Moorron
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 posted on 1/6/08 at 09:05 AM |
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oil pressure problems again
Hi again, need some advice please.
Fitted new piston, rings, OIL PUMP and replaced the head on my turbo charged cbr1000f engined indy. I fitted a restrictor into the oil feed to the
turbo to help limit the oil to it because when hot the oil pressure at idle was 0, fine when running anything over 1500 rpm. running around the other
day to stick some miles on it so was driving under 6k rpm and leaving the boost as low as possible i monitored the oil pressure, like before i blew
the engine up oil pressure is good when running and 40 psi at 4k rpm but still 0 at idle.
Yesterday i nailed the car for the first time, all stayed in one piece but i noticed just after this that oil pressure was not 15 psi at 4k RPM, much
lower than even before. When booting it the oil pressure rises qiuckly to the max 100 psi so the pump sounds fine, but why would i loose loads of oil
pressure at lower rpm? the engine was no hotter the the other day when i did 50 miles on it so i dont think the oil had thinned out even more than
before.
I re started the car about 3 hours later (engine was still warm but showed under 50c on the water gauge) this time the oil at idle was just over 0 psi
but it was cold and when it is cold it useally reads 50 psi (oil is thicker?)
So what have i done, engine runs fine but i dont like seeing 0 psi even at idle.
To sum up
when cold at start, idle is 50 psi
when hot idle was 0 psi
when hot at 4k rpm 40 psi
now, when hot 4k rpm 15 psi.
Could it be the releaf valve in the sump?
please advise.
Andy
Sorry about my spelling, im an engineer and only work in numbers.
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viatron
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| posted on 1/6/08 at 09:09 AM |
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dont know much about bike engines but sounds the equiv of shot mains of big ends in a car engine, did you just fit new pistons and rings or did you
renew the bearings as well?
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David Jenkins
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| posted on 1/6/08 at 09:12 AM |
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I don't know much about bike engines either - but I had identical symptoms when the oil pump relief valve stuck open on my x-flow engine.
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andyharding
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| posted on 1/6/08 at 09:13 AM |
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Without really knowing a lot about BECs I would guess the standard oil pump can't deliver the increased flow of oil required by the turbo. You
could test this by blanking off your turbo oil feed/return and using a small electric pump ie screen washer pump and small tank to supply the turbo
while having a test drive. Obviously not a permanent solution but could narrow it down for you.
Are you a Mac user or a retard?
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Moorron
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| posted on 1/6/08 at 10:35 AM |
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quote:
Originally posted by viatron
dont know much about bike engines but sounds the equiv of shot mains of big ends in a car engine, did you just fit new pistons and rings or did you
renew the bearings as well?
just the pistons, due to a scratched bore. i had it hooned too.
the engine was fine just cracked the head so replaced those bits.
i fitted the new oil pump so i was sure i was geting max oil pressure because i was going to tap of it for the turbo.
think the sump needs comming off and the relif valve stripping.
sigh
Sorry about my spelling, im an engineer and only work in numbers.
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ChrisGamlin
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| posted on 1/6/08 at 11:34 AM |
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Yep sounds like it could be the PRV stuck open.
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jambojeef
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| posted on 1/6/08 at 02:13 PM |
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Having had identical issues with mine - I doubt it is the relief valve somehow.
Im sure we can get this sorted:
Where exactly have you tapped into the high pressure oil for the turbo feed?
And whats the diameter of the restrictor in line to the turbo?
Also where and how have you connected your oil pressure gauge?
I have made several different versions of the oil supply / return for my turboed CBR1000 and mullered an engine in the process by dropping the oil
pressure to the mains too much.
Mine has about 60ish psi @ 4000rpm when oil is at 95 degress.
On idle with oil at the same temp im getting about 15ish psi.
I have a 1mm t-piece / restrictor on the oil pressure switch tapping which feeds an SPA oil pressure sender.
Geoff
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jambojeef
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| posted on 1/6/08 at 02:21 PM |
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Just thinking about the pressure relief valve...
Have you modded the sump at all? I ask because there is a cast lug in the sump pan which holds the pressure relief valve up into its seat so the
o-ring hold pressure.
Just a thought that if you had modded the sump the relief valve could have become upseated.
As I say, just a thought!
