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What is this Engine Noise??

Bross82

Bross82

1/2 ton status
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Feb 11, 2002
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Spencer, MA
The motor is a 305 with about 155,000-160,000 miles on it. This mainly started after I had my exhaust system replaced from a 2 1/4 to 2 1/2 inch full dual system. But, when it started, it went away after warming up. Now, it is doing it constantly. There does not seem to be an exhaust leak, it seems further up near the head than where the exhaust starts.

The engine makes a ticking/clacking noise while running mainly in drive when the rpms are down lower. But it will still do it while driving, just doesnt really do it as often when in park.

I'm thinking it may be a sticky lifter, but I'm not sure. I have very limited valve train experience. But, if I'm able to tell the condition of the rocker arms when the engine is off, they dont seem very loose. A slight bit of play from side to side only, and I was told from someone at a parts store this is normal since if they are hydraulic lifters, that they arent applying the pressure they would on them while running....

If this is a sticky lifter, what is involved in changing the lifters. Can I take out the intake without taking out the distributor. Also, can the rocker arms be taken off without having to do anything to the valves? If I'm right, the keepers should hold the springs and valves in place while I remove the rocker arms, push rods and lifters right?

I have included this link to a video while it is running with the passenger side valve cover removed: (It is about 10 MB, please give it a minute to load)

http://logeeland.assumption.edu/~mporter/files/MOV00817.MPG

Any help is greatly appreciated. I have been trying to determine what this noise is being cause by so I can finally drive it again.
Thanks!
 
An ehxaust leak will make a ticking noise wear the pipes bolt to the manifolds
you have to pull the in taketo change the lifters
pull the valve covers and see if you can move any push rods up or down
but with what you said ide say exhaust.

90 jimmy
 
Find a piece of tubing, fuel line or heater hose what ever, stick it up to your ear, now VERY carefully probe the suspected areas with the other end of the tube, this will isolate alot of the noise that is around an engine while running. If you hold it around the exhaust and it's leaking you should hear it get louder as you pass over the leak. Same with the lifters if one is sticking, it'lll creat slop in the valve train for that valve and you should be able to isolate teh sound of a ticking rocker arm . Old trick but i've located all sorts of problems with the old tube method. Vacuum leaks, ticking, etc. Just be very carefull around moving parts.
 
it's your egr butterfly valve. it is located on the pass side it kinda looks like a engine brake. I took mine off when i did mu exahust.
 
it seems that when exhaust is leaking at at exhaust port gasket that its most noticeable at idle speed and such, and sounds awful lot like a tick instead of what you would tihnk an exhaust gasket burn out leak would really sound like\

neat video there of the engine, so theres a big ol edelbrock carb on that lil 305 ? hummmmmm

too bad cant see all the rocker arms in the video to make sure they are all moving good/noticeably and all about the same


are they ?
 
it's your egr butterfly valve. it is located on the pass side it kinda looks like a engine brake. I took mine off when i did mu exahust.
Click to expand...

I'll have to check that out and see if thats it...

it seems that when exhaust is leaking at at exhaust port gasket that its most noticeable at idle speed and such, and sounds awful lot like a tick instead of what you would tihnk an exhaust gasket burn out leak would really sound like\

neat video there of the engine, so theres a big ol edelbrock carb on that lil 305 ? hummmmmm

too bad cant see all the rocker arms in the video to make sure they are all moving good/noticeably and all about the same

are they ?
Click to expand...

...so when you say leaking from the exhaust port, do you mean where the exhaust manifold connects to the pipe? I'm pretty sure its not leaking from there, but I can double check again. My old exhaust system gave me a lot of problems blowing those exhaust donuts for some reason, especially the driver side. But nothing so far as I've noticed with the new system. The tick though, does sound awful, especially if I rev the engine a little. That's why I haven't been driving it, just don't want to have a lifter or something go major on me.

