Anyone made a cooling system pressure tester? Were could I get a gauge for 0-10 psi. I'm thinking of splicing a T into the expansion tank line rather than messing with the cap.

I did exactly this and used a length of tubing to connect the tee to a "turbo" gauge salvaged from a 240 Turbo. It was interesting to see that the first thing to happen after a cold start was that the pressure gauge started to move up well before the temp gauge did. I recall that it levelled off at about 6-7psi (75kPa = 11psi cap).

Another aspect was to see how long it took for pressure to decline to ambient after a hot shutdown. A looong time, ie: no leaks in the cooling system.

I removed the whole issue after a few months, as there were no signs of anything wrong and it just added potential leak points.

I also made up a system pressure tester using an old 0-30psi gauge, a bicycle pump and two short pieces of rubber tubing. One piece of tbg had the gauge clamped into one end and the other end clamped over the little upper bleed nipple on the radiator. The other piece clamped onto the corresponding nipple on the expansion tank, with a Schrader tire valve on its other end. Pump until the cap starts to vent and check the reading. Then watch to see if pressure bleeds off more than about 1 psi per minute, and if coolant appears at suspected leak points, etc.
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Bob: son's 81-GL, dtr's '94-940, my 83-DL, 89-745(V8) and 98-S90. Also 77-MGB and some old motorcycles.

Yes, a tire valve and bicycle pump was a thought.

Volvodad,


I first installed the gauge to test a theory. I surmised that if the cooling pressure rised beyond normal, then the engine was running hot. In other words, pressure was directly related to coolant temperature.

What I found was a high rest pressure (cap vent) and a variation in cooling system pressure with engine vacuum.

Removal of the cylinder head gasket reveled a compromised fire ring and damaged casting. This was the large cooling passage cylinder head. Replacement of the cylinder head and gasket brought pressures to normal.


Goatman

81,


Been there done that. Ashcroft gauges on eBay. Pictures tommorrow.


Goatman