Loud Knock - Very Scared, Need Help Immediately Options

[Nor.Cal.914]

My dad had mentioned before that he thought the valves were too tight and they were hitting the tops of the pistons . . . It was a guess, but I think he could possibly have been right. What do you guys think in relation to that? If that was the case, what could the damage possibly be? Oh and another thing I noticed, even though I don't think it matters, as soon as the knock started, I stopped the car and looked underneath. My whole motor looked like it was shaking like crazy. The driver's side exhaust was shaking worse than anything I noticed. It's obvious this isn't any kind of exhaust leak or anything of that sort, but I thought I would mention that. Since I noticed the knock increased in speed, I guess that pretty much rules out having anything loose around in the motor. Anyways, I thought I would mention this and see if anyone could help me anymore. Thanks
-Chris

[Dr. Roger]

hmmmmm, can't get over 4K RPM's
loud RPM-relative noise

when's the last time you checked your valve clearances? (keeping valve clearances too loose will effectively make the valve duration shorter)

were the cases split lately? (cam one tooth retarded?)

checked oil lately? (pre seizing engine)

lastly, that engine rev thing usually is an ignition timing or fuel mixture thing. i guess that thing never got resolved yet?

stand on one foot and do the chicken dance. (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

sorry, the last suggestion was for my own amusement. (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

l

[Nor.Cal.914]

From what I can remember, my dad checked the valves not too long ago, but like I just said that's most likely what happened. The cases were not split recently to my knowledge. We bought this motor a few months ago and basically popped it in the car and went. I'm hoping to god that nothing major has happened, but I'll have to wait and see. The 4000 rpm problem was never solved but hopefully will be sometime. If not I'm just going to have to do what I've been planning on, and rebuilding the 1.8 as strong as possible. I'll get back to everyone with any updates. Thanks for the help so far
-Chris

[Nor.Cal.914]

Forgot to put, yes we did check the oil as soon as we got home. It had plenty so I don't think that had anything to do with it. Thanks
-Chris

[bondo]

QUOTE (NeunXIV @ Dec 8 2005, 06:48 PM)

My dad had mentioned before that he thought the valves were too tight and they were hitting the tops of the pistons . . . It was a guess, but I think he could possibly have been right. What do you guys think in relation to that? If that was the case, what could the damage possibly be?

Could be a bent valve.. If a valve hits the piston and bends, it will no longer fit down the valve guide and get stuck. This will leave you with a valve partially open and your rocker clearance would be huge. but your clearances would have to be way tight (valve doesn't close all the way) to get valve to piston contact. You'd have no compresson on that cylinder and you'd probably notice pretty quick.

[Dave_Darling]

Have you popped off the valve covers and looked yet? That's the first step in diagnosis. Check the visible parts of the valve train and see if anything obvious is wrong.

No, go do it. Really. Report back on the results, and we can go from there.

--DD

[Nor.Cal.914]

Would a loss of compression make the car feel like it has no balls anymore? If that's a dumb question, sorry (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) but I want to understand as much as I can about this car. When I drove my car for the first time after we got the 2.0 in it, it felt like it had tons of torque and some pretty big balls. But then a little later on, after some adjustments, can't remember on what (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif) it felt like it had no balls and all the kick was basically gone. I don't think this has anything to do with the valve clearance, but I just wanted to ask anyways. Thanks
-Chris

[Nor.Cal.914]

I haven't popped the valve covers off yet, but I plan to sometime tomorrow afternoon. My dad wants me to take of the HE's to make it as easy as possible to access the valves. Sorry to make it a long wait, but I don't really have a choice right now. I'll make sure to get back with what I see. I'll take some pics after I pull them off and show everyone how it looks under there. Thanks
-Chris

[mightyohm]

Don't take off the HE's to do the valves. You are likely to break an exhaust stud and then it won't go back together again.

Sounds like you need to do a compression test. That is the first step in addressing the problem.

If the valves have hit the pistons it's probably time for a rebuild. (IMG:http://www.914world.com/bbs2/html/emoticons/unsure.gif)

[bd1308]

NUH UH.

dont take those HEs off.....do it with them on.

if you pull a stud youll be SOL.

b

[Nor.Cal.914]

Ok ok I won't pull them off. I'm really concerned about my motor right now and if this is a major problem or not. If it's not, then I got very lucky. But if it is, I'll be out of my car for probably a long while (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif) I'll post some pics and let everyone know what turns up with the valves after I take the covers off. Thanks
-Chris

[bd1308]

these motors take an absolute beating and still go...

when my car ran lean over the early fall...it made a loud middle-of-the-engine knock knock knock that was scary.

but i fixed everything and it went away...no doubt fuel delivery related in my case...

i would start with the valve cover inspection....

jack up the car and pop those suckers off....

b

[Nor.Cal.914]

Yeah I definetly will. Quick question though to whoever can answer this. A stock 1.8 runs 93mm pistons and clyinders . . . would I be able to put 2.0 Euro 94mm pistons and cylinders in the 1.8 without any trouble at all? Let me know. Thanks
-Chris

[Rand]

Hey Chris... just curious about the cars in your signature... are they yours?

[Nor.Cal.914]

They all belong to my family. The 914 2.0 and the other 914 are both "mine." The 930 and the mustang are my dad's and the 911S is my brother's car. I'm 16 so they bought me the 914 since I wanted a Porsche and my little beauty didn't cost but $1,000 (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) But it's had a lot more money put into it to get it to where it's at right now. And now I just f**ked it up with this whole thing happening. If what happened is something major, I'm going to get rid of the 2.0 and just rebuild my stock 1.8 with some nice brand new parts. Thanks
-Chris

[Rand]

Very cool Chris! Some great cars in your fam!

Sounds like you got an amazing deal on your 914.

I hope this knocking problem turns out to be something less serious than you feared.

Keep us posted.

[Nor.Cal.914]

QUOTE (Rand @ Dec 8 2005, 08:44 PM)

Very cool Chris! Some great cars in your fam! Sounds like you got an amazing deal on your 914. I hope this knocking problem turns out to be something less serious than you feared. Keep us posted.

Thank you very much. Well I'm praying right now that it's nothing serious. I'll make sure to keep everyone posted. Thanks
-Chris

[914fan]

Check to see if your dizzy is loose. That is an easy fix for the nock. Also check if your alternator is loose. The bracket could have broke or just loosened. Ask how I know that.

[dmenche914]

If you got a gage run a compression test. be sure to short the center coil wire when you crank with the plugs out if you have electronic points. this test will tell you if a valve is stuck open, burnt, too tight, bent, and is fast and easy to do. do it with warmed engine, all plugs out. to remove plugs, before removing plug, use compressed air or brush/rag and spray can cleaner to clear out the plug base area to prevent dirt from falling into the cylinder as plug is withdrawn. The plug is recessed, and lots of dirt will collect there and fall in.

[Dave_Darling]

QUOTE (NeunXIV @ Dec 8 2005, 08:08 PM)

A stock 1.8 runs 93mm pistons and clyinders . . . would I be able to put 2.0 Euro 94mm pistons and cylinders in the 1.8 without any trouble at all?

Nope. I believe the pistons will come out of the tops of the cylinders if you do that--the wrist pin is in a different place in the piston, so you wind up with Significant Problems. (I could be thinking backwards about which pin is where; if I am then you'll wind up with waaaaaaaaay too much deck height--about 4x the recommended amount--and the engine will run, but like absolute crap.)

--DD