I was just driving my car a minute ago and something very bad just happened. I had a concern about my revs earlier and how it wouldn't let me go over 4000 rpm. Well, I just replaced the coil and was trying it out to see if it helped my revs go past 4000. When I took it up there, something happened and a very loud knocking noise started happening. Another person on this thread had a post about a loud knocking noise that he heard when he started his car. Mine seems to be making the same kind of noise. I need help immediately! Any help as soon as possible would be helpful, please. Thank you very much.
-Chris

Does it knock faster as revs rise? Does it knock at idle, or only when on the gas, or only when you let off, or only above a certain rpm?

It's a constant knock. It happens at idle and driving. I didn't push the revs at all because I was really scared that something was going to happen. It doesn't seem to increase when the revs increase but I didn't push anymore than 2000 rpm when I was taking my car back. Any help would be great. Thanks
-Chris

I feel your pain, man. (I'm the other person) Hopefully you can get an expert to come listen to it. After Sean and Herb listened to mine, I had some guidance. I haven't acted on it yet, but soon.

Did they have any idea on what it was? Let me know. Thanks
-Chris

They said it was definitely valvetrain related and the problem would probably be obvious upon removal of the valve covers. I haven't done it yet because the engine is coming out of the car anyways and it'd be easier to mess with after removal.

I'm confused by your answer to James' (lapuwali's) question....

Are you saying the speed/frequency of the knock doesn't change with engine RPM???

If it doesn't increase with engine speed, it's likely not serious, and is more likely something external to the engine has come loose and is hitting something else.

I'd check the engine bay and see if anything is loose (airbox, battery). Make sure the engine and transmission mounts are solid. Check the rear shocks. See if you can make it clunk by bouncing the rear of the car up and down (engine off).

Check the distributor to make sure it's not loose. Check the coil you just replaced to make sure it's not loose (in fact, I'd start there).

Real-real loud? See if your plugs are all still in...stripped out spark plug.

If not then it's bad dude...go smoke a...wait your a 16yr/old...Belay the order.

Ok I'll try to answer all questions at once. As far as the knocking noise, it doesn't "speed up" or become any louder with an increase in the revs. It isn't LOUD, but it's loud enough to hear clearly in the interior of the car. When you say "check the coil", do you mean if it's just sitting loose or if the plug wire/and wires are loose? I will go out right away and look around the engine bay and see if anything has come loose at all that I can see. I will try bouncing the car a bit as well to see if I can hear anything either. I'll get back to you guys with any new findings I have. Thanks again for your help so far. I'm going to try and take the valve covers off in a bit too, but I'll get back to you when I do. Thanks
-Chris

Nothing about the knock changes with the engine RPM or rolling speed of the car?

By check the coil, I meant make sure you tightened it back down again after you changed it, to make sure it's not just rattling around loose.

If it's steady in volume and frequency, it's unlikely to be loose or missing plugs (good guess though), and they're generally loud enough that you have to yell over them. Valvetrain noise will almost always change in frequency with engine speed.

Rule #14 of auto mechanics: if it starts making a new noise after you do something, check whatever it was you just did, then check everything around that. Anything you touched during that procedure is a prime suspect. Only then should you start worrying about other things.

I will definetly put the old coil back on then see what happens. The knock does not increase in volume at all when I start rolling, driving, or revving the engine. As I said before though, I did not push it anywhere at all over 2000 rpm because I was so scared that something went really wrong. But I'll go put the other coil back on and see if anything at all changes then let you guys know. I checked for anything loose and shook and bounced the car as much as I could and didn't see anything or hear anything knocking around. I'll get back to everyone after I take another look and change back to the other coil. Thanks again for the help so far.
-Chris

sorry to rain on your parade, but your lugging the engine at 2 grand......

