Sticking intake valve - any ideas on fixing the "bucket"?
07-04-2014, 05:58 PM
#11
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Location: Michigan again!
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Finally did a leak down test - not good
If I did it correctly, I think that there may be a mechanical issue and not a spring issue. I attached a drawing of the results. The 100 psi was the max limit of my little compressor, but I think the results tell the tale. We got the turbo on and finished May 1 - took one more test drive and broke something. Makes a ticking sound like a tappet, but there aren't any on the 3.7 which uses the Direct Actuated Mechanical Bucket system.
On the last one on the driver side, and the middle cylinder on the passenger side, as soon as I put the pressure into the cylinder I could hear the oil bubbling back toward the scavenger pump and turbo - took the oil fill cap off and the sound stopped but I could feel the air coming out of the fill cap.
The middle on the driver side and the front on the passenger side wouldn't pressurize at all - as soon as I put the pressure to the line it went from 100 psi to almost nothing and showed a 90% leakage on the gauge.
Disconnected the line to the cylinder and the gauges jumped up to show about 50psi on the tool and leakage gauge showed 70% - connected it to the cylinder tube again and it dropped immediately.
The front on the driver and the back on the passenger showed 55% and 65% leakage.
So looks like an engine replacement. I don't have a boroscope/camera so couldn't look in the cylinder but my guess is that there is a chip in the piston top ring land. Maybe we ran a little lean at WOT, although I never heard any detonation.
I am attaching a scan drawing of the results.
Anyone have a boroscope/camera I can borrow?
At least the car looks good
On the last one on the driver side, and the middle cylinder on the passenger side, as soon as I put the pressure into the cylinder I could hear the oil bubbling back toward the scavenger pump and turbo - took the oil fill cap off and the sound stopped but I could feel the air coming out of the fill cap.
The middle on the driver side and the front on the passenger side wouldn't pressurize at all - as soon as I put the pressure to the line it went from 100 psi to almost nothing and showed a 90% leakage on the gauge.
Disconnected the line to the cylinder and the gauges jumped up to show about 50psi on the tool and leakage gauge showed 70% - connected it to the cylinder tube again and it dropped immediately.
The front on the driver and the back on the passenger showed 55% and 65% leakage.
So looks like an engine replacement. I don't have a boroscope/camera so couldn't look in the cylinder but my guess is that there is a chip in the piston top ring land. Maybe we ran a little lean at WOT, although I never heard any detonation.
I am attaching a scan drawing of the results.
Anyone have a boroscope/camera I can borrow?
At least the car looks good
04-04-2015, 08:47 PM
#12
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Join Date: May 2006
Location: Michigan again!
Posts: 8,579
Replacement engine is in and the car is back on the road finally! Picked it up at MRT today and drove it carefully home - I have no faith in the BBR supplied tune to take it WOT again so kept it out of boost. But it is running fine (other than my oil pressure gauge won't work for some reason so need to take care of that now).
We had to pull the oil pan from the old engine because during shipping the pan cracked on the replacement. No big surprise that we found some parts there after the failure. I was expecting to see bits of ring land and it was chunks of piston skirt.
Now to get the tuning set - need to get it on the dyno with a competent tuner so I can drive it and take advantage of the power!
It wasn't a valve - and this is all we found. Still need to tear it down for a complete autopsy.
We had to pull the oil pan from the old engine because during shipping the pan cracked on the replacement. No big surprise that we found some parts there after the failure. I was expecting to see bits of ring land and it was chunks of piston skirt.
Now to get the tuning set - need to get it on the dyno with a competent tuner so I can drive it and take advantage of the power!
It wasn't a valve - and this is all we found. Still need to tear it down for a complete autopsy.
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Calizic
4.6L (1996-2004 Modular) Mustang
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08-28-2015 01:46 PM