Remember that 2.8/2.8 swap I did? Well, my friend recently told me the engine's got a knock to it... dammit. Looks like that $100 2.8 engine wasn't such a bargain after all! I don't know the specifics of the knock, but maybe I'll check the timing. We never did resolve that. Otherwise...

How do you tell where the knock is? With a piece of heater hose used as a stethescope? Or is there a more technical way of figuring that out (bearings, rods, etc?)


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

As far as I know, there are only 2 kinds of knocks - ignition and bearing. As much experience as you have, Tom, I'm sure you can recognize an ignition knock. Those, of course, usually occur during "hard use" - lugging up a hill, punching the gas, etc.

Bearing knocks are generally noticable nearly all the time, although might be hard to hear at idle. There are really only two questions with a bearing knock - is it a main or a rod bearing and which cylinder? Both these questions are pretty much moot, since you can't live with either very long and the fix requires tearing the engine apart during which you're going to replace all the bearings anyway.

The heater hose "stethiscope" will work, although your might find a long screwdriver pressed to your ear works a bit better. Gotta be "flexible" since the engine will rock a bit so if you don't move your head you'll get pounded, but something about the solid connection seems to make hearing it easier.

Hope this helps.
T

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Maroon '92 RS 3.1L AT PW PDL CC Tilt

 

Hi Tom
Let me tell ya about rod/bearing knocks.
You can almost live with them forever.
It will occur when the engine is warmed up, right?
Thicken the oil. Use 1 quart of straight 50 weight. That will take care of it.
I had a rod knock in the small block chevy I had under my 1967 RS/SS Camaro 4-speed convertible.
I dorve from LA to almost the Oregon border on it. I raced a Mercedes at 100 mph with that engine with the rod knock.
Drive it until it falls apart.
Just thicken the oil.
OR your oil pump pick up tube could have fallen off.
Easiest way to tell is check the oil pressure.
IF it real low, your pick up screen may have fallen off the pump.
Beyond that, thicken the oil & try to kill it!
Have fun. I made a 2" hole in my piston. But, never threw a rod thru a block yet.
I also sold that engine to someone (they even heard the knock) for $200.
How does the rest of it run? If strong & good, go get another short block. You should know how to get it in & out easier, now.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

does engine sound like cluk clunk clunk no loud but faintly noticeble?

 

Ok First Of ur good u can put ur hand on different parts of the engine and almost "feal" it knocking. When i was looking at buying a thirdgen i found out that the 2.8 liter v6's are notorius for getting the "knock" i found out that the knock is most likely caused by a bent piston rod BIG ****IN PROB i wouldent recomment buying an engine with a knock but hey whatever.

U fig it but im wright!

NitruSOx

 

Hi TomP,
I think You are sure it's not a valve, or could it be? it's halfway a question for my self.

Horst


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www.marion-becker-nidda.de
91 Firebird 3.1
Modsynomax ultra flow stainless steel

 

I have found the best thing to find noises is a long solid piece of metal on the part you want to hear and the other at your ear. You will be surprissed at what you can hear with that.! I could hear 1 ball bearing bouncing around in a water pump in a friends car!

 

What is a knock? (obviously a sound that can be heard due to an ignition or bearing problem, be more specific please)

 

My friend thinks a pushrod could be loose... I've yet to hear the motor, though... our work schedules aren't on the same track lately. Could a loose pushrod be the deal?

Bummer to hear that spark knock is the ping I'm used to... I was hoping this clunking of his couldn't be a simple timing problem. I'll tell him about the heavy weight oil and screwdriver ideas, and caution him about a concussion!


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

if it is a push rod beware of an impending flying rod!. but yes it could be one off center making the noise. I would take off the covers and see if you can move them by hand. if they have a lot of play you have found your problem. you should not be able to move them very much.

Then again it might be a bad seat as well...but I would think they would be both self centering and seating...good luck though...

TomP sorry for before but I am getting tired of getting bashed for what I say.

