Bizzare, SEVERE knocking from top end

[huafist]

Ok, here's the story:
'95 TSi AWD, Kelford cams, EVO 8 springs/retainers, otherwise the shortblock is stock. Was driving back from my office, and all of the sudden, all 4 wheels lock up for a brief second, then resume driving. It does this twice. First thought is "well crap, transfer case is going out." For the rest of the drive home, I'm hearing a knocking that seems to be getting worse the farther I go. I'm thinking the xfer case has puked its guts out and causing the knocking. I get it home, turn it off, curse like a wounded pirate for a minute, and let it sit.

That was 2 - 3 weeks or so ago. I finally decided to check into it yesterday afternoon. I pulled the transfer case and opened it up. Yeah, it was very low on fluid (would guess 1/6 of a quart in it), but the bearings looked good, the tooth wear pattern was good, no metal in what fluid did come out, and it turns smoothly and doesn't have any play WTF

So, I put the transfer case back in the car and buttoned it up. Fired it up, and again, knocking like a french whore. I shut it back off, checked the timing, which is dead on, balancer (missing 3 bolts and the roll pin!!!, but the rubber was ok ; I took it completey off and checked it.) I replaced the roll pin in the sprocket, put the balancer back on, and replaced the missing bolts (still have no idea where they went ; they were in there when I put the balancer on last time, and so was that damn pin). Fire it up again, same noise. Kill each cylinder individually by pulling the the injector clip off, but the noise doesn't go away. The higher you rev, the worse it gets. It sounds like a pushrod V8 does when the lash is VERY VERY loose.
I pull the valve cover, everything looks ok on a cursory check, so I run a compression test - 175, 130, 175, 175. Poured a capful of oil in Cylinder #2, no change in compression numbers.

Oil pressure is good, so I know I'm not losing a main bearing. Sound remains after killing each cylinder, so I'm doubtful it's a rod bearing. I did a BSE about 6 months or so ago when I did my cams/springs, so it can't be a balance shaft.

I'm about out of ideas - does anyone else have an idea that could cause this? The fact that it did it immediately after the wheel lockups has me scratching my head; I don't see how it could be related if it didn't skip timing, but it has to be somehow. The only think I could think of left would be a wiped intake cam lobe on the cam causing the valve to not open like it should.

 

[RadDsm]

Just a thought. I don't think the Evo 8 valve springs have enough pressure for the Kelford 272s, maybe you had some valve float and did a little damage to a valve(s) in the cylinder with low compression?

 

[huafist]

Just a thought. I don't think the Evo 8 valve springs have enough pressure for the Kelford 272s, maybe you had some valve float and did a little damage to a valve(s) in the cylinder with low compression?

While that's possible, I dunno. It's made less than 5 trips to 7k since installing the cams, and from the research that I did before buying them, I found a lot of people were having success with the EVO8 spring/Kelford 272 combo. I guess if nothing else, I'll check valve seal.

 

[tron2119]

Umm no. The kelford 272's REQUIRE dual or Kiggly or equivalent beehive springs (a lot stiffer than the Evo 8 springs). I guarantee that those people having good luck will not have good luck for long.

 

[huafist]

Umm no. The kelford 272's REQUIRE dual or Kiggly or equivalent beehive springs (a lot stiffer than the Evo 8 springs). I guarantee that those people having good luck will not have good luck for long.

Even if that's the case, it's unlikely that it would cause the knocking sound, and beyond unlikley that it would cause the wheels to lock up momentarily.
If it had floated a valve that bad, it would've bent the #@*(!)# out of it, in which case I'd have found followers laying in the head when I pulled the valve cover.

 

[tron2119]

True. Just trying to help you avoid further problems.

 

[huafist]

True. Just trying to help you avoid further problems.

Notice I never said you were wrong

 

[tron2119]

Yes sir Hope you get this figured out.

 

[BogusSVO]

With the wheel lock up, something stopped moving like it should.

You make no mention of engine stall at the time of wheel lock up.

I would check the clutch, the PP may have come loose enough to come cocked and lock up the rest of the drive line.

 

[huafist]

With the wheel lock up, something stopped moving like it should.

You make no mention of engine stall at the time of wheel lock up.

