Too much crank case pressure?

Jeff Chambers · 02-11-2005, 09:49 AM

It doesn't necessarily mean that the rings are bad. I could be that the end gaps are just filed too large or that they haven't completely seated. It also may be a result of the type of ring used. If you've gone with a small package (.043/.043/3mm) or a super low tension set, this would be expected. Do the leakdown and see if it shows signs of any real problem.

In terms of an evacuation system, you can go cheap or go expensive. A header system probably won't solve your problems but a pump system would. A complete Moroso setup might cost you $700-$800 by the time you buy the pump, pulleys, brackets, hoses, etc. I use an air pump off a late model truck so by the time I bought the hoses, fittings and purge cannister I had about $250 into the system. It pulls a good 10 in-Hg at mid track under heavy load, but I burn up a pump every 30 passes or so (the air pumps aren't meant to spin with a motor at 8500rpm even though I've got it pullied down the pump still sees 5000). Thank heavens that Autozone exchanges them. A good Moroso or similar set though will be trouble free and will pull 14+ in-Hg for maximum HP gain. Don't try to pull too much vacuum though or you'll start affecting your engine oiling.

Michael Smith · 02-14-2005, 09:26 AM

Well I did the leakdown test yesterday and this is the results:
cyl 1: 18% 5: 14%
2: 14% 6: 14%
3: 13% 7: 13%
4: 14% 8: 16%
Also when I would listen or feel for air comming from the intake, exhaust, dip stick, or oil fill cap it always came from the oil fill cap in the valve cover for every cylinder so would this be blow-by? I used a snap-on tester and it said no more then a 30% difference in leakdown between the cylinders so am I correct to assume that the #1 cyl is close to this but still within tolerance? What do you think of the numbers for a new built engine with about 500-600miles on it?
The ring set used was a stock replacment moly rings end gap was standard .014-.016 no filing on the ring gap. Well what do you all think? thanks for any input and thanks Jeff for the reply.

02-14-2005, 09:26 AM	#2
Michael Smith Registered Member Join Date: Feb 2003 Location: Washington Posts: 33	Re: Too much crank case pressure? Well I did the leakdown test yesterday and this is the results: cyl 1: 18% 5: 14% 2: 14% 6: 14% 3: 13% 7: 13% 4: 14% 8: 16% Also when I would listen or feel for air comming from the intake, exhaust, dip stick, or oil fill cap it always came from the oil fill cap in the valve cover for every cylinder so would this be blow-by? I used a snap-on tester and it said no more then a 30% difference in leakdown between the cylinders so am I correct to assume that the #1 cyl is close to this but still within tolerance? What do you think of the numbers for a new built engine with about 500-600miles on it? The ring set used was a stock replacment moly rings end gap was standard .014-.016 no filing on the ring gap. Well what do you all think? thanks for any input and thanks Jeff for the reply.

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02-11-2005, 09:49 AM	#1
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: Too much crank case pressure? It doesn't necessarily mean that the rings are bad. I could be that the end gaps are just filed too large or that they haven't completely seated. It also may be a result of the type of ring used. If you've gone with a small package (.043/.043/3mm) or a super low tension set, this would be expected. Do the leakdown and see if it shows signs of any real problem. In terms of an evacuation system, you can go cheap or go expensive. A header system probably won't solve your problems but a pump system would. A complete Moroso setup might cost you $700-$800 by the time you buy the pump, pulleys, brackets, hoses, etc. I use an air pump off a late model truck so by the time I bought the hoses, fittings and purge cannister I had about $250 into the system. It pulls a good 10 in-Hg at mid track under heavy load, but I burn up a pump every 30 passes or so (the air pumps aren't meant to spin with a motor at 8500rpm even though I've got it pullied down the pump still sees 5000). Thank heavens that Autozone exchanges them. A good Moroso or similar set though will be trouble free and will pull 14+ in-Hg for maximum HP gain. Don't try to pull too much vacuum though or you'll start affecting your engine oiling. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"