Cooling System Service Procedures

Created: 3/1/99

Last updated: 

Author/source: Swingle and others mentioned

1. Flushing Procedures

2. Bleeder Valve ByPass


1. COOLING SYSTEM FLUSH Mike Carollo/Dave Swingle


The only method I know and the one that I have used is the method described by Mike Substelny which is the Don Steger method that was published many years ago in one of the first Delorean World magazines.

For best results, and to catch the most concentrated antifreeze for disposal, drain the system. Draining the system and the engine block first catches most of the old coolant, and then the backflush goes a lot quicker and doesn't dump as much antifreeze on the ground.

To drain the system, remove the lower radiator hose connection. Careful - itís plastic. To drain the engine, remove the two block drains. The driverís side one is located just above the catalytic converter, the passenger side one is next to the oil filter. These can be removed using the same tool you have for removing the oil drain plug.

Reconnect the lower radiator hose but leave the block drains open. Remove the half inch hose connected to the overflow bottle at the filler neck. You then shove the end of the hose into the garden hose and wrap a wet towel around the connection to slow the leak. (OR make a brass fitting to connect to a garden hose with a 5/16" brass hose -to- barb fitting). You then turn the hose on to a low pressure. This forces fresh water through the system by way of the heater core in an opposite direction that it is suppose to travel and the excess comes out of the top of the overflow bottle or the block drains. You do this until you get nothing but clear water. Put the block drains back in.

Next you reconnect the heater hose to the overflow bottle and disconnect the upper radiator hose from the engine at the housing that contains the bleeder screw. (This is the larger of the two large radiator hoses) You then shove the garden hose down into the upper hose connection and wrap that wet towel around the connection again. Or make another PVC barb to hose fitting - 1-1/2" barb is the right size. Turn the water on low pressure and this will force clear water through the radiator the opposite direction it is used to. You do this until the excess fluid coming out of the overflow bottle is clear. This will also largely purge the system of air. It is also helpful at this time to disconnect the upper bleeder hose at the radiator to let any trapped air out. Careful here, too, this is a small plastic fitting.

When finished you then pour two fresh gallons of antifreeze (if using distilled water put it in first) into the upper radiator hose. This will displace the water in the system and eventually as you get the end of the second gallon into the hose you will see green coming out of the overflow bottle. You then quickly reconnect the hose.

The method of bleeding with the pressure tester is next. There is no special tool for a Delorean! The pressure tester is the same as used on any other car because it connects to the overflow bottle where the pressure cap sits which is the same size as any other car. The pressure should be 14 PSI. The bleeder screw is on the upper water pump housing. If your car has the ice shield recall kit remove it for access. The bleeder screw is brass (soft) and hard to get to unless you use a 6-point deepwell 10mm socket. If stripped it can be replaced with a standard 10 mm x 1 brake bleeder fitting available at Trak.

Once you put pressure on the system and release the bleeder screw a couple of times you should build up pressure and let the system sit for a while and see if it holds or bleeds down. You should also physically inspect for leaks at all joints! Your pressure should hold indefinitely as long as you have no leaky connections.

Hope this helps. I don't recommend running the car to bleed it just because you want to be neat. I consider this dangerous.


2. DeLorean Overheating Problem/Solution - Arnie Brandon

For some years, the Pacific Northwest DeLorean Club has used the below described solution to the overheating problem. This system was designed by Toby Peterson and Arnie Brandon, of PNDC.

The problem occurs when air is allowed to enter your cooling system (when the system is worked on or the overflow bottle is allowed to get empty) and the result is an air lock of the cooling circulation system. This is why all production DeLoreans came with an air bleeder valve located just above the water pump.

To overcome this problem permanently, merely remove the air bleeder valve and insert a single hose barb. The hard part is finding one. Threads are M10x1, barb size is 5/16 (8 mm). I made this up using a Motormite #43502 3/16xM10.1.0 Brake Fitting (Trak), and a Weatherhead #10004B-B03 1/4" hose-to-tube fitting (Midwest Hose Supply or

NAPA). To this hose barb, attach 44 inches of very good 5/16" heater-rated hose (NAPA 5/16=8mm PN M082 82). Use a hose hanger to fasten the hose to the rear of the engine compartment, so that it will not interfere with any of the belts. Run the hose behind/over the overflow bottle and toward the front of the bottle. Loosen the small return hose to the bottle and insert a brass 5/16 T-fitting (Motormite 43071) and about 2" of the 5/16" heater hose. Connect the 44 inch hose to the T-fitting. Use small (3/4") stainless hose clamps on all (4) connections.

This essentially eliminates the air-entrapment overheating problems incurred in DeLoreans. The higher pressure at the top of the engine provides a small flow of fluid (and any trapped air) towards the bottle. Air bubbles go up into the overflow and are replaced by fluid from the bottle. All you have to do is keep fluid in the bottle.

For $17.00 plus $4.00 for US destination shipping and handling, you can get this complete kit (barb, hose, T-fitting, clamps, hanger and hanger-screw) with full installations instructions to cover this 15 minute install.

Mail your check to:

Arnie Brandon President

Pacific Northwest DeLorean Club

12839 SE 45th PL

Bellevue, WA. 98006-2031.


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