Technical All exhaust pushrods bent?!

Hey all, confounding issue here. A friend brought me his car he couldn't get started. 318 Mopar, was a running engine that blew out the rear freeze plugs, so they pulled it out, fixed the freeze plugs and while they were in it, put some additional work in it. The heads were rebuilt, new stock cam installed with new hydraulic lifters and pushrods. New timing set as well. After putting it all together, the engine would not fire. Like, not even try to fire. Generally, even if the timing is off, it'll spit and sputter and cough. But not here. At this point I offered to help.

First checked the easy stuff. Check for spark. Pull plug and ground it, crank, spark jumps. Reset the timing to TDC, plug wires were somehow 90 degrees off. Reset the plugs and firing order, still nothing. Check the carb, no fuel. It has a new mechanical pump, but isn't pulling fuel and pushing it up to the carb. I bypassed the mechanical pump and jumped in a 12v electric pump just to test it out. Now there's plenty of fuel. Crank it... Nothing. Put compression gauge on the engine. Friggin 0 compression in all cylinders. Zip, Zero, Nada. Mind you this is a 318 Chrysler small block. Rockers are shaft mounted and non-adjustable. Pull the valve cover off...every single exhaust pushrod is bent to hell. But ONLY the exhaust pushrods. Intake pushrods are fine.

From what I can tell, the parts that were used were all "stock" replacement parts. But what would cause this? My hypothesis is that the cam was improperly installed, maybe a tooth or two off, and on cranking slammed the piston into the open exhaust valve. The idea of this makes me cringe as it would necessitate at least half an engine tear down. But I've never seen such an issue, and the fact that only the exhaust pushrods bent, literally all 8 of them, leads me to believe that it's more than a coincidence. I'd love to hear some of your thoughts.

 

Oh crap, time to put a degree wheel on it and check to see when the valves are opening!

 

they timed the cam wrong

 

Camshaft timing.
Probably looking at some bent valves as well.

Tommy

 

Sounds like the cam timing is retarded.

 

You guys are confirming my thoughts. Was hoping that there was some dumb, quick fix I wasn't thinking of, but it is what it is.

Now I'm hoping that it didn't bend the exhaust valves in the process.

 

Well,,,it is always good to have hope,,,,but if the pushrods are bent,,,that means the exhaust valves are not moving,,,,,so you should show some compression at least.
If 0 gauge reading,,that doesn’t sound good.
Hope I am wrong.

Tommy

 

In addition to having 8 pushrods bent, you also have eight more items that are bent. You will discover these when you pull the heads. The head rebuilds they had done will need to be partially redone. Cams that are not timed correctly are not a good thing.

 

I try not to smoke the Hope-ium when I'm putting an engine together. I'll pull it and tear it down to do it right.

That being said, the subject vehicle is marginal at best. You guys think the cam and lifters are salvageable after going through this? Mind you the engine has never fired with this valve train.

 

Yeah, that's my thinking as well. Was hoping maybe just dropping in some new exhaust valves would do the trick. I'll do a leakdown test to see how trashed they are but I have a feeling it's probably not promising.

 

I would not waste my time . Pull a head.

Ben

 

Cam and lifters should be okay,,,they are new right?
Just do a good visual inspection,,,,replace the pushrods,,,and repair the heads.
If no visual damage to the lifters and lobes,,,I don’t see any reason to worry.
Just inspect them well.

Tommy

 

Yeah, cam and lifters are brand new. A $165 cam and lifter set is legitimately a significant percentage of the vehicle's total value, so I'm trying to minimize the monetary outlay as much as possible.

 

Pull the timing cover and you will probably find the problem.

 

Did they mill the heads? Are the valves hitting the pistons now? Milled heads + higher lift cam = valves further down in the cylinder

 

Timing gears where put in at 12, 12 not 12, 6, cam timing is 180 out.

 

Not the only thing that is/was.......

it happens.......raise your hand (mine is) if you never made a mistake.....

 

Compression test first ,,, I always say it,,, I was taught that,,, and that’s why.

The valves collided and bent = no compression.
Bent pushrods because the valves bent first.

 

Heads were not milled, seems just a basic freshening with a valve job was done. One of the factory heads was cracked, so the machine shop had a good core and that one was rebuilt and put on. So one head is indigenous to the engine, and one is a close facsimile as a replacement. Initially I thought this might be a contributing factor to the situation, but every exhaust push rod was bent, both on the original head and the replacement. And in exactly the same fashion. So mentally I've ruled that out as a red herring.

Similarly, the came that was utilized in the rebuild is hardly a "high lift" cam, and I would describe it as barely a step above stock. Here's the link for the cam used.

https://www.summitracing.com/parts/sum-k6900

Considering the specs on the cam, I'd rule out excessive lift or duration to be the culprit if the cam were timed properly.

 

Show me this ,,,,

 

Gonna be a lot of valve "smiles" on the piston tops...I bet 8..one under each exhaust valve...might have bent the heads on every one...

 

My hand is raised, too. I've screwed up plenty of stuff. Thankfully not this one though, even though it's sort of my problem because this thing is tying up space in my shop and my friends need the help getting it running again. I'm going to be driving my Olds to Canada this weekend for the Jalopy Jam Up (or at least attempting to), so he has the keys to my shop, they can come and pull the engine and have their run of the place while I'm gone.

 

The heads are cast iron, I'd be willing to bet the valves and pushrods would yield before the cast iron of the head. I can tell you the only smiles are going to be on the pistons. Hopefully the pistons are not damaged to the point of not being able to use them.

 

I would certainly do a compression or leak down before pulling a head, it is certainly not a waste of time. I’ve seen plenty of engines smack valves and not bend them, however I have seen plenty bend them as well


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I agree, and it won't take long to check.

 

I'll bet if you ask him, he will say that the engine cranked real hard the first few revolutions, then turned easier after things got "clearanced". The fact that you are getting no fuel may be because the fuel pump eccentric is missing or the woodruff key got sheared. Eight bent exhaust push rods leaves me to believe that the timing gears are (were) properly bolted down although bending 8 pushrods could have sheared the woodruff key. For the pistons to have hit the exhaust valves that hard the valves must have been open way late. This means the intake valves are also open way late which puts them open deep into the compression stroke. That could account for absolute zero on the compression test.

 

Did he compare the old push rod lengths with the new ones? I mean before it was put together.

 

Yes, allegedly he did as I inquired about this. That was my first thought, pushrods are too long and that bent everything up. But after looking at the parts available I determined this wasn't the cause. I thought perhaps he bought pushrods meant for mechanical lifters instead of hydraulic flat tappet, but if that were the case, the pushrods for the mechanical lifters are shorter, and after measuring these it wouldn't seem to be the problem.

 

Thanks for all the replies everybody. I'll most certainly be doing an autopsy on this one. I don't want to get into this engine too deep this week before my trip to Canada, but I may pull off the front accessories and timing cover to see what's going on out of morbid curiosity. I'll be sure to keep the thread updated