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MG MGB Technical - 72 MGB roadster dry start

I wasn't able to find anything on this topic in the archives, so I wanted to post the question. If my car sits overnight or longer, oil appears to drain out of the filter to the extent that when I start it I get a lot of valve/cam clatter. I get around this by pulling the coil lead off the distributor, and crank the car in five-second increments until the oil pressure comes up on the dash gauge, reconnect the coil lead, and start the car.

Is this typical, or would this indicate a problem with either the oil filter, the oil pump, or something else? I use Wix filters, but I replaced the original oil pump eight or nine years ago with one from VB when I had the engine out for a clutch/OD replacement. I've had the car for about thirteen years. So far as I know, except for the oil pump, the engine is original. I just rolled over 93k miles yesterday.

Any information on this topic would be appreciated.

Thanks in advance.
glq Greg

Greg. I have used the Mann W917 oil filter for a number of years on my cars having the inverted type oil filter, which I assume is the type you have. I started it a while ago after two days without being run. It started and I had oil pressure within three seconds.

So, the first thing I would do is try the Mann filter since I, and a number of others, have had good experience with them.

The second thing I would do is note how long it takes to get oil pressure on initial starting (not after having turned the engine over to either fill the filter or prime the pump). It normally only takes me about ten seconds when changing the oil (leaving an empty filter to be filled before the pressure would show). If it takes more three seconds, it may indicate the oil is draining out of the filter.

Is the stand pipe of the 18V oil filter adapter in place and in good condition? (This is the pipe coming upwards out of the threaded area in the center of the adapter. I have seen two examples where this pipe was missing and allowed the oil filter to drain even if it had a good anti-drain back valve.)

What oil are you using and what weight? I would expect, even after sitting for some time, that there would still be some oil present on the cam, in the lifters, and on the valve train. That should be more than sufficient to protect them from scuffing on start up. But, when using modern oils, a bottle of ZDDP additive would be wise.

If your oil pump shows a good reading on the dash pressure gauge, I would assume it is working properly. All of them will take a few seconds to get the oil circulating on start up, but no more than a few.

Please let us know what you find out.

Les Bengtson

I agree with Les, most likely to be filters with poor or no drain back valve of absence of the centre tube. I always use the Mann W917 as well, this has been shown to be best on our engines. The "clatter" is the timing chain tensioner getting up to pressure.
Allan Reeling

Thanks for the information. The center tube is in place. I recently switched from the tall Wix filter recommended for the MGB to a shorter one that was only about an inch taller than the center tube to see if it had any impact on my problem. Although it doesn't take as long to fill, it still loses oil through the tube.

Since I bought the car, I have used Castrol GTX 20w50 as the owner's manual suggests. I have read other posts on this BB about oil and now add a bottle of ZSSP additive with each oil change. I am thinking about going to Valvoline VR-1 racing oil 20x50 because it already has a zinc additive in it. This would be the less expensive alternative.

After reading your posts, I started my car a few minutes ago after having driven it yesterday afternoon. I got oil pressure within a couple of seconds without a lot of valve train rattle. Until my oil change at the end of last year, I had not used a ZDDP additive. Could it make that much difference?

I don't know whether a different brand of oil filter would make any difference. I think I would still have oil running back into the sump through the tube going into the oil filter.

I appreciate your comments. I will keep an eye on my start-ups, and try them without first priming the oil pump and filter to see what happens.
glq Greg

That would be ZDDP in the second paragraph.
glq Greg

The oil won't run back through the tube, it just drains out of the filter, consequently the pump has to fill it again before pressure is up. Screw on a Mann!! No you wouldn't notice the difference, anti-wear ZDDp is a longer term thing. Look for classic oils, GTX is not the formula is used to be!
Allan Reeling

I don't know if Castrol varies in different regions so you'd have to check the data sheets but in the UK many owners use Castrol XL 20w/50 (many get it from MGOC Spares who are Castrol agents)

as comparing manufacturers catalogues with all their database discrepancies and errors I'll leave that part to you but this might help -
Nigel Atkins

This thread was discussed between 14/07/2013 and 16/07/2013

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