18 replies to this topic

[UnKnowledgeableMiniDriver]

I've just rebuilt my 1275, definitely fitted the o-ring between the gearbox and engine. However I'm getting an issue with building oil pressure. I backfilled the oil pump through the oil filter banjo whilst pushing the car backwards in 4th to re-prime the oil pump. This gave me oil pressure. The next day I turned the engine over again and had no oil pressure. I removed the Banjo turned the engine over and oil came out. Reconnected the banjo and had oil pressure again. Started the engine to seat the new head gasket. Let it cool for about 1.5 hours. Turned over again with distributor disconnected so it wouldn't start, and no oil pressure again.
If I disconnect the banjo, I get oil pressure but leave it and the oil pressure won't build again. Anybody experienced this before?

[Lplus]

I've just rebuilt my 1275, definitely fitted the o-ring between the gearbox and engine. However I'm getting an issue with building oil pressure. I backfilled the oil pump through the oil filter banjo whilst pushing the car backwards in 4th to re-prime the oil pump. This gave me oil pressure. The next day I turned the engine over again and had no oil pressure. I removed the Banjo turned the engine over and oil came out. Reconnected the banjo and had oil pressure again. Started the engine to seat the new head gasket. Let it cool for about 1.5 hours. Turned over again with distributor disconnected so it wouldn't start, and no oil pressure again.
If I disconnect the banjo, I get oil pressure but leave it and the oil pressure won't build again. Anybody experienced this before?

Did you backfill oil through the banjo hole again before reconnecting?
 

[UnKnowledgeableMiniDriver]

I've just rebuilt my 1275, definitely fitted the o-ring between the gearbox and engine. However I'm getting an issue with building oil pressure. I backfilled the oil pump through the oil filter banjo whilst pushing the car backwards in 4th to re-prime the oil pump. This gave me oil pressure. The next day I turned the engine over again and had no oil pressure. I removed the Banjo turned the engine over and oil came out. Reconnected the banjo and had oil pressure again. Started the engine to seat the new head gasket. Let it cool for about 1.5 hours. Turned over again with distributor disconnected so it wouldn't start, and no oil pressure again.
If I disconnect the banjo, I get oil pressure but leave it and the oil pressure won't build again. Anybody experienced this before?

Did you backfill oil through the banjo hole again before reconnecting?

No, just disconnected. I've since replaced the oil filter and removed the oil filter housing and checked it's all clear. Removed the pipe going to the mechanical oil pressure gauge and oil comes through there, and will keep oil pressure until it's left for a while again.
I've ran the engine and timed the ignition and it kept pressure the whole time. Left it off for about an hour and it won't build pressure again

Edited by UnKnowledgeableMiniDriver, 29 March 2024 - 05:44 PM.

[Shooter63]

What sort of oil pressure are you getting with the engine running?

Shooter

[UnKnowledgeableMiniDriver]

What sort of oil pressure are you getting with the engine running?


Shooter

Around 60lb, before I rebuilt this was it normally was

Edited by UnKnowledgeableMiniDriver, 29 March 2024 - 06:14 PM.

[Lplus]

 

 

I've just rebuilt my 1275, definitely fitted the o-ring between the gearbox and engine. However I'm getting an issue with building oil pressure. I backfilled the oil pump through the oil filter banjo whilst pushing the car backwards in 4th to re-prime the oil pump. This gave me oil pressure. The next day I turned the engine over again and had no oil pressure. I removed the Banjo turned the engine over and oil came out. Reconnected the banjo and had oil pressure again. Started the engine to seat the new head gasket. Let it cool for about 1.5 hours. Turned over again with distributor disconnected so it wouldn't start, and no oil pressure again.
If I disconnect the banjo, I get oil pressure but leave it and the oil pressure won't build again. Anybody experienced this before?

Did you backfill oil through the banjo hole again before reconnecting?

No, just disconnected. I've since replaced the oil filter and removed the oil filter housing and checked it's all clear. Removed the pipe going to the mechanical oil pressure gauge and oil comes through there, and will keep oil pressure until it's left for a while again.
I've ran the engine and timed the ignition and it kept pressure the whole time. Left it off for about an hour and it won't build pressure again

 

So the oil pump is able to draw oil from the sump to prime itself, but only when the banjo bolt is removed.  Presumably it isn't capable of drawing oil against any sort of resistance from the oil filter and bearings.

 

On the basis the o ring is correctly in place, I'd wonder about the pump. Was it a new pump?  new gasket? and where from if it was?

