Discussion
I've just had a most unusual thing happen on a Mini I'm working on. Whilst running the engine at low revs to set the mixture and adjust the timing, the oil pressure suddenly failed completely. There is simply no movement at the gauge whatsoever. Thgere are no external leaks either. This has never happened ever in my experience as oil pressure usually reduces due to bearing failure or just gets low over time. It appears that no oil is being pumped at all as I removed the pressure relief valve to see if that had stuck open and I cranked it quite a lot with the plugs removed and the pressure valve removed. No oil came out at all. Prior to this the pressure had been excellent at all revs with c.45 to 50 psi at tickover when hot and c.75 psi at 3000 rpm+ when hot.
Current thoughts are oil pump drive failure (why I wonder?), or fracture of the pick-up pipe (that would be a first for me too). I guess all will be clear once the engine is out, but does anyone have any other ideas.
Unfortunately I didn't build the engine, so the engine config is unknown. It could, just possibly, have a pin drive cam and have a short reach oil pump, i.e., an 850/998 pump in a 1275 non-'S' block, instead of the long-reach required for the big engines. AP list the short reach pump for all Mini engines and the pin only just engages into the pump slot which I've always thought a bit unwise.
Please let me have your thoughts,
Peter
Current thoughts are oil pump drive failure (why I wonder?), or fracture of the pick-up pipe (that would be a first for me too). I guess all will be clear once the engine is out, but does anyone have any other ideas.
Unfortunately I didn't build the engine, so the engine config is unknown. It could, just possibly, have a pin drive cam and have a short reach oil pump, i.e., an 850/998 pump in a 1275 non-'S' block, instead of the long-reach required for the big engines. AP list the short reach pump for all Mini engines and the pin only just engages into the pump slot which I've always thought a bit unwise.
Please let me have your thoughts,
Peter
pete
i think this engine has been trying to tell you something for weeks!
i guess you can find out what its other issues have been now its comming out.
i reckon (bearing in mind what you have told me about the joker who 'built' this engine) that like you said, either its a cheap oil pickup which has been catching the crank, or the drive has seared of the oil pump - ive seen this happen recently where somene bult a car that gave over 100 psi of oil pressure when running, the poor pump couldnt cope and snapped the tounge off - instant zero oil pressure!
i think this engine has been trying to tell you something for weeks!
i guess you can find out what its other issues have been now its comming out.
i reckon (bearing in mind what you have told me about the joker who 'built' this engine) that like you said, either its a cheap oil pickup which has been catching the crank, or the drive has seared of the oil pump - ive seen this happen recently where somene bult a car that gave over 100 psi of oil pressure when running, the poor pump couldnt cope and snapped the tounge off - instant zero oil pressure!
Hi Rich,
Yes, my thinking is that it's got to be an oil pump issue and either the drive has sheared off, or the drive spindle is not a tight enough fit onto the rotor, or it's a pin drive and a short spindle pump has been installed which only engages on the very end and has now fractured.
It will be sensible to get the engine out anyway and ensure that all the issues are addressed in one go. It certainly seems as though the No 4 inlet cam lobe is a few degrees retarded for the No 1 inlet lobe, which points to bad cam machining.
I wonder what else I'll find when I strip it right down. I'll be calling you for some bits shortly and the lump will be coming out on Saturday as I have another job to finish first.
Hey ho, it all makes work for the working man to do!
Yes, my thinking is that it's got to be an oil pump issue and either the drive has sheared off, or the drive spindle is not a tight enough fit onto the rotor, or it's a pin drive and a short spindle pump has been installed which only engages on the very end and has now fractured.
It will be sensible to get the engine out anyway and ensure that all the issues are addressed in one go. It certainly seems as though the No 4 inlet cam lobe is a few degrees retarded for the No 1 inlet lobe, which points to bad cam machining.
I wonder what else I'll find when I strip it right down. I'll be calling you for some bits shortly and the lump will be coming out on Saturday as I have another job to finish first.
Hey ho, it all makes work for the working man to do!
Retirement from my 'proper' job has meant just more Mini work - not a bad thing.
