Zero Oil Pressure
Discussion
New version of an old theme I think. Went to give Brm Brm her once over before going to Thruxton tomorrow only to start her up and find zero oil pressure (definitely not an indication problem).
She has done this twice before, once last year after standing unused for 3 weeks - cured itself after I filled her up with oil, once after the engine had been out over the winter - couldnt find anything obvious but the pump gears were changed as a precaution. And now this, again I've been away so she has not been used for 3 weeks.
The Oil system has not been disturbed recently and the oil level was half way up the dipstick. She also appears to have a modified pressure relief valve (large dome headed screw sticking out of the relief valve cap) so I dont think its that, and the oil filter is mounted remotely and above the pump.
So, first question - does anyone know what is going on,
if it is air in the pump I dont understand how its getting there and how can I prevent it.
Second question, how do you get the pump off, it appears to need a special tool, anyone know what it is or where I can get one, I cant see any way of getting a socket on to 2 of the fasteners even if I could find one with the right number of splines.
Any help or advice gratefully received - looks like i'll be going to Thruxton in the tin can
!
She has done this twice before, once last year after standing unused for 3 weeks - cured itself after I filled her up with oil, once after the engine had been out over the winter - couldnt find anything obvious but the pump gears were changed as a precaution. And now this, again I've been away so she has not been used for 3 weeks.
The Oil system has not been disturbed recently and the oil level was half way up the dipstick. She also appears to have a modified pressure relief valve (large dome headed screw sticking out of the relief valve cap) so I dont think its that, and the oil filter is mounted remotely and above the pump.
So, first question - does anyone know what is going on,
if it is air in the pump I dont understand how its getting there and how can I prevent it. Second question, how do you get the pump off, it appears to need a special tool, anyone know what it is or where I can get one, I cant see any way of getting a socket on to 2 of the fasteners even if I could find one with the right number of splines.
Any help or advice gratefully received - looks like i'll be going to Thruxton in the tin can
! Might be a bit late, but then again you may be up half the night so here goes:
I think you can get the oil pump bolts out with an 8-point 8mm ring spanner, cos that's what I used to strip and rebuild mine.
It could be the oil pressure relief valve has stuck, in which case a few judicious twats (techie term) with a tapping stick may unstick it.
If not, try pulling the distributor out and applying an electric drill to the oil pump drive by means of a long bolt, piece of rod or similar with a slot cut in the end. This should prime the oilways; best evidence that it is, is shown by oil seeping from around the rocker arms though obviously you need a rocker cover off to see this.
No oil feed is almost certainly due to the relief valve being stuck open. Otherwise you have a catastrophic failure somewhere such as main bearings or similar, but I guess you'd know about that.
Ian
I think you can get the oil pump bolts out with an 8-point 8mm ring spanner, cos that's what I used to strip and rebuild mine.
It could be the oil pressure relief valve has stuck, in which case a few judicious twats (techie term) with a tapping stick may unstick it.
If not, try pulling the distributor out and applying an electric drill to the oil pump drive by means of a long bolt, piece of rod or similar with a slot cut in the end. This should prime the oilways; best evidence that it is, is shown by oil seeping from around the rocker arms though obviously you need a rocker cover off to see this.
No oil feed is almost certainly due to the relief valve being stuck open. Otherwise you have a catastrophic failure somewhere such as main bearings or similar, but I guess you'd know about that.
Ian
Ian's right - try winding up the oil pressure with an electric drill throught the distributor drive.
There are various possible causes, but I would suspect you have a modified "tadpole" oil pressure relief valve as someone has modified the cover to allow you to adjust the oil pressure. It is easy to check by removed the valve cover (you will need to re-prime again).
My personal experience of this mod is not good - and I strongly recommend you go back to the original setup (but keep the adjustable pressure mod).
Don't be tempted to run the engine with no pressure!!!
There are various possible causes, but I would suspect you have a modified "tadpole" oil pressure relief valve as someone has modified the cover to allow you to adjust the oil pressure. It is easy to check by removed the valve cover (you will need to re-prime again).
My personal experience of this mod is not good - and I strongly recommend you go back to the original setup (but keep the adjustable pressure mod).
