Engine noise any ideas? Help needed


Pete180

Pete180

Lost in dreams..
Joined
Apr 13, 2012
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1,574
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EM1 Coupe
Hey guys,

Currently have a rebuilt NA high comp B18 being run in, has not been tuned yet but is on a base map for now. It's done just over 1000 miles and drives nicely, but there is a funny knock/rattle noise coming from it which has been around for quite a while :( On bone cold starts I hear this rattle for about 1-2 seconds max then it stops, which sounds really in the head. When the engine is hot up to temperature, it does it around 2.5k to 3k rpm but stops past 3k.

In person it sounds like it's really in the head, almost like it's bang under the rocker cover towards the back of the head. Bottom end knock is a thought in mind which I know on video, it does sound like. The rod bearings were just checked 4 days ago and all replaced for brand new Clevite bearings as 1 did pick up some light marks. Possibly bits from machining(?) it was bored out. Not enough to damage the crank and No bits were found in the sump. The noise however is still there, and has been for about 2months now sounding the same hasn't changed. The engine still even pulls nicely. I've been told bad LMAs are a possibility and can sound like a knock, I do have aftermarket dual springs in there too and the LMAs are just the old oem piston type! May this cause noise?

I caught a video, and on camera it does sound worse like a knock. This is with the new bearings in and sounds the same as before. My phone isn't that great :( Any ideas or suggestions? Thanks in advance!

 
I have a noisy LMA at the moment but it just sounds like a light tap once the oils up to temp. If you've replaced the rod bearings and are confident it's not them I would be swapping the LMA's for new ones.
 
lma's can go bad in several ways, they can get worn out and a bit sloppy and make a more consistent noise or they can get slightly damaged or scored by dirt or poor lubrication and cause more intermittent noises like you describe,

I would think its always a good idea to use new ones with high lift cams as the Pistons in the lma's will be pushed further down
 
When did the noise start? Gotten worse?
The least id be doing is pulling the cover off, possibly the cams out if needs be and checking all the surfaces over for any obvious signs of wear/pitting etc to try and find where the issue lies.
From the video it sounds more like a thud than a knock or tap.

Any work done to the head?
 
EK9 Matt said:
I have a noisy LMA at the moment but it just sounds like a light tap once the oils up to temp. If you've replaced the rod bearings and are confident it's not them I would be swapping the LMA's for new ones.
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Yeah that's what I thought that LMAs were more of a ticking high pitched sound but I have read online they can become a knock like sound. Obviously don't want to waste money but may give it a try changing

oifovo said:
Have you checked valve lash?
Click to expand...

Yes mate that's been checked and adjustments were made where needed but nothing abnormal
 
b16 mini said:
lma's can go bad in several ways, they can get worn out and a bit sloppy and make a more consistent noise or they can get slightly damaged or scored by dirt or poor lubrication and cause more intermittent noises like you describe,

I would think its always a good idea to use new ones with high lift cams as the Pistons in the lma's will be pushed further down
Click to expand...
Ah right okay, I did read upon that they can make quite a noise similar to knocking. Is definitely on the list to possibly change, obviously don't want to waste money but was told the aftermarket valve train may have an adverse effect on the lmas like you say.
 
jesse888 said:
When did the noise start? Gotten worse?
The least id be doing is pulling the cover off, possibly the cams out if needs be and checking all the surfaces over for any obvious signs of wear/pitting etc to try and find where the issue lies.
From the video it sounds more like a thud than a knock or tap.

Any work done to the head?
Click to expand...
It started roughly say 2/3 months ago, the car hasn't been used that much as been bit busy and the noise is off putting so avoided dyno for now. It hasn't gotten any worse that I've noticed pretty much sounds exactly the same. Head has C6 cams, port n polish, aftermarket dual springs and retainers, oem c4 valves, oem piston lmas. That's about it. Could a valve issue cause this noise
 
On first initial start is it loud then quietens down once oil pressure is reached? Have the rocker cover off and see if anything is going on.
It sounds bottom end to me :( but I may be wrong.
 
