Compression Test on 1UZFE
04-08-03, 03:40 PM
#1
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Compression Test on 1UZFE
Gang,
I have been getting a lot of blow-by and my car was idling rought so i decide to get a compression test. Here are the results:
Dry Test:
Piston # 8 = 170
Piston # 7 = 170
Piston # 6 = 165
Piston # 5 = 125
Piston # 4 = 175
Piston # 3 = 85
Piston # 2 = 175
Piston # 1 = 75
Wet Test on Piston # 1 & 3
Piston # 1 = 90
Piston # 3 = 115
What does it mean? Any cylinder over 110 is good. Wet test mean the tech put 5 drops of oil into the chamber and compress test again to see if the compression increase. If it does increase, it just validate that somewhere is leaking pressure. From the dipstick inspection, the head gaskets still very good. This engine have a life of 155,000 miles on it. I dont think its my TT cause the problem. I think its the abuse of my driving cause the weakness in the rings. So, what does this all mean again? Its time for me to get my spare engine out and send it to the machine shop to get some forged JE dish pistons and some Moly Rings. If the price is right I will do the followings:
*JE Custom Dish Pistons
*Moly Rings
*Steel or copper Gaskets
*ARP Studs
*Double Valve Springs**
*Blue Print & Balance
*Port & Polish Heads**
*O-Ring Block and Heads**
**Optional
If not, I will do the basic. Most likely JE Pistons, Moly Rings, ARP studs and Gasket.
I have been getting a lot of blow-by and my car was idling rought so i decide to get a compression test. Here are the results:
Dry Test:
Piston # 8 = 170
Piston # 7 = 170
Piston # 6 = 165
Piston # 5 = 125
Piston # 4 = 175
Piston # 3 = 85
Piston # 2 = 175
Piston # 1 = 75
Wet Test on Piston # 1 & 3
Piston # 1 = 90
Piston # 3 = 115
What does it mean? Any cylinder over 110 is good. Wet test mean the tech put 5 drops of oil into the chamber and compress test again to see if the compression increase. If it does increase, it just validate that somewhere is leaking pressure. From the dipstick inspection, the head gaskets still very good. This engine have a life of 155,000 miles on it. I dont think its my TT cause the problem. I think its the abuse of my driving cause the weakness in the rings. So, what does this all mean again? Its time for me to get my spare engine out and send it to the machine shop to get some forged JE dish pistons and some Moly Rings. If the price is right I will do the followings:
*JE Custom Dish Pistons
*Moly Rings
*Steel or copper Gaskets
*ARP Studs
*Double Valve Springs**
*Blue Print & Balance
*Port & Polish Heads**
*O-Ring Block and Heads**
**Optional
If not, I will do the basic. Most likely JE Pistons, Moly Rings, ARP studs and Gasket.
Last edited by Lextreme; 04-08-03 at 04:57 PM.
04-09-03, 08:55 PM
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According to the manual, compression pressure should be 178 psi, minimum is 142 psi, and difference between cylinders is 14 psi or less.
If adding oil helps the compression, chances are the piston rings and/or the cylinder bore are worn. If pressure stays low, a valve may be sticking or seating is improper, or there may be leakage past the gasket.
tvd51
If adding oil helps the compression, chances are the piston rings and/or the cylinder bore are worn. If pressure stays low, a valve may be sticking or seating is improper, or there may be leakage past the gasket.
tvd51
04-19-03, 09:41 AM
#4
I know the stock rings have a pretty low tension,since my car will blow off a quart if I drive @ 100 all day.The high revs/light load condition led me to this conclusion.
Maybe some of the boost has been blowing past the factory rings and heated em up/tweaked them to having even less tension?
Maybe some Deves,gapless rings would be the answer.
I found 10/W40 oil to give a boost in low end power from better compression as well,so I use that or 0W40 Mobil one;you might try 20/50 Kendall,that's the stickiest oil I've ever used and really helps out with any slop/wear issues.
Maybe some of the boost has been blowing past the factory rings and heated em up/tweaked them to having even less tension?
Maybe some Deves,gapless rings would be the answer.
I found 10/W40 oil to give a boost in low end power from better compression as well,so I use that or 0W40 Mobil one;you might try 20/50 Kendall,that's the stickiest oil I've ever used and really helps out with any slop/wear issues.
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