Knocking Sound any ideas?

[mattasi]

So I went out driving to do some logs in ECM link. When I got home I noticed a knocking sound. So I reved it up a bit in neutral and sure enough there was a wierd sound, a knocking sound, something like what a flat head motor sounds like. At first I thought a spun rod bearing, but the knocking fades in and out, not relitive to RPM. It's random, no knocking at idle, just when I reved up a bit. I checked the oil before and after driving and it's not losing oil, leaking oil, or buring oil. I pulled the valve cover and all the rockers and lifter look good, no movement or anything. I have no balance shafts. I changed the plugs, but they looked great. I drained the oil and looked at it for 30 minutes and couldn't fully decide if there were any metal flakes, if there was they sure were small because I couldn't see anything in there. I checked the mechanical timing and everything lined up nice. Compression test came out between 172-178 on all cylinders. It idles nice just has that knocking sound when reved past idle. I haven't tried to drive it so I don't know any driving symptoms to tell you, it was driving and running excellent on my drive home, just started knocking in the driveway. I am in the process of pulling the oil pan, man I tell you they like super super glued the oil pan on or something . Crazy I tell ya.

Any Idea's on the knocking sound? Is it time for a short block rebuild?
Any thoughts on getting the oil pan off without bending the hell out of it? I don't know what sealant they used but it is seriously on there, I was pulling on it with all my weight and hitting it with a hammer.

 

[g4ebguy90]

When you get that pan off. Look for metal in the pan first off.

Second, wiggle each rod. If they move just like a mm or 2, you know barely at all your good.

But if you can move it past Half a finger nail length per say, you have a spun bearing. You should be able to actually making a knocking sound yourself with the rod if it's that bad.

I had a car do that, ran just fine, pulled into my driveway and there it was... knock not at idle either if I remember right, just on rev. Hard to tell if it was bad or not honestly. I caught mine just in time.

 

[mattasi]

I am going to re-attempt getting the oil pan off today, It was late last night so I stopped after getting a nice cut in my hand from punching the dam oil pan haha... I just don't see why they sealed it on there so good.

 

[g4ebguy90]

Just use a nice flat head and pound the hoe... I had a problem like yours, turns out it had 1 bolt in it.

I think I punched mine to and hurt my hand...

 

[idkiliketurbos]

What about a blown exhaust manifold to head gasket? I am literally just going through this project and am working on the fix now. I am missing a stud in the upper right corner and I see exactly where it blew out the gasket. It sounded just like you are describing. I can hear it louder the more I get on the throttle. When you rev it up a little in neutral, does it stop when you let off the pedal?

 

[Calan]

Check to make sure your harmonic damper hasn't started to come apart.

Any thoughts on getting the oil pan off without bending the hell out of it? I don't know what sealant they used but it is seriously on there, I was pulling on it with all my weight and hitting it with a hammer.

Use a 1" wide putty knife to carefully pry it away from the block, and slowly work your away around it.

 

[mattasi]

@calan, I already checked the harmonic damper, and it is good. Not serperating at all.

@idkiliketurbos, When I rev it up in neutral it doesn't stop the knocking when I let off the gas. When I let off the gas in neutral, it flutters in and out till it gets to idle and then sounds fine. I have listened to lots of videos trying to find something like my sound. The closest thing I can find that sounds like it is piston slap. This is a wierd one, so I can't rule out the exhaust leak but I don't think thats it.

 

[Calan]

Can you post up a a video of it?

Just out of curiosity... have you done a leak-down test on it?

 

[mattasi]

Sorry guys I didn't record the sound before taking things apart. I haven't done a leak down test. Actually I need to find out how to do one.

 

[Calan]

http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

 

[mattasi]

Thanks for the Link, I will check that out.

 

[Calan]

The reason I mentioned the leak-down test (not that this is your issue)... I lifted my head at 33psi a while back, and it sounded like a piston was trying to come through the block. The compression test looked decent, but a careful leak-down test showed a very small amount of leakage from cylinder #1 into the coolant after 15 seconds at 100psi or so. Nothing else was noticeable.

When I pulled the head, I found an area around cylinder #1 near the water pump and at the back of the block where compression was obviously blowing past the head gasket. It was only happening at very high cylinder pressures though, and it made one hell of a racket.

