Turning motor by hand
Turning motor by hand Hello all. I just pulled an lq4 out of an 01 2500 for a swap I'm starting. The motor is still fully assembled on my engine stand, spark plugs and all. How much torque should it take on the crank bolt to turn it over? This one feels like it turns over far easier than the 5.7 from last year's swap. Thanks guys.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
If it feels like you are not fighting much compression, then my above statement stands. It's not so much the amount of resistance, but WHAT is resisting the turn. In one full turn there should be four spots where it gets tougher because of the compression.
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Launching!
Joined: Apr 2005
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Find TDC, have a good breaker bar on the crank bolt and hold it or it will force the piston to move when you apply the forced air in the cylinder. Have some oil available as well.
Many say run the engine and let it warm up a bit before performing the leakdown.
Good luck!
Yea u can leak down test it or use a standard compression checker. Use the starter to turn it over and check the highest reading for each cylinder. A good engone will be around 150psi or more.
U want all cylinders to be within the same readings. If it seems low. Add a lil bit of oil and see if readings come up. If so rings are worn.
U want all cylinders to be within the same readings. If it seems low. Add a lil bit of oil and see if readings come up. If so rings are worn.
It's very straight forward. Do yourself a favor and get a good leak down tester though.
Find TDC, have a good breaker bar on the crank bolt and hold it or it will force the piston to move when you apply the forced air in the cylinder. Have some oil available as well.
Many say run the engine and let it warm up a bit before performing the leakdown.
Good luck!
Find TDC, have a good breaker bar on the crank bolt and hold it or it will force the piston to move when you apply the forced air in the cylinder. Have some oil available as well.
Many say run the engine and let it warm up a bit before performing the leakdown.
Good luck!
Yea u can leak down test it or use a standard compression checker. Use the starter to turn it over and check the highest reading for each cylinder. A good engone will be around 150psi or more.
U want all cylinders to be within the same readings. If it seems low. Add a lil bit of oil and see if readings come up. If so rings are worn.
U want all cylinders to be within the same readings. If it seems low. Add a lil bit of oil and see if readings come up. If so rings are worn.
Was able to do a compression test on the stand yesterday. We have between 180psi and 200psi across all cylinders except for #8 which was at 155psi and #4 which was at 175psi.
We pulled the rockers from those two cylinders and added 100 psi of air pressure. Both cylinders had significant air leakage coming from the exhaust port. At this point it's probably somewhat safe to blame the leaky valves for the lower compression readings on these two cylinders.
Pulled both heads. Cross hatch looks very good except on #3 and #5. Each has a very small area that the cross hatch is gone. Cylinder walls are super smooth on all 8. Very minimal carbon build up on the pistons.
At this point we feel safe to put our top end package together and run this motor.
We pulled the rockers from those two cylinders and added 100 psi of air pressure. Both cylinders had significant air leakage coming from the exhaust port. At this point it's probably somewhat safe to blame the leaky valves for the lower compression readings on these two cylinders.
Pulled both heads. Cross hatch looks very good except on #3 and #5. Each has a very small area that the cross hatch is gone. Cylinder walls are super smooth on all 8. Very minimal carbon build up on the pistons.
At this point we feel safe to put our top end package together and run this motor.