Worrying Engine noises/knock

Conda

Conda

Daily Driver
Hey all,

Been getting a lot done on the 87 X1/9, and it's really been getting better. Today I had a bit of less than stellar time with it though. As I was messing with the headlight aiming I was letting it idle and was every now and then checking the temp as I haven't idled it for a long time period before. It stayed below 200 and everything was fine temperature wise.

I was about done with the headlights so I went into the cabin and gave it a little rev, instant loud knocking from the back on increased rpm. :(

Here is a video of the noise experienced.

Knocking is most prominent at 1:05 and 1:16

This only occurs on a hot engine, and only knocks on throttle input. Does not knock at idle or when cold.

After checking, it seems to be most prominent from the upper end, was not able to reproduce again after taking the video. Was going to try to see if the clutch made an impact. Hoping it might just be ignition timing issues.

Anyway, I really appreciate the help you guys have given me getting this thing back on the road, anyone have any insights or suggestions on the noise?

Thanks so much
 
even at a base idle, it sounds like the valve train is a bit sloppy. My vote would be to pull the valve cover and check valve lash. But sooner would be way better than later.
 
I would think if it was something rattling it woulden't increase/decrease with idle as it does. It is definitely in relation to the rpm of the engine. I will have a look at the valve train as soon as i can.
 
checking valve lash it not that tough. pull the valve cover (will have to pull a few other things but not bad) and use a bent set of feeler gauges (don't try to use the straight one's they just don't fit and will give a false reading. Bent ones can be purchased at most auto parts stores for little of nothing.
 
I did not hear a pre-detonation knock on the video. The timing would need to be way advanced to get it with no load. I agree with Rod about checking the valve train. It is pretty quick to do and may help confirm or eliminate if the problem is coming from there. You might also want to throw a timing light on it first and see if the advance is in the right range and stable at a given rpm.

The other possibility of an intermittent knock could be an intermittent lean mixture. I've never had an FI X so I'm the wrong person to ask about that. I suppose intermittent injectors could create the right conditions.
 
Have you completely removed all the old gas it came with?
I agree with dllubin, put a timing light on it.
Kinda seems like too much advance for the fuel on closed throttle, check your throttle switch for continuity when closed.
Check that the flyweights in the distributor are lubricated and operate smoothly without sticking.
 
I listened to the video segment with the "knocking" several more times. If this was an old American car, I'd say check the water pump. Haven't heard a bad X1/9 pump so I can't say what they sound like. The bad water pumps often started out very intermittent as well.
 
As mentioned the valves sound loose. Pre ignition sounds more like marbles dropping on a tin can and usually happens under load. My way out there guess is piston slap.
From my experience slap can be intermittent in the beginning but just before the piston goes it will become a quite predominant sound.
Some where west of Indio Ca. at Sirocco summit on I-10 I left half of a Toyota Land Cruiser engine laying in the road because I put off addressing the problem to long.
 
Definitely remove the valve cover, check valve adjustment & cam lobes & bucket shims for wear. Mine sounded similar when a couple of the cam lobes decided to eat themselves. The wear will be obvious if it's there. Take pics. All this can be done with minimal disassembly, so don't rush to pull the motor!
 
Wouldn't hurt to check the oil level too. And if you pull the valve cover verify there is oil in the wells next to each shim/bucket.
 
Thanks for the suggestions guys, I have noticed a what sounded like a belt squeak that seemed to go away when hot, but I think that is un-related.

All original gas has been removed from the tank, I originally filled it with 93 octane but the last gas I put in it was 87 both non ethanol.

I will pull the valve cover when I get it back in the garage and have a look. I need to do the timing belt on this motor and have all the stuff for that along with a clutch kit, if its any more than the valves I'll drop the engine out of the car.
A lot of this stuff is new to me, so I really appreciate the input. I've never messed with engine internals before.

Thanks again. If anyone else has suggestions I'm all ears :)
 
Last edited:
Ah the joy of used project cars, looks like the o2 sensor isnt hooked up to anything. Could this cause a lean condition?

On another note, where does the o2 sensor wire hook up, and if it isnt the other connector i have above the intake here, what is that connector for? XD

9Pk93dX.jpg


Edit: found it, over on the right by the alternator. Hooked it up. I know this wont solve the valve chatter, but you guys think it might help the noise if it was because of running lean?
 
Last edited:
Do check into this before doing the t-belt. If you find something you will be their anyway very soon to have to do the t-belt r-r again (not that it's tough) once you've done one. next one might be an hour or two..

Keep us posted we love pictures (and videos)
 
The top wire is for a test machine/tool. I do not know if anyone has ever seen of the use for it. But that is what it's for.

The lower wire I would put money on being the right one. would have to compare the color of wire and trace it down.

I am 99.9% sure my o2 sensor is bad and I get no strange noises (just bad fuel mileage) (the 20's) and my wife's X gets low 30's (I really should look into this for the $$ I would save in fuel)
 
wouldn't hurt to remove the water pump/alt belt either to dismiss those 2 things. Doesn't sound like a rod knock, more like valve train noise
 
Update! Pulled the valve cover, and checked valve clearances. I don't think they look that bad compared to spec, maybe a touch tight.
All are in inches, E is exhaust and I is intake, 1 cylinder is belt side
1E .015
1I .010
2I .011
2E .014
3E .014
3I .011
4I .010
4E .015

Spec ive seen is
Intake: .011 to .014 in
Exhaust: .015 to .018 in

Those seem slightly tight but i would not expect those to cause that much valvetrain noise, then again i am very new to this whole thing :)

The cams look smooth and even, i will post a link to a imgur album of pictures taken during the process, if you look through them I appreciate it.

Imgur Album https://imgur.com/a/2eknMgB

I got the shim removal tool on the way, so I will replace the shims to get them all within spec.

What do you all think?

Thanks again!
 
Last edited:
Double post update, a quick check over of the driven accessories. I cannot detect any issues with the water pump or alternator. Will try running it with belts removed.
 
You must log in or register to reply here.
Back
Top