What are typical symptoms with these 3.5TT ecoboost motors when you have compression loss in a cylinder?
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Cylinder compression
- Thread starter StealBlueSHO
- Start date
Would I be seeing misfires?
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Compression Test .Z
Make sure the oil in the crankcase is of the correct viscosity and at the correct level and that the battery is correctly charged. Operate the vehicle until the engine is at normal operating temperature. Turn the ignition switch to the OFF position, then remove all the spark plugs.
Set the throttle plates in the wide-open position.
Install a compression gauge in the No. 1 cylinder.
Install an auxiliary starter switch in the starting circuit. With the ignition switch in the OFF position, and using the auxiliary starter switch, crank the engine a minimum of 5 compression strokes and record the highest reading. Note the approximate number of compression strokes necessary to obtain the highest reading.
Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
Compression Test — 3.5L Engine Test Results
The indicated compression pressures are considered within specification if the lowest reading cylinder is at least 75% of the highest reading. Refer to the Compression Pressure Limit Chart.
If one or more cylinders reads low, squirt approximately one tablespoon of engine oil meeting Ford specification on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.
Compression Test — 3.5L Gasoline Turbocharged Direct Injection (GTDI) Engine Test Results
The indicated compression pressures are considered within specification if the lowest reading cylinder is at least 75% of the highest reading. Refer to the Compression Pressure Limit Chart.
If one or more cylinders reads low, squirt approximately one tablespoon of engine oil meeting Ford specification on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.
Compression Test — Interpreting Compression Readings
If compression improves considerably, piston rings are worn or damaged.
If compression does not improve, valves are sticking or not seating correctly.
If 2 adjacent cylinders indicate low compression pressures and squirting oil on each piston does not increase compression, the head gasket may be leaking between cylinders. Engine oil or coolant in cylinders could result from this condition.
Use the Compression Pressure Limit Chart when checking cylinder compression so that the lowest reading is within 75% of the highest reading.
Cylinder Leakage Detection
When a cylinder produces a low reading, use of a cylinder leakage tester will be helpful in pinpointing the exact cause.
The leakage tester is inserted in the spark plug hole, the piston is brought up to Top Dead Center (TDC) on the compression stroke, and compressed air is admitted.
Once the combustion chamber is pressurized, the leakage tester gauge will read the percentage of leakage. Leakage exceeding 20% is excessive.
While the air pressure is retained in the cylinder, listen for the hiss of escaping air. A leak at the intake valve will be heard in the Throttle Body (TB) . A leak at the exhaust valve can be heard at the tailpipe. Leakage past the piston rings will be audible at the PCV connection. If air is passing through a blown head gasket to an adjacent cylinder, the noise will be evident at the spark plug hole of the cylinder into which the air is leaking. Cracks in the cylinder block or gasket leakage into the cooling system may be detected by a stream of bubbles in the radiator.
Make sure the oil in the crankcase is of the correct viscosity and at the correct level and that the battery is correctly charged. Operate the vehicle until the engine is at normal operating temperature. Turn the ignition switch to the OFF position, then remove all the spark plugs.
Set the throttle plates in the wide-open position.
Install a compression gauge in the No. 1 cylinder.
Install an auxiliary starter switch in the starting circuit. With the ignition switch in the OFF position, and using the auxiliary starter switch, crank the engine a minimum of 5 compression strokes and record the highest reading. Note the approximate number of compression strokes necessary to obtain the highest reading.
Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
Compression Test — 3.5L Engine Test Results
The indicated compression pressures are considered within specification if the lowest reading cylinder is at least 75% of the highest reading. Refer to the Compression Pressure Limit Chart.
If one or more cylinders reads low, squirt approximately one tablespoon of engine oil meeting Ford specification on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.
Compression Test — 3.5L Gasoline Turbocharged Direct Injection (GTDI) Engine Test Results
The indicated compression pressures are considered within specification if the lowest reading cylinder is at least 75% of the highest reading. Refer to the Compression Pressure Limit Chart.
If one or more cylinders reads low, squirt approximately one tablespoon of engine oil meeting Ford specification on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.
Compression Test — Interpreting Compression Readings
If compression improves considerably, piston rings are worn or damaged.
If compression does not improve, valves are sticking or not seating correctly.
If 2 adjacent cylinders indicate low compression pressures and squirting oil on each piston does not increase compression, the head gasket may be leaking between cylinders. Engine oil or coolant in cylinders could result from this condition.
Use the Compression Pressure Limit Chart when checking cylinder compression so that the lowest reading is within 75% of the highest reading.
Cylinder Leakage Detection
When a cylinder produces a low reading, use of a cylinder leakage tester will be helpful in pinpointing the exact cause.
The leakage tester is inserted in the spark plug hole, the piston is brought up to Top Dead Center (TDC) on the compression stroke, and compressed air is admitted.
Once the combustion chamber is pressurized, the leakage tester gauge will read the percentage of leakage. Leakage exceeding 20% is excessive.
While the air pressure is retained in the cylinder, listen for the hiss of escaping air. A leak at the intake valve will be heard in the Throttle Body (TB) . A leak at the exhaust valve can be heard at the tailpipe. Leakage past the piston rings will be audible at the PCV connection. If air is passing through a blown head gasket to an adjacent cylinder, the noise will be evident at the spark plug hole of the cylinder into which the air is leaking. Cracks in the cylinder block or gasket leakage into the cooling system may be detected by a stream of bubbles in the radiator.
