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Bent pushrod
https://slantsix.org/forum/viewtopic.php?t=26015		 Page 1 of 3
Author:  drrw [ Tue Nov 27, 2007 11:02 am ]
Post subject:  Bent pushrod
Looking for some input. If you're on the evbc, you've already heard this.

Preface: 225 slant six, 300 miles on rebuilt everything.

Today I was out running errands. I was going up a fairly steep incline in first gear (4-speed) at what I'm guessing was about 3500-4000 rpm. I noticed it started sounding like there was an exhaust leak or something. After waiting for a light, I carried on and it sounded ok. My next stop at the post office was pretty much downhill (literally) from there and it seemed like everything was back to normal. So I left the post office and started up an equally steep, but faster, hill in second gear and I hear the same kind of noise. This didn't go away at the top. It sounded bad, like metal hitting metal, and at the same time like a huge exhaust leak. I was only about a half mile from my house at this point, so I'm praying that it makes it home. Fortunately, I could coast a lot of the way (lots of hills near my house if you haven't figured that out). So I get home, open the hood expecting to see, well, something, anything weird. I'd been envisioning rods sticking out of gaping holes and such, but there was nothing to be seen. I started it back up and checked (with a timing light) that every cylinder was firing, and they were. I pulled all the spark plugs and they all looked perfect. Then I took off the valve cover. One pushrod, number one exhaust, was not where it should be and was bent. The adjuster was where it was supposed to be. That is, I couldn't put the pushrod back without loosening the nut a lot. Fortunately, I have all my old parts, so I got out an original pushrod and put it in and adjusted it. The engine started, but sounded a little rougher, although this may have been due to my foul mood at the time.

The only way I think this would happen is if the valve got stuck open, right? How can I confirm this if the valve is back where it's supposed to be now. I didn't watch it run after I swapped pushrods. That is, I didn't watch the valvetrain since I put the cover back on. I'm looking for opinions as to my next step. Should I warm it up, readjust all the valves and hope for the best. Should I pull all the pushrods and replace them and ...Do I need to pull the head to figure this all out (really don't want to do this)? Any other options will be enthusiastically entertained.

Thanks, Daryl
Author:  Shaker223 [ Tue Nov 27, 2007 12:17 pm ]
Post subject: 
Sounds like the valve/guide clearance may be to tight. The only real way to fix it is to pull the head and give it the proper clearance and make sure it is not galled. The lazy way would be to pull off the valve seal and hope that more oil makes it down there. :D
Author:  sandy in BC [ Tue Nov 27, 2007 12:53 pm ]
Post subject: 
Id run it with the new pushrod for a while and see if it does it again. If it doesn t do it again shrug your shoulders twice and move on......



You could move to Nebraska and avoid hills........
Author:  Joshie225 [ Tue Nov 27, 2007 1:08 pm ]
Post subject: 
I 2nd the tight valve guide motion. I would run a compression test and see if maybe the valve didn't stick open and get whacked by the piston. Chances are slim it was hit and got bent, but I'd check anyway. If you haven't lashed all the valves since the engine was first assembled I'd certainly do it. If the valve lash is correct and you have a compression problem or you bend another pushrod then the head has to come off.

Does the car sit much or is it driven regularly? Is the valve gear oiling well? Do you have standard umbrella valve stem seals or something else?
Author:  drrw [ Tue Nov 27, 2007 1:50 pm ]
Post subject: 
Thanks for the responses. They are somewhat coinciding with those in my head which are: Do nothing or do everything.

To answer Josh's questions.
Quote:
Does the car sit much or is it driven regularly?
I have just started (last few months) driving it at least once a week.
Quote:
Is the valve gear oiling well?
I believe so, however I haven't stared at it since I did the last adjustment of the valves. All I can confirm is that there is oil up there, enough I can't say.
Quote:
Do you have standard umbrella valve stem seals or something else?
Standard stuff.

To go further, if I take the head off, will it be obvious if there is a clearance problem as opposed to an oiling problem? Will it look the same as a piston with the same issues?
Author:  Joshie225 [ Tue Nov 27, 2007 3:07 pm ]
Post subject: 
I asked about the car sitting because oil will drain off valve guides and leave them pretty dry. Not enough oil or very good valve stems seals will only make this worse. My race car once seized the #1 exh valve, but that was after it sat for several months. It had positive valve stem seals. Also, old gas will really gum up valve guides. I had a '64 Valiant that stuck some valves due to old gas. The car was only running on three cylinders when I got it. I put a bunch of Marvel Mystery oil down the intake and replaced the bent pushrods. I also ended up replacing the valve stem seals as the car wouldn't stop smoking after that. Smoked after the seals too until I got the muffler good and hot and burned off the excess oil. The Valiant was lucky. I replaced the valve stem seals on the car. The race car head had to come off.
Author:  terrylittlejohn [ Tue Nov 27, 2007 3:50 pm ]
Post subject:  pushrod
is it a stock cam or a higher lift cam ,if so was the guide to valve retainer clearence checked, if this is the first time since rebuild that you pushed the rpms while going up hill it might have hit the guide. :?:
Author:  drrw [ Tue Nov 27, 2007 4:30 pm ]
Post subject: 
Quote:
is it a stock cam or a higher lift cam
It's not stock, but not very high lift, it's an Erson camshaft part # E470301 RV10M. I don't think I checked that clearance as it never occurred to me that it could be an issue.

