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 What is too high oil pressure?

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T O P I C    R E V I E W
rattyPosted - 02 Jan 2015 : 14:32:55
We have had a new engine built up using a 1.7 crank and bought a Burtons Hi pressure oil pump suitable according to Burtons for V4 or V6. The problem is it is reading 100 psi from cold and 80 psi when warm. Surely this is too high? I bought the same pump for the other car and that runs 75 psi cold 55 to 60 hot. Any ideas anyone? we have ordered another pump from Burtons.
15   L A T E S T    R E P L I E S    (Newest First)
DirtbikerPosted - 07 Jan 2015 : 18:43:38
Good luck at the weekend!

Is the event Friday and Saturday? Unfortunately working on Saturday but if there is anything happening on Sunday I'll try and make it along.

Cheers
pchristyPosted - 07 Jan 2015 : 18:07:10
He told me he was putting half a ton of lead in the front!!!





--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"
john-saabPosted - 07 Jan 2015 : 18:03:10
Great work Peter..I think he asked me in a round about sort of way but mentioned that the car had been lightened and adding me to the mix might undo some of the work (cheeky git)

'73 96 (Vernon),'74 95 (Veronica)plus 4 other 95's and 2 96's
pchristyPosted - 07 Jan 2015 : 14:50:07
I should have a good view of the event - I'm navigating for Ratty!!!





--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!"
john-saabPosted - 07 Jan 2015 : 08:24:41
I have 2 MOT's to sort (modern cars) in the next 2 days and if they both pass without much effort I'm going to try and get there.


'73 96 (Vernon),'74 95 (Veronica)plus 4 other 95's and 2 96's
rattyPosted - 07 Jan 2015 : 07:45:19
Thanks Nick it is all coming together both cars Ratty and Badger are entered. The big challenge on the Exeter is Simms Hill at Ilsington, nr Newton Abbot/ Bovey Tracey. I don't think any Saab has ever climbed it over the years. It is a good vantage point if anyone is interested. Providing we don't break down! we should be attempting to go up at approx. 2.00pm on Sat. 10th. Some years you are doing well just to finish and get to the end. Weather forecast is for rain. This year there is a channel 5 Fifth Gear Ford escort mk 1 entered which they are borrowing.They also have 2 film crews there as well.So with a bit of luck we should be on the tv in a month or so's time!
Nick96Posted - 06 Jan 2015 : 20:23:41
Ratty
Good luck on the Exeter,at weekend,hope there'll be some pictures on
FB
rattyPosted - 06 Jan 2015 : 06:55:24
Fitted new Burton's hp pump last night start pressure 100 psi same as the other one. It is staying in! Should do 100+ miles today so will see how it settles down.
WoodyPosted - 04 Jan 2015 : 23:23:41
Fired the Troll up this morning, it was absolutely freezing, and took a while to get the engine going, as I hadnt run it for 6 weeks or more. Last outing was to the last Limes Cafe meet for UKSaabs in November. Pic below of oil gauge at start up. Didnt have time to run up to full temp to get hot reading. Will try another time.

metterslPosted - 04 Jan 2015 : 19:48:26
I have a v6 pump, in its box...bought in the 80's from Ford for the 2.8 l cologne engine, its about 25% bigger in diameter than the V4 pump. I was trying to save money as it was about half the cost of a Saab reconditioning kit, let alone a new pump and ford UK wouldn't supply cologne V4 parts. I didn't fit it in the end as it would have meant enlarging the sump, bashing it out didn't give enough clearance. I fitted a SAAB reconditioning kit to the original, but have since wondered if I should put a new pump in...my standards have risen quite a bit since I was 18 and did the work. The engine has yet to run...30 plus years later, sealed and kept inside, it still turns over easily.
The pressure is set by the relief valve spring pressure, a high pressure pump has a stronger spring.
Capacity is set by the size of the pump. Putting a bigger capacity pump onto the engine will mean more oil out of the bypass, but not necessarily more pressure. The pressure will in any case be set by the engine condition, smaller clearances of blocked oil ways will mean higher pressure. 10psi per 1000 engine revs needed is apparently the maxim...so 50-60psi max should do us. Higher pressure than needed uses more power.
I did study all this when I trained as an engineer, but 30 years in commercial jobs means I am a bit rusty.
There is a lot on the web about this topic if you Google it.

Lee
rattyPosted - 04 Jan 2015 : 18:55:29
Sump off this morning. Main bearing caps off, everything was all lined up as should be.Plenty of oil everywhere.Pump removed to be stripped and checked a second time. However new pump should arrive tomorrow from Burton's and will be fitted. They don't specify what the oil pressures should be. I also can't get my head around that the pump is suitable for a v4 or a v6. Surely the pressure would be considerably different between the two? JDT and Simps. Any thoughts? Everyone else thanks for your observations and comments. A final conclusion and result will soon be! Will let you know the outcome.
DerekPosted - 04 Jan 2015 : 12:22:48
Before doing anything I think I'd have a word with Burtons. Tell them about the different pressures with the same new pumps. They might agree to swap it but it would be worth stripping it down and checking all of the relevant clearances. It might be that all of the numbers measure at the very bottom of the range giving a very tight pump. Measure the spring. Burtons should be able to give you all of the numbers.
A wee bit off topic but if there is an option of a high capacity rather than a high pressure pump would a high capacity one be better with modern oils? What does a standard new pump produce 70/50 cold/hot? Isn't that enough? Lots I could speculate about here.......
metterslPosted - 04 Jan 2015 : 11:01:43
You could always move to a modern thinner oil if you are worried...these engines are 20/50 originally aren't they? (mine hasn't run for 30 years so I forget) 10/40 is pretty standard in more modern engines and should lower the pressure a little but still protect all the parts.
Modern oils are more effective at preventing engine damage anyway.
In the end the aim of the oil pressure is to stop the bearings touching when the compression stokes fire (as well as providing oil flow over the other parts).
I'm not sure why higher oil pressure would be a benefit, but will take engine power to achieve.

Have a look here for more information.

http://www.classicinlines.com/OilPressure.asp

Lee

rattyPosted - 03 Jan 2015 : 23:12:05
Woody that is interesting. So far presuming your guage is accurate then you are using the highest pressure with no ill effects? perhaps we are worrying too much? Still can't get my head around the fact that we have rebuilt 2 engines , one 1.5 and 1.7 otherwise the same spec.and both using Burton's high pressure pumps, all new of course, different pressures in first post. Why? Pump faulty or blockage, misalignment, etc?
WoodyPosted - 03 Jan 2015 : 21:30:32
My rally engine used to run 100 at start up and 70-80 when warm. It has settled a bit since the reassembly. Have to crank her up tomorrow and see.
Blowing oil out via crank seal did happen but that was down to crankcase pressurising and not the pump.
I wouldn't worry about it. Certainly not enough to pull the engine and strip. Just check you have good oil flow at the rockers and the oil is clean.

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