What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Popping exhaust

M

Mudslutk51984

Registered Member
Joined
Dec 7, 2016
Posts
91
Reaction score
21
Location
Commiefornia

What the hell is this noise?! I changed all the vacuum hoses and that’s when it started sounding like this.. also after the hoses the check engine light came on... my obd doesn’t work either... the part in the video where it goes lower rpm is when I put it in gear... help??!! It’s a 1984 k5 350 4 barrel quadrajunk. I also unplugged the coolant sensor on the thermostat and a couple other plugs but everything is plugged back in
 
Last edited:
Sounds more like a lower end knock or loose torque converter bolts to me,but its tough to tell on a video,the audio can make things sound much different than "in person"..
 
The fact the knock is reduced or goes away when he puts it in gear is a common symptom of loose torque converter bolts or a cracked flex plate,but it could be a main or rod bearing too,perhaps a bad harmonic balancer..
I doubt changing the vacuum hoses had anything to do with that--even if you installed some on the wrong fittings I doubt it would make the engine knock like that..and it sounds like it idles OK,usually if you screw up the vacuum hoses, it wont..
 
check torque converter bolts, slide under it while its running see if it is engine....
 
is the exhaust hung properly? had a camaro knocked like this hung the exhaust and it quit
 
A leaking exhaust valve or a pumped up hydraulic lifter can let the fuel/air mixture ignite in the muffler or exhaust manifold or pipes,but usually it'll be more of a popcorn popping sound ,not a knock or thud..loose baffling in the muffler can make rattling noises or vibrations,but I've never heard one knock before..

I have seen a few rare cases when a double walled y-pipe had the inner pipe come loose or collapse and make weird noises before..one of the teachers Buick's in shop class had a 430 with a collapsed y-pipe,it wouldn't go over 40 mph ,acted like it had a clogged converter,but it didn't make any weird noises..
 
That’s exactly how I described it sounds like pop corn.. any vacuum modules that can screw with fuel mixture? It’s just real odd it happened after I messed with the hoses and unplugged a few electric things (but plugged them back in)... I can’t figure it out
 
Well,there are some things that are vacuum operated that can affect the running of the engine--if you still have the EGR valve hooked up,if the vacuum hose routed to it was not hooked to the right port on the carb or ported vacuum switch,and it gets manifold vacuum ,it might let it stay open or partly open,and lean out the fuel mixture,but usually the engine wont idle ,it will want to stall,or at least idle lousy, if it opens at idle..

If your distributor has a vacuum advance ,where the vacuum hose is hooked to can affect the timing,but I don't think an '87 would have vacuum advance,they stopped using that around 1980 or so,and instead used a ignition module with more than 4 prongs,that advances the timing electrically by rpm instead..

It might be some other part just decided to crap out by coincidence,like a spark plug decided to foul,or stop firing regularly..a bad plug wire,or having one on the wrong spark plug and screwing up the firing order can also make it run that way--if you have taken any plug wires off or moved them I'd make sure they are on the right cylinder and not damaged at all!..
 
I replaced the cap rotor plugs and wires.. it’s an 84 and doesn’t have a vacuum advance.. the check engine light came on with the exhaust noise.. it does idle worse as well.. I’ll see if I can make a detailed video tomorrow if everything I did and how it idles... stay tuned and thanks for the replies really super appreciate it
 
Double check the firing order. Also if it has the electric carb, be sure the plug is connected properly.
 
You got a catalytic converter on that thing? Cat could be breaking down and plugging itself with the pieces. The pieces move around relative to the exhaust flow and change the sound as they block and unblock. When it gets blocked it increases the back pressure and starts to run rich, which causes other problems.
 
If the cat plugs up it can cause all sorts of weird random things to happen depending on how much stuff blocks the pipe. My brother borrowed a van once and the cat insides all broke apart.... van wouldn't go over 30 up a hill. blew vacuum hoses off the motor and made all kinds of weird noises that sent us on diagnosing goose chases ...Made the highway trip to Arizona super fun. When we got to where we were going we spent 2 days roto routing the cat out from the end of the exhaust pipe till we basically had an empty shell for a cat. van ran fine after that.
 
You must log in or register to reply here.

Latest Posts

Top Bottom