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Old 02-22-2012, 10:37 PM   #1
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Default boost and leakdown tests make no sense

Did a boost leak test, found EGR valve leaking. Blocked it off and with the crank at TDC air now exits through the exhaust. Slowly rotated crank 3 times and could hear a woosh each time there was overlap but other than that no change with the boost leak behavior.

Picked up a HF leakdown tester and I get 60 on 1, 2 and 4 (haven't tested 3 yet) but I cant find where the ------- air is going. Hear it goung in but nothing from exhaust intake or dip stick, no neighboring cylinders either. After car cooled a bit took the rad cap off and it is bubble free during tests. WTF?

Car runs good, pulls nice and strong so I'm doing something wrong, right?
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Old 02-22-2012, 11:52 PM   #2
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#3 not surprisingly did the same thing. Eventually pulled the pos tester out and upped the pressure from 15 to 30, immediately got air out of a neighboring cylinder. Put 3 plugs back in and air is now pouring out of the tail pipe.

I guess it's good that I forgot to put a clamp back on an intake pipe which started the whole idea of building a boost leak tester. At least now I know what to search for. lol
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Old 02-23-2012, 09:43 AM   #3
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you should be pushing 100psi for a leakdown test.

Are you making sure you are perfectly at TDC on each? The plugs should be removed from all cylinders when you do it, findin gwhere it's leaking should be easy.

It'll come the from the intake, oil filler cap, rad cap, or exhaust.
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Old 02-24-2012, 02:02 AM   #4
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Could this cause my problems? Rotated the crank until the exhaust cam mark lined up correctly and less air leaked out the exhaust but it was still leaking.






HF tester is a cheap pos and only good to 15psi before the 2nd gauge maxes out. Only useful part in it is the threaded hose.
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Old 02-24-2012, 05:47 PM   #5
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Seems like having the exhaust cam retarded one tooth would cause a lot more overlap.
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Old 02-24-2012, 05:54 PM   #6
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Not to mention the slack in the timing belt will also lead to irregular readings.
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Old 02-25-2012, 12:29 AM   #7
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Posting this for anyone who finds this looking for MSM timing (any NB?). TDC is not pictured above, the second pulley mark should like up with the T line not the first. This is verified by pulling the middle timing cover and looking down at the crank. Did not fix my exhaust valve leak so the head comes off.
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Old 02-29-2012, 07:49 PM   #8
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Shop says the leakage is caused by buildup, will know in a few days if that's the case or if it needs more work. Seems odd to happen after only 50k, no? Anything I can do to prevent it? The EGR valve leaks to atmo and has for an unknown amount of time, that plus bigger than stock injectors means the engine was one rich bastard. Would that do it? That poor little IHI must have been working it's *** off trying to keep boost up.

I foresee a UPS box or 3 in my future.
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Old 02-29-2012, 08:16 PM   #9
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I highly suggest:
http://www.flyinmiata.com/index.php?...umber=35-69000

Although at 50k you probably don't need a new front seal. Made my timing belt job a snap, especially since I have a cut VC and didn't have to remove it with the ninja tool. Fool proof timing. More or less.
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Old 02-29-2012, 08:36 PM   #10
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Had I not spilled oil & coolant all over the belt I'd just order up a head gasket some ARP studs and call it day. It's only $20 for the cam and crank seals, so very worth it while I'm in there. What about the idler and tension pulleys? Is it really worth replacing those?

I want the ninja tool just for the bottle opener, never mind that one hangs on the wall 6 feet from where the car sits.
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Old 02-29-2012, 09:08 PM   #11
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Quote:
Originally Posted by midpack View Post
Had I not spilled oil & coolant all over the belt I'd just order up a head gasket some ARP studs and call it day. It's only $20 for the cam and crank seals, so very worth it while I'm in there. What about the idler and tension pulleys? Is it really worth replacing those?
Every 60,000 miles, I do this:

http://parts.arlingtonmazda.com/prod...KMK003%29.html

Helps keep Murphy away from my car. They have similar kits for all years and options.
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Old 03-03-2012, 08:57 PM   #12
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Do the idler and tension pulleys if you are replacing the belt.
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