bent pushrod

[Steve Cole #22466]

My car is seriously testing my will.  

When we last left my current saga, I was in the middle of an attempt to trouble shoot an oil pressure idiot light and fixing a leaky exhaust in my 1961 intake manifold.

Well, in the mean time, Ive replaced my oil pressure sensor (havent tested it yet) and Im just about ready to install my replacement intake manifold. Today I needed to do some small tasks like clean the gasket surfaces and extract a broken valve cover bolt. I was on cloud 9 after having successfully removed the broken bolt when I said to myself, Hmm. where did that pushrod go?

Basically, the forward pushrod on Cylinder #4 had bent (cracked) and had dropped down into that space within the head. I was able to see it & extract it without incident thanks to one of those remote snake-type grabbers. I dont know when this happened or how long ago but obviously I need to correct it.

Since I already have the valve covers off, is there much to it? Should I just order new pushrods for all the cylinders? What should I be aware of & watch out for??

As always, thanks.

[JIM CLC # 15000]

12-03-05
Steve, I think you will be safe with just replacing the one push-rod.
Good Luck, Jim

[John #22631]

Steve, Dont discount the fact that the valve lifter could be collapsed. When you remove the rocker support install the new push rod and then push down on it and see if there is spring action in the lifter itself.
Just a thought!
John Serio

[Porter 21919]

Steve,

I agree with Jim, just replace that one pushrod.

Although a SBC allows for hydraulic lifter adjustment unlike a 390/429 years ago when I first got my 66 Vette two lifters wouldnt quite down, pulled the push rods and rolled them on a table saw, they were bent, replaced them, end of story. If you remove any of them always reinstall at the same location.

Dont get discouraged, youll get there.

Porter

[Steve Cole #22466]

Well- another day, another discovery.

So I went outside tonight to try & check Johns theory about the lifter (inconclusive, BTW), when I foun another broken push rod.

This one was from Cylinder #1, and this one was broken in half. One part of the rod was at the base of the #1 pushrods and the second half was lying adjacent to my missing #4 pushrod.

Especially with tonights development, I plan on replacing all of the pushrods. The remaining pushrods are all seated properly but since I basically have everything exposed and open, Id rather do the work NOW than have it happen in the future at a less convienent time.

Now, with respect to the repair: can you confirm what I think the repair process is:

* remove 4 bolts securing the rocker arm assembly
* lift & set aside the rocker arm assembly
* Replace pushrods (1, 2, or all)
* Replace the rocker arm assembly making sure all pushrods seat properly on both ends
* Tighten 4 bolts per torque specs.

Is it really this easy?

[Bruce Reynolds # 18992]

Gday Steve,

Well, it is that easy replacing pushrods, but I would be really looking at why the pushrods were bending, and breaking, in the first place.

Has your timing chain stretched, or slipped that much that the cam is so out of sync that the pistons are hitting the valves and forcing them back up into the head and therefore bending the pushrods?

Have you replaced the valve springs with extra heavy duty springs, and the pressure on the nose is too great for the pushrods?

I have bent many pushrods in my race motor, but that was because of spring pressure, and custom built tubular pushrods.

Bruce,
The Tassie devil(le),
60 CDV

[Steve Cole #22466]

I dont have many answers, Bruce. As far as I know, everything is original equipment. I know I have my hands full on EXTERNAL issues so I havent done anything to the internals. I certainly would enjoy having the peace of mind by knowing the answers to those questions but I probably wont know that until the day comes that I need to rebuild the engine (which better not be right now!).

Ill start with replacing the pushrods when I get them in a couple of days..

[Bruce Reynolds # 18992]

Steve,

While you have easy access to the valve springs, see if you can press the valves down, and see if there is any difference in the pressure required to open the ones with the broken pushrods, compared with ones that are okay.

You may have some tight valve stems in the guides?

By the way, how was the engine running before you noticed the problem of the bent/broken parts?

Bruce,
The Tassie Devil(le),
60 CDV

[wm link]

a good backfire will bend  pushrods, or lifters that are not fully pumped up. If the piston hits a valve...you usually bend it and lose that valve as well. The timing chain is a good one to check as 61 was the first year of the nylon coated version I believe. Was the car run on varnish gas? That can cause the valve guides to stick to the valve, holding it long enough to damage the valve train...Ive got one of those projects on a 472.

[Steve Cole #22466]

Bruce-

Well, my automotive mentor is actually amazed at how well it ran given the recent flurry of discoveries. That said, the car ran somewhat rough and getting a smooth idle was always a challenge. It still managed to produce around 18 ft/lbs of vacuumn pressure (the gauge would dance around slightly).

Performance under a load (going up a hill at slower speeds) left A LOT to be desired and I would frequently shift the transmission into the second drive for that added boost of power. During this type of situation, there was also some knocking of the engine.

This, of course, is combined with the fact that I had a substantial crack in my intake manifold.

Wm-

What is varnished gas? I might be too young but Im not familiar with the term! Since I have owned the car, I have always put in a mid grade gas (89? 91?), usually from a major gas station such as Texaco. Ive never added a lead additive. The carb is new and the gas tank was refurbished this past summer. The fuel pump isnt the original but its probably old. I have a replacement but havent gotten around to changing it.

[wm link]

Varnish gas is stale gas...gasoline actually degrades into varnish. It will seize parts...almost like sugar in the gas. The smell is very strong and the color is a yellow to orange.  

[Bruce Reynolds # 18992]

Steve,

I hate to have to say this, but I really think that your engine is really looking for a rebuild.   And, I mean a total rebuild.

