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endobear

4.3 Bent/Broken Pushrod(fixed, now lifter noise)

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Last trip out the rail developed some valve/upper end noise after a high revving pass . Pulled the valve cover and one of the cylinder #1 pushrods was bent and broken.

Its a turbo, e85, Brodix heads.

Should I just put a new set of pushrods in and run it?

Is there anything else I could have hurt or need to check? 

I assume I broke the pushrod by over revving it but idk.

 

20180310_173039.jpg

20180310_173053.jpg

Edited by endobear

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I would check piston to valve clearances. That contact is what is normally causes this to happen. I've been there!

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28 minutes ago, endobear said:

Last trip out the rail developed some valve/upper end noise after a high revving pass . Pulled the valve cover and one of the cylinder #1 pushrods was bent and broken.

Its a turbo, e85, Brodix heads.

Should I just put a new set of pushrods in and run it?

Is there anything else I could have hurt or need to check? 

I assume I broke the pushrod by over revving it but idk.

 

20180310_173039.jpg

20180310_173053.jpg

I did something similar to the old mans 454 in his truck back in the day. He replaced the rods and ran it, but!! His wasn't as high zoot as yours and he knew for a fact valve interference wasn't the cause. 

Ive seen you flog this thing before with zero issue, I'm not sure a piston to valve clearance issue just developed? 

What ignition is on it? I know it isn't racer oriented but have you considered turning down the rev limiter a wee bit? :D

 

haveyou checked the lash on the others? 

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Holey Commander 950 computer and MSD ignition.

Pulled the spark plug on that cylinder and it had zero metal on it. Not sure but I would think the plug would show some debris if the valve was hitting the piston.

I also drained the oil through a strainer and didn't find any metal.

Yeah. I learned my lesson. Ill keep it below 6500rpm next time. That damn Bronco I was racing was fast....

Haven't checked the lash on the others yet.

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Put the piston at TDC and apply 50lbs of air into the cylinder with a compression test hose, remove the valve spring and wrap a rubber band around the base of the valve stem in case it slips out of your fingers, let the air out of the cylinder and spin the valve. You would definitely feel if it were bent (as well as the cylinder not holding air).  It helps to have a second person to assist with this.

If there is no apparent valve damage, reassemble. Do a compression check and verify that cylinder is similar to the others. You may also want to pull the intake and look at the lifter, assuming it's a roller it might be a good idea to replace it also as long as the cam lobe looks good. If the valve springs have more than a few hundred hours on them they are done too.

There is a remote possibility that the rod bearing has failed and is allowing the piston to travel past TDC and hit the valves, you would probably have seen a bunch of metal in the oil though, which you said you didn't. Probably an easy fix.

We see broken springs and bent pushrods at the dealer all the time, usually a new spring and pushrod is all that's required.

EDIT: One piece chromoly pushrods would be a nice upgrade at this point.

Edited by fortyfour

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Compression is good.

Installed new one piece chromoly pushrods. Still has a little tap going on. Pulled push rods and reinstalled them 3 times. No change. Sounds like it could be coming from the lifters. I think they are hydraulic lifters. No clue what cam this motor has. Its a built up late 80s 4.3 out of an Astro van. Motor was built in 2010.

What should I do from here? 

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being a SBC you can pull the intake and look at the lfiters to see if any damage and pull one out to see if the cam has a flat spot on it,

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14 hours ago, J Alper said:

being a SBC you can pull the intake and look at the lfiters to see if any damage and pull one out to see if the cam has a flat spot on it,

Will do.

Pulling her out of the storage unit today.

Going to recheck compression, do a leak down test and pull the intake apart if those come back ok.

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if a lifter collapsed or cam is going flat, thats a good reason your push rod died. 

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Possible rocker stud pulled out a little? 

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20190211_144558.thumb.jpg.841d07d2b527ecc0de7c7bcfe65040d0.jpg

On 1/24/2019 at 9:19 AM, Chevy1925 said:

if a lifter collapsed or cam is going flat, thats a good reason your push rod died. 

How can I tell if a lifter collapsed?

Contact at the cam from the roller looks a little wider at the noisy area. Lifter has a tiny bit of visual wear. 

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I never found bent valves with compression checks.  Leakdown tests were necessary.

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On ‎1‎/‎23‎/‎2019 at 6:13 PM, J Alper said:

being a SBC you can pull the intake and look at the lfiters to see if any damage and pull one out to see if the cam has a flat spot on it,

How can I tell if the cam has a flat spot?

Looks and feels good.

The wear on the cam from the suspected lifter is not centered and a little wider. Roller on the lifter looks good and is smooth.

Edited by endobear

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On ‎1‎/‎24‎/‎2019 at 9:46 AM, Legit Duner said:

Possible rocker stud pulled out a little? 

Idk. I suppose I should check.

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23 hours ago, Rockwood said:

I never found bent valves with compression checks.  Leakdown tests were necessary.

Well, I didn't have what I needed to do the leak down test and tore it down anyways. I had a feeling I was guffing up.

Did do a compression test and I'm at 119-120 on 4 cylinders and 110 on 2. Cylinder #5 and #2 were 110.

 

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does it have adjustable rockers did you set the lash  

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55 minutes ago, diesel-e said:

does it have adjustable rockers did you set the lash  

Yes. I set the lash.

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On ‎2‎/‎11‎/‎2019 at 3:31 PM, Rockwood said:

I never found bent valves with compression checks.  Leakdown tests were necessary.

Bought a HF leak down tester. Tested with all rockers arms and lifters pulled.  Between 22%-35% loss on all cylinders . I assume I'm ok on the valve, rings and head gasket end of things.?

Could hear air in the bottom end. Which I think is normal. Felt a tiny bit of air out of one intake port.

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2 hours ago, endobear said:

Bought a HF leak down tester. Tested with all rockers arms and lifters pulled.  Between 22%-35% loss on all cylinders . I assume I'm ok on the valve, rings and head gasket end of things.?

Could hear air in the bottom end. Which I think is normal. Felt a tiny bit of air out of one intake port.

Was the breeze felt on the bent pushrod cylinder?

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Opposite side 

Hmnn..

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2 hours ago, endobear said:

Opposite side 

Hmnn..

Probably got away with it then. :bigrin 

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