Pressure testing coolant system

[awolff280sl]

Is there a pressure tester that adapts to the coolant overfill tank (or somewhere else along the system) to pressure test the system for leaks in a 280sl?

[jameshoward]

Do you suspect a leak? The system is under quite a bit of pressure after the vehicle has been in operation for a while at normal temperature and if there was a leak, you should see it. Assuming your coolant has a good colour to it, look for changes in the colour of the metal veins on the radiator.

I have just re-cored my rad for several reasons not least because I snapped the drainage plug off the bottom. My post on the renewal is a few weeks old and a few pages back.

Bottom line is that the rad cannot really be tested on the car I would think. It isn't hard to remove (20 mins) just read my post first and the one that linked to. When my rad was tested in the shop I was quite surprised how little pressure they put it under to test it.

JH

[al_lieffring]

I have a pressure tester adapter that I made out of an old pressure cap. Another way that I have done this is to remove the hose from the tester pump and get a barbed hose fitting that fits in the tester, usualy 1/8 npt and attach it to one end of the 8mm hose from the radiator to the fill tank using a T fitting (5/16") and a short piece of hose.

Even though there is pressure in the system when the motor is warmed up, lots of coolant leaks won't show up unless the motor is tested cold. Leaky water pumps are prone to test OK hot but will leak when put under pressure cold.

Al Lieffring
66 230SL

[awolff280sl]

Not leaking yet, but it just might once I finish intalling a Frigiking A/C redo. I might want to pressure test it once I put it back together.

[jameshoward]

Al,

Thanks for the explanation. With my rudimentary physics (which goes as far as metals expanding when hot) I don't understand why leaks wouldn't show up when the engine is both hotter and under pressure, but your advice is good to have and something to look out for.

As for pressure testing before you put the rad back in (if it's out) I would have thought the easiest way to do it would be to take it to a local shop and have them blow air through it in a dip tank. That's how we found all my small leaks.

JH

[graphic66]

If the radiator is out of the car you can test it by attaching a bicycle inner tube over the inlet and outlet with clamps. You cut the tube, a mountain bike tube works best. A 2.00 X 26" works great. After cutting the tube put each end on and pump up the tube and put the radiator in water. You can also let it sit overnight if you just want to see if it leaks or not. Pump the tube right up so it balloons out. Soldering poked holes is very easy, corrosion is almost impossible, you can chase that around for some time.