Broke my 1200 oil pump - replace or repair?

[Colin Lindsay]

I broke my oil pump!! Took the sump off the 1200 engine to see if it was actually pumping (it had been) but on replacement I managed to crack the end plate. No idea how, but it happened.

NOW: first instinct would be to buy a new one (this one was an old pump, good condition but reused) but I've heard all the horror stories about the quality of replacement pumps these days. Anyone got any recent experience?

Second thing would be to replace the end plate that is broken from a spare unit. I'm not sure what condition the spares are so am debating just reusing the plate rather than the entire unit, in case the replacement is worn. Anyone see any problems with this? I'm always paranoid about oil and oil changes so want the best for the engine, but the rotors and the rest of the pump are excellent.

 

 

[johny]

First Colin measure the tolerances on this pump - endfloat, rotor to cylinder and cylinder to casing. If all good I see no problem using another end plate of the same type (never seen those cut outs before!) providing its flat and doesnt increase rotor endfloat....

[Colin Lindsay]

I've inspected my old pumps and I'd not trust them, after all they're in engines that came out of Heralds that were broken. I'd also rather not chance the bottom plate on them either. Seems like I'm buying new... but forty prices over the Net and nothing that has made me reach for the credit card so far. I'll wait to see if anyone has good experience of any.

By the way I found this one earlier, pricey but interesting:

 

 

[Josef]

The bottom plate from any of the spare ones would probably be salvageable. Flat it back smooth on a piece of flat glass and it’ll be fine! Probably better than fine as it’ll be super flat. 

[johny]

You must have heard the stories Colin of new pumps having worse tolerances than the ones being thrown away😂

[thescrapman]

10 hours ago, Colin Lindsay said:

I've inspected my old pumps and I'd not trust them, after all they're in engines that came out of Heralds that were broken. I'd also rather not chance the bottom plate on them either. Seems like I'm buying new... but forty prices over the Net and nothing that has made me reach for the credit card so far. I'll wait to see if anyone has good experience of any.

By the way I found this one earlier, pricey but interesting:

 

 

I have James’s pumps in 2 of my saloon engines, as do lots of friends.

We all felt the additional cost more than compensating for the time he puts into them

 

 

[Colin Lindsay]

2 hours ago, thescrapman said:

I have James’s pumps in 2 of my saloon engines, as do lots of friends.

We all felt the additional cost more than compensating for the time he puts into them

I like the look of that, but it'd be wasted in my estate. Low mileage and all at slow speeds, probably. Having said that, the 'fit and forget' idea of a well setup pump would appeal and over a few years would more than justify the cost, with no worries about the poor manufacture of many repros these days. I might just take the plunge!

[johny]

I know this might be a delicate question Colin but so we can all learn how did the old pump bottom plate get broken? Ive been trying to think of all possibilities and remain mystified - was the rotor not engaged with the drive so sticking out?

[Colin Lindsay]

5 hours ago, johny said:

I know this might be a delicate question Colin but so we can all learn how did the old pump bottom plate get broken? Ive been trying to think of all possibilities and remain mystified - was the rotor not engaged with the drive so sticking out?

Corner-cutting, Johny. I had the engine rebored and all rebuilt but was reusing an old pump that had been providing good pressure, but once the assembled engine was cranking on the starter with the plugs removed I thought it may not be providing the best pressure. I had packed the pump with vaseline to aid startup so wanted to make sure it wasn't blocking anything. Took off the sump and dropped the pump out to inspect it, reckoned it was fine, but then I replaced it from underneath with the drive in place as I was too lazy to find TDC and reset the timing again. The bolts were going into place nicely, no resistance, and I was supporting the pump with one hand and the ratchet with the other when it suddenly cracked and fell off. Old damage, metal fatigue, or something unforseen by not removing the drive and hoping they would engage gently when drawn together, which they seemed to be doing. The engine sat for a long time before rebuild with the pump sticking out so it may have been knocked in passing.

In any case I've gone for that uprated Shacktune pump, arriving tomorrow, so if I get time we'll be complete again by the weekend and I'll have to take the rocker off and find TDC all over again.