 

Tom, Slow down. Approach this realisticly. Go and listen to the engine. Does the noise sound like a knock or a loud tap? Is it under load or all the time? It could be as easy as an exhaust leak. (I've had that one drive me crazy with my brand new 4.3) Is the sound coming from high up in the block or down low? Here's a good one, does the knock time up with crank rotation or cam rotation? (remember the crank spins twice as fast) Don't go off halfed ****ed thinking the engine is a boat anchor just yet. Did you readjust the valves after 500 miles? Before you do ANYTHING, do some detective work and investigate possible sources.

Post the answers to a few of these questions and I'll get back to you as soon as I read them, untill then I'm not guessing what it could be. And everyone else is doing just that, guessing.

What does KED know anyway? He drives a frieght train for goodness sakes......j/k KED

EDIT: the bleep is supposed to be half-co cked, as in a gun.

[This message has been edited by 87RS402 (edited May 14, 2001).]

 

I'll tell ya what I know.
My first engine swap. I bought a rebuilt 350 to go into my RS/SS 350 Camaro Convertible 4-speed. I blew the other engine racing someone. So I get this one, purchased on PRICE not reputation.
Installed it.
Knock-knock.
It didn't happen right away, it took awhile, as I recall. About a month or so.
Did the stick/screwdriver test.
Drove it back to the engine shop.
Yep, it's bad, pull it out.
About to. Go back to engine shop.
Shop closed.
For good.
Drove it, knocking, that way for many years.
Really. It was alot quietier with the thick oil.
It never came out the side.
I tried.
Do the long screwdriver test.
It's amazing what you can hear with that damn tool! You'll have fun, listening to the water pump bearings. Oh, try the alternator, too!
Honest, you will be able to tell if it's a rod knock.
When ya hear it first time, you'll know.
It has a deep metallic sound to it.
Not a light valve tap sound.
Valves ONLY loosen up, if the cam is going flat. Valves you hear, instantly.
Timing will not change it.
It happens upon the engine loosening up, as the tolerences get warmed up.
Kinda like putting bananas/sawdust into a tranny. Works the same way.

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

I was just teasing KED, I've come to respect you for your knowledge. You seem to know what your talking about. It's just important to make sure what the problem is before we go telling someone that their engine is about to let go. No doubt you've heard alot of different knocks in your lifetime and not all of them have been fatal.

The comment I made about crank or cam timing referred to was the knock in rythm with the crank or the cam. If it's in rythm with the crank it's a rod or a wrist pin (could be piston slap too) If it in cam rythm it's in the valve train (it could also be the start of an exhaust leak, then it would be more pronounced under load).

 

Hey Tom...I hate to hear about this.With the work you guys put into this is't almost like a slap to the face.

As far as a push rod popping loose I doubt it.I had a 81 olds a few years ago that came with a diesel motor.The motor was shot so Dad and I put in a 350 chevy.After 3 months it started smoking from one side and had a miss.Dad and I went thru this thing and couldn't find ****.We checked the timing,compression,fuel,spark,etc,etc.

We gave up and drove the damn thing anyway.2 weeks later I put a set of chrome valve covers on and found a push rod had came loose from the rocker arm.I set it back set the valve lash and all was good.
What I'm getting at was it didn't make a single noise.

When my 2.8 started knocking last year I knew what it was when it started.Fortunatly it wasn't so bad,you could hear it from inside the car at a certian rpm and you could hear it under the hood.You could just barily hear it with the car idling.They were all scared up(the bearings)pretty bad but only one was close to spinning.The damn coolent and oil pump didn't get along well
I hope for your friend sake,and your cause I know he will have you under the hood helping ,that it hasn't scared the crank.
My advice is to pull the engine flip it onto it's top and pull the pan.If the crank needs turned it should cost somewhere in the 75 to 90 range.Depending where you take it.The bearings arn't all the expensive.
Turn the crank no more then what is needed.The more you take the weaker it will be.Mine was turned.010 If it needs more I'd buy a new crank or find a doner 2.8 front drive 2.8's have the same crank.Once the engine is out and the crank is fine,it shouldn't take more then a few hours to replace the bearings.
If you guys lived closer to me I'd love to come help.Good luck Tom.