Don't be tempted to run the engine with no pressure!!!
Hi Brm Brm , as a matter of interest your car has got the "tadpole" mod but it has worked ok since 97' maybe they don't like being left for weeks, when i had the car it was used at least once a week, which would explain why i had no problems. Speak to an engine builder for advise on this ( TVR Power happily supplied the Tadpole) It does sound like an air-lock. totally agree with priming via the distributor drive with an electric drill, are you clear on the process ?
if you need any help 020 8715 3160
Tim
if you need any help 020 8715 3160
Tim
Thanks for the advice guys, there is obviously something causing the problem so I suspect I'll end up taking it to bits before I try and re-prime. Will do some research tomorrow.
I may give you a ring if I get stuck Tim - I'm actually in the London area for the next couple of weeks so would also like to chat about the other bits we discussed at Duxford.
I may give you a ring if I get stuck Tim - I'm actually in the London area for the next couple of weeks so would also like to chat about the other bits we discussed at Duxford.
OH Bugger! Well I took all the advice (thanks guys), stripped the oil pump (8mm ring as advised) but couldn't find anything wrong so I replaced the tadpole cleaned everything up and rebuilt. Packed the pump with vaseline, built my primimng tool, re-primed via the distributor (found a piece of copper tube useful to protect the distributor drive gear) and started perfectly, oil pressure back to normal. Went for a drive - all was well with normal oil pressure, shut down and re-started OK
(it was after all late last Sunday). Well, after another week away on business back home tonight so I thought I'd make the most of the weather, jumped in, started her up and............NO OIL PRESSURE again!!!!!!!!!!!!
What on earth is going on?? I'm really scratching my head now so any ideas much appreciated. I cant see how it can be anything fundamental with the engine as it wouldnt have been OK when I reassembled it last week?? Could it be something to do with the pump housing itself eg. the tadpole sticking when cold if the housing has warped. I know I'm clutching at straws but have no other ideas. Answers on a postcard please!
I think you are right. I am guessing that the housing is out of spec and that this is causing the relief valve to jam or the pump to loose pressure as the oil escapes round the side (over the top of the gears between them and the cover).
This would also allow the pump to drain down if not used.
Steve
>> Edited by shpub on Saturday 5th October 08:36
This would also allow the pump to drain down if not used.
Steve
>> Edited by shpub on Saturday 5th October 08:36
What a pain !!As we have heard a few negative comments about the "tadpole" i would try fitting an original pressure relief valve. I would also speak to an engine builder such as V8 Developments 01775 750000 say i suggested you phone them if you wish.
Tim
>> Edited by 2 Sheds on Saturday 5th October 09:01
Tim
>> Edited by 2 Sheds on Saturday 5th October 09:01
I agree with recommending the standard set-up as I said earlier. One other possibility is a crack on the oil pickup pipe in the sump - as this would let the oil drain back. Its not that difficult to check, you need to drop the sump and it is then easy to remove. It is probably worth getting is re-brazed if you take it off just to be 100% sure. Anyway I would only bother with this if you still have the problem after trying the standard valve.
Danny
PS You have my sympathy as I went through the same thing for over 1 year, never knowing if I would get pressure when I went to start the car. I even got to the point of carrying a battery drill and tool to prime the pump in case I got stranded!
Danny
PS You have my sympathy as I went through the same thing for over 1 year, never knowing if I would get pressure when I went to start the car. I even got to the point of carrying a battery drill and tool to prime the pump in case I got stranded!
Danny was right - BEWARE THE TADPOLE!
Close inspection showed that the tadpole had created a nice seat for itself in the relief channel outlet hole and the spring had worn a groove in the bottom of the relief housing bore. I've replaced the whole housing with a new, standard one from Rimmer Bros, and it seems to be OK - steady oil pressure at about 30.
Thanks for all the advice!
Close inspection showed that the tadpole had created a nice seat for itself in the relief channel outlet hole and the spring had worn a groove in the bottom of the relief housing bore. I've replaced the whole housing with a new, standard one from Rimmer Bros, and it seems to be OK - steady oil pressure at about 30.
Thanks for all the advice!
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