I would check the clutch, the PP may have come loose enough to come cocked and lock up the rest of the drive line.

I didn't notice an engine stall, but things like that happen so quick it really would've been hard to tell. What I can tell you is that after it happened, the engine would die if I pushed the clutch in ; the only way I could keep it running in neutral was by feathering the accelerator.

 

[JayRome]

a loud knocking? or more clanking?

 

[DSM Chase]

sounds like something tranny related.

 

[huafist]

a loud knocking? or more clanking?

Very loud knocking. Emanating from valve cover. Like I said earlier, it sounds almost like a pushrod motor with a solid lifter cam whose lash is VERY loose, or has a bent pushrod.

sounds like something tranny related.

That would be my thought on the lockups, but not the knock; it's definitely coming from the valve cover, and it seems to be centered over #2 cylinder. I'm gonna pull the vc later and have a friend rotate the crank by hand while I watch the valvetrain.

 

[JayRome]

possible that one of the roller rockers is out of center on top of the valve stem...

 

[GSTurbo1]

Pull the head and get that valve checked out... more of a metallic ting?

 

[huafist]

Pulled the valve cover this morning and rolled the engine over by hand a few times ; I don't see anything out of the ordinary. I've got a gnawing in my gut telling me it's a cracked piston, but I'm really hoping that's not the case. I would've expected something locking the engine up to the point all 4 wheels skidded for a split second would've been enough force to punch a hole in a piston instead of cracking it, but I dunno. Engine's gonna come out when I can get it in the garage.

 

[born2tune]

It looks like you have checked just about everything. maybe you bent a piston rod, try putting an extension through the spark plug holes and turn your crank and check that they all come up the same height. Just make some good markings, no eyeballing.

 

[onefast2gdsm]

Take the spark plugs out an try to peek inside the cylinder walls. Also drop the xfer case and take the oil pan off. Simple things to check before ripping a motor out if its not simething serious (which it sounds like it is). Did you drain oil to check for metal?

 

[huafist]

Plugs are out, but unfortunately I don't have a bore scope. I can't really see inside the cylinders without one. Oil has been drained, but I didn't see anything in it. However, it's possible that it just didn't come out with the oil. Checking the stroke is a good idea, I'll try that tomorrow.

 

[onefast2gdsm]

Id take the pan off and check for bent rods or play in rod caps.

 

[1995gstdsm]

I spun a rod bearing once and it was soooo loud that you could feel it through the valve cover. I was convinced it was in the head as it was the first time it ever happened to me so i didnt know.

Anyways, good luck to you and hope the best for you

 

[huafist]

I spun a rod bearing once and it was soooo loud that you could feel it through the valve cover. I was convinced it was in the head as it was the first time it ever happened to me so i didnt know.

Anyways, good luck to you and hope the best for you

Well typically when you lose a rod bearing, killing ignition on the affected cylinder will stop the knock - that doesn't happen in this case, and the oil pressure is too good for it to be a main. I don't know what it is, but it's loud and definitely something bad. I guess I'll know when I perform an autopsy. Gonna check for a bent rod today I hope.

 

[keltalon]

Well typically when you lose a rod bearing, killing ignition on the affected cylinder will stop the knock - that doesn't happen in this case, and the oil pressure is too good for it to be a main. I don't know what it is, but it's loud and definitely something bad. I guess I'll know when I perform an autopsy. Gonna check for a bent rod today I hope.

Go ahead and pull the oil pan a was stated above to eliminate the possibility of bearing failure.

 

[huafist]

Go ahead and pull the oil pan a was stated above to eliminate the possibility of bearing failure.

I'm going to, but it's going to have to wait until the garage is freed up ; it's too cold for me to screw with it outside haha ; as soon as I get this 240 mobile under its own power, I'll get the DSM in the garage and get her on jack stands.

 

[huafist]

Bringing this back from the dead - I finally got the DSM in the garage and got the engine tore down - when I did, I not only found the cause of the knocking, but the cause of the lower compression on cylinder #2 - #2 rod is bent, and it kicked the rod bearing out. I'm having a hard time decoding exactly how the engine being locked for a second bends a rod, but it's the only thing that happend abnormal, and the knocking started immediately afterwards. Who knows. I'll have her rebuilt and back in the car by Sunday afternoon.