Posted by: Phil's Classic Chevys | August 9, 2012

The ’31 Chevy Overheating Problems Are Back

Just when things were going well, a few problems cropped up on the ’31 Chevy.  Early this summer it had periods of sputtering, rough running and stalling and the overheating problem was back.  We first attacked the rough running and stalling.

Knowing that spark and/or fuel would be logical places to look we began there.  We disconnected the fuel line at the fuel pump and blew  compressed air back to the tank.  As hoped, bubbles appeared in the tank.  To double check we pressurized the tank and got a good steady flow of fuel to the pump.  We verified the pump was operating properly by disconnecting the fuel line at the carburetor and noticing good fuel flow from the pump into a cup.

Pulling a spark plug wire and cranking the engine yielded a weak spark at best when grounded to the block.  We checked the points (operating properly) and changed the coil.  Still no improvement.  When tracing the wiring back to the starter we noticed a lose connection at the starter switch.  Tightening the connection solved the problem.  I can only wish we had seen that problem early on and saved a lot of time.

Even though the engine was running fine, it was still overheating.  I removed the radiator and had it cleaned.  I was told that the radiator had been notably plugged with rust, but had cleaned up well.  It was also suggested that putting the radiator back without correcting the source of the rust would only invite future problems.

A call to The Filling Station for advice suggested removing the water pump and baffle and checking for rust.  If rust was present behind the baffle it would be necessary to take the head off and clean the water passages.  I could only hope that there was no rust, but that was not to be.  Significant rust in the area behind the baffle was clearly evident.

I called my good buddy Rick and we went to work.  We removed the intake/exhaust manifold, the head, side plate, and the push rods.  The head and valves looked good, but it was obvious that there was rust around the cylinder walls in the water passages.

Rick made a small valved water nozzle and a similar air nozzle and we flushed air and water through the block and out the water pump opening and freeze plug holes.  We also used a small telescoping magnet to remove iron particles left after flushing.  The flushing and magnet operations were lengthy as every time we thought we had removed pretty much everything, the magnet only produced more rust.  Finally we were satisfied with the level of cleanliness in the cooling system.  The following photo shows the rust removed by the magnet.  Probably a similar amount was removed by flushing.  The rust appeared similar to coffee grounds.

Rust from engine

Rust From Engine

We reassembled the engine with all new gaskets and the proper bolt torque settings supplied from The Filling Station.  I changed the oil using a recommended non-detergent brand and we started her up.  She ran great and much cooler than before.  The new exhaust manifold gasket had also solved an exhaust leakage issue and helped the engine run quieter.

After satisfying ourselves that things were much improved, the car was taken to a large local car show and received an award for “Best of Show.”  It was a satisfying reward for more than a few hours of labor.

Reassembled engine

Reassembled Engine

Looking (and Running) Good

Looking (and Running) Good


  1. Great job! I’m looking forward to a ride!

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