Still got oil pressure problems on cold start... Help!
Discussion
Whenever I start the car from cold, it takes about 4 - 5 seconds after it fires for the oil light to go out and the gauge to move.
I think this is too long.
Whilst this happens, the engine clatters away to itself, and I cringe lots.
I've had the pressure relief valve out of the pump cover, and notice it is scored, though only very shallow (can hardly feel them at all).
Re-assembled it, having removed some very slight burrs from the top edge (probably still there from manufacture!).
No difference. Rats.
When driving, the oil pressure's great, as soon as you pull away, it nips up to about 45PSI, and when youre gunning it, it rises again up to about 70PSI by about 5kRPM.
When I changed the oil, I did prefill the filter, but it has drained, and now the sump is above the top mark.
Basically, the pump seems to have to reprime itself (perhaps refill) the oil filter every time I start it cold.
HELP!
Ed.
P.S. PH2821A fitted, and it appears to have the rubber valve in it.
I think this is too long.
Whilst this happens, the engine clatters away to itself, and I cringe lots.
I've had the pressure relief valve out of the pump cover, and notice it is scored, though only very shallow (can hardly feel them at all).
Re-assembled it, having removed some very slight burrs from the top edge (probably still there from manufacture!).
No difference. Rats.
When driving, the oil pressure's great, as soon as you pull away, it nips up to about 45PSI, and when youre gunning it, it rises again up to about 70PSI by about 5kRPM.
When I changed the oil, I did prefill the filter, but it has drained, and now the sump is above the top mark.
Basically, the pump seems to have to reprime itself (perhaps refill) the oil filter every time I start it cold.
HELP!
Ed.
P.S. PH2821A fitted, and it appears to have the rubber valve in it.
I may get shot down in flames for suggesting this but try fitting the filter the other way up so it hangs down. Mine has always been fitted like this and I have never had a problem. I have never understood the reason for so many wedges I've seen, having the filters 'upside down' on top of the mounting. Why? Seems like it is a recipe for trapping air and making oil changes very messy. With the filter below, any air comes to the top and the filter will act like a sludge trap should the element become holed.
When I change my oil I simply disconnect the oil pipes from the housing and plug them to prevent any drain down, then take off the mounting and filter together and change the filter away from the car where any spillage is easy to wipe up. I have never bothered to prefill the new filter and oil pressure is there withing seconds of start up. It's the cleanest and easiest car to change oil on ever.
Come on then all ye more informed than me peeps, start a shootin
When I change my oil I simply disconnect the oil pipes from the housing and plug them to prevent any drain down, then take off the mounting and filter together and change the filter away from the car where any spillage is easy to wipe up. I have never bothered to prefill the new filter and oil pressure is there withing seconds of start up. It's the cleanest and easiest car to change oil on ever.
Come on then all ye more informed than me peeps, start a shootin
Some more information:
I am going up to DJ Ellis tomorrow to get the base plate machined to accept a tadpole valve, since the existing oil pressure relief valve bore is worn.
I also noticed that the oil pipes have gone really hard and are cracking, so a warning to other people out there: check the pipes, and replace if necessary!
Thirdly, I noticed that one of the segments of the 1 way valve in the oil filter has been pushed over centre. I pumped air into the centre of the filter off the car, and air peed out of the overturned valve segment! This gives me an idea as to whats happening:
I think that as i prime the pump, there is a decent sized pocket of air in the filter, which compresses as the pump is spun on the drill. When I take the drill off, the pump RUNS BACKWARDS FOR SEVERAL SECONDS. I presume this is some pressure relieving itself. I suspect that the air pocket in the top of the filter is re-expanding and the path of leas resistance is to push the rubber valve out and spin the pump backwards. Remember, at this point the dizzy is out, so theres nothign to stop the pump going backwards...
Once this has happened (i.e. the rubber valve in the filter has been pushed out), oil is free to leak back down in to the pump, past the pump gears and after a few hours, the pump empties. Cold start: clatterclatterclatterclatter... Lets hope it hasnt knackered the engine... Its probably been started like that 10 - 20 times...!
So, how the hell do I remove all air from the oil filter to prevent this?!?!
I may put a hydraulic flapper check valve between the pump and the filter...
Any other ideas??
Ed.
I am going up to DJ Ellis tomorrow to get the base plate machined to accept a tadpole valve, since the existing oil pressure relief valve bore is worn.
I also noticed that the oil pipes have gone really hard and are cracking, so a warning to other people out there: check the pipes, and replace if necessary!
