bent pushrod/broken valvespring..need help?
 

Well on my way to work tonight, cruising around 70mph. I started to get a loud ticking, like a bad exhaust leak. really loud. limped it up a ramp to the gas station. took off the driverside valve cover. found a broken spring. took off that rocker it looks fine. crane gold 1.6 nsa rr's. anyway the pushrod is bent, not really bad, but bent nonetheless. I have to tow it home tomorrow. any ideas on why it could of broke. I am running the k-motion k750 or k800's. dualcoil springs. good to .600 lift. 7.2" hardened pushrods. and stock new oem lifters. that is the only spring that I see broken. I had these in for atleast 10,000 miles. since I put h/c in the car. never had a problem. I hope I didn't bend the valve. and how do I go about putting on another spring. I know how to put in the pushrods. and how to adjust the lash on the rockers. I just never put in a spring. can I just blow air in the cylinder to hold up the valve to put on the new spring? and how do I get the retainer/lock off? I have never replaced a spring before, any one have any ideas or a process on how to put the spring on I would really appreciate it...thanks...Lonnie

No clue on why it broke but as far as removing the spring... the best (easiest) is to get that piston at TDC, and then use a special fitting to fill the cylinder with compressed air, you then compress the spring and use a magnet to remove the lock... since its broke i think y ou should be able to pick up the valve with a magnet or pliars or whatever and then fill the cylinder with compressed air (be sure the other rocker is loose on that cylinder. If the valve fails to stay up when you fill the cylinder with air, you have a bent valve (or burnt valve or blown rings but im assuming the valve is the only thing that MIGHT be damaged here). once you pull the lock off just pull the rest of the spring off. to install a new one you do pretty much the same thing, up to and including compressing the new spring and then put your locks on, use a bit of grease on them and theyl'l stick to the valve stem then remove your spring compressor and they should stay.

Which valve bent? exhaust or intake?

No reason to put it at top dead center and do the compressed air. You just need to do one or the other. I prefer the TDC as you know the valve won't fall in the cylinder that way.

Im not sure which one, when I get the car home in the morning, i will post a pic. and let you know which one. how do I know it will be at tdc? I really appreciate the help. Now I just have to get summit to overnight a spring and new chromoly pushrods to me and hopefully get it running on tue. oh yeah, I don't have a spring compressor, can I get one at advance, or just use my hands or anything else? thanks guys....

its easier to get the retainers out if you do compressed air, TDC is just a backup measure to keep it from falling.

You might be able to take the broken one off with your hands but i seriously doubt youl'l be able to compress the springs, whats the seat pressure on those springs isnt it ~ 160lbs? If you can compress that by hand... I fear you. Youl'l need a special valve spring compressor made for compressing springs on the engine (some require the head to be off). and if its under the cowl youl'l need a special short one, i advise getting the special short one for under the cowl so in the future you will always be able to use it

just make sure to check the valve, if it bent a rod more than likly the valve hit the piston, everytime I ever bent a push rod the valve was bent.

well..
 

well I towed the car to my father's house. and looked at it alittle more. thank god I have the dual coil springs on there, it seems the inner spring did not break, holding up the valve. so Im overnighting a new spring from summit and new pr's. I wonder if my pushrod lengths are wrong. the guy who built the heads, and put the springs on there, said I just needed the 7.2" pr's. so that is what I got, but the locknuts on the polylocks. are rubbing on the top of the rr's. on each side. all of my rr's have scrapes on the top of them where the locknuts are rubbing them. is this normal, it just seems that I would of had a problem before the 10,000 miles since I had the h/c. I guess I'll get a pr checker and make sure the lengths are right.... :confused:

That is a wise idea. An even better idea would be to get some quality one-piece chromemoly pushrods instead of cheaper hardened ones. I'm just assuming that's what you have since you bent one and you didn't say exactly which ones you had.

Those springs have really high pressures and are pretty heavy IIRC. Did your H/C guy recommend those?

If you just got the cheap hardened pushrods they aren't any stronger than stock pushrods, the outside is just case hardened so you can run guideplates with them. Theres a good chance the spring pressure alone caused the pushrod to bend, I've seen it happen to my friend before.

Well I talked to the head guy again, and he said that he put in the k-750's single coil with a inner dampening spring? I never heard of that, have you guys? yeah I just have the comp hardened pushrods. I will order a new set of chromoly pr's. and I will get a length checker, to make sure. but he says I just need the 7.2" but Im taking no more chances.

you still need to check that valve....the damper isn't goin to be enough to hold the valve up at any rpm...chances are it probly kissed the piston. I never thought k-motions were really for street use or mileage, thats what I have been told....how old are the springs? k-motion switched the material a few years ago b/c the older ones were too brittle. I think those were the h-11 tool steel ones.

I run that same spring. Are yours shimmed at all?

I don't know if there shimmed or not, I do see some kinda flat washer looking thing on the top/bottom of the spring. I don't know hardly anything about these? Im not sure why it even broke. this setup is about 1 yr. old. and about 10,000 miles on them.

I have a friend who is real good with engines, I pulled the plug, we are going to shoot air into it to make sure the valve isn't bent. I just had a spring overnighted from summit's. 43.00 after shipping/handling. man that sucks, I hope I don't break anymore. Im going to get a pr length checker, and make sure I have the right length. what length are you running for pushrods? Im running 7.2" that is what the head builder said I needed, does your rr's have scrape marks on the top of them,like the locknuts are rubbing them?

No I have a girdle, you just need to check for the PR I was using a 7.3, now i'm using a 7.150 just check it and see......You paid $43 for one spring?