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MG MGB GT V8 Factory Originals Technical - Oil Pump Flow Direction

Hi all, can someone tell me please the direction of oil flow from the MGB V8-style oil pump? Does it come out of the forward union or the rearward one?

I know the filter is used with oil going in down the outside and returning up the middle, but am not sure about connecting to the pump. For my filter base that means the oil should enter via the front facing union - this seems contrary to what I see on most conversions.

Thanks. Mike.
Mike Howlett

This is a good one. It cropped up a few months ago and caused some head-scratching then. On factory V8s the filter head is marked with a flow-direction arrow that points to the back of the car. The rear outlet of the filter goes to the rear port on the pump, indicating that oil goes in there and hence comes out of the front port, which goes to the cooler, and from the cooler to the front port on the filter. Later factory V8s have the oil gauge pipe on the pump and not the filter head, and it screws into the front port i.e. the outlet, which is logical as it will then get the benefit of oil pressure direct from the pump and not after it has been through the resistance of the cooler as it was originally. Of course that is nothing but driver kidology as the pressure at the filter will be the same as before, and at the bearings even less!
Paul Hunt

The plot thickens! I happen to have both the first and third editions of Roger Williams' book on MGB V8 conversions. On page 30 of the older book, his oil flow diagram shows the oil exiting the rear union on the pump, going to the filter then to the cooler, before returning to the front union on the pump.

On page 30 of the new edition, although the diagram is the same, the flow has been reversed. It now shows the oil leaving the front union on the pump, going to the cooler first, then the filter before returning to the rear union on the pump.

Can we assume that the original diagram was incorrect and was put right? As Paul mentions, the oil pressure gauge outlet is on the front union of the pump, so perhaps that is the outlet.

There must be someone who knows for sure.
Mike Howlett

More logical argument for the direction I described is in the Workshop Manual Supplement for V8s when it talks about priming the pump if you have failed to pack it with Vaseline before reassembly. It says to remove the hose that comes from the cooler from the front of the filter head, the arrow on the filter head indicating that is its inlet, and fit a funnel in the end of the hose. Pour oil into the funnel, and turn the engine *backwards*. Gravity being supposed to run the oil through the cooler and into the pump itself, then turning the pump pushes it backwards through the pickup into the sump.

If the later V8 conversion book shows it the way I have described, it is pretty strong evidence that the original diagram was incorrect, especially if you take into account the other two logical deductions.

But without disconnecting a pipe at the filter, turning the pump or cranking the engine and seeing which half oil comes from, you aren't going to know for sure. But then that needs an assembled and working engine ...

Paul Hunt

I have been through this, the original picture is incorrect.
Regards
Tony
Tony Bates

" But then that needs an assembled and working engine ..."
Nearly there Paul. See picture.
Thanks Tony, that is the conclusion I have come to as well.


Mike Howlett

Mike, a bit off topic, but I'd be interested in how your engine steady bar works out. I've been down that road & had to change the mounting point from the fender to the chassis rail rather quickly. Barrie E
Barrie Egerton

The steady bar is the one sold by Clive Wheatley. Its at the bottom of this page http://mgv8.homestead.com/bgeng.html
I'm a little way from running the engine yet. What was the problem you had Barrie?
Mike Howlett

Mike, on hard accelleration, the LH front wheel tended to lift & the car altered course alarmingly.The bar I used came from a P6B Rover V8.It was a very easy installation, but just didn't work for me. Barrie E
Barrie Egerton

Hi all,
Sorry to continue off topic
I took a picture of this engine steady fitted to a V8 Roadster on the MGOC stand at the Classic Car show last year and was planning on going this route. I have my engine in now and have had it running and it does move a lot on blipping the throttle. It looks like a Mini steady bar to me?
cheers
Steve

Steve Danson

Steve, this looks a safer bet than Mikes' or the one I fitted. The bar is much further back & not in line with the front wheel. Barrie E
Barrie Egerton

Just to stir the pot: As mentioned before, I fitted an original V8 motor to my MGB. because the filter was missing, I purchased a new one with mounting bracket from the local MG parts supplier. On this new unit, the connection pointing to the rear is stamped "IN". When I queried this last year in this forum, I was advised that the rear oil pump connection was the outlet (I can't remember who it was that sent this advice, and the messages have now been cleared).
However, this makes sense to me, as the pipes would be very untidy if one connected the front oil pump union to the rear of the filter.
Chris Barrow

It only makes sense if both the oil filter housing markings *and* the pump direction were different to what the books say, in which case your plumbing would be the same as everyone elses. However none of us actually knows how the oil is circulating until we take a pipe off the filter housing and turn the engine, and we would each have to do that to make sure there is not some quirk in the oil pump and its drive and passages i.e. front cover that mean it goes in one direction on some engines and the other way on others. These engines had many different applications with various front covers. I'd also be wary of a newly purchased filter housing, you have no way of knowing that it isn't for some other application where the direction *should be* the other way. It certainly doesn't matter which way the oil circulates through the cooler, how about the filter? Unless and until any pressure relief valve opens if the filter should become blocked that probably makes no difference either.
Paul Hunt

Everything I've read says the oil should enter the outside of the filter and return up the centre, so if you look at the underside of your filter head you can see which union should be the "IN" and which the "OUT".
Mike Howlett

This thread was discussed between 17/01/2009 and 09/02/2009

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