350i 1987

350i 1987

Author
Discussion

tcpc

Original Poster:

166 posts

269 months

Wednesday 12th February 2003
quotequote all
hello,

about a minute or so after coming off the motorway today some off my coolent decided to leave via the small plastic tank which is next to my expantion tank,
can anyone tell me what the p.s.i should be in the tank,

the temp gauge was normal and there did not seem to be any warning before in happend,

got home ok and topped up coolent level and let the car idle for 20mins or so and did'nt over heat and the fan cut in and out, all seems to be ok,

i was thinking that the expantion tank cap might need to be replaced,

has this happend to any off you guys and how did you get round it, i am hoping that renewing the cap gets me out off trouble.

when filling up the coolent should it be from the blanking cap or from the expantion tank

thank you

Tony

bobfrance

1,323 posts

278 months

Thursday 13th February 2003
quotequote all
Mine has done this once or twice.

If you had recently filled up with coolant then it could just be excess fluid being expelled as it heats up.

It's well worth replacing the cap (with the correct one of course)for what it costs.
But first make sure that it is seated properly (ie make sure there's no crap around the neck of the tank and inside the cap),as a poor seal could cause it to bleed out.

To top up coolant levels I usually remove both caps turn the heater to the hot setting to prevent air locks, then fill from cap near the nose of the car (not the expansion tank).
It can be a slow process as you keep topping it up but be patient.
Once filled I usually turn over the engine for a few minutes to pump the water around and hopefully prevent any airlocks, then replace the caps.
Once warm it always pushes out a little coolant.

Are you sure that your temp guage is accurate?

A cylinder head gasket (one only slightly gone) could cause the cooling system to become pressurised, but this is unlikely, so best to rule out the cheap stuff first.

tcpc

Original Poster:

166 posts

269 months

Thursday 13th February 2003
quotequote all
thanks for your reply Bobfrance

i thought the cooling system was a pressuried one,

i got two new caps today and all seems to be ok, the old ones were well past there sell by date.


Tony

bobfrance

1,323 posts

278 months

Friday 14th February 2003
quotequote all

tcpc said:
i thought the cooling system was a pressuried one,

It is, I just meant over pressurised.

Anyway, sounds like you've sorted it.
Nothing better than a cheap fix

Happy motoring!

Brm Brm

217 posts

285 months

Friday 14th February 2003
quotequote all
..........and the pressure cap rating should be 15lb if I remember rightly. Hope you have no more problems!

tcpc

Original Poster:

166 posts

269 months

Friday 14th February 2003
quotequote all
verything still seems to be ok