Bent Pushrods, Need Help!

[EYUKINS]

Hello all. Just found this website and already think it's excellent.

Here is my situation;

I was given a 1984 Corvette Coupe with 61k. The reason it was given to me is because it was sitting in my buddy's driveway for 5+years, prior to that the car was driven VERY HARD- it was his first car. Besides the problems of a car sitting for 5 years- debris in every nook and cranny, gastank full of water and no coolant, the car had no battery, alternator and a broken alternator/p. steering bracket. I figured and was told that once I replaced that the car would be all set. It was not.

I got the car running and it would drive in reverse only, not in any forward gear. An occasional backfire from the carb, and the rearmost pipe on the exhaust manifold would get RED HOT.

Took the heads off and found some of the pushrods were snapped in half!, one lifter was popped out of it's slot and I noticed the intake manifold gasket had a "clogged" port, it was almost like the factory forgot to remove a piece of the gasket.

Exchanged the heads, added new gaskets, rods, lifters and cyl. head bolts. Cleaned it all up and put it back together. Went to start it up and crank,crank,crank....BANG! from the carb again. Figured the timing was off and rotated the distributer 180 degrees (while at tdc) to point at #1.

Tried to start it up and no crank just BANG.

So I took the intake manifold off and found that some of the rods are bent!

WHAT IS GOING ON HERE?

ANYBODY HAVE ANY ADVICE ON WHAT COULD CAUSE THIS OR WHAT MY NEXT STEP SHOULD BE?

I'm about to pull the camshaft out and see if this is a cause of the problem, thought I would check here first.

Any advice is much appreicated.

Thanks.



My problem is this;

 

[wingnut]

cam timing.chains jumped.

 

[baseballcorvette]

HEY I WOULD CHECK YOUR FIRING ORDER SOUNDS LIKE A WIRE ON THE WRONG DIST TERMINAL.I WOULD ALSO LOOK AT THE COND. OF YOUR SPARK PLUGS AND REPLACE THEM AND THE WIRES. CHECK ALL YOUR BASICS...... GOODLUCK

 

[boss64]

I agree with the timing chain answer. Pull the front cover and check the cam timing.

 

[vader86]

Sounds like the timing chain to me too

 

[Rowdy1]

Valve Timing

Start at the begining. Pull the cover off the timing chain and line up the marks, if they will. Sounds like the chain jumped or, the cam was installed wrong. And if that's the case, there's where your bending comes in. That's if the valve were adjusted right. If you're planning on keeping the car, or for that matter, selling it for anything, if it were me, I'd check the whole engine out, bearings and all. I'd add that if the cam is out of time, you'll never time the engine, you could have wires wrong by someone before you, a few things. Keep us posted on what you find out and decide to do. Good Luck!

 

[EYUKINS]

Thanks all.

I've replaced the basics- plugs, wires, fluids and filters.

I'ts 11 am Detroit time, looks like my day will be spent with the timing chain! Thanks again for the advice.

Will keep posting as things progress.

 

[EYUKINS]

Ok, removed timing cover and the marks are all at 12o'clock as the books says they should be. Went ahead and removed the camshaft, looks fine however I know I need to inspect it beyond just looking at it. I'll most likely buy a new cam. Any idea on price? I guess I'll find out soon enough.

What would the timing gears look like if the chain has "jumped" I assume the marks would not line up at 12 o'clock...right?

So after I took out the cam I took a look at the lifters that I previously installed, it seems like some of them are different. The retaining spring/clip that holds the valve in place inside the lifter is set deeper on most of the lifters. I'm starting to think i was sold about a dozen wrong lifters.

would this cause my rods to bend? I would think so but am not sure. Do you recommend I buy a new cam?

 

[Rowdy1]

When You Say...

12:00 O'clock, do you mean the cam or the crank? When properly installed they should meet, crank at 12, cam at 6. As for the chain, before you pulled it off, it should have been "fairly" tight on the gears, facing the engine, putting your fingers on each side, push the chains together, towards each other. They shouldn't move all that much. This is kinda hard to diagnose without seeing it. Can you post any pictures? Cams are cheap, $70 to $100. I'm still not sure what you're seeing when you explain the lifters but I don't think it was assembled right. In order to bend push rods, the timing and or valve adjustment has to be off.

 

[SPANISHVETTS]

Since this is an 84 why don’t you look at crate engines? The ¨cross-fire¨ was bit of a dog to begin with. If the engine was in that bad of a condition the big end and rings are not going to be in any better condition.

It is a real B!%@# to spend time and money on the heads and then have an unhappy insert send a piston on a one way trip into the valves. (Been there, done that.)

If you really want to stay with the existing block you should consider a total rebuild. Either way, Crate or Rebuild, you will save tons of $ in the long run.

 

[Dave C. '04 Z06]

Something you might check is make sure the rockers are adjusted right.

If whoever adjusted the rocker arms just torqued them down then you'll bend the pushrods and all sorts of bad stuff. Make sure they are turned down 1/2-3/4 turn from zero-lash and no more. Since you say the lifter plungers are deep then I would suspect the rockers were not adjusted right.

On a side note, the cam and crank timing dots will line up two ways, at 12:00 on the crank and 6:00 on the cam, or both at 12:00 since the cam spins at half the speed of the crank.


Good luck!

-Dave C.