However, I'm feeling like Josh has struck a nerve. Previous to the last tank of gas, I put some Sta-bil in the tank because it wasn't getting used much. If I do have varnish on the valves and this "extreme" uphill at temp finally caused it to stick one, maybe I can get them clean with some BG44K through the tank?

Anyway, I think first I need to check the compression, warm it up, readjust the valve clearance, check my vacuum is stable, and then see where we're up to.

Thanks for the input and I'll update as things progress.
Author:  Doctor Dodge [ Tue Nov 27, 2007 9:40 pm ]
Post subject: 
Pour some oil over the rocker arm assembly and valve springs prior to doing your start-up and valve adjustment.

When the engine is warm and running, look to be sure oil is coming out the tip of every rocker arm. Replace any rocker arms that are not flowing oil out the tip and top groove.
DD
Author:  drrw [ Tue Nov 27, 2007 9:56 pm ]
Post subject: 
Thanks Doc, I'll do that. I actually did that same thing the first time I adjusted the valves. I definitely need to verify that oil is getting where it needs to.

Daryl
Author:  DonPal [ Wed Nov 28, 2007 4:06 am ]
Post subject:  Bent Push Rod
I recently had a bent push rod caused by a sticky rocker arm.

Oil flow to the rocker arm itself was fine. however varnish build up on the rocker shaft immediate adjacent to the rocker was the problem.

Apparently when I recently adjusted the valves the sliding motion of the feeler gage nudged the rocker arm slightly into the varnish buildup area?

I disassembled the rocker assembly, used fine wet sandpaper on the shaft, and reassembled with plenty of oil for the startup phase.

No problems since.
Author:  MitchB [ Wed Nov 28, 2007 9:04 pm ]
Post subject: 
A while back, I put my rebuilt head on that I knew was well prepped. After maybe 5000 miles, while at highway speed, the #1 exhaust valve hit the piston, hung open and bent the pushrod. I pulled the head, replaced the guide, valve and pushrod. Why did the valve hang in the guide?

My assessment was the engine was running lean. As I recall, I ended up jetting four sizes up. Coolant flows primarily from the back of the head to the front and out the thermostat housing (or to the bypass hose). So the #1 cylinder runs hottest. I was using a 180 thermostat at the time, yet I believe the valve ran excessive heat due to a lean condition and seized in the guide as a result. I have over 60K miles without further incident and the car runs great.

Mitch
Author:  drrw [ Sat Dec 08, 2007 5:24 pm ]
Post subject: 
Well, here's where we stand.

Last week I did a compression check and that was fine.

Today, I finally had time to deal with it more thoroughly. I made sure nothing else was bent, poured some oil over the valves, and started it up. It started, but sounded a bit rough, like the timing was off or something. So then I hook up my timing light and sure enough the timing is way off, and I mean way off. So far off that I can't figure out how it is running. While this is going on I see that there is plenty of oil flooding the rockers. So I turn it off and stare at the wires for a while, wondering how it could be so messed up. Then I realize the number one wire looks a little different. Turned out I hadn't pushed it completely onto the plug. That will delay your timing. I'm still amazed it was firing so consistently, and consistently wrong. It sounded so much better after that. :wink: I warmed it up per the fsm and readjusted all the valves. They were consistently slightly loose, about 1-2 thous each.

Soooo, I drove it around the block at varying degrees of caution and abandon, and it sounds fine. Not sure what to do now, if anything.

Daryl
Author:  sandy in BC [ Sat Dec 08, 2007 5:57 pm ]
Post subject: 
..sounds like time for a ceremonial burnout.....Its Saturday (Hockey Night in Canada) so make sure you do it between periods....and downwind of your neighbours.

Just because you are paranoid doesnt mean it wont happen again....
Author:  drrw [ Sat Dec 08, 2007 8:04 pm ]
Post subject: 
Canadian Hockey Night.....if only. Not only don't we have a national hockey night, I don't get the Versus channel, and there's no regular tv broadcasts (NBC) until New Year's. At least that first game is the Penguins.

Maybe tomorrow at halftime of the Steelers game. :D
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