engine knock

B Komar · 06-12-2001, 05:23 AM

Well I about threw up yesterday! I was coming home from the store and passed a car...I believe I might have over revved the engine. When I got home I have quite the clunk going on internally. The engine still runs fine but makes a racket. I checked the compression and its 130,130,130,145. I checked the valve adj. and its fine. Everything is correct except the clunk that speeds up with engine RPMs. After all this work....then this. Where do I start... What does this sound like? And how much do you think to fix ($$ ballpark) I can take the engine down to longblock and take it to a shop. This engine only has about 12,000 miles on it, so I dont think it'll require a full rebuild, hopefully just repair whats knocking in there. I'm about ready to give up... Brian

SteveStromberg · 06-12-2001, 06:45 AM

Check for a bent pushrod. Also run engine then stall motor with Ing. on how long does it take for oil light to come on? Steve

B Komar · 06-12-2001, 07:55 AM

Thanks Steve, Is it the push rods that go if you over rev? I hope thats all it is! What does the oil light and how long it takes to go out tell me? Brian

SteveStromberg · 06-12-2001, 08:30 AM

The oil light should come on After the engine has stopped for few seconds 1-3 seconds this check is for oilpressure in the crank shaft if the light comes on as soon as the engine stops NO delay you could of spun a bearing on the crank. Steve

B Komar · 06-12-2001, 08:35 AM

If it is a bent push rod...am I wrong to think that the first place to look would be in the cylinder with the higher compression? Maybe the exhaust valve stays closed due to the bent rod? Brian

paulhagedorn · 06-12-2001, 08:57 AM

I would say that you are making a reasonable assumption to check the higher cylinder, but it isn't uncommon for the cylinders to have varying pressures in them. I can't remember what the spec is for a fresh engine, but 130-140 sounds about right.
One thing to make sure is that the oil light actuallt does come on when you first turn the power on the car and before you start the engine.

There is a possibility the transmission is also suspect. It is still spinning without a gear being engaged.

Just some more thoughts for you,
Paul

Conrad W Peden · Conrad W Peden's Garage

Are the valves gaps correct?

I had a cam follower detonate on me and it took only about 15 to 30 seconds then BAM! Lots of noise.

If it is the follwer then it can possibly be fixed with the engine in the car but chances are there are pieces of it all over the place inside.

When mine went it took the pushrod and rocker with it. Lucky me it didnt bugger the follwer bore. I went for a full bottom end rebuild. Cant quote price.. did it myself.

Good Luck

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CWP/VIR
72 914 L20E in rusto.
73 914 L20E 2.0L in resto.
http://members.rennlist.com/a914lover

Eat-um-up · Eat-um-up's Garage

Check your heat exchangers. my 914 loves to develop exaughst leaks. Mine has a similar sound if i think what your saying is what your saying. those damn copper rings like to break a seal anytime they can.

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Sweet Blue 72' 914
Check it out at
http://www.geocities.com/eat_um_up/914.html

Eat-um-up · Eat-um-up's Garage

Hey guess what!! after my stupid little comment my engine decided to have a knock. and its not the heat exchangers. it sounds like something inside is broke. could be a hydlic lifter stuck but i dont think so. best part is... I drove it home just fine and parked it for the night. the next morning when i start it.. knock knock knock

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Sweet Blue 72' 914
Check it out at
http://www.geocities.com/eat_um_up/914.html

B Komar · 06-14-2001, 07:46 AM

I've been sick the last couple of days (not car related) so I haven't gone out to check anything yet...its 95 degrees outside today so it'll probably be tonight before I go out and check stuff. I hope this isn't an OMEN. I just spent over $3000 on this car, I don't really want to spend too much more. Not to mention the countless hours putting it all together. I'll let everyone know what I find tomorrow. (praying it's just a bent pushrod) BTW: if it is a bent pushrod...and I pull another one out of another car, should I use the rocker that was attached to that rod in the other car or just use the one that was attached to the one that bent? Thanks, Brian Hope everyone doesn't develope knocks after this thread (sorry eat-em-up)

Eat-um-up · Eat-um-up's Garage

Well thanks B Komar. I just went out there and i found out my exaoughst valve on my #1 cylender backed off a little. I readjusted it and it wors fine now

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Sweet Blue 72' 914
Check it out at
http://www.geocities.com/eat_um_up/914.html

B Komar · 06-15-2001, 08:14 AM

OK guys...I figured it out! I did the oil light test and it took forever for the light to come on...like 8-10 seconds. I almost thought I had a bad light or something...so apparently I have good main pressure and not a spun bearing. So I went to work on the valvetrain. When I pulled off the valve cover I noticed that one of the valves was really loose. I started by taking off that set of arms and I think I found the culprit! One of the adjuster screw tips had broken off! It was flat against the arm and the threads. So there was about 1/8 to 1/4 inch of play between the arm and the pushrod. I went to my old 2.0 and pulled one of the adj screws off and it was too thick..actually seemed Heavy Duty compared to the ones on the car now. I had to go out to my old 1.7 and pull one off that fit. Now I just have to adj. the valves again and see what happens. GAWD I hope this is all it is! I'll keep you posted! Brian

pbanders · pbanders's Garage

Hope you found the culprit. Now - how did that happen, an over-rev? Do you have a rev-limiting rotor? For me, it's been a very cheap and very effective insurance policy.

Brad Anders

[This message has been edited by pbanders (edited 06-15-2001).]

Dave at Pelican Parts · Dave at Pelican Parts's Garage

In 73, they changed to M10 adjuster screws. Earlier motors had M8 ones.

--DD

B Komar · 06-15-2001, 01:33 PM

THERE IS A JEEEZUS! I'm here to tell you!

WHEW!!! that's all it was! I put it all back together and adjusted the valves and it's good as new. Like a new lease on life! I looked all over for the piece that broke but to no avail. Hope it fell out when I first took off the valve cover, but I changed the filter and oil just in case. How do I get one of the rev limiting dealies??? I do believe I need one of those! I'd like to say that I will drive more sensibly but...this car brings out the best (read:worst) in me! The big one averted this time! Thanks a ton for your replies...they actually helped me sleep easier (REALLY!) Thanks, Brian

Jake Raby · 06-15-2001, 02:24 PM

Glad we helped, that is a common thing..

Dave at Pelican Parts · Dave at Pelican Parts's Garage

See the second item in this catalog section: http://www.pelicanparts.com/catalog/shopcart/9144/POR_9144_igniti_pg1.htm#item3

--DD

John Rogers · 06-15-2001, 05:14 PM

You might want to think a little about the rev limiting rotor button? It works by killing the spark to the plugs but the fuel injectors keep right on pumping and when spark comes back you can get a big bang! Good luck.

Eat-um-up · Eat-um-up's Garage

where can i get a rev limiter?? first time ive heard of one of these

SteveStromberg · 06-16-2001, 05:37 AM

You can get rev limiter rotors for about $22 hit the parts section PP has them listed,also seeing as you have 1700 rockers you can use the 911 valve ajusters. . Steve

[This message has been edited by SteveStromberg (edited 06-16-2001).]