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Guess The Engine Knock: Video Included

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Old 03-20-2017, 05:06 PM   #1
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Guess The Engine Knock: Video Included

Ok turns out the '82 beater has a pretty loud engine knock only under certain conditions and hoping someone knows the noise before I dig in too deep. Feel free to toss out ideas or let me know why mine are all wrong!


Knock situation:
- Engine under load (brake stand OR hard acceleration)
- Only over ~2500rpm
- Warm or cold


No knock situation:
- Neutral or park with gradual throttle up to any rpm
- Gentle driving around
- Brake stand under 2500 rpm


The simple things I started with:
- Separated plug wires (especially 5 and 7)
- New cap and rotor
- Fresh fuel
- Oil change (no metal)


Current Ideas:
- Rod knock
- Head gasket
- Broken motor or trans mount


See video below of brake stand from 1000rpm up to ~3000rpm:
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Old 03-20-2017, 05:38 PM   #2
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Re: Guess The Engine Knock: Video Included

Hi Vincevs. Sounds like a rod knocking. Missing and knocking. Determine which cylinder is missing, pull the valve cover and see if it has a bent pushrod or jumped out from under the rocker. If you don't find a bent pushrod, then you probaby have a rod knocking (spun or stacked bearing). Don't spend any money on that engine until you determine what the knocking and missing is.

al
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Old 03-20-2017, 06:47 PM   #3
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Re: Guess The Engine Knock: Video Included

It's my understanding that rod knock is all the time and not just under load at mid rpm... is that wrong? Maybe this is the start of it?
Also, this car is only for a 1000 mile car rally so no worries about spending money on the motor. Max budget is $700 including the car. Ha ha. This is a find the problem only question.

Last edited by vincevs; 03-20-2017 at 06:52 PM.
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Old 03-20-2017, 07:03 PM   #4
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Re: Guess The Engine Knock: Video Included

Hi Vincevs, if it is a bottom end knock then the damage is done. You need to determine that and stop running the motor before it grenades. A lower end knock can come and go a little but the crank is already damaged, *if it is a rod*.

You should check the cylinder with the miss as it is most likely the rod with the spun or stacked bearing. Confirm the push rods are properly seated under the rocker. This can cause noise similar to yours. It would be nice if were only a pushrod jumped or bent , then you could easily replace it.

al
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Old 03-20-2017, 07:30 PM   #5
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Re: Guess The Engine Knock: Video Included

bent pushrod as mentioned above would be the first port of call, if its not a bent pushrodrod, retension the rockers, make sure they are all rocking. If after verifying the pushrods are straight, you come across a rocker that isnt lifting, you may have wiped a lobe off of the cam. - new camshaft

being under load there is another option. i had an exhaust header leak that only appeared under load initially, after a couple of hundred km it developed into all the time but would increase in severity. a set of copper header gaskets for the exhaust fixed it up.
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Old 03-20-2017, 07:51 PM   #6
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Re: Guess The Engine Knock: Video Included

is there any metal in the oil after running a few minutes?
a mechanics stethascope or long screwdriver to your ear could help isolate where the noise is coming from?
could be a badly stretched timing chain jumping around to?
hopefully not a rod knock.
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Old 03-20-2017, 10:46 PM   #7
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Re: Guess The Engine Knock: Video Included

Thanks guys. I will update as I walk through the possibilities.
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Old 03-21-2017, 12:36 AM   #8
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Re: Guess The Engine Knock: Video Included

Ok i am alone tonight to harder to diagnose but here is what I came up with... so long screwdriver gives me no noise from the top end or manifolds other than a pretty good whine from the distributor. Pulled the valve covers and the push rods are straight and everything else seems to be in place. Also seems like when i put it under load every knock lines up with a little puff out of the carb.
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Old 03-21-2017, 12:49 AM   #9
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Re: Guess The Engine Knock: Video Included

Video #2

Oil photo with some metallic when you run your finger in the corner:


Next will be to see if all the rockers move, compression check, followed by oil filter and dropping the pan for a closer look.

Last edited by vincevs; 03-21-2017 at 02:17 AM.
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Old 03-21-2017, 12:51 PM   #10
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Re: Guess The Engine Knock: Video Included

Looks like bearing material to me. No need to "drop the pan" for that.

Knock w/puff out of the carb under load = head gasket; blown between, most likely, #5 & #7.

Time for a new motor; or at the very least, unless it's a 267 or a 305, a crank kit. If it's one of those, then the only "correct" answer is a new motor with a 4" bore.
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Old 03-21-2017, 05:09 PM   #11
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Re: Guess The Engine Knock: Video Included

This is a 305..
So if it's indeed a head gasket can I not just fix the head gasket or do you think it caused further damage? No evidence of coolant in the oil but if so a 4" bore sounds like a great plan... just won't fit my $700 car rally limit.

