cause for concern?

[andymadmak]

last night I was putting my 400se away after a short run and it did someting it's never done before: there was a large puff of steam from under the bonnet and a strong smell of coolant. It stopped very quickly and a quick gander revealed that the top of the expansion tank was wet (on the outside) so clearly there had been a bit of a blow off there. The temp gauge had gone a touch higher than it normally does at the point of blow off too.(oo err missus)
The point is, in five years and despite running in some VERY hot ambient temperatures it's never done this before.
Is it just "one of thos things" or a sign of something on the way out?

Andy 400se

[rev-erend]

Andy - I've heard of this before.

It's just a sign that the car needs a dam good
clear out - of course I will volunteer....

Seriously - I don't think the expansion tank is
sealed well or pressurised.

Nothing to worry about just keep an eye on it.

But I would recommend giving it a damm good thrashing
this weekend.

I'm gonna give mine a quick run down the mulsanne
straight tomorrow, followed by Indianapolis then arnage... can't wait.

[jmorgan]

I take it you have no tube to carry excess away? I'd keep an eye on it. Are you having to top up the coolant often (assuming not as you say this has just started)?

[andymadmak]

I do have a tube connected to a little ancillary container at the side. Its just that this stuff came out from round the cap, almost as if it was an explosive decompression. Haven't had to add water for a couple of years. Dry as a nut in fact!
I'll keep and eye and see what happens - oh and give it a darn good thrashing this weekend as per Revs instructions !

Andy 400se

[andymadmak]

well, I gave it a damne good thrash this weekend and there has been no repeat performance. All seems well in fact.
The only difference I can now see is that I reckon my oil pressure is a tad lower. At 2000rpm I get 25psi on the guage, rising to 40psi at 3000rpm. It used to read 25psi at 1800rpm and 40psi at 2750 (ish).
Just had oil change, and its up to the mark. Not using any either in normal use (Used about 1 litre on my 1200 mile high speed le mans Odyssey)

Does any one get radically different readings to this?

Andy 400se

[danny hoffman]

I would guess that the pressure differences are due to the oil change - I always see slight differens when I change mine for a few hundred miles.

What oil are you using?

Danny

[2 sheds]

Oil pressure change probably down to different grade of oil ?
The sudden burst of steam could be down to seized pressure cap suddenly releasing.
Tim

[andymadmak]

Using Castrol GTX2 (as recommended by RT racing) Grade is the same as last used ( 15w 40 I think, from memory)

Was just wondering what oil pressure guage readings you other wedge boys get?

Andy 400se

[jmorgan]

Sorry for the delay but up the scale at between 25 and 50. The gauge is reading low so a bit higher is to be had. Thats at normal running around 2500 revs.

[hiway86]

I bought a beater and am trying to get roadworthy. My '86 280i reads a max of 25-30, down to nearly 0 at idle.Does this mean a bad oil pump? I put rebuilt heads on 3000 mi. ago and get a puff of smoke at start up occasionally. Are valve guides wearing due to top end starving for oil?

[mrcrappy]

when you had the oil change the garage didnt fill the rad for you did they, mine runs perfectly if the expantion tank is below half full, any more than that and it gurgles and leaks out.

[wedg1e]

hiway86 said:

I bought a beater and am trying to get roadworthy. My '86 280i reads a max of 25-30, down to nearly 0 at idle.Does this mean a bad oil pump? I put rebuilt heads on 3000 mi. ago and get a puff of smoke at start up occasionally. Are valve guides wearing due to top end starving for oil?

Could be just that the valve stem seals are tired - it is 17 years old after all! Depends on the mileage as well: my 100,000 mile 2.8 never had very good oil pressure, but she went OK and didn't smoke. Bear in mind as well that TVR mated Italian (or US!) instruments to a German pressure transducer - mucho potential for calibration errors...

Ian

[hiway86]

The rebuilt heads were machined for unleaded with new valve guides.3,000 mi. ago. Got 'em shipped here from Ferraday Engineering, The Workshop, in Stafford. Good folks there. Original heads were both cracked (maybe due to excessive heat, lack of oil pressure?). I guess I should check the pressure coming into the sending unit before I panic.

>> Edited by hiway86 on Monday 7th July 03:02

[Podie]

Mate of mine had this on his Marcos... he was told that it was becuase the engine was hot and he'd turned it off, before the fan was allowed to cut in... something like that..