As far as I could tell, again not having any real experience watching rocker arms, they seemed fine. No vertical play when the engine was off, and it was still hard to pinpoint the noise actually being any louder with the valve cover off and running. Maybe I'll see if I can get a better shot of all the arms moving tomorrow.

ha...yah, actually that carb was on there when I bought the truck...still want to get around to finding out what model... actually as far as the carb goes, with goin from 2 1/4" to 2 1/2" pipes, could the engine running too lean cause it to do this?

Thanks
 
for the egr valve...should the engine come stock with it? According to the guy I bought it from, this is a 305 out of a pickup w/o AC. But, origionally the blazer had AC. Not sure if that would have any bearing on this....I looked around, looked at the emissions diagram under the hood and looked in the haynes manual for what it should look like...the best i could find was where it should have been, there was a thin metal plate bolted to the intake just to the left of the carb. could it have already been removed??

also, while i'm looking at all of my vacuum lines and stuff. would any of it change from the original diagram under the hood if the carb had been changed? which hoses go where...also, what is that plastic ball shaped thing at the very back of the driverside fender, right against the firewall?....it has always had a hose coming out....but never been connected to anything with the end all dry rotted and falling apart, even when it ran good before it was just sittin by the fender... is that anything to do with the other emissions/vacuum lines?

hopefully i can get these lines straightened out and take another possible cause of this problem off the list. Thanks.
 
I think what I've been trying to figure out is close to the same problem as this other post...

http://coloradok5.com/forums/showthread.php?t=135298

But, I dont think I have the low oil pressure problem. Is this still probably the same issue?

One thing that happened though.. One of the times I took the valve cover off, I had poured a little bit of oil over everything (springs, rocker arms...). I got it all back together (put the cover on and connected all the lines i had touched) and I thought a friend found the problem to be a disconnected vacuum line....I started it up....ran perfect, no unusual engine compartment noises. let it run a few minutes, rev'd it a couple times, shut it down. then i checked the oil level, (i had done an oil change since it sat for so long). started it up...it still ran good for a few more minutes. put it in drive moved to the end of the driveway, and the noise started back up again. so i just backed it up and parked it. my above posts were after this happened. could
pouring the oil over everything be just coincidence when it stopped or is something maybe not getting oil?

thats what also got me thinkin it was maybe something not running correctly in the valve train or maybe not getting proper oil.

also, one of the valves on the 6 cylinder must leak oil pretty bad. when it was running (even back when it didnt make any noises) i'd have to change that plug every oil change or two, and it would have oil gunk hardened all between the gap of the plug. could it be leaking so bad now that it is affecting the overall combustion in that cylinder making that noise?.... I don't get much if any smoke coming out the exhaust though. i just changed the plug again with the oil change, it was gunked up, but nothing unusual as far as that cylinder is concerned and it still makes the noise.

Thanks
 
too bad cant see all the rocker arms in the video to make sure they are all moving good/noticeably and all about the same



I agree,,,,,to me it looks like the 1st rocker right behind the alternator is not moving much,,,just my .02 cents,,
 
hmmm....you might be right, it is a little tough to tell though.

ok, so if that is it....what is it most likely? the rocker arm, lifter .... thing is though, i honestly didnt notice the noise get any louder between the cover being on or off, and couldnt really tell still what it was coming from if that makes any difference.

i'll see what i can do this sunday. tie stuff back better and get a longer steadier shot. thanks again.
 
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ok, i got a couple more videos of it running to check out. it wasnt really making the noise this time when i took the picture of the valve's moving...but i did get it to do it later when in reverse or drive (but i think it will do it in park sometimes, it seems to happen once the rpms change) and it seemed like the noise was louder this time from underneath. In the last picture you can really hear it, there was also some other noise that i haven't heard before besides the knock type of noise...


rocker arm video from above the fender

rocker arm video from over the carb

video underneath motor


thanks,

matt
 
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