F1 Bleeding

Evo Cymru

Evo Cymru

Member
Messages
688
Hmmm - interesting? So tried again this morning. With power on and key to on, the pump primes for 4 secs and then again after 30 secs. With the engine running, it primes for 4 secs and then again after 6 secs as before?! Some fluid coming out the reservoir still but I kept it running for longer this time and the pump kept working. CC light still on and N flashing on the dash. Will do a reset and try again a few times more before I try the gears I think.

It seems not to be maintaining pressure somehow, hence running again after a short time. Would this indicate air in the system or a broken/worn accumulator??
 
CraigWaterman11

CraigWaterman11

Sponsor
Messages
762
Olly I'm not totally sure now. I can tell you when I replaced the clutch in the car with everything apart I had the same thing happen after being put back together. CC light came on N was blinking until I put it into gear and backed it off the car trailer into the dealership. As soon as the car's input shaft gear box speed sensor matched the wheel speed sensors it all went back to normal. Of course your situation is totally different. I mean we both understand it's a shot in the dark because there's no way to know for sure until you get it plugged in. You can try it and see if it works. Remember that pressure controls two separate things the throw-out bearing and simultaneously the shift actuator. IMO you will be able to hear when it shifts if it sounds right or not. When you shift the sound will give you an indication as to whether the pressure is low or high, and additionally whether it shifts at all. Part of the reason the pressure sensor is on the car is to give the TCU the go ahead as to whether the pressure is correct to shift or not, correct? So you might find that it won't try to shift at all. But the long and short of it is this, you cannot mess anything up by attempting to shift if you have fluid in the reservoir, and the system is bled out. I think you have covered these two last things very well.
 
Evo Cymru

Evo Cymru

Member
Messages
688
Cheers Craig - just had another go! Same start up as before but this time no flashing N. After a minute I could hear the pump starting to struggle again! This time switched off before pump stopped completely. Jumped in the car and then tried changing gears with engine off. Was able to change gear! Could hear gear changes and pump working on each change, N R 1. Pump sounded like it was back to normal. Going to drop the car tomorrow (currently on stands) and try moving the car whilst listening to the pump to see what it's doing.
 
Zep

Zep

Moderator
Messages
9,302
Just a thought regarding the measurement of the system pressure. If a suitable gauge were connected to a port in the system (such as an open bleed nipple) it would be possible to measure and set it without the need for a diag machine. Any thoughts?


Sent from my iPhone using Tapatalk
 
CraigWaterman11

CraigWaterman11

Sponsor
Messages
762
@Olly okay cool......remember if you attempted to run it on stands it will set everything off even with the ASR off , including the "CC" light (ask me how I know) because the gear box input shaft speed sensors need to match the rest. So do it with it on the ground.

@Zep yes I think you could. Only caveat being is if the end of the bleed nipple is smaller than the rest of the system which would give a false high reading, correct? Kind of like when you use a nozzle on a water hose to control it. Either way it was quite an excellent idea. I cannot remember how small the end of the bleed nipple is. But Zep I like it! Hmmm, I wonder if you could put your own small shut off valve there. Then you could attach a bleed nipple or alternatively screw in your own hydraulic pressure gauge when you wanted to check it. The bleed valve right under the gear box is a perfect location for it.
 
CatmanV2

CatmanV2

Member
Messages
48,843
Unless I forget my physics, surely the pressure is independent from the size of the aperture?

C
 
CraigWaterman11

CraigWaterman11

Sponsor
Messages
762
On a more serious note though, yes the system pressure itself wouldn't change but would it give a false high/low reading if the pressure was further pressed through a smaller fitting? You could be correct, and I could be completely off it might not have any effect on it at all......

(BTW I really hope we don't have many women visitors on this forum or I might of just gotten myself in trouble)
 
CraigWaterman11

CraigWaterman11

Sponsor
Messages
762
Now Chris has me looking all over the internet as to whether I was crazy or not. Now I'm more unsure of what was said as when I originally thought it. ROFL.....Here Chris see if this quote fits or not.

"Putting your thumb over the end will increase the pressure just upstream of the obstruction, and then lead to a steeper pressure gradient through the pinch point. Flows in pipes have substantial viscous effects, and you cannot apply the standard Bernoulli "constant upstream velocity" if you're going to put your thumb over the end."

Read more: http://www.physicsforums.com
 
Zep

Zep

Moderator
Messages
9,302
Bang on Chris and Craig. Bernoulli only applies to flow through an orifice. As we would have no appreciable flow and there would be no pressure drop. Because we are talking about static pressure the system would reach equilibrium regardless of the size of the orifice. I knew the day job would come in handy at some point.

