Check Your Screws!!!

[s14unimog]

So my fun ended the other night with some loud mechanical racket and the 240 getting a ride home on a flat bed. After pulling the VC, I noticed that my number 4 cyl. intake valve side rocker arm had kicked its guide; but luckily not damaging anything in the top end. I pulled all of the plugs and all but that number 4 cyl. looked great. After a closer inspection, it appeared to have been mangled by something. I threw a compression tester on that cylinder and its still holding (I need to do a leak down). So I'm stumped and looking around for answers. After speaking to a buddy of mine about the issue, he thought I should check for missing screws in the throttle body plate.

So sure enough, I pulled my cold pipe and I've got 1 of the 2 screws that affix the valve plate to the actual hinge...

My next question, should I move straight to tear down? I worry about the condition of my turbine blades, so I plan to pull the turbo. Then there is the concern of what happened to the screw. I'm sure it must have been blown out, but after looking at the plug, its apparent that it bounced around in there a few times.

Has anyone experienced this? I can honestly say, I didn't see this coming...

[garagelu]

After you you check everything out and make sure its ok, put some loctite on those screws.

[s14unimog]

Two steps ahead of you. What a shitty little thing to happen.

[S14_Kouki]

I had a rocker jump off with my rocker arm stoppers and 2 of my shims went somewhere in my engine and yes I did do a complete tear down of my engine to find them.

[s14unimog]

I was lucky, my rocker arm guide didn't got very far. When the screw got stuck in the intake valve, it kept the valve down, so once the cam lobe moved the rocker had play and the guide popped out. Rocker arms don't protect against valve side movement. I'm hoping I lucked out and it passed through without beating up too much. We'll see...

[s14unimog]

The plot thickens, That screw didn't rattle out, the center butterfly valve hinge shaft actually separated across one of the screw holes. Once I get a new throttle body, I'll double check cable tension; I can't believe it actually broke...

[Ceepo]

should post some pictures :D

[s14unimog]

So here's what happened, it turns out that the actual throttle body hinge cracked and separated across one of the screw holes. After the screw got loose, it traveled to the rear most intake valve of the number 4 cylinder and was hung up in one of the intake valves for a split second; allowing the rocker arm to kick its guide. Once it made its way into the cylinder, it bounced around, destroying that plug, and apparently has caused some sort of coolant pressure issue. After carefully inspecting that cylinder for the screw I found this mangled puppy on the end of my magnetic wand. I pulled the VC and found the guide, reset the rocker arm and crossed my fingers. The mechanical racket is obviously gone now but the problem now is that I have a coolant pressure issue. After restarting the car, I noticed my radiator lines were quite pressurized. After releaving the cap pressure safely, I restarted the car and noticed, what looks like air bubbles, and a constant overflow...

SO my question now, what could a loose screw in the number 4 cylinder have done to the coolant system. I realize the next step should be leak down and most likely a head pull but one could hope...

http://img.photobucket.com/albums/v721/s14unimog/Throttlebodybreakage001.jpg
http://img.photobucket.com/albums/v721/s14unimog/Throttlebodybreakage002.jpg

[PinkPanther]

since you have combustion chamber pressure leaking into your coolant system its safe to say that you either blew your headgasket somehow, cracked or gouged the cylinder head into a coolant passage, or cracked a sleeve in the block.

[Matej]

A couple weeks ago, I was riding with my friend, and somehow the rubber seal ring that goes between the MAF adapter got sucked out and caused his throttle body to get stuck wide open while driving in traffic.
Pretty wild experience.

Now most of it is somewhere inside his motor. The car seems to run fine though, haha.

[s14unimog]

since you have combustion chamber pressure leaking into your coolant system its safe to say that you either blew your headgasket somehow, cracked or gouged the cylinder head into a coolant passage, or cracked a sleeve in the block.


these were my thoughts, what a bitch of something to happen...

[PinkPanther]

Yeah man that really blows, hopefully its nothing major...i can't believe your throttle shaft broke like that. Have you ever messed with the closed throttle screw? Is the plate all full carbon on the back?

[s14unimog]

I checked the complete sweep of the pulley from closed throttle to WOT and found nothing that would suggest excessive stress to the hinge barrel. I didn't notice any excessive carbon build up either. I'm hoping the same, I guess I pull the head and take a look **low sigh**:down:

[4x4le]

i can't believe your throttle shaft broke like that.


Maybe a little more common then you think.

http://i300.photobucket.com/albums/nn40/4x4le/misc/1018081253.jpg

I had the same thing happen to me, however when mine broke I had had something go wrong with my bov and it wouldnt open causing lots of surge. I was at a drift event and didnt want to mess with it so I just let it surge for the rest of the day. Half way through the day I wished I would have figured out the problem, because I knew it somehow caused another problem as my throttle kept sticking shut (hard to open) and my car was idle searching hard core. My screw took out my IACV, No biggy because s14unimog sent me one lol.


Man, best of luck with your engine.

