Intro.
If you’ve ever had to, or wish to, replace your coolant then you need to know how to complete the job, by “burping”, or eliminating any air that has been introduced into the cooling system.
Background.
The purpose of the cooling system in a car is to move an effective amount of heat away from the engine, through a heat transfer process involving the circulation of a cooling media (“anti-freeze”, aka “coolant”) from the engine, to a cooling source (radiator with fans, or higher speed outside air blowing on it).
The system is generally passive, requiring only occasional preventive maintenance such as: checking periodically the fluid levels (when car is off and cool), and checking periodically for coolant leaks (through tell tale green or orange drops under the car).
If you have ever encountered a moderate, controllable overheating issue (for example an alternator belt snap – which also powers the water pump that moves the coolant in the system), or if you are just flushing your coolant system, the next step is to remove the trapped air from the system. Note: A severe overheating problem introduces the potential for more serious mechanical ailments, such as blown head gaskets or warped heads – I don’t cover that here, and you should never, ever, allow your D (or any other car) to seriously overheat. Trapped air in the cooling system will seriously disable the thermal efficiency and in some cases, the function, of the cooling system so it is vital to eliminate it from the circulatory system.
A well maintained cooling system is essential to keep your car in top mechanical condition, and unlike conventional cars, our cars have a long coolant path since the engine is in the back and the radiator is in the front.
Procedure
Once you’ve remedied the issue that led to overheating and/or you have replenished the coolant (btw: coolant is recommended to be replaced every 2-3 years), the next step is to “burp” the system. There are two main locations in the DeLorean, to facilitate the release of trapped air from the cooling system. The first is located on the top cover of the water pump, where you will see a brass fitting poking out of the somewhat domed shaped cover, under the bracket for the throttle spool. The second location is upfront, at the radiator’s passenger side.
Burping your cooling system, OEM style:
If you have an OEM, non modified cooling system, it will take you longer to burp your system, and it will be messier, than with post production modifications, but it will be just as effective. The procedure is as follows:
a) After the fluid is replenished where the level is about an inch or two from the cooling bottle’s neck, start the car and watch the flow. Doing this actually bleeds some air, but this only works for a short time, until before the system actually begins to pull heat out of the engine. Be prepared to add a little more coolant if the level goes down too much (near the bottle’s internal hose opening. When the fluid level appears to be stable (within a few minutes), cap off the bottle.
b) With the engine still running, rotate the wheels to the extreme right, verify the parking brake is on, and then go to the front passenger side wheel (optional: with a small bucket to attempt to collect the soon to be flowing coolant). You should now have visibility and access to the radiator. Note: Goggles strongly recommended at this step. Loosen the clamp from the smaller hose at the top and GENTLY pull/work the hose out. Note: If your car is stock it has a plastic radiator and the fittings at this point you are working on, can easily snap – and ruin an otherwise good day and simple procedure (consider an update to a metal radiator in the future). Here is the messy part, at some point after removing the hose, or immediately, you will get a flow of coolant mixed with air coming out of this hose. As soon as you see only coolant flowing out, quickly (but GENTLY on those plastic radiators) reinsert the (gushing) hose back on the fitting (goggles come in useful here), and re-tighten the clamp. Congrats, you’ve bled the radiator …but no time to celebrate yet, move to next step.
c) Now, go to the engine bay, and locate that brass fitting above top of the water pump. At the fitting stick a clear vinyl hose routed to a small bucket, to prevent a second coolant shower, this time into your engine bay. Now turn the fitting CCW until you get a flow, and re-tighten it when as above, only fluid is visible through the hose.
d) Turn off the car and come back after it has cooled off. It is a good time now to change that shirt and get that sticky smelly coolant off your arm.
e) After the car has cooled, open the coolant bottle and check the level, top it off to about an inch above the internal hose inlet. Close it up, and start up the car.
f) Let the car warm up, if all went well, congratulations, the cooling system is void of any trapped air, and as effective as possible.
Optional:
g) If a test drive after step f still produces high temp, then park the car let it cool off. Repeat step b, but DO NOT start the car, just set it up first. Start the car, put hose back into the radiator after you get a steady stream of coolant. Turn off car, change shirt again, enjoy your ride.