Again...not saying this is your issue. But bad (or "almost bad") headgaskets can cause all kinds of strange things to happen, including sounds that you would swear are being caused by a bearing going south or a bunch of small nuclear weapons being detonated in your engine bay.

 

[mattasi]

@calan So I Went out and bought a Leak Down Tester, but didn't get to use it because I found the problem last night.

To get the oil pan off I had to hammer 4 flat head screwdrivers into one side just to get enought leverage not to bend the oil pan.


Anyways... Got the oil pan off and guess what... Metal shavings,...

It is a sad day for my DSM ..
Ok but seriously, what now? Go ahead and pull the bottom end and have English Racing rebuild it? I want to do this properly because I will probably never sell this car. So please feel free to tell me things you would want to know if this just happened to you.

 

[mattasi]

UPDATE!!
Ok so I am going to have English Racing do the motor work. I am pulling the motor out and taking it to them. It will be around two months till I get the motor back. So lots of time to clean up the engine bay I really want to paint the engine bay to look new.

Anyways when I was taking pictures of the shavings in the oil pan I saw a solid piece of metal I though it was a small L shaped allen wrench or something. Below is a picture of what im talking about It is a 4mm tube with a hole all the way threw it, with a slight bend. One end of it looks round and machined nice and the other end of it looks to be sheared off or something. I looked up at the bottom side of the pistons and sure enough one of the pistons had a gash from hitting this piece of metal floating around in the oil pan

Any one know what this piece of metal is? Any guess?

 

[project98dsm]

That sir, would be (part of) an oil squirter.

 

[joe sobo]

i would also look to see if it spun out a balance shaft bearing. that is what i am doing now. perfect engine, but started knocking. not consistant with the revs. took engine apart to find a balance bearing chewed up in the pan, and another one just spinning on the shaft, causeing that knock sound.

 

[mattasi]

I have no balance shafts, and the motor is going to English Racing. But thanks for looking out man.

Am I suppose to be able to see the other oil squirters from the bottom of the motor with the oil pan off? Trying to figure out exactly what happened here.

 

[SBstar]

Something caused the oil squirter to rid itself of it's tube, you probably then lost oil pressure causing the bearing to spin. At least that's my best guess. Why the the tube broke off is a bit of a mystery. When was the last time this bottom end was opened up?

 

[mattasi]

What tube does the oil squirter live in? I never lost any oil pressure. This fully built bottom end has about 30k on it eagle rods arp everything the works.

 

[SBstar]

The oil squirters bolt to the block below the pistons and squirt oil up at them for cooling purposes. Chances are when the new rods/pistons went in someone knocked the oil squirter and over time it broke loose. The part you found was the oil squirter nozzle for lack of a better term, the rest of it will still be bolted to the block. It is however possible that when the rod bearing let loose the knocking caused the nozzle end to fail :shrug: We may never know for sure. I'm guessing this is a 90-92 block so here's the part, if not you'll need the 92-94 ones.

EXTREME PSI : Your #1 Source for In Stock Performance Parts

 

[mattasi]

Very interesting, because I don't see any oil squirters under the other pistons. I have the oil pan off and looking up. I also thought that this was a N/A block that didn't have oil squirters installed. Very confussed on what happened here.

 

[2slow4now]

How much play in the rod bearing? Maybe the piston skirt smacked the squirter and broke it off.

The banjo bolts are on that page as well and thats what allows the oil to go to the squirter. Its like a pressure relief valve once the oil pressure gets up the squirter will open. Its possible something was stuck in the banjo bolt leaving it open and starving the bearing some.

 

[mattasi]

Well I have heard that when you spin a rod you can actually push up and down on the rod to make the knocking sound, but my rods don't move at all, no play up and down and like 1-2mm side to side play on all rods.

 

[SBstar]

That's funny I see them looking up in your block
Or are you saying there aren't any other ones in the other cylinders? Because if the holes are there for them they have to at least be blocked off with something.

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I'm not sure if you already posted it, but do you have the balance shafts in by chance? Could be a balance shaft bearing that tore up. I'd still pull the rod caps and check them, that metal came from somewhere that's in the bottom of your oil pan.

 

[mattasi]

Yea, I saw those that you circled but they are just tab looking things no oil squirter tube comes off any of those on the block. They just look like metal tabs. So maybe they broke off all the tubes on the squirters or something and left this one in the oil pan? Thanks to everyone helping me figure out what happened here.

No balance shafts