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f23a leakdown test, air leaking thru intake valve

Old 11-16-2009, 09:46 PM
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Default f23a leakdown test, air leaking thru intake valve

Hi there,
I'm going to blabber a bit about my woes and use you guys as my sounding board. Hope I find a good audience that may give me some decent feedback...

Here goes:

My 98 accord engine is kind of dying (low compression on cyl. 4) so i picked up a salvaged motor from a fellow via craig's list for a few bucks. (now i'm thinking I should have got the other motor from the other guy...)

I was going to service the engine before i dropped it in, like do the timing belt, h2o pump, etc.

Well, i did a health check by testing the leak-down. Cyl. 2 and 3 are leaking air via the intake valve . I can hear and feel air hissing out. Leakdown gage was reading something like 80psi on tank side, 15psi on engine side. However, cyl. 1 and 4 were reading about 100psi on tank side and 95psi on the cylinder side with little hissing. I never used a leakdown gage so I'm not sure this is right. I will say that this engine is on a bench so its cold.

Current timing belt is secure so i'm sure the pistons havent hit the valves and bent them.

I noted a few other visual clues:
- Drained oil, it was nice and clean; dark but clean and transparent, not opaque or sludgy.
-The h2o pump inlet and engine head h2o outlet are suspect of something contaminating it. There appears to be foamy oil/antifreeze mixture. Did it overheat and crack the head or cylinder block? But the oil drained clean... Anyone got an opinion?

I wonder what is causing the leak through the valves? Could they be bent? Could the head be cracked or warped?

I already ordered head bolts and a top end gasket kit so thats on the way.

I guess I have to open up... Tomorrow my friend will come over an verify the leak-down readings with me. I should open it up and measure the head for warpage. I dont have a run-out gage, so I wonder how I can measure and see if the valves are bent.

BTW, does anyone know where I can buy replacement OE style valves at a reasonable price (something reasonably below dealer cost)?

Oh, I'm a motorcycle guy roadrace a CBR600RR so I'm not too familiar with the car suppliers.

Thanks for being a sounding board o'might message board!


Last edited by zeroice; 11-16-2009 at 09:58 PM.
Old 11-17-2009, 07:21 AM
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Just to rule out something easy, check the valve lash. Too-tight valves are a possible reason for leakage through intake valves, although (unfortunately) that's a long shot.
Old 11-17-2009, 08:45 AM
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I did check the valve lash and there should be sufficient clearance. I didn't measure it, but there was clearance as I could feel the rockers rock.
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