[UnKnowledgeableMiniDriver]

I've just rebuilt my 1275, definitely fitted the o-ring between the gearbox and engine. However I'm getting an issue with building oil pressure. I backfilled the oil pump through the oil filter banjo whilst pushing the car backwards in 4th to re-prime the oil pump. This gave me oil pressure. The next day I turned the engine over again and had no oil pressure. I removed the Banjo turned the engine over and oil came out. Reconnected the banjo and had oil pressure again. Started the engine to seat the new head gasket. Let it cool for about 1.5 hours. Turned over again with distributor disconnected so it wouldn't start, and no oil pressure again.
If I disconnect the banjo, I get oil pressure but leave it and the oil pressure won't build again. Anybody experienced this before?

Did you backfill oil through the banjo hole again before reconnecting?

No, just disconnected. I've since replaced the oil filter and removed the oil filter housing and checked it's all clear. Removed the pipe going to the mechanical oil pressure gauge and oil comes through there, and will keep oil pressure until it's left for a while again.
I've ran the engine and timed the ignition and it kept pressure the whole time. Left it off for about an hour and it won't build pressure again

So the oil pump is able to draw oil from the sump to prime itself, but only when the banjo bolt is removed.  Presumably it isn't capable of drawing oil against any sort of resistance from the oil filter and bearings.
 
On the basis the o ring is correctly in place, I'd wonder about the pump. Was it a new pump?  new gasket? and where from if it was?

I put a small amount of gasket paste on the o-ring so it stayed in place when I fitted it the engine to the gearbox, so, think it should have been sat correctly.
The pump was a new pump from minispares and gasket was a Klinger gasket.

I'm going to attempt to replace the o-ring again the gasket on the pump. Is there anything else worth replacing that could cause it whilst I've got it all split?

[imack]

Check the oil pump mounting bolts aren't too long, causing them to bottom out and preventing the gasket from sealing properly. Also check that the oil pick up pipe mounting face is smooth and flat so it is able to seal to the gearbox gasket correctly.
Check the oil pick up pipe for damage or perforation.

[Cooperman]

Check the oil pressure relief valve. They can stick partly open if a small piece of debris gets in.
However, if that's not the problem then suspect the pump. I recently rebuilt a 1275 engine and used a new pump which had been on the shelf in my workshop for a couple of years. First I got some pressure, but then on next starting it, the pressure would not build up. Checked the relief valve, but that was OK. Bought and fitted a new Metro Turbo pump and immediately got 65 psi on the starter motor with plugs out and 85 psi on start up. Threw the duff pump in the bin.

[Lplus]

Check the oil pump mounting bolts aren't too long, causing them to bottom out and preventing the gasket from sealing properly. Also check that the oil pick up pipe mounting face is smooth and flat so it is able to seal to the gearbox gasket correctly.
Check the oil pick up pipe for damage or perforation.

This, plus check the end of the oil pump drive  flange isn't bottoming out in the end of the camshaft slot (assuming a slot drive pump.) and preventing the pump seating.  Yes it can happen.  I had to take a small amount off the end of the drive flange on a new pump for the last engine I did because it was slightly too long.  I can't recall where I was warned of the possible problem, might have been in the new cam instructions.

Edited by Lplus, 30 March 2024 - 08:33 AM.

[UnKnowledgeableMiniDriver]

So far, from what you've all said, I've checked pick-up pipe and it's flush against the side and has the gasket fitted.
The o-ring is in between the gearbox and the engine. However, the o-ring sits on the gasket not the metal face, is this correct? In my head it should be sat on the metal and not the gasket. The o-ring protrudes by about 12 to 15 thou of an inch without the gasket present. With the gasket sat on top it protrudes about 6thou of an inch.
Does anyone know how thick the o-ring should be?
There's no up and down play in the oil pump, and when I removed it, it sat flush against the face of the engine without the gasket present. It was well attached to the gasket and needed a few taps with a rubber mallet to move it

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[Beezle]

I'm thinking duff pump!
As in it's able to work when it has some nice viscous oil oil to pump, but when left to drain and air to enter isn't capable of expelling/pumping out the air.

P.S. MiniSpares will tell you everything it does / makes / sources is the very best quality, but that doesn't make it true....

Edited by Beezle, 31 March 2024 - 09:53 AM.

[imack]

Dismantle the pump and check for damage and measure the clearances.

[Cooperman]

It won't be the O-ring. 

If it's not the pressure relief valve it will almost certainly be the pump. Fit a new Metro-Turbo pump and your problem will almost certainly be solved.

[GraemeC]

I prefer to trim the gasket around the o-ring groove - that’s how the original BMC gaskets were. However I doubt this is your problem.

When you’re looking for oil pressure each time - is this by turning over on the starter or with the engine running?
If with the starter how long are you trying for - it will take some time even if you previously had pressure.