Discussion
I thought I had encountered most Mini problems, but my 1310cc 1964 'S' has me really puzzled this time, so any ideas or opinions would be much appreciated.
My engine and transmision have just been completely rebuilt with everything renewed including pistons, bearings, oil and water pump, timing chain - in fact every wear part. It has just done one fairly hard rally at the conclusion of which it had managed to pump a lot of oil into the cooling system. I suspected a defective head gasket (BK450) so I changed (BK450 again) it and flushed out the entire cooling system with 5 litres of 'Hyper Clean' until I got completely clean water when I ran a hose onto the heater valve and ran water all through the system. I did this twice.
The block has ARP head studs and I dry torque to 50 lb. ft. The c.r. of the engine is 11.1:1.
On Friday I did about 50 miles and it has now got a load more oil in the coolant. The face of the head appears fine and the head was new and skimmed about 3000 miles ago as was the block about 12000 miles ago when the engine was first built.
I am guessing a cracked head or cracked block, although that's not something I've ever come across before, well, not from oil to water.
The oil pressure is quite high, it being a new engine, at just over 80 psi cold and 60 hot.
I don't want to change the block if it doesn't need it, even though I do have a spare that needs sleeving, as genuine 'S' blocks are like 'rocking horse droppings', but how in hell do you pressure test an 'A-series' block's oil way into water area? I have a shelf full of 12G940 heads and can easily gas flow another. I guess it's easy to crack test the head as there is only one oil way and one could plug one end and put, say, 10 bar pressure on the other end on a test rig.
Any suggestions?
Peter
My engine and transmision have just been completely rebuilt with everything renewed including pistons, bearings, oil and water pump, timing chain - in fact every wear part. It has just done one fairly hard rally at the conclusion of which it had managed to pump a lot of oil into the cooling system. I suspected a defective head gasket (BK450) so I changed (BK450 again) it and flushed out the entire cooling system with 5 litres of 'Hyper Clean' until I got completely clean water when I ran a hose onto the heater valve and ran water all through the system. I did this twice.
The block has ARP head studs and I dry torque to 50 lb. ft. The c.r. of the engine is 11.1:1.
On Friday I did about 50 miles and it has now got a load more oil in the coolant. The face of the head appears fine and the head was new and skimmed about 3000 miles ago as was the block about 12000 miles ago when the engine was first built.
I am guessing a cracked head or cracked block, although that's not something I've ever come across before, well, not from oil to water.
The oil pressure is quite high, it being a new engine, at just over 80 psi cold and 60 hot.
I don't want to change the block if it doesn't need it, even though I do have a spare that needs sleeving, as genuine 'S' blocks are like 'rocking horse droppings', but how in hell do you pressure test an 'A-series' block's oil way into water area? I have a shelf full of 12G940 heads and can easily gas flow another. I guess it's easy to crack test the head as there is only one oil way and one could plug one end and put, say, 10 bar pressure on the other end on a test rig.
Any suggestions?
Peter
All stud holes are well chamfered and it's clear that the oil is going in under pressure.
I'm glad that neither of you guys have ever heard of a block allowing oil under pressure to get into the water.
I do have to whip the engine out again as my new transmission is also playing up with, probably, a layshaft or layshaft bearing on the all-new box having given up. I am never surprised by Mini transmission problems as putting 117 bhp, under rally conditions of constant reversal of power/torque from 'full-on' to 'full-off' through a gearbox originally designed for 34 bhp is never going to be an easy thing and even with better materials one might expect problems. When it's all down I can have a good look and I may just do another head and try it. What I done want to do is rebuild it all (again), put it in and have the same problems.
I thought I'd seen almost everything with Mini engines over the last 45 years, but this does have me puzzled. I am even wondering if I got 2 gaskets from a bad batch, but I know that's also unlikely.
I'm glad that neither of you guys have ever heard of a block allowing oil under pressure to get into the water.
I do have to whip the engine out again as my new transmission is also playing up with, probably, a layshaft or layshaft bearing on the all-new box having given up. I am never surprised by Mini transmission problems as putting 117 bhp, under rally conditions of constant reversal of power/torque from 'full-on' to 'full-off' through a gearbox originally designed for 34 bhp is never going to be an easy thing and even with better materials one might expect problems. When it's all down I can have a good look and I may just do another head and try it. What I done want to do is rebuild it all (again), put it in and have the same problems.
I thought I'd seen almost everything with Mini engines over the last 45 years, but this does have me puzzled. I am even wondering if I got 2 gaskets from a bad batch, but I know that's also unlikely.
selbymsport said:
Hi Peter,
Never seen a cracked block or head cause an internal leak, but the head block interface can be troublesome. A crack coming from a stud hole may be a source of trouble, also it sounds obvious but do you chamfer the entry of the stud holes.
That would be my guess, possibly the stud has cracked the block. Is the block 11 studded? I knwo when I had mine done I was told that sometimes when it is done it is possible to crack the block.
Wildfire said:
Hi Peter,
Never seen a cracked block or head cause an internal leak, but the head block interface can be troublesome. A crack coming from a stud hole may be a source of trouble, also it sounds obvious but do you chamfer the entry of the stud holes.
That would be my guess, possibly the stud has cracked the block. Is the block 11 studded? I knwo when I had mine done I was told that sometimes when it is done it is possible to crack the block.
