Oil pressure drop at 80mph

Oil pressure drop at 80mph

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midas dude

Original Poster:

213 posts

214 months

Tuesday 13th February 2007
quotequote all

Any ideas why this maybe?
At75 pressure shows approx 32psi,(2800 revs)accelerate even gently to 80 and pressure starts to drop away rapidly.Foot off throttle and pressure rises.
Any explanations most welcome,thanks,AL
96 ,450

.Mark

11,104 posts

275 months

Tuesday 13th February 2007
quotequote all
Does it always do it?

Mine did it once and it scared the poop out of me yikes

Was cruising along, put my foot down to pass something and the pressure fell, pretty quickly backed off ready to kill the engine when the pressure came back! A bit of experimenting showed it happenend consistently, I came off at a slip road and all was back to normal. Most odd.

This was about 2 years ago so pretty confident it was a one-off.

midas dude

Original Poster:

213 posts

214 months

Tuesday 13th February 2007
quotequote all

It started on a recent trip to Norfolk,then on the next trip to Potters Bar.Oil levels are fine.
Having work done just prior to service,but would prefer this sorted now.

midas dude

Original Poster:

213 posts

214 months

Tuesday 13th February 2007
quotequote all

Mark,did you trace what the problem was eventually,or does your pressure still drop?

GreenV8S

30,150 posts

283 months

Tuesday 13th February 2007
quotequote all
Check the oil level, if that's OK try gently wriggling the loom to the pressure sender and see if you have a broken wire, faulty sender or poor connection in there.

midas dude

Original Poster:

213 posts

214 months

Tuesday 13th February 2007
quotequote all

Will give those a try,but how would that explain the problem only as the speed hits 80?
Thanks V8S,AL

.Mark

11,104 posts

275 months

Tuesday 13th February 2007
quotequote all
midas dude said:

Mark,did you trace what the problem was eventually,or does your pressure still drop?


Never did trace it, it did it once and that was it - oil levels were good, engine temp was fine.

Not a sign of it ever again - not much help to you I know.

Chimjunkie

2,879 posts

210 months

Tuesday 13th February 2007
quotequote all
This is obviously a very effective speed limiting device!

I would attach a multimeter directly to the sender and view the reading at various speeds with loom disconnected. Then see if a drop is noticed. At least this will indicate if an electrical gremlin...

Jon

Edited by Chimjunkie on Tuesday 13th February 21:42

midas dude

Original Poster:

213 posts

214 months

Tuesday 13th February 2007
quotequote all

Your right Chimjunkie,effective too.

slikk

2,135 posts

242 months

Tuesday 13th February 2007
quotequote all
Its possibly one of these two things:
1. The oil pickup pipe has worked loose on its bolts and is not allowing oil up to the pump, or
2. (And this happened to me) A piece of the silicon sealant used as a sump gasket found its way into the strainer on the pickup pipe. The oil pressure was normal until i accelerated and this would subsequently suck the silicon up against the strainer and starve the pump.

FYI, removing the sump takes less than an hour.

HTH

Kim

midas dude

Original Poster:

213 posts

214 months

Tuesday 13th February 2007
quotequote all

Cheers Slikk,will look into these tomorrow,Al

ekim

233 posts

208 months

Wednesday 14th February 2007
quotequote all
Mine has started to do this from time to time, when i was on the run to garstang on the sunday just gone mine was reading lower than normal at higher speeds yet the temp and levels were fine but the next day all was as normal again. Most strange.
Does anyone know what the correct pressure readings should be when the car is at running temp?

pullingpower

260 posts

233 months

Friday 2nd March 2007
quotequote all
Bump,
I have a similar problem.Pressure usully fine on start up and when I start driving. It is only after engine warm and I start to press on that pressure will rapidly drop to below the 0 level on accelerationeek, sometimes even just lightly touching the accelerator can cause a drop. It can be intermittent. It is worrying when the pressure drops on accelerating as I would think that a loose connector would cause pressure always to read low or zero rather than just on acceleration. Again it tends to be at higher speeds normally.
Does anyone know what happens, or have you found an answer yet midas dude as I would be inetrested to know what you found.
Cheers, Mike

spend

12,581 posts

250 months

Friday 2nd March 2007
quotequote all
You should have a working oil pressure light (from pressure switch nitthe sender) which will flash if pressure drops below 10-5 psi (IIRC I'm no manual nerd). If your gauge reads below this and the light stays off, simply your gauge/sender is at fault somewhere. Sphincter moments are only neccessary when the red light comes on!.

Dave

midas dude

Original Poster:

213 posts

214 months

Friday 2nd March 2007
quotequote all

Cant say for certain,but my mechanic is of the opinion its the oil pressure spring,wont know for sure till next week.(when replaced)
Will be able to update then if you wish?
(front end being painted,pick up next weekend)

pullingpower

260 posts

233 months

Friday 2nd March 2007
quotequote all
Yes, I would have though negative or zero pressure reading would mean engine pulp all over the road and end of chim as I know it but it is annoying. I wonder with it being intermittent, could it be oil starvation due to lack of flow to the pump?

ubernoober

534 posts

209 months

Friday 2nd March 2007
quotequote all
spend said:
You should have a working oil pressure light (from pressure switch nitthe sender) which will flash if pressure drops below 10-5 psi (IIRC I'm no manual nerd). If your gauge reads below this and the light stays off, simply your gauge/sender is at fault somewhere. Sphincter moments are only neccessary when the red light comes on!.

Dave


This is my take too. I see my pressure drop to zero (no red oil light) at any time, just seems to drop away gently, stick around zero for a few seconds then gently come back up - like the pointer's feeling a bit weary for a while. Funnily this has only happened since I've been driving in cold weather with the heater on. Oil levels are good (just had a 48k service at Fernies). Have to wait and see if it goes away in the warmer weather.

TVR Thunder

270 posts

227 months

Saturday 3rd March 2007
quotequote all
I had this problem last year, traced it to the oil pressure switch connector, clean it completely and re-attach. ensure the contact is sound. no problem since.

Ian.

spend

12,581 posts

250 months

Saturday 3rd March 2007
quotequote all
TVR Thunder said:
I had this problem last year, traced it to the oil pressure switch connector, clean it completely and re-attach. ensure the contact is sound. no problem since.

Ian.


I'm a little confused, did you mean the oil pressure sender (the thing that activates the gauge, oil pressure switch is what it says ~ it turns the light on).

Dave

GreenV8S

30,150 posts

283 months

Saturday 3rd March 2007
quotequote all
spend said:
You should have a working oil pressure light (from pressure switch nitthe sender) which will flash if pressure drops below 10-5 psi (IIRC I'm no manual nerd). If your gauge reads below this and the light stays off, simply your gauge/sender is at fault somewhere. Sphincter moments are only neccessary when the red light comes on!.

Dave


However, do make sure you know which is the oil pressure warning light, and that it does actually work, before you use it as evidence of oil pressure. It's easy o confuse it with the no-charge warning light. The oil pressure warning light and no charge warning lights should both come on with the ignition. The way to tell them apart is that the no-charge warning light should normally come on as the engine spins down if you rev it and switch off. However, if you have got a car that uses an LED instead of a bulb for the no-charge warning light, it may not do this. In that case you'll have to find some other way to confirm which is which.