[s14unimog]

Damn Brandon, you weren't kidding; same exact thing happened. I would have given anything for it to have only trashed my IACV

[s14unimog]

So the story continues... Check out what one little screw does inside the cylinder; looks like its time to rebuild...

http://img.photobucket.com/albums/v721/s14unimog/HeadRepaircont2.jpg
http://img.photobucket.com/albums/v721/s14unimog/HeadRepaircont3.jpg
http://img.photobucket.com/albums/v721/s14unimog/HeadRepaircont1.jpg
http://img.photobucket.com/albums/v721/s14unimog/HeadRepaircont5.jpg
http://img.photobucket.com/albums/v721/s14unimog/HeadRepaircont6.jpg

Fortunately the cylinder walls are surprisingly unharmed. What a lame thing to have happen...

[steve shadows]

If you follow my posts,

I post this in almost evey single Greddy IM thread, including the recent write up about installing it

Make sure you either upgrade your TB or you tack weld the bolts to the plate

[s14unimog]

no shit? How does the IM have anything to do with it?

[Yellow4g63]

Don't feel too bad. My Factory SR20VE throttle body did the same thing to me. Sucked the screw right into the motor!!!!!! it got caught in the intake valve :(. Threw a few shims and tweeked that valve.

http://nissaninfiniticlub.net/photopost/data/500/4316VEhd1-med.jpg

Here u can see it stuck by looking at retainer thats not meeting the rocker arm:(
http://nissaninfiniticlub.net/photopost/data/500/4316VEh_1_-med.JPG
http://i137.photobucket.com/albums/q211/Bluerb240/SR20VE/VEhead2-1.jpg

Funny thing is the car ran on 2 cylinders lol it got me home lol.

[s14unimog]

damn, I was completely unaware that this is such a common problem. Sorry to hear that man

[4x4le]

Damn, looks like im welding my screws on my new n15 tb!
That tb is too expensive to get new now, and i dont want anything like that happening to my engine! I probably wont be so lucky this time!

[ILoveJDM]

this shit just happend to me tonight, was driving home, car started misfiring, i could literally feel a ticking feeling all the way through the throttle cable onto my foot when the screw was bouncing around hitting the intake manifold.

got home, left side screw when you look at the throttle body is missing, shaft is cracked in half. i think the screw is sitting in the IM somewhere, but i cant see it, i have the TB off, but i can still hear a random bang like its trying to escape and there is tons of dimples on the inside of the mani.

im 99% sure the reason steve says this for greddy IM's is that the position of the rotor is at a funny angle and causes the rotor to be tweaked when the cable is pulled. i am positive thats why is broke.

[heavenboundkevin]

dude, op, its sucks, but its a good thing you seem to have the know how on fixing the problem!

[jspaeth]

How do you guys feel about running a loop of safety wire around (under the head, like a ground) each of the two throttle plate bolts to hold them together?

Would this be worse or better?

If nothing goes wrong, it wouldn't interfere

It wouldn't prevent cracking, but maybe it would prevent a loose screw from getting sucked into the motor?

Or would it create even more problems?

I dunno.

[s14unimog]

I'm 99% sure the reason Steve says this for GReddy IM's is that the position of the rotor is at a funny angle and causes the rotor to be tweaked when the cable is pulled. i am positive that's why is broke.

I never thought about that but yeah that does make sense. I actually sent him a PM about this asking why he thought the manifold had anything to do with it but never got a response. When I hook everything back up I'll inspect the angle and see if I can reorient my cable pull direction to be better in line.

dude, op, its sucks, but its a good thing you seem to have the know how on fixing the problem!

yeah, live and learn I guess. Hopefully my experiences will help others avoid it.

How do you guys feel about running a loop of safety wire around (under the head, like a ground) each of the two throttle plate bolts to hold them together?

My concern with that route is that it may be difficult to secure the line somewhere inside the IM without affecting the sweep of the throttle plate its self. Not to mention, I would worried it might get hung up and cause your TB to stay open; would be an accident waiting to happen.

Before I reinstall mine, I plan to tack weld the screws in place. At least if the hinge breaks, the screws won't go anywhere.

[Driftastic]

hahaha.....i found my culprit. mine had the same symptoms i read above and i noticed that the throttle plate was missing a screw. I thought it was just missing.....never thought that it would be in the motor, thats probably what finally made me drop a valve.

[jspaeth]

I never thought about that but yeah that does make sense. I actually sent him a PM about this asking why he thought the manifold had anything to do with it but never got a response. When I hook everything back up I'll inspect the angle and see if I can reorient my cable pull direction to be better in line.



yeah, live and learn I guess. Hopefully my experiences will help others avoid it.



My concern with that route is that it may be difficult to secure the line somewhere inside the IM without affecting the sweep of the throttle plate its self. Not to mention, I would worried it might get hung up and cause your TB to stay open; would be an accident waiting to happen.

Before I reinstall mine, I plan to tack weld the screws in place. At least if the hinge breaks, the screws won't go anywhere.


No!!!!!!!! Not like that!

Safety wire them TOGETHER....meaning make a loop of wire that bolts under one screw, tightly connected to another loop that goes under the other screw...

Two loops, conneted to each other, and one screw goes through each loop, with the head of the screw tightened down onto the loop of wire.

[s14unimog]

^ that makes more sense and I would think it could be a preventative measure for this but wouldn't tack welding the screw to the hinge plate be simpler? You can buy a use throttle body for almost nothing these days...

either way, everyone should be conscientious of this issue and inspect it regularly...unfortunately...