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Low Coolant Light Experience

new 07/21/2004, updated 8/10/04

It seems like recently I've seen a few references to intermittent low coolant lights with no one seeming to have any hard answers. I doubt that I have a hard answer but would like to share an experience I had early last summer (almost 35K ago).

I was due for a coolant flush and refill. I had a bottle of Prestone flushing agent and went through the routine of draining the system, putting in the flushing agent and distilled water, warmed it up real good, drained, filled with distilled water, warmed up real good again and then drained and refilled using the regular Prestone antifreeze and distilled water. I did a short test drive and with everything looking good and made about a 45-mile trip down I-70 that evening and back home - without incident. The next morning when I backed the car out of the garage, I saw a puddle of antifreeze on the floor. The seal had gone bad in the water pump.

I bought a rebuilt water pump from my local NAPA store and put it in. Because I suspected the Prestone flushing agent had caused the seal to fail, I wrote to Prestone. During the week or so that I waited for a reply, I had several instances of the low coolant light coming on. It was always happening in some curves on my way home from work. The temp gauge never got above normal but the light would come on in a very predictable manner. The tank was never low but when I checked things closer, I noticed a lot of air bubbles (foam) in the coolant tank. I was afraid that not only had the Prestone flushing agent took out my water pump seal, it had also caused a head gasket to fail.

Long story short, I flushed the system out again and this time refilled it with the Havoline Extended Life "orange stuff" (yeah, I know! So far the stuff still looks real good but it's time to flush the system again and I'm going to go back to "the green stuff"). I have not had any foaming or low coolant light incidents again.

I theorized that under the right circumstances, the coolant mix in my engine was foaming up for some reason and that under my cornering situation, the coolant in the tank sloshed just enough that a very foamy mix was what was contacting the low coolant sensor and causing the light to come on because it was not conductive enough. The reason I haven't seen the light since is because the coolant mix I am now running doesn't foam up at all.

Is it possible that this foaming action is taking place in other peoples cars - and causing intermittent low coolant lights. Is it also possible that the foaming is more pronounced under higher temperatures and pressures? Could something like this have led to Larry's engine failure?

Dave Witte
97PG 132K (Welded)

Under the circumstances I now face, I have an increased interest in this topic.

Thanks Dave.


>I read your write up on the site and was just wondering where you found a 5/16 hose barb with garden >hose shut off?

The 5/16" to hose shut off was cobbled together with pipe fittings.

Try this for a forced flush.


First off the easiest place to drain the system is at the tee on the lower radiator hose. There is a metal union there that will come apart (not easily the first time). You do not need to take the plastic air deflector off to do this. Drain old coolant into a 5 gallon bucket. Reconnect lower hose.

Remove the upper radiator hose at the water pump. Put the garden hose in the degasser tank at the radiator cap opening. Use a towel to semi seal the opening and turn on the water.

When you have flushed to your satisfaction reconnect all hoses and add a can of radiator flush. Drive the car around for 15 minutes and come back, drain and re-flush with the garden hose. At this time too flush the degasser tank good with the garden hose. Allow to drain, then reconnect the lower hose again and fill the system with distilled water. Run for 1-2 minutes the drain again.


Then push compressed air (Human powered is acceptable) down the small hose that goes from the degasser tank to the valley between the heads while having the radiator cap off. Reconnect the lower radiator hose and the small hose at the degasser tank. First pour in 6 quarts of straight antifreeze, then fill to the hot mark with distilled water (about 5 quarts). This should give you a 50/50 mixture with the distilled water that is left in the engine from the last flush. You may want to add 6.5 or 7 quarts straight antifreeze first if you want a stronger mixture.


No need to worry about air in the system as the degasser will very efficiently remove it. The level will drop an inch or so after filling and driving around.

Items needed:

2 channel locks 5 gallon bucket 2 gallons antifreeze 4 gallons of distilled water can of radiator flush

Paul Nimz
'97 TR
'93 EG mtx

Subject: Coolant Flush

Hey Paul, Iím just getting ready to do a coolant flush on my 96. I read your write up on the site and was just wondering where you found a 5/16 hose barb with garden hose shut off? I know itís optional, but it sounds like it would come in handy.

Also I notice recently some discussion of some radiator flush having maybe not been so good. Do you have a recommendation on that?

Thanks for the write up and all the help you offer.

Rich Larsen

For the record - I used a multi spray end on the garden hose ( red one - from Sears ) the "full action " setting on the dial just happened to accept the 5/16" hose .

Rick B


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