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Thermostatic Switch springs a leak!


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Completed the fitting of my new SPAL electric 'pull' fan tonight. Looks great. To trigger the fan I've fitted a stainless bottom coolant hose complete with thermostatic switch. Unfortunately, once I filled the system with coolant there was a small but steady leak (big drips) from between the brass housing of the switch and the aluminium washer it was supplied with. I initially thought there was a spec of grit between the two surfaces because it was so localised despite my tightening the assembly enthusiastically! Needless to say I've removed the pipe and switch and cleaned all of the surfaces.

 

My question is, in addition to the aluminium washer what else can I do to ensure a leak-free performance from between all of the matin surfaces of the pipe, washer and switch housing. Some kind of paste, sealant or different washer material perhaps?

 

Grateful for your thoughts.

 

Dave

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Dave, I wonder if you have over tightened the switch in the bung and now the crush washer is no longer sealing ?. Try a new washer and less enthusiasm the next time you tighten it. I would hesitate to use teflon tape on the thread as that may work temporarily but mask the real problem until the joint is under pressure and hot.

 

Stan

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If the leak is between the ally washer and bung, then it's possible the bung has warped when it's been welded meaning the mating surfaces are not flat.

Test with a steel rule or straight edge.

If it's warped then it's up to you. Personally I'd send it back asking for one that's not warped..But if you want to then either use a fibre washer (red type) or you could lap the surface of the bung using a flat surface and some fine wet and dry.

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Hi Dave

 

If you find it is warped, you could try doubling up on the washers first before waiting for a replacement pipe.

 

Brass is soft and cracks easily, fingers crossed that never happened when you tightened things together???

 

If all the above/previous suggestions are exhausted and it still leaks, I'll pop round with some of this http://www.ebay.co.uk/itm/40618655-Loctite-234546-/192143241820?hash=item2cbca1325c:g:yUoAAOSwzgBY28Vt , it's a fantastic thread sealant, hence the price.

 

Richard.

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Much appreciated to get good feedback from TR owners around the World!

 

I'll check for flatness of the mating surfaces and try a new/red washer if all looks okay. Fingers crossed.

 

All the best you guys,

 

Dave

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Richard.

 

That's very kind. I'll get new washers this morning and let you know how I get on. I'm desperate to get the car on the road for next Sunday's Drive It Day. We're off to the Lanark Rural Villiage if it ever stops raining!!

 

Dave

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Andrew

 

Just to let you know that you were spot on; the bung is slightly warped and failed the 'flat-edge' test. Also the welding had nibbled away at the circumference of the bung in two places leaving small traces of weld splatter across the face where the aluminium washer sits ......... or rather it doesn't.

 

I can't imagine I'll get an acceptably flat surface if I filed it, so it's a phone'call to Rimmers tomorrow to discuss quality control and get a replacement. Maybe they'll refund me for the lost coolant too: that's why I don't use Evans Waterless.

 

Thanks for the guidance.

 

Dave

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Hope you have more luck than I had. All I got was "we've sold loads of these and never had a problem reported."

Think they're closed until Tuesday.

Alan.

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Richard.

Uncanny. I took your advice and went down the fibre washer route but first, and against my better judgment, carefully filed and polished (with 'wet & dry') the offending, flat surfaces including that of the aluminium washer. I'll fit it all after work tomorrow and see if there's any improvement. It certainly won't be any worse. ????

Dave

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Hi guys

 

I had a very similar problem a few years back when fitting a SS rad pipe with a thermo switch boss ( although admittedly the supplier wasn't Rimmers) and it looked like the weep was coming from the joint between the boss and the thermo switch, but it turned out that the welding of the boss to the pipe was not 100% watertight - a quick reweld sorted it.

 

Bearing in mind it looked like the original weld of the boss to the pipe ( both S/Steel) was done in ordinary steel, not stainless, I felt confident of having a go myself - no problems since touch wood!

 

cheers

 

Rich

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