98 Blazer "clicking" noise (CEL on)
 

Hey Forum,
Having troubles with the Blazer for the past few weeks. Started making this reallllly loud "clicking" sound that is audible even inside the passenger area with the windows up. The sound it is making is the same as if you said the word "took" repeatedly.

The noise speed changes with RPM as well.

I have only been able to work on it on the weekends as it's a daily driver, and so far I have replaced plugs, wires, rotor, cap, and oil change. Currently, the CEL is on (solid, not flashing) and code is 0301 (cylinder 1 misfire).

The CEL was not present until I took off the EGR to clean it really well. When I reinstalled it, CEL came on immediately.

I've also attached a picture of the driver's side exhaust manifold. It appears that the second bolt from the front of the car is sticking out about an inch (I felt it by hand it and it was not "loose" however"). The very front-most "bolt" appears to be a threaded bolt with a nut on it. The others are all bolts.

I have some suspicions about the work done prior to my owning the Blazer, but this doesn't seem right.

Would that bolt sticking out cause an exhaust leak? Would an exhaust leak cause the symptoms I'm experiencing?

Car idles rough (doesn't die) and CEL is on solid (0301). "Clicking" sound appears to be hte loudes directly behind the throttle body, just in front of the rotor and on the very top of the engine.

I'm running out of ideas... Thoughts?

Here's a phone video of the ticking:

Possibly a bad lifter, rocker arm, push rod, or a broken valve spring, (or any combination of them). Sound travels and its location can be deceiving, but with a P0301, I'd say pull the driver side rocker arm cover and look closely at both rocker arms on cylinder #1. They should both be tight throughout the entire rotation of the crankshaft. Might need a friend to turn the crank while you check the rockers.

Rocker arm, valve & push rods & possibly exhaust leak. Rottidog rubs his hands together ... OK here we go.
My thoughts from recent maddening experience:
1st that bolt is not right IMO & could be the root cause of the 301 & the ticking sound because it's an exhaust leak. That could mess up 02 sensors etc & give you that popping sound & yes it will increase with engine revs.
I agree on pulling the valve cover & to make things easier to find which valve may be the culprit I'd say remove the molex plugs from the coil & have someone crank it over with the valve cover removed.
That way you can see the rockers working, put a block of wood on the poly lock in the center of the rocker & listen as you watch them move & synchronize the sound to movement.
Also look up/Google 'how to adjust hydraulic lifters" & see the procedure so you can try to tell if they're not right but more likely a bent push rod (for some unlikely reason). When the specific rockers are at a certain point you should be able to twist the push rods by hand with "some" resistance. This also depends on how full the lifters are IE just ran the engine for a while (lifters are full) or stone cold (lifters are empty or down). If you can twist a push rod a bit or 3/4 of the way & it stops but you can go 3/4 of the way back then you have a bent push rod - easy to replace.
You can go to Harbor Freight & get a ignition bump switch. Basically it's a push button that hooks up to the power & solenoid of the starter that you push to turn the engine over without it starting.
This, like having a friend turn the engine over with the coil disconnected will allow you to watch the rockers & sync the sound with a particular cylinder, but you can do it yourself.

Sorry, reminds me of a joke:
What's the definition of a Yankee?
Same thing as a quickie but you can do it yourself!

that all sounds a bit over my head... i'm ok with most car stuff, but the engine/transmission work has always been "no man's land" for me...

do you know the correct size of that bolt in the manifold? I might try replacing that first with a new bolt. From there, I might get brave and pull a valve cover off. I really don't think i'd know what im looking at underneath it though :icon_dunce:

edit: cylinder 1 is the driver's side front-most cylinder?

Guys, I got a hold of a code reader that allows me to see freeze frame data. Here is what I got:

Fuel System 1: Closed Loop
Fuel System 2: Closed Loop
Load Value: 3.1%
Coolant Temp: 138degrees
STFT - Bank 1: 8.5%
LTFT - Bank 1: 0.0%
STFT - Bank 2: 15.6%
LTFT - Bank 2: 0.0%
Manifold Pressure: 12.9 in.hg
Engine RPM: 592 RPM
Vehicle Speed: 1mph


I/M Status
Monitors not ready
Misfire: OK
Fuel System: OK
Comp Com: OK
Catalyst: No
Heated Cat: N/A
EVAP System No
2nd Air Sys: N/A
A/C: N/A
02 Sensor: No
02S Heater: OK
EGR System: OK

Codes present: 0301, 0753 (appears unrelated to the bad running condition, but figured I'd mention it)

Already tried: New rotor/cap, wires, plugs, checked all connections

So that I'm not just throwing parts at this problem, what's the best plan of attack. Those fuel trims look off.

*UPDATE*

So today I was told I couldn't borrow my Dad's truck this week, so I was pretty much forced to get the Blaze runnin' or I'd be walkin' 30 miles to work...

Started with plugs (old ones looked original!), crossed my fingers, but no dice. Started up a lot easier, but the "clacking" sound was still there...

Knew what I had to do... bit the bullet and pulled the driver's side valve cover. Started it up and watched all the lifters... sure enough, the front-most one wasn't moving up and down, just "flopping" left to right about 1/4" making the clacking sound I was hearing.

I tightened the nut back down and it fixed the problem!

I plan on re-doing all the lifters next weekend in more detail as I'm sure the others need attention as well.

Talk about sludge... wow! the stuff that was caked on the inside of the valve covers was/is thick like tar... I left it alone for the time being so as not to disturb the sludgegods.

So far, I'm a happy camper! Also that new code reader found a code my small Actron didn't which indicated my Transmission solenoid "A" was bad. Going to replace that next weekend as well and hopefully that will fix the issue I sometimes have where 1st won't engage when leaving from a stop/idle.