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header tank lack of coolant

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raw
Posts: 48
Joined: Wed Aug 17, 2016 7:54 pm

header tank lack of coolant

Post by raw »

h aving the problem of header tank lack of water after a journey I decided to blank of the gap between the rad and top of the grp top panel resulting in a marked temp difference I then fitted a catchment bottle to the rad bolts beneath the header tank thinking at last problem sorted alas a journey of 20 mile on sunday upon opening the bonnet revealed anti freeze all over the rad top right hand corner blowing from underneath the header tank pressure cap the two rubber type of cap and still revealing no water in top tank . at a loss now what to try next ?

PatrickDixon
Posts: 67
Joined: Sun Mar 20, 2016 7:59 pm
Location: Gloucestershire UK

Re: header tank lack of coolant

Post by PatrickDixon »

A new radiator cap.

Vortex O'Plinth
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Re: header tank lack of coolant

Post by Vortex O'Plinth »

PatrickDixon wrote:A new radiator cap.
This would seem the obvious solution. Are you sure the cap is contacting properly on the lower seal. I've made the same mod to the cooling system and initially I bought a short reach (25mm) 7 lbf. double sealed recovery cap as that appeared to match the filler on the header tank. On fitting it was obvious that although sealing at the top, the spring was not being compressed so the lower seal wasn't contacting. I replaced it with a long reach version (35mm) and it's working fine.
Nick

"Don't bother with the Air & Space Museum - there's nothing to see.......".

Ian Slade
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Re: header tank lack of coolant

Post by Ian Slade »

Use a plain sealing cap on the header tank, take the overflow to a second header tank with a 7psi cap, fill at the header tank until the second tank is half full, then cap both, the relief pressure is only 1-2 psi which isn't much, so possibly may be relieving early. The SP was renowned for emptying the header, normally the level was at the bottom of the tank but one always topped it up a bit to see how far it had dropped
Owner since the 70's, Genghis is slightly to my left.

Dragon
Posts: 89
Joined: Wed Mar 02, 2016 12:14 pm
Location: Goodrich,between Ross-on-Wye and Monmouth, UK.

Re: header tank lack of coolant

Post by Dragon »

Nick (Vortex) has the most likely answer.
Pressure caps of 7psi release pressure are made in long-reach and short-reach. Triumph cars used short-reach and there are more Triumphs about than SPs, so possibly the short-reach are more easy to find than the long-reach.
The SP250's header tank is made for the long-reach cap, and a short-reach won't even touch it's sealing ring.
Reminds me of the DLOC International Rally at Warwick in 2004. A couple had driven their SP from some distance to the North, and had severe loss of coolant and overheating. The cause was exactly this, they had fitted a new pressure cap but it was the short type, not the long.
Wilf,
SP250 104008, Herefordshire.

Ian Slade
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Re: header tank lack of coolant

Post by Ian Slade »

Wilf, if you use a modern secondary tank, all you need is is the same cap as fitted to the secondary tank to the SP spec. irrespective of whether or not the correct length of cap is fitted the SP loses water, the short cap loses too much water, it's really a case of confidence that you haven't lost too much with the correct cap
Owner since the 70's, Genghis is slightly to my left.

Josef Eckert
Posts: 86
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Location: Königswinter/Germany

Re: header tank lack of coolant

Post by Josef Eckert »

Could be a blown head gasket?

Ian Slade
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Re: header tank lack of coolant

Post by Ian Slade »

Unlikely Josef, blown head gaskets result in overheating, this is just blowing out water due to normal pressure, looses about a 1.5 pints and stays there
Owner since the 70's, Genghis is slightly to my left.

Bud
Posts: 318
Joined: Fri Feb 12, 2016 9:06 pm
Location: Rochester, NY

Re: header tank lack of coolant

Post by Bud »

See the final Leno video SP blog with his comments about short reach caps and boiling away problems at the end of the clip. Anyone can unknowingly take something apparently so simple for granted.

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