------------------
Kevin S
89 RS w/2.9
modded some but not heavily


"I am just as enthusiastic about flying saucers as I always
was, but the problem is that we are in the middle of a
long, long trough. There's only so many times you can pick
over old bones. There just aren't enough new sightings. It
is not like being a philatelist - there is always something
new to say about stamps."

- Denis Plunkett, 70, a retired civil servant from Bristol
who founded the British Flying Saucer Bureau, which has
suspended its activities because of an apparent sharp
decline in the number of alien visitors to Earth.

 

87RS402, thanks for the ideas! That'd be great if it was an exhaust leak... we did need to replace some studs on the exhaust manifold for the y-pipe. One question though, if the 2.8 has the hydraulic lifters, I thought we didn't have to re-adjust them? (Altho the pushrods locations -were- mixed up, they're not with their original lifters.)

Karl, you love trying to blow those engines up, eh? I gotta get down to this Camaro & hear it knock, see what's up with it. I honestly haven't had a chance to see the engine since we last worked on it.

Kevin, thanks for the quiet-but-loose-pushrod info. As to pulling the motor again- I don't think that'll happen. Well, at least, I don't want it to happen! I don't think my friend wants it to happen, either. I don't feel as if all was lost though, I learned a lot, and had a great time doing it. I'll just make sure the next engine is "known" as good!

Camaro_hunter_d, after the way you "talked" to me (and the other members here!), I don't give a damn about your apology. I haven't "talked" to you since all that went down, and I intend to keep it that way. Nothing I write on this message board is for you. As I said before, I'm done with you.

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been edited by TomP (edited May 15, 2001).]

 

Hey 87RS402,
I PROMISE, I knew you were only kidding.
I thought I'd give the real skinny on why I knew it, first hand, the bad news about the noise.
As I said, when I did my first engine swap, I blew it on two of the three. This was my first goof, but, it ran and I eventually sold that block. Someone else paid me for my problem. Imagine that!
I am building the "1970 LT1" for this same Camaro. It's the one I'm porting and polishing old 1969 Z-28 heads (186) for. One head is done (not assembled) another is awaiting my return to the grinder, after I do:
1. MPFI head swap job on my 1985 S-10 Blazer (with the carb, I'm still trying to figure out how to remove, to get to rest of the intake bolts, then it's down hill), then
2. Swap engines on my Honda 1972 CB 175 motorcycle, with the damaged 200cc block on it. This is the second swap that went wrong.
Oil problem.

Me know alot? LOL!
I just blew it, doing things enough times & have some great friends (HERE, ALSO) that get my A$$ outta trouble!
Hey, ya shoulda seen me, first time I took the air cleaner off my 1966 Corvette & Dropped the carb stud down the carb.....
or the time I "adjusted" the door closure striker plate on my Dad's 1954 Corvette & all I eventually heard was a "Klunk!" from the plate support dropping where I couldn't see it.
My Mom goes....."You BETTER fix that before your Father gets home!"
Wish some things in my life were/had easy answers like some cars!
When you drive the car, Tom, you will eventually know what's going on, light engine load, you'll hear the knock. Hard on the engine, may not hear it, but, when you back off the gas, you'll then hear it.
Valves need to be adjusted, correctly (key word), once. If a cam goes/is going flat (I had that too), valves will go outta adjustment.

Why can't your friend drive it to you?

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Chat Soon,
KED85
Karl
1985 Firebird 2.8 to 3.4 swap project for Smog Happy LA, CA

 

I hate those words! He could drive it to me, but either I'm at work, or he's at work; it's one of those deals. He's not even driving it now; the starter solenoid's on its way out, and he doesn't want to get stranded.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Well tomp fine screw you too then...
hope the engine blows...

I tried to be nice...

[This message has been edited by Camaro_hunter_d (edited May 15, 2001).]