Burping your cooling system, an easier alternative:
In the new Millennium, the procedure above can be performed faster and with almost no messy coolant spills. This entails installing two simple, inexpensive, easy to install modifications to your coolant system. ...actually both these devices have been around (and proven) for quite a few years. They are:
1. A cooling system auto bleeder.
Back in the 90's DPNW's Toby Peterson came up with (the first of quite a few) novel solutions for our cars. Specifically for this application, he experimented and created a method to always have the pump bleed off air, safely, effectively, and automatically. How? Remember the fitting on the top of the water pump? Well the water pump fitting is connected to a hose that runs to a T-splice, into the coolant bottle, and the fitting is left in an open position. This results in that any air in the system automatically gets removed, and vented away, always. No mess, no fuss.
This is available from two vendors that I am aware of:
DeLorean Parts NorthWest's (DPNW)
Wings-B-Cool™ Cooling System Self-Bleeder Kit
(Includes both auto bleeder and radiator bleeder discussed below - each with a shutoff valve)
Special T Automotive's
Air Bleeder Cooling Lines
(This is what came on my car, and in pictures shown here.)
This is what it looks like installed on the water pump side (black hose, attached directly to fitting):
...and this is the other end of the hose, on th eT-splice (on the left in picture):
2. A radiator bleeder
Remember the pulling, the gushing, the reinsertion of a gushing, small coolant hose in the radiator? Well friends say goodbye to that with this nifty device:
DPNW'sWings-B-Cool™ Radiator Bleeder Kit
This essentially consists of spliced in valve on the smaller (top) coolant hose on the radiator. See picture below:
Now to bleed the system, you just attach a hose to the new fitting (which is provided in the kit), the other end to your trusty little bucket/container, and open the valve to check for air, close it when done, a 1 minute operation, with no spillage.
The burping procedure using these little mods
a) After the fluid is replenished where the level is about an inch or two from the cooling bottle’s neck, start the car and watch the flow. Be prepared to add a little more coolant if the level goes down too much (near the bottle’s internal hose opening. When the fluid level appears to be stable, close up the bottle.
b) With the car still running, rotate the wheels to the extreme right, verify the parking brake is on, and then go to the front passenger side wheel. You should now have visibility and access to the radiator bleeder valve. Put in a clear hose (provided with kit) into the valve, put the other end in a container (see picture).
Open valve, watch for fluid flow only (no air bubbles), close valve, remove hose. Congrats you’ve bled the radiator and you shirt, hair, face, and arms are probably still dry.
c) Turn off the car and come back after it has cooled off.
d) After the car has cooled, open the coolant bottle and check the level, top it off to about an inch above the internal hose inlet. Close it up, and start up the car.
e) Let the car warm up, if all went well, congratulations, the cooling system is void of any trapped air, and as effective as possible.
Optional:
f) If a test drive after step e still produces high temp, then park the car let it cool off. Repeat step b, but DO NOT start the car, just set it up first with the valve open. Start the car, shut valve off after you get a steady stream of coolant only. Remove the hose and container and enjoy your ride.
In closing...
See, much simpler, much dryer, and not even having to mess with the water pump fitting. ...and pet friendly too! (If you haven't heard, spilled coolant will make a curious pet that decides to taste and drink it, either very sick, or worse.)
So, it’s very useful, very effective, inexpensive, what’s the catch?
The only one that I know of, is that while the auto bleeder is happily bleeding air away from your cooling system, the question that should really be asked is: “How am I getting air into a closed coolant system?” In other words, the auto bleeder is actually so effective, that it may mask an issue with the system.
There are two ways to get around this:
1) My workaround to that is a weekly preventive maintenance of checking for leaks on the garage floor and checking your fluid levels. If your car has neither issue, then chances are very good your system is in good working conditions.
2) DPNW's product actually has a in inline valve on the hose to the T-connection. This allows you run it open as you long as you wish, then perhaps on a periodic basis, close it for "normal"/OEM operations. Neat trick. Here's a picture of the valve in a closed position (to set it on "auto bleeder" mode, you would run your car with the valve swung over 90 degrees from where pictured).
Photo courtesy of DPNW.
Keep cool.
Addendum:
"While you're there".... I noticed that the vent line from the coolant was set to drip right on top of the frame. And when it did, it would splatter around the corner of the engine bay. : (
So, a quick trip to Lowe's for a longer and new hose, then a couple of tie wraps later, I rerouted the line so that it would vent underneath the car.
Picture below, underneath, looking up toward the rear tire, shows the the results.
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Thanks.
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