Well of course I know I'm lugging the engine by only going to 2000 rpm but I was so scared to push it because I didn't want anything to happen. Ok and I'm sorry for saying the wrong thing, but I just went out and put the old coil back on and nothing changed. What I said wrong was I thought the noise didn't increase with the revs, but I just went and revved it a little and it does increase in speed a little bit. The noise level of the knock does NOT increase, but the speed of it does increase. So sorry again for saying the wrong thing, but I just noticed it now. I guess I was too scared about what happened to notice it earlier. Anymore help that could be provided would be great. Thanks again
-Chris

I hate to be the bearer of bad news but it sounds like it may be a nut came off of the cam gear and is flopping around. (I hope not) Check your timming. You could have changed it. (lets all hope)

If this happened to me, I wouldn't start it again until I crawled underneath and pulled the valve covers off. See if anything looks weird. Should only take you 30 minutes and can illuminate a lot of possible issues.

For future reference, when I get around to doing this, what exactly should I be looking for as far as something gone wrong? Is there anything obvious that would be out of place or not normal? Let me know. Thanks

I definetly won't be starting it again until I check that, I started it only to see if putting the old coil back on had changed anything. Thanks
-Chris

QUOTE (NeunXIV @ Dec 8 2005, 06:35 PM)

For future reference, when I get around to doing this, what exactly should I be looking for as far as something gone wrong? Is there anything obvious that would be out of place or not normal? Let me know. Thanks

Make like you're adjusting the valves, but check all the clearances instead of adjusting them. If it's valve related you'll probably find the problem.

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

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.

sorry, the last suggestion was for my own amusement.

l

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

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

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.

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

Would a loss of compression make the car feel like it has no balls anymore? If that's a dumb question, sorry 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 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

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

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.

NUH UH.

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

if you pull a stud youll be SOL.

b

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 I'll post some pics and let everyone know what turns up with the valves after I take the covers off. Thanks
-Chris

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

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

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

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 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

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.

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

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.

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.

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

Knocking? Oh yeah - I had that in my 2.6L four some time ago..

I think my photo gallery speaks volumes.. Hopefully, it's not what I experienced.

2.6L Big Four Failure

Good luck!

-greg-

could be broken valve spring. I had it happen, used a rusted spring and it broke.

Well I'm getting my car back home tomorrow from where it was left at my friends house. As soon as it's back in the garage, I'm going to begin the tear down. I'll take the valve covers off first like you guys said to check for any obvious damage. I'll take some pics too so I can show everyone how it looks. I'll get back to everyone once the car is home and the valve covers are popped off. Thanks
-Chris

Just looked at your 2.6L motor failure Greg. That sucks that something like that had to happen. I'm hoping nothing like this has happened with my motor That would mean lots of time out of a car! Well I'll let you all know what turns up. Thanks again
-Chris

Ok well I got my car home about 1/2 hour ago and put her up on jacks. I've been trying to pull my heat exchanges off for probably that whole time and they've been giving me hell. But I was able to pull off the passenger side valve cover. It looked fine to me, but I have to wait until my dad gets home to have him look at it. I'll take pics in a little while to show how it looks. I should have both valve covers off with some pics in a few hours. Thanks
-Chris

YIKES - STOP - dont take off those heat exchangers. Asking for big trouble. If its too late and you've stripped the stud out of the head, there is unused thread further up in the head, but you have to get a longer stud. That will buy you some time. Otherwise, trying to put in a helicoil with the engine installed can be done, but is easy to mess up, in which case your head may be toast. If the engines is coming out anyway, have all those studs checked/replaced. It would be a heart breaker to rebuild the engine, install it, strip the studs out, and then have to remove and dismantle the engine again. 914 heads are made of mushy alloy.

My heat exchangers aren't the nice SS ones that I see for sale on rare occasions. I have the pain in the butt header, heat exchanger, muffler setup. Three seperate pieces. So I don't have to worry about stripping the head bolts out because I'm not unbolting the headers. I should've said this before so people didn't get worried. Well I'm going to go get back to work and get some pics up. Thanks
-Chris

that would be the only reason i'd prefer them over the early setup.

plus with the late setup, you could do your own thing with those stub pipes and not have to use the HE's....

b

Just pulled my supertrapps off . . . Look what fell out This cannot be good . . .
-Chris

Little chunks of metal . . . Anyone know what these could possibly be from? Please let me know. Thanks
-Chris