As Rich knows, I'm currently working on the 'Mini From Hell'. It's an "Ebay special", bought as a 1970 Cooper 'S' just requiring minor work to complete its rebuild into a 1972 shell. However, it's not a 72 shell, it's from a Mini Rio. Everything I've looked at has been wrong, from the different sized rear brake cylinders (3/4" one side and 5/8" the other), to the drive shafts jammed solid into the Hardy-Spicer splines (had to angle grind one side off!), to sheared-off trapped nuts at the rear sub-frame attachments, to the wrong brake pressure limiting valve and wrong master cylinder. The alternator was out of line, the fan on the wrong way around, the cam timing is still suspect, but it may be the actual cam. The horn wiring was connected to the coil, the carbs were not a matched pair and someone had filed out one of the carb jets, the float chamber pipes leaked, the exhaust manifold (lcb) was not installed properly and the exhaust pipe didn't have clamps, it had jubilee clips instead. The clutch machanism has about 0.050" free play due to worn clevis pins and slave drive rod and now the oil pressure has gone away. And those are just the main areas of problem - there is a lot more.
Never has the term "Buyer Beware" been more appropriate than with this car.
I just feel so sorry for the very nice guy who bought it in good faith, but who has no real prospect of any comeback from the vendor.
As Rich knows, I'm currently working on the 'Mini From Hell'. It's an "Ebay special", bought as a 1970 Cooper 'S' just requiring minor work to complete its rebuild into a 1972 shell. However, it's not a 72 shell, it's from a Mini Rio. Everything I've looked at has been wrong, from the different sized rear brake cylinders (3/4" one side and 5/8" the other), to the drive shafts jammed solid into the Hardy-Spicer splines (had to angle grind one side off!), to sheared-off trapped nuts at the rear sub-frame attachments, to the wrong brake pressure limiting valve and wrong master cylinder. The alternator was out of line, the fan on the wrong way around, the cam timing is still suspect, but it may be the actual cam. The horn wiring was connected to the coil, the carbs were not a matched pair and someone had filed out one of the carb jets, the float chamber pipes leaked, the exhaust manifold (lcb) was not installed properly and the exhaust pipe didn't have clamps, it had jubilee clips instead. The clutch machanism has about 0.050" free play due to worn clevis pins and slave drive rod and now the oil pressure has gone away. And those are just the main areas of problem - there is a lot more.
Never has the term "Buyer Beware" been more appropriate than with this car.
I just feel so sorry for the very nice guy who bought it in good faith, but who has no real prospect of any comeback from the vendor.
Hi Peter, reminds me of a Lotus Elan S4 I bought back in the mid 80's from a trader near Scarborough.
The inlet manifold, cast as part of the head was bodged together with exhaust bodge or dum dum, the new chassis was the old chassis under a nice coat of paint etc etc. Looked absolutely stunning in its shining red fibreglass body but underneath, the bits you couldn't see without stripping it down.........still I traded my Metro turbo in for it and that was another story as they say.
The inlet manifold, cast as part of the head was bodged together with exhaust bodge or dum dum, the new chassis was the old chassis under a nice coat of paint etc etc. Looked absolutely stunning in its shining red fibreglass body but underneath, the bits you couldn't see without stripping it down.........still I traded my Metro turbo in for it and that was another story as they say.
The saga continues!
Just taken the engine out and stripped it. The oil pump is scored and worn, but not so badly that it wouldn't pump anything at all. The oil pick up pipe seems fine.
However, the flywheel was about to fall off and has damaged the end of the flywheel. I reckon we caught it just in time before it did real damage. Then, at the other end of the engine, a duplex chain had been fitted without replacement of the hex head bolts with countersunk ones. The result is a damaged chain and some very second-hand looking bolts.
Crank float is about 0.010" but the existing thrusts are std.
I guess all I can do is to rebuild the entire engine with a new oil pump, new thrusts (big ends and mains are like new still), flush out all the oil galleries and put it back together very carefully. The oil pump is s spider-drive and the cam has no idents at all.
It's a very strange problem.
