Thread: Radiator expansion tank: Alert!

Originally Posted by Wasa57

2000 td5 sls auto ace

While fitting a new coolant expansion tank cap a few days ago, noticed
a stream of coolant out of the overflow pipe as the engine warmed. Hmmm...hadn't noticed that before...
Later, as the engine cooled, could hear a popping sound. Next days after short drive, a check revealed coolant level had dropped by about 1cm. Not good.

The culprit was a pin hole in the neck of the filling chamber, directly where the radiator output pipe enters the inlet chamber, on the inside.
This area happens to coincide with the overflow hole / ring in the filler cap, so the result was instead of flowing into the expansion chamber, the coolant was directed out through the cap and the overflow pipe.

Obviously the usual syphoning effect of cooling fluid in the radiator which draws coolant back from the reservoir was negated by the pinhole (hence the popping sound!)
So, a pinhole in the filler neck left undiscovered may have led to an overheated head, a breakdown (potentially out the back of beyond) and many $$$ in repairs. Have just ordered a new expansion chamber, and thinking seriously about an "engine saver."

Thanks for info. If nothing else - don't "think seriously" - just do it. It's cheap insurance and you have a number of options/prices.

Scuse my ignorance in this one... Having just forked out enough cash to get my disco lifted, new rims n tyres on it and some other stuff getting a changeover motor put in after the old one overheating I'm very interested in what you guys are talking about with the engine saver....

There are a number of threads in this forum.

Dave sells one which regularly appears at the top of the page,- go to the "shop" above or see
Dave's Interesting Things

There is also the South African Madman EMS which incorprates a temp gauge and a low coolant alarm - I saw this morning that TheEntertainer an AULRO member on this forum is a seller.

Se also ENGINE WATCHDOG TM2, Engine Temperature Sensor and Low Coolant Alarm

There are others which I'm sure members can add to

Happy hunting

Thanks - I was looking into getting an Ultragauge which does a whole lot of things, but I don't think has the low water alarm specifically like Dave's unit.. more to think about!!

Originally Posted by Wasa57

The culprit was a pin hole in the neck of the filling chamber, directly where the radiator output pipe enters the inlet chamber, on the inside.
This area happens to coincide with the overflow hole / ring in the filler cap,

That's not a fault. I'm pretty sure that's part of the reservoir design if it is the same tank as use on the P38A (I think it is). My previous tank had it and so does my present tank. I have another spare in the garage, I'll check it.

Hmm, can't find it.

P.S. I used to live in Carnarvon in 1971-72. I worked as a tech officer at the OTC Satellite Earth Station and my wife worked down the road at the NASA Tracking Station doing solar photography.

Originally Posted by p38arover

That's not a fault. I'm pretty sure that's part of the reservoir design if it is the same tank as use on the P38A (I think it is). My previous tank had it and so does my present tank. I have another spare in the garage, I'll check it.

Hmm, can't find it.

P.S. I used to live in Carnarvon in 1971-72. I worked as a tech officer at the OTC Satellite Earth Station and my wife worked down the road at the NASA Tracking Station doing solar photography.

Thanks, it's back to the drawing board for me if the hole is normal. The level has only been dropping since I fitted a new cap a few days ago...the
new cap is identical, and I only bought it because the O-rings on the old one were flattened.

The Big Dish, Sugar Scoop, and a few other bits are preserved up on Brown's Range, with restorative work ongoing towards a museum etc.