Thirdly, I noticed that one of the segments of the 1 way valve in the oil filter has been pushed over centre. I pumped air into the centre of the filter off the car, and air peed out of the overturned valve segment! This gives me an idea as to whats happening:
I think that as i prime the pump, there is a decent sized pocket of air in the filter, which compresses as the pump is spun on the drill. When I take the drill off, the pump RUNS BACKWARDS FOR SEVERAL SECONDS. I presume this is some pressure relieving itself. I suspect that the air pocket in the top of the filter is re-expanding and the path of leas resistance is to push the rubber valve out and spin the pump backwards. Remember, at this point the dizzy is out, so theres nothign to stop the pump going backwards...
Once this has happened (i.e. the rubber valve in the filter has been pushed out), oil is free to leak back down in to the pump, past the pump gears and after a few hours, the pump empties. Cold start: clatterclatterclatterclatter... Lets hope it hasnt knackered the engine... Its probably been started like that 10 - 20 times...!
So, how the hell do I remove all air from the oil filter to prevent this?!?!
I may put a hydraulic flapper check valve between the pump and the filter...
Any other ideas??
Ed.
Once its got oil pressure, its sound as a pound tho...
Danny, youre the second person to advise against using tadpole valve.
confused.......
Thinks I'll go see Dave Ellis and if hes got a replacement original spec one on the shelf, I might buy that...
Will pick up a new oil filter too: I do remember noticing that the valve in the filter wasnt all that when I first opened the box.
Ed.
Danny, youre the second person to advise against using tadpole valve.
confused.......
Thinks I'll go see Dave Ellis and if hes got a replacement original spec one on the shelf, I might buy that...
Will pick up a new oil filter too: I do remember noticing that the valve in the filter wasnt all that when I first opened the box.
Ed.
The filter is supposed to have a flap valve to prevent oil from running back into the sump, make sure you get the correct sort.
The other method is to invert the filter so this doesn't happen.
I don't know why TVR always mounted them the "wrong" way up - but they did fit an oil cooler on my car without fitting a thermostat at all, the oil was permenantly supercooled - wrecked the distributor/oil pump drive within a year.
Russ
The other method is to invert the filter so this doesn't happen.
I don't know why TVR always mounted them the "wrong" way up - but they did fit an oil cooler on my car without fitting a thermostat at all, the oil was permenantly supercooled - wrecked the distributor/oil pump drive within a year.
Russ
when i changed the oil pump on mine a couple of weeks ago the plate i took off was a tadpole one and the new one not,i used the pack with vaseline method and filled the filter and pipes up - oil preasure within 10 seconds of cranking with the plugs out.
now the last time i built an engine up from scratch i primed the pump with a drill through the dizzy - it took ages to get up to preasure (about 5 mins)
for what it's worth i'd stick with the vaseline - it's a bit of a potch but at least it works
as for the drain back problem - sounds like a crap/wrong filter to me
hp
now the last time i built an engine up from scratch i primed the pump with a drill through the dizzy - it took ages to get up to preasure (about 5 mins)
for what it's worth i'd stick with the vaseline - it's a bit of a potch but at least it works
as for the drain back problem - sounds like a crap/wrong filter to me
hp
There is something a little odd going on.
Filter is a Fram PH2821A, and has a NRV in it. The problem is that the NRV gets forced over centre if the backpressure exceeds a couple of PSI. This can be seen by the rubber diaphragm trying to poke through the outer 8 holes in the filter face.
If there is any significant amount of air in the filter, then as you remove the pump priming probe, the pump drive blade can be seen rotating anticlockwise (backwards). This is the pump being driven backwards (gear pumps are backdriveable) by the pocket of air in the top of the filter reexpanding. This backwards flow shoves the NRV in the filter overcentre, and IT STAYS THERE (apologies for shouting, but i believe that to be the crux of the problem). What happens next is that (once the car is back together) over a period of hours, all the oil drains out of the filter, back through the pump (OK, its not gonna turn backwards, cos the dizzy is preventing it now, but a SLOOOOOOW leakage will occur due to running clearances of the gears), and into the sump.
Nest time the car is started cold, the pump has to partially/totally reprime itself, which takes about 5 seconds in my case!
No issue on hot start, cos the oil hasnt had hours to sloooowly drain back down. Oil pressure comes up within half a second.
I realised today that I hadnt been filling the filter properly, and made damned sure it was full today. Also had the missis turning the pump drive slowly whilst i put the filter on to make sure as little air got in as possible.
