aggravation

I have a slight leak in what I think is the passenger side end tank. It could be in a hose though, I haven't taken the time to locate it because it's very small and only seems to leak while driving.
For example, I've driven the car twice, around 20 miles each trip, since last adding any coolant to the tank. right now it's about two inches below the line of the reservoir. That's how little it leaks, when it's parked it doesn't seem to leak at all.

My question is, if I'm driving along, say worse case scenario, at highway speeds, coolant temp at 195 degrees and it suddenly develops into a big gushing leak will I be able to pull over and stop before damage is done to the engine?

I'm in the middle of other repairs and due to the cost of replacement radiators and/or the hit and miss of finding a qualified shop to do the end tank repair, I'm hoping to just add the 3/4's of a quart of coolant it needs every other use for a while until I'm ready to find and fix the leak. Am I making a bad gamble doing that?

heinrich

you need to fix it. Can end up with a big flow and strand you or mix coolant and oil in the engine

Garth S

As a temporary measure, back off the rad/expansion tank cap so there is no back pressure on the cooling system - this will reduce any leak by 90% or more: monitor the temperature ( and coolant level), but it should not be a problem even in SC this time of year.
When ready to diagnose, obviously start with the hose connections - then if no leak evident, make/borrow/buy a pressure tester,clamp it to the expansion tank, and the leak will appear ....

aggravation

On the mixing oil and coolant point. Would that be by overheating and having coolant pass through a gasket due to the overheating conditions? Or is there some other scenario that can cause this event?
I'm probably asking a dumb question but I'm just not that experienced with the workings of combustion engines and automobiles in general so I want to make sure I'm not ignorant of some other fundamental potential failure regarding the cooling system that I should know about!

Mrmerlin

hey Agg, the end tank seal is probably the culprit you can drive the car but as stated let the cap off to the first notch you dont really have any worries about then oil mixing with the coolant unless the internal tank ruptures just make sure you carry a spare jug of coolant with you , to fix thei you need a new pass side end tank and seal, find a shop that can work on the plastic end tanks the rad has to be compressed to make the seal work and you generally only have once chance at end tank replacment

aggravation

Thanks! You gave me an idea.
I have an ultrasonic leak detector I use sometimes on refrigeration equipment. It can hear a mosquito fart at twenty yards! I bet if I drive it with the cap in place for a few minutes the pressure it develops will create enough of a hissing sound to narrow down the location since it seems to be kind of high on the end tank where I see moisture collect maybe it is the hose connection...it would be nice to be that lucky for a change!

Mrmerlin

another way to see if your tank is getting ready to go is to look at it and compare it to the left side if it looks swollen on its sides then it is probably ready for replacement , but it would be great if it was just a hose connection

heinrich

What I'm saying is a failing tank will not stop, it will continue failing till you have a bigger failure. The coolers in the end tanks do not like any physical movement, and a tank that is expanding/warping/breaking can easily kill the seal/weld between oil and water.

aggravation

Is there an oil cooler circuit in the radiator that can be exposed to coolant by way of end tank failure?!?

heinrich

yes.

Bill Ball

Classic sidetank failure is a crack near the base of the upper hose connector on the passenger side or a gasket leak. If you are losing 3/4th of a quart every time you drive 20 miles, that is a substantial leak. You might not be able to see the source, but it will wet that are and spray on the engine and inner fender on that side.

Taking the radiator out on thse cars is one of the simplest procedures there is. Find a radiator shop that works on Behr radiators with plastic sidetanks and they will pressure test the radiator. They will have no trouble finding the leak. However, the sidetank is not available to them through their suppliers. 928Intl has them.

SharkSkin

If you're adding coolant, you can get by for a short while. I had a slow leak from the WP seal, and went for a couple weeks just topping up with water, about a quart per day. Within a couple of weeks, when I got around to the TB/WP, the impeller had a thin layer of rust on it. YMMV. If I had it to do over again, I'd add coolant one day and water the next or add mixed coolant. Yes, having the rad cap loose helped, but I was only doing short trips.