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laz · Posted: Mon May 11, 2009 6:19 pm Post subject: what's that sound? rod knock?

Anyone wanna watch this video http://vimeo.com/4596972 and guess as to what my problem is? It doesn't sound like any valve noise I've heard. My guess is rod knock. I'll be poking at the car tomorrow evening.

I've got 2 weeks to sort it out. Worst case, I take the car to the race and blow the motor in lap #1 Wink

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Norcal spec E30 #804
Pandamonium Racing, 24Hrs of LeMons

ShadowE30 · Posted: Mon May 11, 2009 8:13 pm Post subject:

i would say loose or broken rocker arm. Pull the valve cover and check it out as a preliminary step.
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People say "Its just a car" but I can't get myself to believe it.

Rodoni · Posted: Mon May 11, 2009 9:02 pm Post subject: Re: what's that sound? rod knock?

Super Eurobeat · Posted: Mon May 11, 2009 9:07 pm Post subject:

pull the valve cover first, happened to a guy here's brother a few weeks ago Crying or Very sad

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There is nothing super about the '88 eta engines except for their gas milage. I have no idea who started calling them super but it must of been someone trying to make themselves feel better about owning an "e". -Alpine E30

Uber E30 · World Challenge Racer Joined: 25 Aug 2008 Posts: 576

laz · Posted: Wed May 13, 2009 1:19 am Post subject:

I pulled the valve cover tonight and there are no broken rocker arms. Is it possible that one is bent instead of broken? The valves all seemed ok, though I could be missing something subtle. Checked compression and every cylinder was 145 +/- 5

We ran the car without the valve cover for a little while, the sound didn't get louder ... so we think it's the bottom end. I'm gotta pull the oil and filter and look for sparkles.
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Norcal spec E30 #804
Pandamonium Racing, 24Hrs of LeMons

Super Eurobeat · Posted: Wed May 13, 2009 1:34 am Post subject:

If you can...minding the exhaust....use a stethoscope or a long extension up to your ear to hear specifically where the sound is coming from.
They are at harbor freight for a couple bucks, not a bad investment!
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There is nothing super about the '88 eta engines except for their gas milage. I have no idea who started calling them super but it must of been someone trying to make themselves feel better about owning an "e". -Alpine E30

bythabay · Posted: Wed May 13, 2009 2:20 pm Post subject:

A quick way to find a rod knock is one by one remove (and ground out) each spark plug wire. Doing this takes the load off of the connecting rod bearing. If there is in fact a rod knock the pitch of the knock will change when that cylinder is canceled out....Hope this helps

laz · Posted: Wed May 13, 2009 4:17 pm Post subject:

I took the car by Bavarian Motorsport today and got Ramon to diagnose it. He says rod knock. Good enough for me.

I'll probably try the spark plug thing for experience, but it looks like I'm either doing rod bearings and crossing my fingers, shopping for a motor, or both.
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Norcal spec E30 #804
Pandamonium Racing, 24Hrs of LeMons

laz · Posted: Sun May 17, 2009 7:02 pm Post subject:

Definitely a bad bearing:

We replaced em and buttoned the car back up. I'm hoping it'll make it through the weekend of racing...
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Norcal spec E30 #804
Pandamonium Racing, 24Hrs of LeMons

Rodoni · Posted: Sun May 17, 2009 8:07 pm Post subject:

My brother told me you guys talked. If you are still interested, LMK, he gave me the okay to sell it Smile

Alex
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