Once its sat for a few hours, I'll try a start and see what we've got...
If its still no good, I plan to put a flapper check valve upstream of the filter, as they are MUCH more resistant to reverse pressure than the flimsy little oil filter valve.
Many thanks for your replies on this: I think I have it licked (or will do with a flappy valve anyway!)
THanks again,
Ed.
P.S. That pump base plate was a total bitch to refit... Made worse by the fact that i have Power steering and hence myriad sundry excrescences in the way...
Filter is a Fram PH2821A, and has a NRV in it. The problem is that the NRV gets forced over centre if the backpressure exceeds a couple of PSI. This can be seen by the rubber diaphragm trying to poke through the outer 8 holes in the filter face.
If there is any significant amount of air in the filter, then as you remove the pump priming probe, the pump drive blade can be seen rotating anticlockwise (backwards). This is the pump being driven backwards (gear pumps are backdriveable) by the pocket of air in the top of the filter reexpanding. This backwards flow shoves the NRV in the filter overcentre, and IT STAYS THERE (apologies for shouting, but i believe that to be the crux of the problem). What happens next is that (once the car is back together) over a period of hours, all the oil drains out of the filter, back through the pump (OK, its not gonna turn backwards, cos the dizzy is preventing it now, but a SLOOOOOOW leakage will occur due to running clearances of the gears), and into the sump.
Nest time the car is started cold, the pump has to partially/totally reprime itself, which takes about 5 seconds in my case!
No issue on hot start, cos the oil hasnt had hours to sloooowly drain back down. Oil pressure comes up within half a second.
I realised today that I hadnt been filling the filter properly, and made damned sure it was full today. Also had the missis turning the pump drive slowly whilst i put the filter on to make sure as little air got in as possible.
Once its sat for a few hours, I'll try a start and see what we've got...
If its still no good, I plan to put a flapper check valve upstream of the filter, as they are MUCH more resistant to reverse pressure than the flimsy little oil filter valve.
Many thanks for your replies on this: I think I have it licked (or will do with a flappy valve anyway!)
THanks again,
Ed.
P.S. That pump base plate was a total bitch to refit... Made worse by the fact that i have Power steering and hence myriad sundry excrescences in the way...
Are you certain the NRV does stay overcenter when the engine is running? I'd have thought the normal flow would return it to the correct position. Are you absolutely certain that the direction of flow through the filter head is correct? You may be better off doing away with the NRV completely. I'd also consider leaving the filter loose while you spin the pump to prime it, and only tighten it to seal afterwards.
Pressure has settled a little now. I do still have pressur erelief valve issues, but thats not the main problem.
Yep, valve defo stays overcentre, as when I spin the filter on its fine, and when I remove it its overcentre. However, the fram filter has a large circular flap which seats on the inside face of the filter top, outside of the 8 or so holes. when the valve has flipped, I notice that the lip of the valve flap pokes through one of the holes only, so forward flow of the valve is still possible round the rest of the perimeter holes.
I suspct that the problem is the way I prime the pump. I shouldnt use the drill, and should, as advised above, take the plugs out and spin it over until the light goes out. That way, the pump cant be backdriven, the pressure will bleed away through the engine (as it should!), and the valve will never be flipped.
Blummin 'eck, what a day!!
Ed.
Yep, valve defo stays overcentre, as when I spin the filter on its fine, and when I remove it its overcentre. However, the fram filter has a large circular flap which seats on the inside face of the filter top, outside of the 8 or so holes. when the valve has flipped, I notice that the lip of the valve flap pokes through one of the holes only, so forward flow of the valve is still possible round the rest of the perimeter holes.
I suspct that the problem is the way I prime the pump. I shouldnt use the drill, and should, as advised above, take the plugs out and spin it over until the light goes out. That way, the pump cant be backdriven, the pressure will bleed away through the engine (as it should!), and the valve will never be flipped.
Blummin 'eck, what a day!!
Ed.
As said before, pressure is way too high indicating oil pressure relieve valve issues (but as replaced should be fine now - the spring is very important and would replace that myself in the process). And did you try a new (other) filter? Perhaps the one you have is not ok.... It seems that sometimes we buy new parts and they are worse then the old used stuff!!!!
Rob
Rob
The tadpole wrecked my engine as it was very poor quality metal and the steel became pitted where is seated. It also jammed open as it was oversize. Been running the standard setup now for 40,000 miles and no probs. I always prime my engine via the dizzy drive, and I also get back pressure winding it backwards.
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