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Help . . . My HPC has a temperature and a dreadful thirst . . .


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  • Area Representative

As a mechanical ignoramus, I throw myself open to the advisory mercies and the POBC . . .


Approx 100oC water temperature when engine hot.

No fan operation (fuse ok).

Cold feel to big bore pipes into and out of radiator until way past when they should be warm.

They warm eventually but I think that's diffusion of the heat from the engine side across, over time, rather than water movement.

Top of rad is too hot to touch for more than a few seconds.

No leaks from under car or around any water pipes as I can see, though I think I'll change to silicon when sorted again as not sure if current black rubber ones have ever been changed and look 'tired' at bends

Turn car off and water boils and pours into the overflow/reservoir, bubbling like a witch's cauldron on full boil. Quite scary to watch actually . . .

Some steam and liquid escapes from the cap when it's obviously fighting the full pressure cauldron effect..

Then when all has calmed down, the reservoir is bone dry, completely empty and with a brown residue . . . almost scale like from what I can see. Maybe radiator waste?

There's no creamy gunk under engine oil filler cap or on the dipstick which has normal oil colour to it, but don't know whether gunk absence definitely excludes head gasket?


As a recent owner, I can check a fuse, I can change a plug, but beyond that I'm clueless . . . any pointers most welcome.



Beryl the Yellow Peril (HPC)


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If it's actually boiling, that means it lost pressure somewhere ???


Check cap, although that won't explain pipes not getting hot, sounds like thermostat blocked (wot Ian said !), causing the cap to fail under pressure ??


Not that I'm an expert of course




Roadsport SV 1.6 Sigma 150

in Viper Blue here

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  • Area Representative



That's be brilliant. This club and its members and the friendship shown continue to amaze me.


Can you PM me your address and/or simple directions from Wolvey.

I know I can almost throw a stone there but not quite.

Also an idea of when you'll be working on yours.


If I fill Beryl's reservoir to brimming, then I take it that I'm okay to limp over with her as she is?



Beryl the Yellow Peril (HPC)


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Cheers guys.

Yet more reinforcement (as if I needed it) as to what a great club this is.

Went over to Guy's yesterday afternoon as per offer above.

He led and I assisted. Actually, more learned than assisted.

Best day I've spent with the car since having her, blats included (Thanks again Guy).

He said the VX was notorious for nasty airlocks, and so it proved to be thankfully just that.

Ramped her up as high as she'd go, took all hoses off, flushed system out, refitted, refilled and bled.

Also removed/ cleaned up oil pressure valve.

Checked fan switch/gauge.

Checked low oil pressure light on dash via oil pressure sender.

Didn't remove/check thermostat as (after all the above) the car is now running at 75oC on open road and 80oC on slowing/in town, with fan cutting in as and when necessary.


Only weird thing is the oil pressure reading still. At least having tested sender and warning light link means the worry about pressure has gone.

Light isn't and has never been on, but the gauge's lack of movement through rev range is strange.

2.5 bar on start up.

2.0 bar at idle (warm or cold)

2.5 bar on road (average speeds)

3.0 bar (just) at 6000 revs plus, when road tested for water temp etc after we'd finished.

Maybe change (or borrow one to test mine) a Caerbont 10 bar VX (1996) oil pressure sender?

I'd be interested in thoughts of the masses on this oil pressure issue.





Beryl the Yellow Peril (HPC)


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*thumbup* to Guy, well done...


Depends what actual checks were done on the pressure sender. If it was just checked to ensure that the warning light came on when the sender indicated a low pressure then this is still not a setup that I would be comfortable with. The electric senders on Seven oil pressure systems are notoriously unreliable (search archives for conformation!). The peace of mind after fitting a mechanical gauge is worth every penny of the minimal cost (can't remember exactly but below £100.00). I ran for 20+ years before I changed mine and now wish I had changed far sooner. A gauge that you are not 100% sure of is worthless in my opinion

I'm sure that Guy will help if you decide to bite the bullet 😬

(Or I will if he won't *smile*)

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Go for a mechanical oil pressure gauge. Only about £45 plus whatever adaptor you need at the engine end (maybe another fiver), plus postage. Blatmail 7ERRY (or send one to me if you can't find him on here) *thumbup*


Doesn't cost much more than a new electrical sender, and will easily outlast it !!!!



Edited by - Stationary M25 Traveller on 12 Apr 2009 19:48:12

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Having spent a few hours with Giles's car yesterday it seems likely that the oil pressure sender is faulty. As others have said they are unreliable. However I don't have a full multimeter at home so could not test the resistance change and had no spare to try. I can 'borrow' a calibrated gauge for next week end to check for sure.


The oil pressure light switch is a seperate unit and does work so gives some confidence. All other signs are that oil pressure is OK. Releif valve checked and cleaned, plently of oil splashing around the rocker cover, and after a hard blat no sound of rattling tappets. BUT with out another sender or alternate gauge to check with I am still nervous. I think Giles is going to visit a friend with a workshop who should be able to test it.


Any other means of indicating low oil pressure?



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