Hobourn-Eaton oil pump bolt size.

[JOWETTJAVELIN]

After everything was going so smoothly, and EVERY single nut and bolt on the engine was removed fairly easily, one bolt on the oil pump just will not be moved. To make things harder, it is recessed and the minimal provided space around the bolt makes it hard to get a socket or spanner fully on. The other two came off just fine.

I have used a combination of AF spanners and some Metric sockets so far on the rest of the engine, which have worked perfectly, but I do not want to round this bolt off. Is it Whitworth and what size?

Any other tips to try and get the bleeder off?

[moggiethouable]

According to the Leyland manual and I quote "The oil pump is extracted by removing the two 3/16 in. hexagon headed bolts and spring washers locating the pump to the crankcase and easing the pump downwards.This is accomplished without interfering with the ignition timing." (Simple eh?)
Ive never removed one personally but I hope that helps with the spanner size.
Dont ask me if its Whit or what because I dont know, sorry.
The manual again says they should be tightened to 9ftlb only.

[bmcecosse]

Well -I'm guessing that instruction above ^^^^^^^ is NOT for the A series engine !!!!!! The securing bolts (1/4" unf) have always had 7/16" AF heads in my experience......certainly NOT Whit or Metric anywhere on the engine.......... I assume you have knocked down the little lock-tabs. If it's damaged then you could try 11 mm or maybe even 10 mm socket on it. It should not be tight - not much more than 'nipped up' really.

[moggiethouable]

Well -I'm guessing that instruction above ^^^^^^^ is NOT for the A series engine !!!!!! The securing bolts (1/4" unf) have always had 7/16" AF heads in my experience......certainly NOT Whit or Metric anywhere on the engine.......... I assume you have knocked down the little lock-tabs. If it's damaged then you could try 11 mm or maybe even 10 mm socket on it. It should not be tight - not much more than 'nipped up' really.

Right again B.M.C. there is an assumption that future pumps are either the same or the detail offered on Series MM engines is not necessary in such detail, as its not listed.
Series 2 engines are apparently fitted with what is termed a Burman rotary vane type oil pump, but sadly thats as detailed as it gets.
Then the only detail on the hobourn pump is "The cover and body of the new pump are dowelled together.................by a 3/16 in. countersunk screw.
"The assembly is held securely together by the 3 cylinder block attachment bolts"
"Securely "appears in this case to be an understatement.

[bmcecosse]

If it has an H-E pump fitted then someone must have been at the engine before - so that pump may be ok to use again. Strip it down and inspect the lobes on the rotor.

[moggiethouable]

Well -I'm guessing that instruction above ^^^^^^^ is NOT for the A series engine !!!!!! The securing bolts (1/4" unf) have always had 7/16" AF heads in my experience......certainly NOT Whit or Metric anywhere on the engine.......... I assume you have knocked down the little lock-tabs. If it's damaged then you could try 11 mm or maybe even 10 mm socket on it. It should not be tight - not much more than 'nipped up' really.

I hope the attached opens up, it is my second and therefore final attempt having minimised it again.
Part number BH604141 does indeed google as 1/4 unf, not that I would have the temerity to doubt you B.M.C. [frame][/frame]

[JOWETTJAVELIN]

If it's damaged then you could try 11 mm or maybe even 10 mm socket on it. It should not be tight - not much more than 'nipped up' really.

11mm socket worked perfectly on the other two which came away without much protest, but on the sole remaining bolt the 11mm begins to slip and 10mm is too small. I haven't had another go at it yet. Both my S.II engines are from late (1955/6) cars, so it seems these H-E oil pumps were fitted as standard from engine no. whatever as it says in the B-L workshop manual.

As you all know about the big end failure on the other engine, this must have been the cause of the low oil pressure rather than the pump, which if you remember showed excellent (65-70 psi) figures at cold-start.

If I cannot get the bolt off I might just have to leave the Hobourn Eaton in situ and hope for the best, since the bearings feel to be in good condition (no play), and it might be running with excellent oil pressure.

I'll keep you posted.

[bmcecosse]

Get the pump off! Have you used the CORRECT size = 7/16" AF... Use a ring spanner or a socket. Feeling the bearings is no use - take the caps off and inspect....... And ANY pump will make 65/70 on cold 20W50 oil..........

[JOWETTJAVELIN]

I have a good old set of Jenbro AF spanners, yes I used the 7/16". The problem is, you just can't get enough purchase with an open end spanner because the bolt head is recessed.

[bmcecosse]

Open end is hopeless....... You can't expect to work on Minors without a GOOD set of AF sockets and ring keys.

[JOWETTJAVELIN]

Aha... success: just been out to the garage to tackle this with fresh gusto and found another socket set I'd forgotten about. Sure I had to improvise to get some extra leverage, but a 7/16" socket did the job. Result: one free Hobourn-Eaton oil pump! I am a happy chappie as this means I can now put the whole engine back together.... no more stubborn nuts or bolts!


If you can't do something one day and are out of ideas and patience, walk away. Come back the next day with a fresh approach - works every time![frame][/frame][frame][/frame]

[bmcecosse]

Just use the CORRECT tools.....NOT Whit or Metric on A series engines.....or gearboxes.....or back axles......

[JOWETTJAVELIN]

Well what do you think of this oil pump? True I haven't stripped it down yet and it's the first time I've ever stripped an engine, let alone an oil pump. Can't see any sliding vanes yet unless they're inside.

[autolycus]

The other clue to the thread type (Unified as against Whit or metric) is the head of the bolt. The indented circle usually denotes UNF or UNC.

Kevin

[bmcecosse]

Open the pump - but it's not a vane type......that's been replaced with what may be a 3 lobe pump. Let's see the condition of the lobes!