Gee, I hope not, but it's something to check when it's all in pieces again. It's a genuine Cooper 'S' block with 11 stud configuration from original. I guess if it's a small localised crack emanating from a stud I can try to grind the crack right out weld it up, check to see I've got it all and re-machine. Ardrox or a similar crack detection fluid should show it up. I must say I've never heard of this happening to such major effect, but there are new things to lean about Minis all the time. It seems a bit unusual for cast iron to crack from a stud as normally the stud thread fatigues and strips causing a need to 'helicoil' for the stud, but other things can and do happen. It will be a pity if the block is scrap, but fortunately I do have a spare.
I'm certainly going to get the head pressure tested as this is easy to do compared with a block and it's a very nice gas-flowed head. Alternatively I do have another head already flowed which just needs valves and a check on combustion chamber size.
myname said:
just a wild thought, but you've not somehow managed to have the head skimmed too much and juuuust broken through to the oilway up to the rockers maybe?? Vizard mentions this, just a thought...
No, there's plenty of 'meat' between head face and oil way.That's more of a problem with the 12G295 head, like the one I'm preparing for a Mk1 Sprite engine at present where there is 0.120" total thickness and it'll need skimming about 0.040" to get the c.r correct for an 1118 cc rally engine.
I'm still wondering if it might just be residual oil in the cooling system and I think I'll change the rad, all the hoses, the heater unit (I have a couple of spares) and again flush it all out before I do anything really serious and before I strip it out to do the layshaft (again).
I've just had a suggestion re the oil contamination of the water. Apparently another guy who rallies a Mk 1 Cooper 'S' had exactly the same problem and it proved equally hard to diagnose.
In the end it turned out that the seepage was in the oil pump area and one of the oil pump bolt holes had broken through very slightly into the water jacket. Current water pumps have 2 bolt holes whilst the Cooper 'S' had 3. However, during the many re-builds over the years most builders went to the 4 bolt variety leaving 3 redundant holes when a 2-bolt, as currently available, is fitted. Clearly this is a 'suspect' interface area with so many unused holes and I do know that the bottoms of the holes are very close to 'break-through' although with a bolt fitted this would not normally be a problem. I had a 4-bolt pump intil the last re-build, after which the problem manifested itself.
When I strip and rebuild I'll countersink the redundant holes and fit the 1/4" UNF c's'k head bolts, like the ones which go under the dulpex timing chain on the front plate, with Loctite sealer to ensure this will not be a recurring problem, if it is indeed the problem.
Anyone any thoughts on this?
Peter
>> Edited by cooperman on Monday 22 May 09:54
In the end it turned out that the seepage was in the oil pump area and one of the oil pump bolt holes had broken through very slightly into the water jacket. Current water pumps have 2 bolt holes whilst the Cooper 'S' had 3. However, during the many re-builds over the years most builders went to the 4 bolt variety leaving 3 redundant holes when a 2-bolt, as currently available, is fitted. Clearly this is a 'suspect' interface area with so many unused holes and I do know that the bottoms of the holes are very close to 'break-through' although with a bolt fitted this would not normally be a problem. I had a 4-bolt pump intil the last re-build, after which the problem manifested itself.
When I strip and rebuild I'll countersink the redundant holes and fit the 1/4" UNF c's'k head bolts, like the ones which go under the dulpex timing chain on the front plate, with Loctite sealer to ensure this will not be a recurring problem, if it is indeed the problem.
Anyone any thoughts on this?
Peter
>> Edited by cooperman on Monday 22 May 09:54
Certainly sounds feasable.
I happened to be looking in an old MiniSport catalogue this morning and saw this pic:
looks to me like the 4 bolt pump (no. 5 in pic) has a bolt hole overlapping the oilway in the 2 bolt (no.4).
If this is the case it could well be the problem.
cooperman said:
I had a 4-bolt pump intil the last re-build, after which the problem manifested itself.
I happened to be looking in an old MiniSport catalogue this morning and saw this pic:
looks to me like the 4 bolt pump (no. 5 in pic) has a bolt hole overlapping the oilway in the 2 bolt (no.4).
If this is the case it could well be the problem.
Oh Yes. Look at the different casting design for the pumps.I m now almost certain that the problem emanates from there.It makes sense that if the holes drilled for the 4-bolt happened to have gone right through - and my engine was machined by someone else about 10 years ago - this would be exactly whay would be likely to happen with a 2-bolt pump, bearing in mind the gasket land there is small and it's only a paper gasket, not a composit gasket with sealing rings like the head gasket.
Problem solved- looks like it!
Thanks everyone. We've all learned a bit more about Minis now!
Peter
Problem solved- looks like it!
Thanks everyone. We've all learned a bit more about Minis now!
Peter
I haven't had the time to get the engine out yet. Currently I've my Rover rally car to do some more preparation on as we've finally sourced some good suspension from GAZmatic and I'll change the whole lot. Then I've been painting my grandson's Mini which is almost finished and very nice it looks too. I'm building a A-H Sprite 1118 cc engine for a friend's historic rally car plus a '61 Mini 850 engine is in work as well.
Maybe I'll pull the lump out next weekend for a 'look-see' and I'll let you know what I find. I'm 99.9% certain we know what the problem is now, so it's just a case of doing the mod to prevent it happening again. If I could find a new Metro 4-bolt oil pump I would be happier. Any ideas?
Peter
Maybe I'll pull the lump out next weekend for a 'look-see' and I'll let you know what I find. I'm 99.9% certain we know what the problem is now, so it's just a case of doing the mod to prevent it happening again. If I could find a new Metro 4-bolt oil pump I would be happier. Any ideas?
Peter
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