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No Oil Pressure!


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#1 Haz20

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Posted 10 January 2019 - 12:13 PM

I’m a student engineer and the proud the owner of a 1992 mini with the original A+ series engine. I recently dismantled the whole engine to replace old parts. I put everything back together correctly and it turns lovely.

However, I have no oil pressure. I read a couple topics on this but can’t seem to find the fault. I haven’t started the engine only been turning it over. I’ve primed the pump multiple times and fed oil manually through the whole system. I did this aswell as turning it over after priming while waiting a good 40 seconds of solid turning over and got nothing.

Furthermore, I took apart the engine again to ensure the gaskets where properly fitted and that the o ring was in place, also checked the pressure relief was not jammed open. After putting it back together again, priming and turning over several times, I had pressure, I don’t know what I did different because everything was fine when I checked. However after leaving for 10 mins and turning over again, no pressure, since then I’ve been constantly priming and turning over but no luck.

Further useful information, when turning over without the oil filter pipe, oil comes out of the hole at a reasonable rate. Also when priming most of the oil sinks down the hole without turning the engine, I’m worried it could be internally leaking if that’s a thing, but I did get pressure for a moment, and haven’t taken it apart since only been priming.

Any help and advice will be greatly appreciated.
Thanks,
Harry.

#2 nicklouse

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Posted 10 January 2019 - 12:21 PM

possible problems.

 

the bolts holding the oil pump in place are too long.

 

the oil pump gasket is not correctly punched causing sealing issues.

 

both are known issues and should be checked.



#3 imack

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Posted 10 January 2019 - 01:36 PM

Agree with nick, oil pump gasket and bolts need checking.
Did you check cam end float with pump fitted? If not, pump drive may be bottomed in cam slot and pump not seated on gasket fully.

Edited by imack, 10 January 2019 - 01:39 PM.


#4 rww

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Posted 10 January 2019 - 04:04 PM

  After rebuilding our race engine multiple times I am still amazed ( and stressed) how long it takes to get initial oil pressure after a rebuild.

 

    I assume you have the plugs out to reduce compression. Ensure that the battery you are using is fully charged. You mention 40 secs of continuous turning on the starter motor. Although I have never timed it I reckon that sometimes, depending perhaps on how much priming I have done, I have spent five minutes spinning the motor until it reluctantly builds pressure. Thereafter, it is almost instant. I have never had issues with long bolts or faulty gaskets. Trust your build, keep spinning until you are convinced there is a mechanical fault.



#5 Moke Spider

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Posted 10 January 2019 - 06:29 PM

possible problems.

 

the bolts holding the oil pump in place are too long.

 

the oil pump gasket is not correctly punched causing sealing issues.

 

both are known issues and should be checked.

 

and another item is a badly worn pump.



#6 Cooperman

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Posted 10 January 2019 - 06:39 PM

In all the years of playing with Minis, I have only had one fully rebuilt engine on which I could not get oil pressure. It was an A+ 998 just over a year ago.

In the end the engine came back out of the car and I could find nothing obviously wrong. Mini Spares sent me another pump which I fitted and as soona s I spun it over the pressure came right up to over 50 psi on the starter. Conclusion was a defective new pump.

One thing to check is the pressure relief valve. These can stick after a new build and then the pressure won't come up on the starter.

If there was a brief pressure indication I would crank it quite a bit more before stripping it right down again.



#7 Rorf

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Posted 10 January 2019 - 07:01 PM

Another trick is to remove the oil pump top cover and put some multi purpose grease inside, it assists in helping to suck the oil up when doing the initial priming. Obviously this is done whilst building the engine. 



#8 Wiggy

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Posted 10 January 2019 - 11:18 PM

The first time I took my engine out, I kept it upright. Once back in the pressure built quite quickly.

The second time I laid it on its back to do what I had to do. I span it and span it for ages without achieving pressure. Pooed my pants, I did.