Seeing as the Intake Manifold was as badly cracked as I have ever seen one, I have a fair idea that the engine has done a LOT of miles, and will hazard a guess that all you will be using out of the original motor is the Heads, Block, Rods, Most all bolts and nuts, Crank, and Sump and Rocker Covers and dipstick and tube.

I am sure that the crank will require grinding, the block boring, and the heads reconditioning.

You will need New Pistons and Rings, Big Ends and Main Bearings, Camshaft, Followers, Pushrods, Gaskets, Oil Pump, Timing Set, plus, the usual other things hat go with a rebuild.

Bruce,
The Tassie Devil(le),
60 CDV

P.S.   Vacuum is measured in Inches, not Foot Pounds.

[Steve Cole #22466]

Youre right Bruce- thats definately not what I want to hear but I would like you know your reasoning behind that opinion. The odometer is at 76,000 and I have no reason to think that its anything but 76,000. Considering how well cars were made during this time, Im kinda hoping that I can make it to about 100,000 before I need to prepare for an engine rebuild. I just dont have the $2,000 or so to pay for all the parts & services and I certainly dont have the proper facilities for doing the work.

[By the way Bruce, I think you know this but Im not trying to be argumentative- Im trying to decipher a lot of different opinions about my current problem.]

Wm-

I cant say that Ive smelled anything other than the traditional smell of good gas but I will admit that prior to my purchase of the car, it probably sat unused alot more than it was driven.


Heres a link to a machine shop near me with the rates they charge for various services:

http://www.action-auto.com/content/shop.html TARGET=_blank>http://www.action-auto.com/content/shop.html

Anyone have an opinion on the rates their charging? Inline with your past work? More expensive? Cheaper?

Thanks!

[Bruce Reynolds # 18992]

Well Steve,

The reasoning behind my opinion is:

(1)   Your description of the way it drove before the present strife.
(2)   The fact that the Intake Manifold was so badly cracked.
(3)   The fact that there two broken/bent Pushrods (they dont break on their own).
(4)   Prior knowledge of things mechanical in that when a motor is pulled down, it will need a total rebuild.

I have seen newer engines with a very high mileage that are in better condition than older ones with relatively low mileage.   It all depends on maintenance, or the lack of.

A low mileage engine can be easily wrecked if it suddenly is driven hard in the hands of a new owner.   I never trust an Odometer in a car, unless it is completely docymented, and then I am still a bit suspicious.

An engine will seemingly run beautifully for a long time as all the parts will wear in at a corresponding rate, and once something is disturbed to interrupt the enmeshing of all the parts, something will usually go wrong.

I have received imported engines that are all there, but once they are stripped, the only salvageable parts have been the Crank, Block, Rods, bare Heads, and a few tin parts.

I am glad that I can do all my own work, apart from the machining and balancing, as I couldnt afford to pay those prices.

Bruce,
The Tassie devil(le),
60 CDV.

P.S.   Please dont let be put you off, as I hope that you only have bent pushrods that require replacing.

[denise 20352]

Youll know the smell of bad gas.  Its an unmistakeable stench.

I had a bent pushrod on my 76 500 which caused a lifter to go SCHWOOOP! up out of the bore and my oil light to come on.  I replaced the lifter as well as the pushrod.  The rod was laying in the gallery in an S shape, which, I assums, means that the crankshaft beat on it.  I have a knock in the engine now, which may or may not be related, but Ive driven the car thousands of miles since replacing the pushrod and it hasnt blown up yet.

With the car bogging down and chattering going uphill, I would be concerned about a timing issue.  If the ignition timing is correct, the timing chain may have jumped.  If it is possible to get to the lower pulley and put a long wrench on to turn it, you can look at the distributor rotor as you turn it back and forth.  A visible amount of hysteresis indicates wear in the timing chain.

-denise

[Porter 21919]

http://www.misterfixit.com/chanslop.htm TARGET=_blank>http://www.misterfixit.com/chanslop.htm

[Steve Cole #22466]

Denise-

Its funny you mention that test because I just learned about it earlier today. Ill try it tonight & post an update.


In the meantime, heres a link to an MP3 audio file Ive posted of my cars engine earlier this summer:

http://home.earthlink.net/~scoler/engine.mp3 TARGET=_blank>http://home.earthlink.net/~scoler/engine.mp3

Just right click on the link, and save it to your computer. It should play fine with Windows Media Player (or Quicktime for Mac users).

I created this because I wanted to have a before & after record when I was beginning to get serious about eliminating my exhaust leak. I think I can say with certainty that this does represent the way the car ran with the missing pushrod from cylinder #4. This may, or may not, also represent the engine minus the second bent pushrod on cylinder #1.

In the beginning of the clip, I was facing the engine from behind the radiator. Theres a slight audio shift (I moved towards the drivers side) and then another shift for the rest of the clip as I shifted towards the passenger side (where the exhaust leak was comming from).

[Bruce Reynolds # 18992]

Steve,

Yes, I can hear a very bad exhaust leak, and I thought it sounded like a well running single cylinder stationary engine.

But, I still am of the opinion that you should delve a bit deeper, and check the condition of the timing chain, and the TDC (Top Dead Centre) to the timing pointer on the harmonic balancer.

If you have a slack chain, then you will have to pull the engine to change it properly.   Yes, I know it can be done in situ, but it is a real hassle, and as you have to drop the sump, it is a good time to check the bearings and the like.

Bruce,
The Tassie Devil(le),
60 CDV

[denise 20352]

And here it is with most everything filtered out except the tick tick.

http://www.americansoapbox.org/tmp/ticktick.mp3 TARGET=_blank>www.americansoapbox.org/tmp/ticktick.mp3

Dont you love technology?

-denise

[densie]

> Yes, I know it can be done in situ, but it is a real hassle,

   OK, Ill bite...what is a situ?

-denise