B16Swt said:
On first initial start is it loud then quietens down once oil pressure is reached? Have the rocker cover off and see if anything is going on.
It sounds bottom end to me :( but I may be wrong.
Click to expand...
It does it on bone cold starts, hear it for about 2 seconds then totally stops. From inside the car with the bonnet up it sounds very ticky 'ratatat' kind of sound. When hot its around 2.5k I did find this post:

https://www.ek9.org/index.php?threads/cold-start-death-rattle.39706/
 
Looks like the first thing to do then is too take the rocker cover off, timing belt off, cams out, cam followers out and replace the lma's. You might find something during the process.... and you might find a broken / weak lma causing your knock.
:nice:
I do have a spare cylinder head I could strip the lma's out. But I have no history on the head itself so I wouldn't know if the lma's are any good.
 
B16Swt said:
Looks like the first thing to do then is too take the rocker cover off, timing belt off, cams out, cam followers out and replace the lma's. You might find something during the process.... and you might find a broken / weak lma causing your knock.
:nice:
I do have a spare cylinder head I could strip the lma's out. But I have no history on the head itself so I wouldn't know if the lma's are any good.
Click to expand...
Obviously don't want to spend on bits that aren't needed and make no difference, but yeah it is worth a shot as you say. Do you think the upgraded valve train may have any affect and cause this? like the stiffer dual springs etc as the lmas are just the old stock piston type right now, so I would be looking to try the new spring type. If you have a set of those that'd be great! but if in the end it made no difference that'd be a bummer.

I'll try to film a bone cold start up when I can. Thanks everyone for replies.
 
If you're on bigger cams then yes the LMA's take more of a hammering because they take up the free play of the vtec lobe when not in vtec. Even type r LMA's are stronger than stock ones for the cams.
 
Looking on tegiwa's website the lma's should be changed if upgrading the valvetrain / cams
 
EK9 Matt said:
If you're on bigger cams then yes the LMA's take more of a hammering because they take up the free play of the vtec lobe when not in vtec. Even type r LMA's are stronger than stock ones for the cams.
Click to expand...
It's currently got oem C6 itr cams in there but aftermarket dual springs and retainers. But yeah the LMAs are just original piston type
 
Right well I caught this naaasty sound on bone cold start up. This start up sound has been around for good few months sounding the same. Doesn't do it on a second cold start up, probably due to oil pressure. Oil pressure gauge would be beneficial here for sure, plan to get one soon as I can. It does sound worse here on camera than to ear.

 
From experience that noise sounds like bottom end knock. BUT if it was you'd expect to hear it constantly especially at idle.
From what you've said in your write up though you've pretty much ruled out the bottom end. But there was a slight pick up on a rod bearing?
Did you measure your main bearing and rod bearing clearances?

I'd be checking the oil again, and then the LMA's personally.
Hope I'm helping and not confusing the situation :nice:
 
B16Swt said:
From experience that noise sounds like bottom end knock. BUT if it was you'd expect to hear it constantly especially at idle.
From what you've said in your write up though you've pretty much ruled out the bottom end. But there was a slight pick up on a rod bearing?
Did you measure your main bearing and rod bearing clearances?

I'd be checking the oil again, and then the LMA's personally.
Hope I'm helping and not confusing the situation :nice:
Click to expand...
Not at all mate, any help and ideas are appreciated :) not fully ruling out anything just yet, but was surprised not more came up in the sump etc. There was a slight bit yeah, changed all the bearings. I would've thought if it was that still, it'd come back over time but it's almost instantly the same. I'll drop the oil again when I can and definitely need to pick up a gauge asap. Cheers mate


Is piston slap a possibility? though usually that goes away when hot right
 
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Piston slap is a possibility, what pistons you running and did you measure your piston to wall clearance? Sounds very bottom endy that though, strange how it goes away. You got good oil pressure??
 
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