Oil pressure on start up

Partly_dave · Post by **Partly_dave** » Mon Dec 17, 2007 1:59 pm

On starting, my oil pressure light remains on briefly. After a few seconds there is a whirring noise from beneath the Bongo (that reminds me of a washing maching starting up its spin cycle) a few more noises and the oil pressure light goes off. It does this everytime from cold, but is worse now the weather is so cold. Am I right in guessing this washing maching sound is indeed something starting to spin up, like a belt driven oil pump? Will it need attention?

I would add that when starting from cold I never drive off straight away. I start it and leave it idling for a while. That is deliberate, as its an old engine and there's always important things to see too, like plugging in my ipod before I set off.

Oil pressure light never comes on again after the starting proceedure.

Bong needs a service (3k miles since last done in June) so will new/clean oil help? It's getting serviced this wednesday.

I always start without any throttle, having waited for glow plug light to go out. I know the book recommends some gas be applied before starting but the van really didnt to like it when I tried doing it that way - a lot of noise and vibration.

Any thoughts?

D

Veg_Ian · Post by **Veg_Ian** » Mon Dec 17, 2007 2:24 pm

Oil pressure light - I think the recent entry in the Bongo clinic addresses this. As with many Japanese OEM filters they come with a valve so that oil remains in the filter after switching off. The majority of after market filters don't have this so it takes a couple of seconds for the circulating oil to fill the filter and extinguish the oil light ie. back up to pressure. It does it on my Bongo and my MR2.

As for applying throttle - is yours a petrol V6? You shouldn't need to blip the accelerator as the autochoke should take care of that. If diesel then no definitely not.

francophile1947 · Post by **francophile1947** » Mon Dec 17, 2007 2:29 pm

Hi Partly_dave
It sounds like you may have a faulty oil filter that is letting the oil drain whilst it's standing with engine off. The pump is having to fill the filter before the pressure builds up enough to extinguish the light.
Has it always done this, or just since the last service?

Ralph · Post by **Ralph** » Mon Dec 17, 2007 2:29 pm

Ours a Diesel goes off as soon as it starts no noise nothing.

Partly_dave · Post by **Partly_dave** » Mon Dec 17, 2007 2:36 pm

Thanks all - I've just checked the clinic too and this does seem to mirror the problem I'm having. The dealer doing the service is the one who sold it to me and so should know to use the right filter. I'll check with them on Wednesday.

dandywarhol · Post by **dandywarhol** » Mon Dec 17, 2007 8:15 pm

I posted a similar question a while back - mine rattles a bit when it's warm until the light goes out (3 seconds) but it's a light rattle like hydraulic tappets, only I know it doesn't have hydraulic lifters

Can't really think what's rattling unless the balance shafts are chain driven and have a pressure tensioner

Talking nonsense - just checked lushprojects - the balance shafts are gear driven

bigdaddycain · Post by **bigdaddycain** » Mon Dec 17, 2007 9:19 pm

Yip, a couple of seconds before the oil light is extinguished here too ....no funny noises though

Ralph · Post by **Ralph** » Wed Dec 19, 2007 11:32 am

Been watching ours on the last few start ups and it takes
maybe half a second to go out, had a Rover a few years
back that took about 5 secs felt like forever but it did
100,000 miles plus and was just the same so probably
nothing to worry about.

johnzbenson · Post by **johnzbenson** » Thu Dec 20, 2007 3:46 pm

As you can se this has been aconcern for Bongo owners for some time (see thread) http://www.igmaynard.co.uk/bongo/forum/ ... highlight=
Essentially the comments about the oil making it up to pressure can take up to 3 seconds when started when cold. i have changed filters to no avail. I make sure the oil is at the top level at all times and still have the 3 second delay (and slight change in engine tone) and this has been the case for over a year- or 10,000 miles. It seems ok- perhaps an oil like magnetech could allay any concerns . my Bongo is on semi synthetic btw.

mikeonb4c · Post by **mikeonb4c** » Thu Dec 20, 2007 4:13 pm

My Spacewagon used to have a delay. Went for 5+ years with no trouble at all.

Hooligan · Post by **Hooligan** » Mon Dec 24, 2007 8:20 pm

Can I ask what oil people are using??..... it may be related to that.

I, like many owners on here, now have the 3 second delay.... but only since changing oil & filter recently.

Having read the posts it would seem not to be the filter, could it be the oil??

I couldn't find 10W/30 so used 10W/40 semi-synthetic as per the recommendations on this site. (Halfrauds own to be exact)

I previously owned a Ford that was VERY fussy about which oil viscosity and type was used... the hydraulic tappets hated anything but fully synthetic.

Thoughts??

Ralph · Post by **Ralph** » Mon Dec 24, 2007 9:38 pm

I use Total 10 40 semi synth and the light is out in maybe
half a sec, I seem to remember but am not certain on this,
that Halfords oil was not the best but cant remember were
I saw it, but in all honesty don't believe it's the oil, did your
old filter have any kind of valve to stop the oil draining
back into the sump, if the filter was partly emptying the
oil pump would have to refill it before pressure came up,
it needs about 7psi ish to turn off the light as far as I know.

BongoMTBer · Post by **BongoMTBer** » Mon Dec 24, 2007 10:06 pm

This is always going to be more of an issue in the colder weather as it takes longer for the more viscous oil to be sucked up the pipe to the pump to enable it to start developing enough pressure to evercome the px. sw. The pump does not pump particularly well when drawing air (empty oil pipe) especially if it is part worn. Once the oil gets between the grears in the pump it will work to the required output levels no problem. So long as it does go out after a few seconds don't worry.

There is normally plenty of capaicty within the oil systems design for a part worn pump. If you have a pressure gauge attached you would notice that when the oil is up to running temperature, the pressure will not reach max working pressure until the engine is above 1500 rpm, even on a new engine. I think my Merc specced 1.2 bar by 1500 RPM. However I would imagine it would probably rise to around 3 bar by about 2000 RPM when the pressure relief valve will come into play and return excess flow to the sump to prevent over-oiling of the engines top end at higher revs.

This low pressure at low revs is why you should never labour a normal car or van engine below 1500 RPM. The bearings rely on the higher pressure under higher loads to produce a surface tension on the oil leading to 'hydrodynamic lubrication' where metal to meatal contact should not take place at all. At lower engine speeds and hence lower oil pressure, the film separating the moving surfaces is very thin, with only the thickness of one molecule. This is called 'boundary-layer lubrication'. With this condition, friction losses increase which produces localised heat, which raises the temperature of the lubricant, thereby reducing its viscosity. The load-carrying capacity of the film is then further lowered. In the worst case, the surfaces can even seize together causing rapid wear of bearing shells.

Oil pressure on start up

Oil pressure on start up

Oil pressure lamp time taken to extinguish