Just taken the engine out and stripped it. The oil pump is scored and worn, but not so badly that it wouldn't pump anything at all. The oil pick up pipe seems fine.
However, the flywheel was about to fall off and has damaged the end of the flywheel. I reckon we caught it just in time before it did real damage. Then, at the other end of the engine, a duplex chain had been fitted without replacement of the hex head bolts with countersunk ones. The result is a damaged chain and some very second-hand looking bolts.
Crank float is about 0.010" but the existing thrusts are std.
I guess all I can do is to rebuild the entire engine with a new oil pump, new thrusts (big ends and mains are like new still), flush out all the oil galleries and put it back together very carefully. The oil pump is s spider-drive and the cam has no idents at all.
It's a very strange problem.
It's not just been assembled with a damaged O ring between the block and gearbox has it?
I'm sure you looked but I'm just paranoid about O rings at the moment having spent ages chasing a problem with my modern Saab. It was hunting slightly - turned out to be a very minor crimp in the O ring beneath the throttle body.
I'm sure you looked but I'm just paranoid about O rings at the moment having spent ages chasing a problem with my modern Saab. It was hunting slightly - turned out to be a very minor crimp in the O ring beneath the throttle body.
It's a 'spider drive'cam, so it's pre A+, as is the block. In fact it's quite an early block, I think, assuming the rods are the same age, as the rods are the ones with the big 'lumps' on the big-end caps ('orrible, I know).
The 'O' ring was in place as it was one of the things I checked first of all.
What really needs to happen here is to use another block, use better rods, re-bore the replacement block and use the correct pistons (21253) not the 21251's currently fitted, fit a new cam with a spade drive, a new oil pump, etc. Before assembly clean out all the oil galleries and fit new gallery core plugs, deck the block and do a 'proper' build using 'best practice' throughout.
I may recommend this to my customer and I think I can source a decent block. I do have a spare 12875 GT crank which would be better than the one damaged by the loose flywheel. It won't be cheap, but at least we'll have the confidence that it'll be right.
The 'O' ring was in place as it was one of the things I checked first of all.
What really needs to happen here is to use another block, use better rods, re-bore the replacement block and use the correct pistons (21253) not the 21251's currently fitted, fit a new cam with a spade drive, a new oil pump, etc. Before assembly clean out all the oil galleries and fit new gallery core plugs, deck the block and do a 'proper' build using 'best practice' throughout.
I may recommend this to my customer and I think I can source a decent block. I do have a spare 12875 GT crank which would be better than the one damaged by the loose flywheel. It won't be cheap, but at least we'll have the confidence that it'll be right.
hi m coming in a little late. It"s actually quiet a common failing on new or old a-series. what's happened is that the oil pressure relief valve has stuck. it's alloy and it will easily score and stick in the gallery with a bit of swarf from as u say a messy engine build.
the trick is to catch it early - spin the engine backwards to prime the pump while forcing oil through the pressure outlet -
then spin engine( without sparks and oil galleries open ) 9 times out of ten you revive pressure
Over the years we've made quiet a few customers for life with the phone call "about their saved engine"
For easy testing of pump and internals - when cold pressure light should estinguish instantly on start up when all back together
the trick is to catch it early - spin the engine backwards to prime the pump while forcing oil through the pressure outlet -
then spin engine( without sparks and oil galleries open ) 9 times out of ten you revive pressure
Over the years we've made quiet a few customers for life with the phone call "about their saved engine"
For easy testing of pump and internals - when cold pressure light should estinguish instantly on start up when all back together
No, it's not the oil pressure relief valve - that was the first thing I looked at as it's happened to me several times in the past. I then fitted a new relief valve and spring after cleaning out the hole. No joy. It really didn't seem to be pumping any oil at all and although the oil pump was badly scored, it should still have pumped something. Anywaqy, I have sourced a new A+ block, crank and pistons as a replacement with only 8000 miles from new. I'll do a precautionary re-build with new rings, thrusts, oil pump and bearings, plus a block deck skim if required. That will sort the problem once and for all. Of course, I'll check the gearbox oil pick up to ensure all is well in that direction.
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