914 1.7 Knocking Sound -- New Here, First Post, Horrible knocking coming from the motor Options

[UberElectricEagle]

Probably will be the last progress report because I think this motor has a few internal issues that will need to be addressed out of the car. Probably best fixed with another motor. I'd give it a full tune up and rebuild the carbs, but I don't think it will matter. Thanks for all the help and ideas everybody.

I got the carb linkage sorted out the best I could. Left carb lost a bolt (out of two) that holds the linkage bracket so the bracket was drooping and slightly opening the throttle plate a touch. Bolt was gone because the threads are stripped! Tightened the one up the best I could, but it will end up moving. Adjusted the small linkage so the throttle plate would close. Checked the main jets and they were clean. Adjusted the carbs the best I could and listened to the air going in through a hose and they were pretty dang close.

Took it out for a drive and the noises are still there of course. Seemed a little more tolerable though; probably because I don't care anymore if the motor blows up. The car was running a lot smoother though, but smelled rich. It actually felt pretty good.

I've actually got it down to two noises. The main noise is more of a quick clacking or rattle type noise which varies depending on the throttle input; and the second is more of a BLAP noise at higher rpm or hard acceleration it seems.

I can make the noises disappear at around 3500 RPM on flat ground and in a couple other instances. Kind of nice and peaceful at that moment.

I can make the motor smoke a lot like a James Bond smoke screen at 4000 RPM and above. It's a pretty blue smoke and lots of it. If I stay there at the high rpm it will just smoke steady. I've also got clean oil coming out of the top of the motor somewhere at high rpm and bathing everything in the center of the engine compartment. Might be the oil pressure sensor. I'm not even going to look into it at this point.

Saw a greenish 914 at the Conway Shell station on my adventure. (I think I've seen it a few times) I thought about going to look at it, but I didn't want to show off my smelly and clacking car if the owner came out.

Thanks for the help, Sam

[UberElectricEagle]

Your idle jets are clogged for #1. I'd put money on it.

What kind of carbs are they? Weber IDF? Sorry if you posted that info, but I am getting dressed for work and don't have time to re-read the entire thread.

Find a good diagram for the type of carbs that you have, and blow out the #1 idle jets with compressed air after giving it a good squirt of carb cleaner. Clean the spark plug. Put everyhting back together and try it again.

If you are making 140# compression, I think you are in really good shape there. If you can borrow a leak tester, it is still a good thing to do.

I still think its easy/cheap stuff. POSITIVE WAVES! (IMG:style_emoticons/default/smile.gif)

When winter comes, consider pulling and rebuilding the carbs. If you have IDFs it will cost you about $70 (shipping included) for the kits and a few hours of your time.

Fresh rebuild is ~#150 compression. Over 130 is great compression. 130-100 is happy diving compression. 95-100 is start looking for rebuild parts compression. under 95 - pullit and start over time.

Also, you want to have compression in all 4 be ~the same.

AND, compression is just 1 part of the story. You really should do leak down too. You can have good compression, but still have crap leakdown. It sounds weird, but I had 115# compression @45% leak on my #1 cylinder. It lead to a full rebuild, as I discovered my case was collapsing at the cylinders and had to be fixed.

But, really. 140#, I think you are going to be just fine once you get fuel flowing.

Could you take and post a picture of the top end of your engine bay, so we can see your carb set up?
Zach

I had time and I went out and bought a new compression tester and a solid long extension so I could get a good reading on all the cylinders. (The first tester I used was old timey and had a rubber nipple and I believe gave me a false reading of 140ish on #1 and 120 on #3. I couldn't even access #2 and #4 with it.) I warmed the engine up on a 10 minute or so easy drive. I removed all the plugs and opened the throttle while I turned over the engine several times and I checked each cylinder and double checked. I got readings of
#1=85 #2=90 #3=74 #4=92
give or take one or two on each. Assuming this gauge works right and I hopefully did it right, these readings are not so great. I believe it's time to do the engine shuffle so I can explore the inside of this one.
Sam

[Rod]

Agreed, those compressions aren't great. take it out do a strip down and see whats going on. New rings and rebuild.

[tat2dphreak]

did you see this over at the pelican site?

http://forums.pelicanparts.com/porsche-914...e-4-engine.html

no affiliation. but might save you a few bucks if you are going to do a stock rebuild

[UberElectricEagle]

did you see this over at the pelican site?

http://forums.pelicanparts.com/porsche-914...e-4-engine.html

no affiliation. but might save you a few bucks if you are going to do a stock rebuild

Thanks for the link.

[VaccaRabite]

Wow, what a difference in compression. NOW things are starting to make sense. If the engine is warm (it would be on a 10 minute drive) and the throttle was open (you said it was) and your valves are right (you just checked them) then it is rebuild time. Your engine is just plain old at the end of its duty cycle.

Zach

[UberElectricEagle]

Wow, what a difference in compression. NOW things are starting to make sense. If the engine is warm (it would be on a 10 minute drive) and the throttle was open (you said it was) and your valves are right (you just checked them) then it is rebuild time. Your engine is just plain old at the end of its duty cycle.

Zach

Yes, a working tester is crucial. 145 didn't make much sense.
Bummer though, I didn't know all this before I bought it. I guess I was due to get burned at some point.
Thanks for all your help,
Sam

[VaccaRabite]

Wow, what a difference in compression. NOW things are starting to make sense. If the engine is warm (it would be on a 10 minute drive) and the throttle was open (you said it was) and your valves are right (you just checked them) then it is rebuild time. Your engine is just plain old at the end of its duty cycle.

Zach

Yes, a working tester is crucial. 145 didn't make much sense.
Bummer though, I didn't know all this before I bought it. I guess I was due to get burned at some point.
Thanks for all your help,
Sam

Its a 30 year old car. This kind of stuff is going to happen. We will be here for help and moral support along the way.

Zach