Video: 97 m3 engine knock/rattle

[m3f_hardtosee]

http://youtu.be/QzFcMCy9uPc














Not sure how to embed videos here.



Had a cylinder #3 misfire I attributed to a failing coil three days ago- intermittent issue, part on order.



Today, took a pull in 2nd gear to 5000RPM or so. about 30 seconds later this noise appeared, with an associated but erratic "blip" in power.



Noise appears to be coming from the top end, I suspect cylinder #1. Checked spark plugs cyl #1-3, all torqued correctly.



Codes thrown were misfires in cylinder #3 (coil most likely) and cylinder #1 (new as of today).



Thinking lifter failure, or could it possible be a spun rod bearing/rod knock?

[m3f_hardtosee]

A friend's bringing his stethescope over, hopefully will pinpoint where the noise is coming from. Will update afterwards.

[m3f_englishtom1596q]

That sounds ....not 100% like rod knock but 100% really really bad... Almost sounds like the cars I've heard with rods through the block lol

[m3f_jayjaya29]

That sounds ....not 100% like rod knock but 100% really really bad... Almost sounds like the cars I've heard with rods through the block lol

+100



Time to pull it apart.

[m3f_hardtosee]

Yea, agreed. Not good at all.



How frequently do exhaust side lifters fail? I've seen a lot of speculation on this, but not much follow-up/failure analysis.

[m3f_DodgeStratus]

Check to make sure your spark plugs are tight.

[m3f_hardtosee]

Check to make sure your spark plugs are tight.

Thanks, did this as described in original post.

[m3f_englishtom1596q]

Yea, agreed. Not good at all.



How frequently do exhaust side lifters fail? I've seen a lot of speculation on this, but not much follow-up/failure analysis.

They're hydraulic and pretty bulletproof. I've never heard of them failing on these cars

[m3f_hardtosee]

They're hydraulic and pretty bulletproof. I've never heard of them failing on these cars

Hmm, I thought so too. Will be getting into it this week, hoping point of cause is a failed tensioner, and what we're hearing is a chain slap -_-



On the other hand, won't be surprised if the head needs some work.



Bright side is- no leaking fluids, no smoke, oil looks clean.

[m3f_hardtosee]

So, we started tearing down the engine. Nothing obvious with the valve cover off, and engine turns over normally w/o coils in.


Unless something obvious is found on the second go-around today, plan is to rebuild the head.


So, looking for some feedback here. As I see it, the following needs to be done:


The basics:

springs

seals

valves*

seats*

retainers

check valve guide tolerances

deck head


One open question - what are people's thoughts on spinning the valves to look for a bent stem (if it's not obvious), and recutting the valves/seats, rather than going with all new hardware?


Other parts to replace while I'm at it:

water pump

cam position sensor (? - maybe)

crank position sensor (? - maybe)

lower chain tensioner (probably not)


Vanos has already been rebuilt in the last 15k miles, so that's fine.


I want to keep the car as close to stock as possible, so I won't be going a cam-upgrade route.

[m3f_ASApM3]

I think rebuilding the head and putting it back together is foolish considering you haven't found any evidence of failure in the head. To me the noise sounds like a broken piston, bent con rod or a spun bearing. I'd open up the bottom end before you proceed blindly.

[m3f_englishtom1596q]

I think rebuilding the head and putting it back together is foolish considering you haven't found any evidence of failure in the head. To me the noise sounds like a broken piston, bent con rod or a spun bearing. I'd open up the bottom end before you proceed blindly.

This 100%. You never figured out where the noise was coming from. You're saying "I've got a clunk in the front end... Better do a rear end refresh!" Pull the motor, open it up and find the problem before you dump money into an engine that's junk

[m3f_matty.]

Almost sounds like you left a socket on the crank pulley. I'd check all belts and pullies before you start tearing down completely..



I'd add a new ccv to your list, as well as clean the icv, new vacuum lines, and knock sensors.

[m3f_englishtom1596q]

If a pulley was bad enough to make that kind of noise it would be obvious and probably chucked the belt off. Dropping the pan would have been the first thing on my list

[m3f_Tock172]

Sounds like a bottom end noise. I would have tried to pinpoint this with a stethoscope before tearing the head apart. Depending on your mileage, the head probably already needs a refresh if it's being taken off, however I wouldn't do this before finding the culprit of the noise. Additionally, I haven't heard of the hydraulic lifters in these engines failing. I think they get old and 'soft fail' and become loud.