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post #1 of (permalink) Old 03-03-2003, 03:49 PM Thread Starter
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304 V8 - how do you break a rocker arm??

I am going to replace a rocker arm on a 304 V8. My question is how do you break them in the first place? It was teh alimiun bridge type. The bridge broke in half and the pivot actually rubbed enough on the rocker that it broek and just flopped around.Hopefully this will be the cure for the loss of compression in my cylinder and the bad smokie coming from the engine. I am just confused on how these things brake, never had one do that.

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post #2 of (permalink) Old 03-03-2003, 04:01 PM
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Re: 304 V8 - how do you break a rocker arm??

Well, alot of race car drivers say the same thing after being put out of the big race, "I don't know how it happened." You know the saying, come on folks, "Sh!t Happens." How have you been driving it? Does the oil pressure gauge work? I'm sure that the pressure would fluxuates<?> with a broken arm. If the oil flow was stopped or lowered you could have ended up damaging other parts of the engine too. I hope that wasn't the case but, just a heads up. L8r,



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post #3 of (permalink) Old 03-03-2003, 04:06 PM
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Re: 304 V8 - how do you break a rocker arm??

I broke 2 trying to tighten them down with pressure from the valves. I think the general consensus is they are POS. Go with the steel replacements and don't look back. If you want to REAL beefy, there are kits that replave them with a Chevy type rocker, but then you have to install studs, etc...
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post #4 of (permalink) Old 03-03-2003, 05:38 PM Thread Starter
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Re: 304 V8 - how do you break a rocker arm??

I cant believe they use those flimsy aluminum bridges. Well I got the new ones on that cylinder, the others are checking out fine for now, I will replace when they bust, or when i get some money.

I really couldnt tell how they broke because i jsut got the jeep. I just finally got into the motor, and the compressino test lead to a dead cylinder, so I pulled the covers and low and behold... broken bridge. [img]images/graemlins/frown.gif[/img]

Well the jeep started up, but still smoked. ran a bit better with all cylinders firing. Very fun trying to find all the problems on the motor, I hooked all the belts on, and the power steering works, but it was neat to see the streams of steering fluid shooting from the cracks in the hose. Oh well, they will replaced in due time. So now I have to figure out what is causing it to smoke. I still have to check the other side of the motor to see if everything is kosher, I know I have one cylinder at 90PSI, and one at 150 PSI, so I have to see what is wrong here. Everything else checks out at 120 so I am thinking the rings will be good. This motor has been sitting for a very long time, If it is smoknig because it was jsut sitting too long, when should the smoking cease???

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post #5 of (permalink) Old 03-03-2003, 06:04 PM
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Re: 304 V8 - how do you break a rocker arm??

If your lucky the smoking may just be stuck rings in the one cyl. from sitting. Keep your fingers crossed and get some time on the engine. Maybe it will come out of it.
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post #6 of (permalink) Old 03-03-2003, 06:23 PM
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Re: 304 V8 - how do you break a rocker arm??

</font><blockquote><font class="small">In reply to:</font><hr />
So now I have to figure out what is causing it to smoke.

[/ QUOTE ]
How long has it been sitting? One thing to think about is the valve seals. I don't have any expertiance with the 304 ,but can somebody tell if the valve seals are umbrella or o ring seals. When I was 16 I got a `56 Chevy 4dr that was parked for 12 years. I fired it up and the bluest smoke came out. We did a compression check and everything was good, it had 64k original back in `80, it was Gramp's car and her passted away, grandma never learned how to drive. She just didn't want to. Well, it had the o-ring valve seals and I replaced them and the thing ran great for a 16 yr olds first car. L8r,



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post #7 of (permalink) Old 03-03-2003, 06:43 PM
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Re: 304 V8 - how do you break a rocker arm??

It's not uncommon for those bridges to break. I've used ATF in the carb while it's running to free up rings before. Just not too much, it will smoke like the devil.
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post #8 of (permalink) Old 03-03-2003, 06:53 PM
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Re: 304 V8 - how do you break a rocker arm??

BU is right too. Umbrella seals are easy to do. Even if it had them before they can get brittle and leak. Might try them if the compression comes back up in the one cyl. after running for a while and it still smokes. Look at the plugs to determine if it's just 1 cyl. burning oil. If it's just the one low one I'd guess rings. Try soaking the bore down with "marvel mystery oil" for a week. Make sure to leave the plug out when you are done. Crank it over a few revolutions and then put it back in. See if that free'd anything up. I have had good luck with it before. (ps. kerosene or atf can do about the same thing) And be sure to change the eng. oil after a short run in time to make sure to get what ever ran into the crank out.
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post #9 of (permalink) Old 03-03-2003, 07:42 PM Thread Starter
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Re: 304 V8 - how do you break a rocker arm??

The engine has been sitting for i believe 6 years. So I am going to try and get it running and start to drive it around to see if it will clear up. I have to repalce the power steering hoses. I was turning the wheel and noticing that the power steering works and then i noticed a stream of fluid spraying out from the cracks in the hose. At least I can expect stuff like this to happen. Thanks for the tips guys!!!
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post #10 of (permalink) Old 03-03-2003, 07:50 PM
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Re: 304 V8 - how do you break a rocker arm??

When i got my jeep, it would blow out white smoke all the time as well. When i did the rebuild i finally found the culprit. CRACKED/ CHIPPED EXHAUST valves.. I did not realize this until i had removed the heads and looked at the valves on the bottom side of the cylinder heads. That's the worst case scenario. Getting heads rebuilt cost me 300 dollars also. Just a thought


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