I think the valve is a possibility, but probably not to be trusted in the long term. Something like a binder fitting would probably be more like it....


Sent from my iPhone using Tapatalk
 
CraigWaterman11

CraigWaterman11

Sponsor
Messages
762
Yes, yes of course, static pressure, sorry it's been one of those days for me. Alternatively, I stated this before why don't we just find a gauge that reads the output data of the pressure sensor already on the car.......It's a 5 volt DC sensor. It's output signal is 0.5-4.5 VDC, it's working range is 0-80 bar, though obviously that system would never have that much pressure. But that's the data of the sensor. Surely we could come up with something, no? Sorry guys, I'm tapped for projects now but I'm for someone else stepping in.
 
Zep

Zep

Moderator
Messages
9,302
If we can identify the signal wire we could measure the voltage, if the range is 0-80 bar over 5 volts then the difference between 45 and 50 psi would be 0.02 volts so not much margin for error.

Evo - if you want to measure the pressure to be sure (assuming it isn't already sorted!) then if you have a branch of Pirtek near you they could sort you out a gauge and a hose to go over the bleed nipple for only a few pounds. It would be an interesting experiment at the very least!
 
CatmanV2

CatmanV2

Member
Messages
48,843
:)

This is why I mentioned static pressure. In a vessel, the pressure *must* be uniform (barring effects of gravity) when measured at any point and no matter the size of that measured area. Flow is all different :)

C
 
CatmanV2

CatmanV2

Member
Messages
48,843
Zep said:
If we can identify the signal wire we could measure the voltage, if the range is 0-80 bar over 5 volts then the difference between 45 and 50 psi would be 0.02 volts so not much margin for error.

Evo - if you want to measure the pressure to be sure (assuming it isn't already sorted!) then if you have a branch of Pirtek near you they could sort you out a gauge and a hose to go over the bleed nipple for only a few pounds. It would be an interesting experiment at the very least!
Click to expand...

Zep, more likely over 12v, given the environment, although I guess it may be TTL :)
Not much better I grant, though

C
 
Evo Cymru

Evo Cymru

Member
Messages
688
Zep said:
If we can identify the signal wire we could measure the voltage, if the range is 0-80 bar over 5 volts then the difference between 45 and 50 psi would be 0.02 volts so not much margin for error.

Evo - if you want to measure the pressure to be sure (assuming it isn't already sorted!) then if you have a branch of Pirtek near you they could sort you out a gauge and a hose to go over the bleed nipple for only a few pounds. It would be an interesting experiment at the very least!
Click to expand...

Well that would be interesting and I did think about something like this when I was trying to set the pressure screw...will see how it goes tomorrow and let you know - should have some more time over Chrimbo..!
 
CraigWaterman11

CraigWaterman11

Sponsor
Messages
762
Chris, well I was too busy making fun when you mentioned it, now of course I saw it. :blushed: But coming back to the pressure sending unit. What's the chances it's just a normal oil pressure sending unit stuck on the hydraulic system. It's highly unlikely that sensor is any different in operation. This is obviously what the SD2/3 or Leo scan tool is reading pressure from. Though I'm not a betting man I'm almost positive you could get a regular oil pressure gauge that operates off of an electrical sending unit and it would read it. I would try it out but I am waiting for leather and my dash is apart. Alternatively couldn't you read it's resistance with a multimeter and figure out what the pressure was at? Either way Zep your idea was definitely the easiest, and would get him a result he could fine tune his pressure with.
 
Evo Cymru

Evo Cymru

Member
Messages
688
OK, had another try with the car today. Could hear pump priming as I put the power on and when I opened the door but it started to struggle after a few 'openings' of the door. Car could shift gear though and pump would go back to priming as normal. Started the car up and it moved around without any problems R N and 1st all engaging properly. CC light still on though. Whilst it idled though I could hear the pump beginning to struggle again though. When going through the gears again (engine off) the pump returned to normal.

At this point I was beginning to think that the problem was with the pressure switch, the pump seemed to be working but not switching off when it reached the right pressure. This would explain why it was still priming each time the door was opened, rather that switching off after the required pressure was reached. So checked the connection and although it seemed fine I sprayed some contact cleaner in the connection and reattached hoping this would do this trick - cost of a new switch £100+ !!

Tried again and lo and behold pump primes on power on but only for a second when the door is opened. No pump struggles! Start up and drive again. No CC light! All gears go!! Listen to car at idle and no pump struggle!

Fingers crossed that this has solved the problem - will test further tomorrow and see how it goes!
 
You must log in or register to reply here.