2QUIK6

Been having some running hot issues on the LT4 truck, I think the thermostat may be sticking...but after it got up to about 250 degrees, maybe more than once since my wife is driving it most of the time... It's now making a grinding noise on the front.
With a stephoscope connected to a peice of steel fuel line tubing, it sounds louder behind the waterpump, and is mainly coming from the opti.
Sounds almost like plastic gears grinding together...like the opti rotor is grinding on the front of the opti.

Anyone else have this happen after a overheat issue?

shoebox

Perhaps the spline drive and coupler are having issues. Or maybe your pump is dragging and causing it. Probably time to pull the pump and see what is going on.

2QUIK6

Got the pump and the opti off...both seem to spin ok, no odd noise with the opti..the wp has a slight rough spot it seems when turning the shaft.
Going to drop the thermostat in some hot water and see what temp it opens at.
But since its off and the wp has a lifetime warranty and I have a spare opti I'm going to swap in new ones.


Geez I hope nothing is wrong with the gear drive...maybe when I put the opti back on I'll fire it up with no wp for a second and see if there's any noise at that point... I surely don't want to have to be pulling the front cover and intake off any time soon.

2QUIK6

ok, heat issue I think is solved..thermo didn't start to open until about 200 degrees and its a 160 thermostat...a new stocker from the auto parts house was wide open at 200...the old one never opened much more than 1/4" at 210 degrees while the new was at least 3/8" or a little more.

2QUIK6

Found source of noise I beleive...the teeth on the wp shaft are worn, pump has less than 15k miles on it.... Probably wouldn't hurt to find a new sleeve too in case those teeth are damaged, not sure how pronounced they should be, but wp shaft is definitely worn down compared to the teeth at the base of the shaft.