Dry Ice Tech: Doesn’t Fit? Freeze It!

Sometimes tough luck will find you at the worst possible moment. The only thing you can do is assess the situation, formulate a game plan and execute it. Project Silvia’s SR23 presented an unusual hurdle as we prepared for a NASA HPDE track event. During a routine oil change, an unexpected part had found its way into the oil pan. Attached to the magnetic oil drain bolt was the oil jet that lubricates the timing chain.

Text and Photos by Richard Fong

DSPORT Issue #134

Small Part, Hard To Access

Dry Ice Tech DSPORT Magazine Issue 134The press fit oil jet somehow dislodged itself from the block and luckily attached itself to the magnetic drain bolt. However, installing a new one would prove no easy task. The jet is normally located approximately one inch above the crankshaft chain sprocket. Reinstalling the oil jet requires removal of the front cover/oil pump. Removal of the cover is easy, but reinstalling is another matter.

When assembling an SR20 block, the oil pump cover is sealed to the block before the upper oil pan and the cylinder head are mated to the block. Thus, the standard repair requires removal of the cylinder head, removal of the upper oil pan, installation of a new chain oil jet, reassembly of the oil pan and replacement of the head gasket.

This does not include removing all of the items that make some connection or another to the cylinder head (intercooler piping, intake manifold, exhaust manifold, turbocharger etc.) With little time to spare, the hope was to find an alternative solution that would save time.

Viable Work Around

[pullquote]WHY NOT SHRINK THE COVER SO THAT IT COULD CLEAR THE CYLINDER HEAD AND HEAD GASKET?[/pullquote]With the shroud, fan, radiator, crank pulley and other accessories removed, the front cover was eventually coaxed out from between the head and head gasket and the upper oil pan. Unfortunately, once the oil jet was pressed back into its port on the block, shoehorning the front cover back onto the engine proved more difficult than anticipated.

The cover needed to be installed straight onto the engine yet the oil pump pickup flange protrudes from the bottom of the cover and needed to be set into the oil pan before the top portion could be tilted straight and onto the block and below the head. With the head attached, this operation proved a daunting challenge to overcome.

Thinking Outside The Box

Dry Ice Tech DSPORT Magazine Issue 134After consulting with Publisher Michael Ferrara and Testing Editor Aidan Spraic about a possible solution to this dilemma, an unconventional idea came to light. Why not shrink the cover so that it could clear the cylinder head and head gasket? If we could just get another 0.020-inch of clearance, we could probably get the cover back in place. Since metals expand when heated and contract when cooled, we wanted a way to maximize the cooling. Chilling this cover would involve more than just putting it into a water ice bath or freezer since aluminum only shrinks 0.0000123-inches for every degree drop (Fahrenheit) in temperature over each inch. Since the front cover/oil pump is about 10 inches in length on the dimension failing to fit, we calculated that we’d need to get temperatures under -100 degrees to get the shrinkage we desired. How could this be accomplished?