Last edited by vincevs; 03-21-2017 at 05:12 PM.
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Old 03-21-2017, 07:30 PM   #12
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Re: Guess The Engine Knock: Video Included

Seems like you aren't listening:

A head gasket CANNOT POSSIBLY put bearing material in the oil.

PERIOD.

Sure, you can swap head gaskets; That might fix the "puff" issue; just don't expect it to do any good in the longer run about the knock. Might run a bit better for a day or 2, but in the end, that won't put the metal back onto the bearings. Might even tear em up the rest of the way faster.

You can P&M all you want about "budget". Best to, instead of attempting to adjust your needs to your "budget", adjust your budget to REALITY. Things cost what they cost. PERIOD. Getting on here and P&Ming about "budget" isn't going to change what's wrong with your car, or what it will take to fix it.

Do what you can to be absolutely certain about it; don't necessarily take my word, or anybody else's, for that; believe ONLY what you see with your own eyes. Take photos if you don't know what you're looking at and post them here, we'll be happy to help you interpret.

My guess would be that there's some abuse in the past of that motor that you're either not aware of or not admitting to. Coming here and beating us over the head about "$700" isn't going to undo the damage. Either you want to fix it, or you don't; "$700" BS isn't going to magically make it all right again.
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Old 03-21-2017, 09:55 PM   #13
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Re: Guess The Engine Knock: Video Included

A cracked flexplate will also sound like a knocking rod.
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Old 03-21-2017, 11:30 PM   #14
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Re: Guess The Engine Knock: Video Included

What is P&M? Just tying to have some fun figuring out what's wrong and if it's over $700 I'm driving the old girl until it blows up. As for following the advise... it looks like I have some major cam failure! Ha ha. Any good posts on doing a cam swap and is it the consensus that it's both cam failure AND rod bearing? Or (with any luck) could the metallic supstance in the oil be cam only?
Videos in next post.

Last edited by vincevs; Today at 08:10 AM.
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Old 03-21-2017, 11:43 PM   #15
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Re: Guess The Engine Knock: Video Included

Driver:
Passenger:
Great Beater Challenge (aka $700 imposed budget):
https://greatbeaterchallenge.wordpress.com
"stupid cars, stupid cheap, stupid fun!"

Last edited by vincevs; 03-21-2017 at 11:47 PM.
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Old Yesterday, 12:52 AM   #16
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Re: Guess The Engine Knock: Video Included

Flattened exaust lobe on the cam will cause a pop out the carb
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Old Yesterday, 01:04 AM   #17
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Re: Guess The Engine Knock: Video Included

Perfect thanks. Looks like I'm in for a cam swap! Any good forum links for doing it without pulling the motor?
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Old Yesterday, 06:59 AM   #18
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Re: Guess The Engine Knock: Video Included

cam failure in your case was likely caused by your primary issue in the bottom end.

either way do not delude yourself into thinking that the missing metal from the cam lobes somehow 'disappeared' and hasn't flooded throughout your oil passages.

although my bet is that bearing failure in the bottom end increased tolerances so much that the cam bearings ultimately starved for oil.

any money, time or effort into doing anything to that motor that doesn't start with a tear down and interior cleaning is wasted.
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Old Yesterday, 10:26 AM   #19
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Re: Guess The Engine Knock: Video Included

put a "budget" junkyard motor in that thing for the race.
i agree, a cam swap is a waste of time and money at this point.
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Old Yesterday, 02:55 PM   #20
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Re: Guess The Engine Knock: Video Included

Ok thanks guys... on the hunt for a cheap 305.
Or maybe just do the Summit K1102 cam for the fun of it and see how it runs because, according to this thread and probably my X wife, I suck at listening... if it ends up that I am still having an issue in the bottom end I'll toss it in the replacement 305.

Last edited by vincevs; Yesterday at 04:32 PM.
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Old Yesterday, 05:13 PM   #21
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Re: Guess The Engine Knock: Video Included

If the metallic substance in the oil is in fact the cam & lifters, it's some of THE HARDEST metal in there. I.e. the most destructive to everything else.

Motors with a flattened cam tend to have gotten that debris and metal chips all in the oil passages and therefore the bearings. They tend not to last long after that. Furthermore, the single most common reason the cam goes flat in the first place (apart from improper break-in, or just, bad luck at that time) is lifter bores that don't point straight at the cam. Meaning, even if you put in a new cam and do everything right, the odds are very high that the same lobe will fail on the new cam for the same reason the old one did.

You can try it though if you don't believe me... you can do it in the chassis, you'll have to remove the radiator and A/C condenser (cond & comp can fold over and sit on the strut tower without unhooking any lines). Then you'll need to remove the vertical brace in the center, under the hood latch.

Time to start looking for a 4" bore block. Installing a 305 is a waste of perfectly good gaskets & fluids, not to mention time and effort.

OBTW; P&M is p***ing and moaning.
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Old Yesterday, 11:16 PM   #22
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Re: Guess The Engine Knock: Video Included

Flat Cam

Last edited by WinningBet; Yesterday at 11:24 PM. Reason: Member already found problem
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