390 Broken pushrod
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From: South Carolina
390 Broken pushrod
Broke a pushrod in the 390. Trying to disassemble now to see if there's any more damage. The pushrods have to come out for the intake to come off, then the heads... I don't know how to get the pushrods out. The rocker arms (Dove shaft set) are loaded up on the springs. Am I going to have to turn the motor a little at a time to unload each spring to take the tension off of the rockers so that the pushrod will come out or is there some other way?
Just trying to get it all apart right now.
Thanks,
Mark
Just trying to get it all apart right now.
Thanks,
Mark
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From: South Carolina
Well figured that part out. Just had to remove the entire rocker shaft assembly. Got the rockers off, then removed the intake. Found one pushrod broken into two pieces, one part still in the pushrod hole, and the other down in the valley out of the way. Had two other BENT pushrods, one about 45 degrees, and one only slightly bent.
The major stuff went down on the number three cylinder and the slightly bent one was on the number one. The broken and very bent rods were both on number three.
Next is to find what caused all of this. Would love to stick some new pushrods in and put it all back together but something tells me to go ahead and pull the heads while I'm going. There may be valve trouble lurking under there.
Will report back with my findings.
The major stuff went down on the number three cylinder and the slightly bent one was on the number one. The broken and very bent rods were both on number three.
Next is to find what caused all of this. Would love to stick some new pushrods in and put it all back together but something tells me to go ahead and pull the heads while I'm going. There may be valve trouble lurking under there.
Will report back with my findings.
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Joined: Jul 2007
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From: Milwaukee, WI
You'd be right to pull the heads. Expect a couple bent valves while you're in there. Any other damage? Was this engine not put together by you? I recently saw suggestion that aluminum rockers are not recommended for street applications. Curious on your thoughts and others.
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Probably will pull heads tomorrow and see what the damage is. Kinda scared because those Edel heads were NOT cheap! No, I didn't put it together, but I have ran it for several years and I've run it pretty hard, so I guess I can't be too mad about it.
As far as the aluminum rockers, I haven't heard of any problems with them. These still look fine.
As far as the aluminum rockers, I haven't heard of any problems with them. These still look fine.
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From: South Carolina
What happened? Mainly my right foot! I got on it pretty good and heard something break and got off of it real fast. Luckily I was almost home and eased her in from there. Yeah, pretty anxious to get the heads off and see what's going on. Something had to happen to break and bend those pushrods like that. I'll try to get some pics of those tomorrow.
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Got the heads off today. Lots of pics -- CLICK HERE Still not sure what happened. Got on it pretty good, felt something break loose, and limped back to the shop. Pics show broken pushrod on #3 exhaust, very bent pushrod on #3 intake, slightly bent pushrod on #1 exhaust. Amazingly, everything else looks ok to me, but I don't know what I'm looking at. Cylinders look good and no apparent valve damage, but then again, I'm no expert.
Ideas are welcome.
Thanks.
Ideas are welcome.
Thanks.
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From: Milwaukee, WI
None of those valves appear broken or jammed open. Out of curiosity, the one cylinder with the clean exhaust valve and chamber... is that the one that had broken pushrods? How high did you rev that beast? Only thing I can figure is you managed to bounce valves back at the pistons.
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From: South Carolina
Yeah, number 3 - that's the one. It over revved real quick, spinning in first gear... not sure how high it got cause my tach died a couple of months ago, probably should replace that! But I think it definitely got too high.
So the question is, could I have revved it to high, floated a valve and only caused pushrod damage and nothing else? Is that even possible? I guess I need to get someone who knows what they're doing to give the heads a better look before I bolt them back on, cause I don't know.
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looks almost like you had a blown head gasket because of the clean chamber. At the very least I would take the heads to the machine shop and have everything looked over. I had a head one time that was slightly warped and would leak a little coolant passed the gasket into the chamber and I ended up cracking a piston when it locked up.
Lead Driver
Joined: Aug 2003
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From: **** hole San Jose ca.
You better check your cam and the lifers for pitting and or damage. This is what takes a beating at high rev's when floating some valves. The lifter kind of bounces on the cam and eats it up..after a while this happens in most engine with a way to heavy of foot...As your pulling way a from a chevy truck !! lol my 2cents
orich
orich
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Yeah, about checking the cam & lifters... lifters are easy enough to pull and check - the motor is still opened up. Have checked a few of them, especially the ones for the cylinders with damaged pushrods - those lifters look good. Nice and smooth with no markings.
So this is probably a dumb question, but aside from pulling the cam, which I really don't want to do, could "peeking at it though the valley holes" be considered enough checking for the cam itself? I'd just be pretty nervous about getting it back in right if I pull it out.
Also, if the cam has taken a hit, would it necessarily show on the lifters?
Thanks.
So this is probably a dumb question, but aside from pulling the cam, which I really don't want to do, could "peeking at it though the valley holes" be considered enough checking for the cam itself? I'd just be pretty nervous about getting it back in right if I pull it out.
Also, if the cam has taken a hit, would it necessarily show on the lifters?
Thanks.
Lead Driver
Joined: Aug 2003
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From: **** hole San Jose ca.
Aw well as you it's not all that ez to see the cam, but yeah you should be able to see pitted to wiped cam lobes. And you ask about the lifters being damaged only if lobe is damaged too, not always this is like the old weak chain which ever of two our softest or weakest will show damage first. It starts out pitting the back side of the cam lobe first where the lifter slams back down on the lobe and it continues to break the metal down as you continue to float the valves. my 2cents
orich
orich
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Looking ar your rockers I see pushrod cup marks from running too long of pushrods with not enough adjusting stud screwed down keeping the pushrod cup away from the rocker while on the nose of the cam. This applied off center pressure on the pushrods, surprised you didn't have more damage with other pushrods. How high was your preload clearance also?
Postmaster
Joined: Jan 2009
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From: Chesapeake, Va.
If you can find a bore scope to use you can check the cam lobes for pits through the lifter bores and when you check the lifters be sure they go back on the same lobe they came off of. While checking your lifters look for very small, even nearly microscopic evidence of pitting. If the is any sign of pitting replace the lifter as it will get worse and wipe a lobe. For checking the valves you can fill the ports with gas or kerosene and see if any leak by the valve and seats. If there are leaks you will need a valve job at least. If any valves are bent, even a little, replace them. It will be cheaper than new heads.
Those big blocks sure sound good up around 8,000 rpm don't they.
Those big blocks sure sound good up around 8,000 rpm don't they.