther]

Originally Posted by 1Kurgan1

but mainly the random tapping is the weird thing.

I think I found out something which is relevant to the tapping being random.

This is a picture of my engine (found from google):



When the engine is making a tapping noise, if I unscrew the yellow cap (where you pour the oil in, marked with a red star) air would get sucked forcibly inside, and the tapping would stop.
I'd screw the yellow cap back on and leave the engine running. After some time the tapping would start. I'd undo the same yellow cap, the engine would suck air and the tapping would stop again.

Also, I'm not really sure of this but from memory I think that the two breather pipes (or whatever they are) which I illustrated in green and blue are switched. They don't cross over. The 'blue pipe' leading from the part where it says "injection" is connected to where the 'green pipe' ought to be connected. And the green one is connected to where the blue one should be. Some months ago we gave the car to a mechanic to change the timing-belt...... hmmmm, that sounds approximately the same time when the tapping/tocking started...

I'll go over and check to see if they are switched really or whether it's my imagination playing up....

[Black Panther]

Guess what.. I was right.

Here's an actual picture of the engine I just took. Compare with above photo (blue & green pipe)..



Well now... argument with the husband. He won't acknowledge that I discovered a fault in the car He insists the pipes can't be bent to be like the one in the google photo.

(Of course, the green rubber part appears to have been 'trimmed' by someone... :rolleyes highly likely the last mechanic we took the car to change the timing-belt, he forgot how the pipes were and did a shitty job..: and the blue one has tore up from being in a too-bent position these past months, it's thick for the duct tape!, so now they've taken shape and it's hardish to put everything back in its proper place!)

However, now even if we move the pipes to the correct position there's still the tocking sound. :/

[twilyth]

I'm just curious. How many antique mechanical devices do you have? I remember the motorcycle with a wet clutch which seemed fairly old and that engine shot doesn't look very modern - except for the yellow cap. I don't mean to be rude, but at some point shouldn't you be trying to upgrade some of these things?

[1Kurgan1]

Weird, I wonder what in the PCV system is ticking when it's not getting enough air. I don't really know a ton about PCV crap, but looks like you replace the hoses and your set. If not, put a valve cover breather on instead of the oil cap, unless you emissions test then I don't think you can do that.

Also Twil I think the oldest that model of SUV she has can be is a 97, so it's decently modern.

[Black Panther]

I'm not in the mood of spending €20,000 for a decent brand new car.

Yup cars are very expensive here (lots of government duty and the like, so I can't just travel 60 miles to Sicily and get one for a good price because customs would slam me).

Cheapest new car currently is the Suzuki Alto for €10,000 and though I've got nothing against it, it's just not my type of vehicle...

Edit: Twilyth, my motorcycle doesn't have a wet clutch... it's old but it works fine

[JC316]

I have never seen a PCV setup like that before, but yeah swap the hoses and see if it helps.

[Flyordie]

Have you been going through oil pretty fast?

lol.

Whats the oil smell like?


bleh.

With a PCV system, when the oil filler cap is removed, it should BLOW air out, not suck it in. (the more air that comes out, the more the piston rings are worn essentially)

[Black Panther]

Oil is normal, change it routinely, never drops below level. Smells normal. Heck engine runs normal except for the tapping. And it sucks IN air when the oil filler cap is removed. Which stops the tapping...

[theJesus]

Originally Posted by Flyordie

With a PCV system, when the oil filler cap is removed, it should BLOW air out, not suck it in. (the more air that comes out, the more the piston rings are worn essentially)

Originally Posted by Black Panther

And it sucks IN air when the oil filler cap is removed. Which stops the tapping...

I don't know shit about engines or cars etc., but now I'm curious if reversing the hoses/pipes (to be criss-cross like the first pic) would make it blow out.

[ThE_MaD_ShOt]

Panther You get the golden cookie award as you have fixed your problem without the excessive cost of a dealer. Kudos to you. And glad you fixed it. Oh and as a person that os forced to screw with cars (Have to make money somewhere and why not at something I am great at) I have seen that a few times before. I have even had one truck that would squeal like a stuck pig because the pcv system was clogged. I mean this thing would be quiet as hell until you drove it for about 10 miles then it would squeal really really load. I took off the oil cap and squeal was gone. Replaced the pcv valve and hoses and a new vented oil cap and it was good to go.

[1Kurgan1]

Originally Posted by theJesus

I don't know shit about engines or cars etc., but now I'm curious if reversing the hoses/pipes (to be criss-cross like the first pic) would make it blow out.

I don't think anything is actually caught in the hoses. Look at the left (S shaped hose). On her engine that hose is too long and actually makes an S shape, where as on the picture she got off the interwebz it's more like two L's facing opposite directions. Hoses in an S shape like that will collapse the corners, you can see it in the picture even (f you water cool you comp people have the same problems and use hose coils, I haven't ever seen it done in cars since you just use the right hose ). But a redneck fix for this might be the same basic idea, the hoses are hardened some she says, so cutting some off and trying to make it fit will be hard, but could put hose clamps on the corners and tighten them down to the hoses original diameter and it might return the curves back to normal diameter rather than being pinched like they are.

[Steevo]

It should suck air in, the pcv is attahed to the intake manifold to create a equal pressure in the engine. your PCV valve is probably stuck closed and is popping cauaing the noise, or it is causing something else to cycle from the pressure