my roommate bought a beautiful '98 NBM SS over the weekend that's all stock except for 4.10s and a lid. it started running kind of rough on sunday night so we got the codes scanned and found out that there was a misfire on #4. we swapped out the coil, wire and plug with those from mine but the problem persisted. finally today i pulled the valvecover and pulled the rockers off on #4, nothing wrong with them. then i tried to pull out the pushrods for that cylinder but there was only one. i looked at where the intake pushrod was supposed to be and saw that the hole had been elongated and there was no pushrod. so i grabbed a pen magnet and fished out the two peices of pushrod (both of which were bent pretty bad). my question is do you guys think it would be ok if he just replaced the pushrods with some aftermarket ones and called it a day, or do you think he should replace the head? this guy has had nothing but bad luck with his cars so far and if you want proof just look up his screen name (athlon2k2). just when he decided to come to the right side of performance cars something like this happens . i'll post up pics as soon as my roommate gets home with his camera. let me know what you guys think.

 

i think so. change the oil since there may be shavings in there. if the engine is shot, then its not gonna screw anything up.

 

I broke 1 of my pushrods and bent 2 others. They made the holes in the head a bit bigger. I pulled them off and had them checked at a machine shop and they said they were ok. Like nino said change the oil and I am sure you will be fine.

 

that's what i figured, i guess he'll be ordering some new pushrods tonight.

 

Well I really hope that will do the trick. All I ask is for a quick car that works. But I haven't had that privilege yet.

Hey Nick I saw the pictures and I wonder how bad the damage is inside. Hopefully not too bad but I wasn't there when you pulled the pushrod out. If it is all torn up inside the guide won't it just bend another pushrod? Well I'll call you later.

-Dustin

 

Actually the hole lets in enough light to see into the motor and nothing looked too messed up. Just buy some more pushrods and we'll see how it goes. What's it going to do mess up the head some more?

 

You might as well buy some good after market push rods instead of using stock ones..you can get a set for not a lot of $$$

 

You can get a used set of 01/02 241 heads for about $150 and some hardened pushrods for $75 in the parts for sale section. On a 98 car he may see 15-20 hp on the newer heads.

 

That's actually not a bad idea Dave, I just don't know if the apartment complex staff would get mad about us doing a head swap in the parking lot . Oh well, he's been without a car for about 5 months now, what's another couple of days?

 

Then I'd have to find him some center bolt valve covers too.

 

Should take about 2 hours.

 

Now you've got me thinking about a cam while we're in there

 

Probably the result of a high RPM missed shift.....the PCM can't control a mechanical over-rev. The previous owner may have pulled the infamous 2nd to 3rd ooops.

 

2nd to third ooops, or third to second oops???I wouldnt think a over rev would happen with a 2 to 3 shift....

 

"2nd to third ooops, or third to second oops???I wouldnt think a over rev would happen with a 2 to 3 shift...."

Yes, it would, if you missed 3rd and kept your foot on the gas. But it wouldn't be a mechanical over-rev like I mentioned. The PCM would step in and start bouncing you off the rev-limiter due to the PCM reading the TPS.

You are correct. Missing 3rd and banging straight back into 1st is the usual culprit. I suppose a missed 4th to 5th, hitting 3rd instead, would cause a mechanical over-rev, too. My bad. The PCM controls the rev limiter via the TPS....if you rev too high in a particular gear by mashing the accelerator, the PCM will step in. If you miss a gear and accidentally downshift, and the engine over-revs, the TPS isn't causing the over-rev, so the PCM cannot control it. A missed downshift at too high an RPM causes a mechanical over-rev...the PCM has no way of detecting or controlling a mechanically-induced over-rev.

Sorry about the boo-boo........

 

At this point, I don't think I'd put hardened pushrods in there. The reason I think so is that if you were to over rev it mechanically through a downshift or missing 3rd and hitting 1st instead, you may risk dropping a valve with the stock springs instead of just bending a pushrod. The stock springs aren't bad, but I wouldn't trust them beyond 6300. The pushrods can act as a fuse for something like this. If they break, no big deal. Just buy new ones, and spend a few hours putting them in. Much easier than rebuilding or replacing the whole motor.

I've never mechanically over reved my engine, but it has hit the rev limiter quite a few times since I've had it. It's harder to bend pushrods or break these motors than what it's made out to be sometimes on here.

Jason

 

Sounds like some of you need to do the driver mod.. ..how do you do all these crazy things you are writing about..mine sees the red line regularly and gets power shifted every day..I built it to be a hot rod and I treat it like one..I guess you could always get an automatic if your too skeeered to drive a six speed.. ..it sounds like the sky is falling the say is falling!!! when you are driving you must pay attention to what you are doing when you are banging gears..

 

My buddy and I were a little curious about how the rest of the pushrods looked so pulled off the rest of the rockers and found 2 more pushrods that were bent. For some reason they were all on the intake side. Needless to say he ordered some comp pushrods from speed inc as soon as we found them.

 

Word to the wise, do not over rev past 6200, or pay the piper you will, I have done this, and bent valves, which is no fun for your wallet. The comp hardened push rods are very nice but risky if you plan on going past 6200rpms without a valve spring upgrade and a bigger cam.

 

On a stock cam there is no need to rev that high..you are long past the power peak