 

[EYUKINS]

****12:00 O'clock, do you mean the cam or the crank?
When properly installed they should meet, crank at 12, cam at
6. *****

Initially the cam was at 6, and the crank at 12. However, after removing the drivers side head, I found that this was tdc at the exhaust stroke. Rotated the crank (with chain still on) untill the #1 piston was at tdc (all the way up) this made the marks crank at 12 and cam at 12.

My haynes shows this 12 oclock/12 oclock in the picture, I assume the engine in the picture is at tdc due to the instructions. I have seen the 6/12 oclock recomendations somewhere, I forget where and why it was showing this. My usnderstanding thus far is the crank revolves fully for every 1/2 revolution of the cam, hence the 6/12 and 12/12 lineup. If you could further explain this concept I'd appreicate it.

****As for the chain, before you pulled it off, it should have been
"fairly" tight on the gears, facing the engine, putting your fingers on
each side, push the chains together, towards each other. They shouldn't move
all that much.****

I believe it was fairly tight. However when I removed the cam pulley, the chain did not "bind" nor was it to difficult to remove.

So I'd say it was fairly tight.
I'm still not sure what you're
seeing when you explain the lifters but I don't think it was assembled right.********

In the picture attached you will see 3 lifters. From top to bottom:
Orginal lifter
New lifter- similar to orginal
New lifter- questionable lifter

The questionable lifter differs in the following way: If you where to measure from the top of the lifter to the retaining ring inside the lifter, the orginal and similar new lifter would measure about 2mm and the questionable lifters would measure 7mm. Another way to explain it would be that the rod would rest 5mm lower than other the rods.



********
As far as the initial reason why the rods broke the first time, may be timing or improper wire placement. Did I mention that when I tried to drive it, it would reverse alright but in a forward gear it had no power and woudl stall.

One thing really puzzels me: WHEN I TOOK OFF THE INTAKE MANIFOLD THE GASKET BETWEEN INTAKE MANF. AND CYL. HEAD HAD 2 PORTS ON THE GASKET "FILLED IN". IT WAS ALMOST AS IF THESE HOLES IN THE GASKET WERE NOT CUT OUT , I'VE ATTACHED A PICTURE OF A NEW GASKET WITH THE "FILLED GASKET" I WONDER IF THIS HAS ANYTHING TO DO WITH THE EXHAUST MANIFOLD CHANMBER CORRELATING TO THIS "FILLED" PORT TURNING RED HOT.

ALSO,
HOW CAN I ADD MULTIPLE PICTURES IN A POST?

THANKS
*****

 

[EYUKINS]

PICTURE POST MORE TO COME

THIS ONE SHOWS TIMING GEAR LINEUP AT TDC ON THE EXHAUST STROKE, 6 OCLOCK FOR CAM AND 12 OCLOCK ON THE CRANK.

 

[EYUKINS]

QUESTIONABLE GASKET PIC

 

[EYUKINS]

IN RESPONSE TO DAVE'S POST;

I DID INFACT JUST TORQUE DOWN THE ROCKERS, SO THAT MAY BE A MAJOR PART OF THE PROBLEM RIGHT?

BUT IT SEEMS THAT THE LIFTERS THEMSELVES ARE PLAIN AND SIMPLY DIFFERENT. IT DOES NOT SEEM LIKE SOME OF THE LIFTER PLUNGERS WOULD BE ABLE TO EXPAND TO THE HEIGHT OF THE OTHERS, SEEMS LIKE THE RETAINING RING OR CLIP RESTS ON A GROOVE THAT IS LOWER THAN THE ORIGINAL LIFTER-PLUNGER-RETAINING RING-GROOVE. IF WHAT I JUST SAID MAKES ANY SENSE? KINDA TOUGH TO EXPLAIN

 

[Dave C. '04 Z06]

I think if you adjust the rockers properly you'll be okay.

The fact that the newer lifter looks a little different there just looks like they're using a different retainer clip in there. As long as it's adjusted properly, they'll work the same.

Remember: 1/2 to 3/4 turn down from zero lash to adjust the rockers. NOT "torqued down until they're tight."

-Dave C.

 

[JR_Vette]

I DID INFACT JUST TORQUE DOWN THE ROCKERS, SO THAT MAY BE A MAJOR PART OF THE PROBLEM RIGHT?

Define "torque down"?

Take a look at this for reference. I'm sure there are better references, but this is a start :

http://www.iroczone.com/projrockers01.html

 

[EYUKINS]

18 ft/lbs, got that from the haynes.

Do I need to compress the lifters before reinstalling them?

 

[Dave C. '04 Z06]

Well, ...


1. You have to replace all the lifters and the cam in your car. You cannot just replace one lifter or two. You can only do that if you have a roller cam.

2. Do NOT compress the lifters before you install them.


3. Do not torque the rockers to 18ftlbs. There is a procedure you have to follow to adjust them which doesn't involve any torquing. I don't have time to type out the whole procedure but you should be able to do a search to find the procedure for adjusting hydraulic lifters.


-Dave C.

 

[yellow91]

Your intake gaskets are fine, the end with the plugged part and a little hole goes to the rear of the engine (infact it should say REAR on the gasket itself) and make sure you install them facing the right way. the rear engine water way from the heads acts as a pressure relief system. I'm talking about the L98 engine like in a 1985-1991 yours may or may not be the same.

But make sure you got the right gaskets for a 1984 Corvette with crossfire injection.