Geoff
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Moorron
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| posted on 1/6/08 at 05:45 PM |
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Hi
i started the car up this morning to see what it was at idle and it is indeed lower than normal when cold.
it did cross my mind if the oil gauge was telling me porkies so before i take the sump off i am going to stick the mechanical one i originally had on
the car to see if i get a different reading.
my current electrical one (revotec) is fitted on a t piece where the turbo oil feed is also taken from and this is off the engine where the original
oil pressure switch was.
Jambo, i tapped the t piece and fited a grub screw with a 1mm hole thru it to limit the supply to the turbo. It doesnt effect the oil pressure sender
as its after this.
The only sump mod i have done is weld a oil return pipe to the side of it.
I havent a problem with knowing its low oil pressure due to me tapping it for the turbo, atleast if this was right then i can find a way round it.
However, what i am more concerned about it one minute its fine, then i nail it to 10k rpm and then suddenly its 20 psi lower at cruising speed.
it might be the oil pump has come loose as i did swap it, it might be the oil pressure valve (i will do a little funky dance if it is) or its
something worse and i will go a sulk in the pub.
The haynes show high oil pressure is due to a sticking pressure relief valve but not lower, it suggests it the pump which is new. so who knows.
Sorry about my spelling, im an engineer and only work in numbers.
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Moorron
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| posted on 3/6/08 at 04:54 PM |
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Just an update to my situation regarding the oil pressure problems I was having.
Last night I got into the garage and first fired the engine up for a few seconds, again it was reading lower than normal pressure at 15-20 psi at idle
cold. So disconnected the turbo oil feed to see what that would do. No difference at all. Hmmm.
So off came the electric oil pressure sender and on with the mechanical one that was originally fitted to the car, same make revotech. This time with
the turbo still disconnected the pressure was 35-40 psi, where it used to be before my problems started.
Last year I wired up the dash to use the bike engines original low oil pressure switch, but couldn’t fit the switch until I managed to find a +
adaptor to replace the ‘T’ one I was using. I removed the mechanical pressure gauge and fitted the switch in its place, reconnected the turbo feed and
started the car up. The oil pressure light went straight out. I started and stopped the engine a few times to see if the switch was still working ok
then left it running so it fully warmed up. Even then the light was out so showing I have a minimum of 15 psi at idle hot (which was always 0 with the
electrical gauge even when I thought it was working ok). If the switch is actually working as it should, then it’s the electrical sender that’s gone
(well still working but not reading the pressure right at lower pressures).
So, if i am right I have never had 0 oil pressure after fitting the turbo but I have a broke electrical oil pressure sender that’s only 1 year old.
The sender was fitted to the engine so was susceptible to vibrations, would this have semi broke it? If I order a new one and mounted it off a braided
line would this be better?
Many thanks
Andy
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JoaoCaldeira
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| posted on 4/6/08 at 10:10 AM |
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Pressure sender should never be mounted on the engine, but remotetly by a braided cable. Check ThinkAuto, they provided my lines / adaptors / ...
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ChrisGamlin
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| posted on 4/6/08 at 09:08 PM |
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Yup mount it remotely on a braided hose otherwise its likely to fail again.
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Moorron
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| posted on 5/6/08 at 09:36 AM |
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CHEERS, i had heard about it but never thought it would do it. Leason well learned.
A local hydraulics place make all my stuff up and its dirt cheap too so will sort out some pipework this weekend.
Thanks
Sorry about my spelling, im an engineer and only work in numbers.
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bernmc
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| posted on 5/6/08 at 01:31 PM |
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quote:
A local hydraulics place make all my stuff up and its dirt cheap too so will sort out some pipework this weekend.
Which firm, if you don't mind me asking?
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Moorron
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| posted on 5/6/08 at 09:39 PM |
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Hi, think its called friction hydraulics in saint gearges telford. Small place but are open 24 hours and make it there and then and cheap if cash.
They have even gave me the bits to take home, cut to length then take back to them to press fit for me.
I think my oil cooler pipwork cost £20 and that had a fair few connections on it.
Sorry about my spelling, im an engineer and only work in numbers.
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jambojeef
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| posted on 6/6/08 at 07:40 AM |
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Excellent,
Sounds like a fix then?
Always keen to hear of the fate of other turboed BECs since Im sure there are some nasty surprises in store for mine!!
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