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MG MGB GT V8 Factory Originals Technical - Oil Flow Direction
|The recent thread on this subject refers. Owing to discussion around this question, I have definitely proved that the oil leaves the engine by the front hose on the oil pump adaptor, passes through the cooler and returns to the remote oil filter head via the front connection, accessible in the diaphragm plate hole.It then passes through the filter and returns to the engine via the rear hose.This is clear when observing the porting design and gear direction on stripped pumps and was further proved by diconnecting the hosing and observing the oil direction when the engine was cranked on the starter motor.It flows from front to rear as stated by the previous respondents.|
This means that the oil must enter the filter via the outer drilled annular area and leave via the central tapped hole in order to flow in the correct direction from the outside of the filter element toward the centre.The oil filter head which I had obtained locally (Mocal type) was found on inspection to be in the incorrect orientation in that the oil entered the filter via the central hole and exitted radially outwards, against the design of most screw on oil fiters.This was subsequently replaced by a correct filter head.
Nice work mate. It sounds like you have it sorted out. One little thing to think of-- When you fit your oil pressure gauge fitting to the system. either fit it to the oil gallery of the block or the side of the pump where the oil returns from the filter to get an acurate reading of what the engine is getting. If it is fitted to the outlet side of the pump before the oil travels through the filter and cooler (if fitted) the reading will be false (high) Cheers Willy
|Hi Will, |
Yes, you are quite correct.In our case,we drilled and tapped the oil filter head before fitting it into the engine bay in the area of the outlet port to feed the oil pressure gauge line. The gauge thus measures the oil pressure into the engine after filtration.
|Ironically the factory did the very opposite, moving it from the outlet (I think) of the filter head to the outlet of the pump precisely because people were complaining of low (or slow to rise) oil pressure! Whether it makes that much difference in practice I'm not sure, a max pressure of 42psi is quoted (and displayed) for both. Wondering if the long run of small-bore pipe was contributing to the slow rise I temporarily fitted a gauge with a large-bore transparent pipe and it took just as long. It is only when you get any back-pressure from the crankcase after filling all those myriad passageways to bearings, tappets and rockers that you get a reading, which is why it takes so long. Still after turning mine off when fully up to temperature and leaving it for a couple of weeks before I examined the main and big-end bearings it was heartening to see just how much oil was left on the shells.|
Your experiment with fitting a gauge and big bore pipe to see if the length of capillary contributed to the slow build up is interesting. I have been meaning to do that one myself.
I think Clive Wheatlet sells a one piece flexible pipe that goes from gauge to pump. I was wondering if this pipe would help get a quicker reading on the gauge, but I guess not.
The only reason I suggested that the gauge be fitted after the filter etc. is because it is good to know exactly what you are getting. A possibility that comes to mind is if the car is fitted with a filter that doesn't have a bypass valve and the filter is a bit clogged and maybee the oil a bit thick or cold there would be a fair bit of difference at revs between the output from the pump and what the engine actually gets.
Having said that,I think the factory oil pump adapter has a bypass valve built into it to stop this from happening but I am sure I have seen one that only had the pressure relief in it and no bypass. Would be a good thing to check on when buying an oilpump end plate for a v8 conversion or replacement Cheers Willy
Ian Many SA's going to the Natmeet- only two from here as far as I know must be all waiting for next year over your way That thing of Kempy's looks the goods He'll just about clean up I reckon. Bye
I am not sure how many are going to Geelong for Easter but I am sure Kempy's monster V8 will be pushed to the limit and clean up! Kempy never takes any prisoners!
|There are two brass blanking plugs on the side of the oil pump, the larger one is the pressure relief valve that gives the 42psi. Maybe the other one is a bypass, the manual doesn't mention it.|
This thread was discussed between 28/03/2009 and 01/04/2009
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