Gonna run a compression test this week... I am not having any misfires or any real symptoms I should say.. I am getting a slight knock almost like piston slap for a short time when the motor is warming up... it’s been below freezing so I’m not sure if I should give it any real thought... after the car goes through it’s warm up the noise is gone and I cannot duplicate it.
Could be nothing, could be something, not sure... but if I am looking at bigger turbos I need to make sure the motor is good...
Still pulls hard and smooth, idles the same it always has. Since I have put on the downpipes there has been a fuel smell but I suspect it’s because the high flow cats don’t do anything.
I don’t want to spend the money shipping the car to LME for turbos and a dyno tune just for them to tell me the motor has a problem...
No codes and all the data logs look good..
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Could be nothing, could be something, not sure... but if I am looking at bigger turbos I need to make sure the motor is good...
Still pulls hard and smooth, idles the same it always has. Since I have put on the downpipes there has been a fuel smell but I suspect it’s because the high flow cats don’t do anything.
I don’t want to spend the money shipping the car to LME for turbos and a dyno tune just for them to tell me the motor has a problem...
No codes and all the data logs look good..
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Macgyver said:
I’m familiar with the startup rattle, and yes, the Motorcraft filter DOES make a huge difference. That startup rattle only lasts for a few seconds.
This lasts until the warmup cycle is almost complete. And it’s not steady in its loudness it kinda fades in and out. I almost thought it was the downpipe connection to the turbo not being torqued down...
I only mention piston slap because tapping on cold starts tends to be a piston slap issue...
Recent oil changes have not had any metal shavings that I could see... dunno... maybe being paranoid (again)...
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Does the rattling issue present itself when idling to warmup, or only when driving around? Severity change with RPM? A steady rattle might have pointed to the timing system, like it does with the F150. Maybe VCT solenoid replacement can help avert that crisis. No one that I know of has torn down a "faulty" engine to determine the possibility of the oil jets not working right to cool the pistons.
Trying to determine loose component vs bearing possibility.
As far as shavings in oil, I assume you have used a good magnet to help pull those out of suspension.
Trying to determine loose component vs bearing possibility.
As far as shavings in oil, I assume you have used a good magnet to help pull those out of suspension.
Only on warm up when it’s been sitting long enough for the engine to go cold.. ie over night and only when it gets below freezing at night. After the warm up cycle it goes away. The sound doesn’t change severity with RPMs but follows RPMs for the first 500 rpm then goes away. Goes away when RPMs increase after but I only give it a little gas when warming it up when diagnosing cause that’s hard on a cold motor...
Very well could be the timing chain rattling, hadn’t really thought the chain might be stretched...
Yea I ran a magnet, shined the lights into it, and opened the filter... no shaving to speak of...
My guess is when the temperatures warm up the tapping will go away... not that that is a good answer.
The only reason I don’t think it’s a loose component is the brief period where it follows the RPM for 500rpms...
Dunno?
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Very well could be the timing chain rattling, hadn’t really thought the chain might be stretched...
Yea I ran a magnet, shined the lights into it, and opened the filter... no shaving to speak of...
My guess is when the temperatures warm up the tapping will go away... not that that is a good answer.
The only reason I don’t think it’s a loose component is the brief period where it follows the RPM for 500rpms...
Dunno?
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stealbluesho said:
The do have a solution for a bad block
https://www.livernoismotorsports.com/product/LPP750101
TopherSho said:stealbluesho said:
The do have a solution for a bad block
This is under consideration... but besides a cold start tapping I have no other symptoms... not ready to throw the towel in on the block lol...
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TopherSho said:
I have checked livelink... and there is no PID/DMR/OSC for that.. which seems weird to me. I am not sure what the threshold is for the oil pressure before a CEL is triggered...
The SHO Platform is quite stubborn and do not emit codes that easily! 
How many miles on your current oil change?
Does it also make that tapping noise with fresh oil?
Agreed with SHOdded above and could be related to the vct solenoids as with time they get dirty!
I think there are four vct solenoids IIRC! Z
How many miles on your current oil change?
Does it also make that tapping noise with fresh oil?
Agreed with SHOdded above and could be related to the vct solenoids as with time they get dirty!
I think there are four vct solenoids IIRC! Z
Filters? I use Motorcraft oil filters as they seem to work best....
Changed oil out about 500 miles ago or so...
Tapping persisted through the oil change. Again, no debris in the last oil or filter...
Maybe Topher is misreading my previous post? I have high flow catalytic converters on my downpipes... they don’t filter much of anything...
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Changed oil out about 500 miles ago or so...
Tapping persisted through the oil change. Again, no debris in the last oil or filter...
Maybe Topher is misreading my previous post? I have high flow catalytic converters on my downpipes... they don’t filter much of anything...
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FWIW went to go take a video.... noise is gone.... perhaps it’s a loose component...
Not sure if it was something in the rotation assemblies it would be consistent....
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Not sure if it was something in the rotation assemblies it would be consistent....
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Wouldn’t be a SHO if it didn’t... at least something from the SHO heritage seems to persist!
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