Once I'd back filled it, through the oil temp sender and span her for a while, the light went out.

Couple of hours later, once I'd changed my underwear, it took another good long cranking for the light to go off again.

My point? Ummm... Oh yes! Don't give up yet!

#9 Haz20

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Posted 11 January 2019 - 08:01 AM

Thanks for all these suggestions, I will consider having a look at the pump bolts and gasket, however the bolts are the original bolts and the gasket is the same as the original, of course it’s a new gasket but it’s identical.

I’m also very confused as to how I had oil pressure once and then after 10 mins of sitting there was no pressure again, I understand how I should start it as soon as I get pressure but I need that 10 mins at least to put sparks back and connect the fuel pump and so on.

I’ll try priming it again tmrw and turning it over again for a couple mins. But When I was turning it over for about 40 seconds the battery earth was burning hot and started to melt the tape covering it, I suppose that’s because I was constantly turning it over for longer than it’s meant to be. Any suggestions on that as I am gonna keep priming and turning over for longe. Also considering I don’t have a spare battery, and yes the one in the car is a new battery.

#10 Haz20

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Posted 11 January 2019 - 08:05 AM

I will also have a look at all the oil components again, such as the pressure relief and the filter, it is also a new filter. But what I’m most confused about is that I did have pressure, after that I didn’t touch anything and then suddenly no pressure.

#11 nicklouse

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Posted 11 January 2019 - 09:02 AM

I will also have a look at all the oil components again, such as the pressure relief and the filter, it is also a new filter. But what I’m most confused about is that I did have pressure, after that I didn’t touch anything and then suddenly no pressure.

 

OK lets think about the system and what makes pressure.

 

you need a pump that can make the oil move and you need some form of restriction to make pressure. without these you will not have pressure.

 

first the pump. if it leaks at a rate that equals its ability you will bet no pressure. (gasket failed or release valve open)

 

lets presume pump is OK and not leaking you then need the restriction. that is the bearings. as they wear the clearances get greater and the pressure drops.

 

then there is the relive valve this is a spring loaded seal that opens when the oil pressure exceeds a level determined by the spring if this does not close the restriction is the system is reduced and the means of holding pressure is lost.

 

the oil filter can only increase pressure if it is not leaking. if it is not leaking it can not reduce pressure. (the bypass valve in the head does not change the oil routing).

 

finally there is the means you are checking for pressure has that changed? is there a blockage? I have a pressure gauge that I can screw directly into the block for just this type of issue.



#12 Haz20

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Posted 11 January 2019 - 10:49 AM

Talking about the bearings, what I tired is filling up the whole oil route. what I did was disconnect the oil filter pipe and put oil down the pipe, the correct direction to the oil filter if u know what I mean. I did this a few times till oil came out of the hole where the t-piece is for the pressure gauge, however I didn’t need much pressure for it to come out that hole, I didn’t have a pump to pump it down the filter pipe so i did it the old fashion way, sucked oil up a tube and blew through the pipe, did this several times and like I said little pressure was needed for oil to come out the hole.

I’m not sure what this means as I was only trying to fill the system with oil. Could this mean problems with bearings

#13 mini13

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Posted 11 January 2019 - 10:54 AM

one other is, there were some problem pumps a while back where the oil way can overlap the cam bearing so they dont make pressure.



#14 Haz20

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Posted 11 January 2019 - 10:54 AM

Also, the pump is working, I will probably need to get into the engine again to fix the problem whatever it is, but I know the pump works as oil cane out the oil filter pipe hole at a reasonable rate when disconnected and turning over.

I also have new bearings and everything is torqued to the correct setting. Although one thing might be good to mention is that I got the conrods and their ends mixed up and just matched them as best as I could, to get the smoothest rotations. they also have new bearings.

#15 Haz20

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Posted 11 January 2019 - 11:01 AM

Forgot to ask if there’s is any reason for the temporary pressure then after letting sit for 10 mins no pressure?




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