01 ROUSH Blown Mustang Compression Test Result and Issue with Cylinder#3

Howdy, today I did some compression test after noticing some white smoke from my Oil cap at Idle and loss of performance. Have a look at my compression test readings and let me know what you think of Cylinder #3 and 4.

Cylinder 1 (150 psi)
Cylinder 2 (160 psi)
Cylinder 3 (Dry 50 psi and Wet 65 psi) I am thinking It is a ring piston issue? Or do you think is a valve seal issue?
Cylinder 4 (Dry 135 psi and Wet 160 psi) do I have to worry about this compression number?
Cylinder 5 (125 psi) do I have to worry about this compression number?
Cylinder 6 (155 psi)
Cylinder 7 (150 psi)
Cylinder 8 (150 psi)

Your suggestions will be very appreciated to tackle the exact issue.

Do a leak down test , to verify rings or valve .

Excess coolant consumption? Leak down test and keep an eye on your coolant reservoir


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As i’ve know if we do a wet test by adding 1 Tbl spoon oil on the spark plug hole and the compression number increases that means ring piston. Correct me if i am wrong?

So, you think there is a possibility of valve issue? If this is the case i will do a leak down test and let you guys know soon. For me i wish it is a valve not ring piston.

Rolltide1006 said:

Excess coolant consumption? Leak down test and keep an eye on your coolant reservoir


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Yes i found that there is an Excess coolant consumption and oil too going from the Max to the Min on the stick.

Ya sounds like a head gasket. Do a leak down on cylimder #3. Id bet you see bubbles in your coolant reservoir while doing the test.


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Rolltide1006 said:

Ya sounds like a head gasket. Do a leak down on cylimder #3. Id bet you see bubbles in your coolant reservoir while doing the test.......

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I agree with this^^^^^^^^^^^^^^^^^^^^

Rolltide1006 said:

Ya sounds like a head gasket. Do a leak down on cylimder #3. Id bet you see bubbles in your coolant reservoir while doing the test.


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Thank you guys for the help. I will do the leak down test within 2-3 days and I'll keep on eye of the coolant reservoir and keep you posted.

Today I did the Leak Down Test for Cylinder #3 and here you go the result:

Leak Percentage with TDC was 28% and there was no bubbles at all in the coolant reservoir. The leak was from the oil cap which is an indication of Ring piston as I thought unfortunately

So, time for build up the bottom end.

Denver_SVT said:

Today I did the Leak Down Test for Cylinder #3 and here you go the result:

Leak Percentage with TDC was 28% and there was no bubbles at all in the coolant reservoir. The leak was from the oil cap which is an indication of Ring piston as I thought unfortunately

So, time for build up the bottom end.

Click to expand...

welp. Slap in some forged rods and forged pistons while you are in there


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Rolltide1006 said:

welp. Slap in some forged rods and forged pistons while you are in there


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Exactly this is the plan. I just disconnected the battery and covered the car to reset for couple of weeks. I will start listing the parts I will go with and get ready for the order.
New thread for the build up will be posted once everything is ready. So, stay tuned