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MG MGB Technical - No oil pressure on startup

A couple of weeks ago I posted on here with a problem I had with oil pressure on my '66GT. I'd done a full service including oil and filter, and since then noticed that on startup after the car had been standing I had no oil pressure for 5 or 6 seconds. The conclusion was that the oil was draining out of the filter overnight and that the engine was starved of oil until the filter filled back up again.

I removed the old Champion C102 filter (lo and behold, it was empty) and got a new Unipart GFE121. I visually checked the anti-drainback valve was in place this time, and...I still get no oil pressure after standing. Now I think it's pretty unlikely that I've had 2 faulty filters from 2 suppliers and 2 manufacturers. Could this be due to the oil I'm using? It's Castrol GTX 15w/40 and was all I could get - could this bee too thin and be causing the problem? I want this sorted for the sunshine - and the bearing noise on startup really makes you wince...

Thanks as always,
Tim.
Tim Jenner

Tim,

I assume that you have the "upside down" type of spin on canister filter?
This drain back problem can go on forever. It is very difficult to get a filter that works properly, none of the drain back valves seem to work.
The solution is to get a filter adaptor that has the canister the right way up.
A good investment compared with fitting new bearings.
You can see what is available on the Moss (USA) website. I assume Moss (UK) have the same item.
Website is:

http://www.mossmotors.com

Go to MGB, then Accessories, then Maintenance.

Mick
M F Anderson

Hi Mick,

Thanks for the response. My car has a modern spin-on type filter (not the old canister type) but it is mounted upside down. Will the filter adapter still fit?

Thanks,
Tim.
Tim Jenner

Tim,

You say your car is 1966. Is a four cylinder, not a V8?
You have a spin on filter, is it already fitted with an adaptor? Doesn't your block casting have the normal fitting for a downward facing canister?

Mick
M F Anderson

Get thee to the Volvo dealer and use their filter which is a Mann one. Turn the key and presto, oil pressure ! I'm using the upside down spin-on adapter.
Al
Al McMillan

Have had this problem a number of times with the 'on top' spin on filter such as GFE121, even UNIPART ones.
Best bet have NEVER had one drain out, use FRAM PH2958A. This is the filter recommended for the V8. If any spin on GFE121 drains out take it back for a refund.
The 66 originally had a canister from the bottom with a throw away element, these also syphon empty. The worst filter is the GHD/N4 - 18GD engines - type with the 'on top' element. These engines always suffer bearing failure prematurely.
Garth
Garth Bagnall

Thanks for the responses, everyone. Mick - yes, it's a 4 cylinder GB engine. Are we guessing that the problem lies with the filter rather than the grade of oil I am using? Does anyone know if the FRAM filters are available in the UK?

Thanks,
Tim.
Tim Jenner

Tim-
Actually, Garth has had good luck so far with the Fram filters. However, trusting to luck is not a good idea. Of the filters made by the five largest filter companies, Fram filters have the worst antidrainback valve design. Whenever a complaint about this design feature is posted on this BBS, it's almost always about a Fram filter. The Champion design is a bit better, but still not very good. Here's an article on the subjct that you can spend a half hour studying: http://www.scuderiaciriani.com/rx7/oil_filter_study/ Avoid using filters that are taller than necessary, otherwise when the engine is shut off any oil above the stand tube will drain out of the filter, leaving an air pocket that must be filled before oil pressure can be achieved. While the choices of filters available are almost endless, the best of these including those from Mann (Part# W917), Purolator Pure One (Part# PL20081), and Motorcraft (Part# FL300), but the most effective is also the easiest to install: the K&N Performance Gold Oil Filter (K&N Part# HP2004). Even in the wilds of Australia I'm sure that the Motorcraft filter should be available, and it's pretty popular with MG owners.
Steve S.

Hi,
I own a 80 MGB and my book don't recommend FRAM filters.
I use the Delco PF13C and never had a problem YET!!!
I was reading somewhere on this site the filters recommended and all the Frams were not. My filter is the Top Loading (upsidedown) type.

Cec
Cec Fry

I agree with Al, go with a Volvo filter. I've been using them for a while now and they work great! Recently, I ran out so I went to the local auto parts store and decided to give the K&N filter a try (twice as expensive as the Volvo). It seems to take forever to get the oil pressure up. I'm going to try to stop by the Volvo dealer this week to pick up a case so I can switch that K&N out before I cause some damage!

Robert
Robert Rushing

Which Volvo filter do I need to ask for (which cars was it used on)?

Thanks,
Tim.
Tim Jenner

The Volvo filter number is 3517857-3. It is white, has a Volvo label, and apparently is made by Mann in Germany
Al
Al McMillan

I've used both Champion and Unipart 'upside down' filters and neither drain out while standing in fact it is a right pfaff to change them without making a mess. Neither does it take as long as that to register pressure. But I drain and change with the engine hot, which means the engine has only been off for a matter of moments before unscrewing the filter. Are you saying yours drains back in this time? Or do you change them cold? I have been using GTX 15W/40 for some time since it changed from 15W/50 with no apparent difference, although this time I used Halfords 15W/50. There was a relief valve in the original 'replaceable element' type filer housing, I'm assuming it is there is the cannister type housing as well, could that be at fault? If Champions used to be fine and now neither they nor Unipart are it seems unlikely the filter is at fault.
Paul Hunt

I have a fair idea what the problem is as I had an old autin Allegro (dont Laugh) that had the same problem .The fault lies in a relief valve positioned on the side of the engine block basically it stops over pressure of oil supply system but as car gets older the spring gets "tired" and can result in no apparent oil pressure for first few seconds after start up cure is simply to replace spring which is a cheap item and less than five minutes to change.
Paul Rodgers

I always change the oil hot and, like you Paul H, I've always made a mess when unscrewing the filter. I took the car to a show in Chatham today and in the 7 hours I was there enough oil had drained out of the filter that there was zero pressure for at least 3 or 4 seconds on startup. This morning, when the car had been standing for a couple of days it took 5 or 6 seconds for pressure to build up.

My confusion on all this stems from the fact that I've never had this problem in the 4 years I have owned the car. This has only started since changing the oil and filter, so the obvious culprit would be one or the other. If the pressure relief valve was faulty, wouldn't I have seen this behaviour before as well? And wouldn't the running oil pressure be different to normal? Or, perhaps the spring is only "lazy" enough now that I have switched to 15w/40?

Thanks again,
Tim.
Tim Jenner

Can an oil pump get sufficient oil around the engine to reach full pressure in less than 5/6 seconds? Clearly if the filter is empty then the pump has to fill that up befor eit can pressurise the system - so will take longer than if it were full.

My GB engine (in 66 BGT) had the inverted tecalemit filter fitted (ie the housing pointed upwards) and oil pressure took 10-15s to arrive. I quickly changed it for the correct downward pointing version and the time reduced to 5 seconds which I thought was ok (certainly worth the oil down the arm each time you change the element).

My second point would be to question what effect the oil viscosity change would have on the oil pressure. If you changed the oil viscosity then surely the time taken to reach full oil pressure would change, since the viscosity of the oil presumably affects the movement of the oil around the engine. I cannot remember which of the numbers refer to the cold, as opposed to hot, performance of the oil but as they are both lower than 20w/50 it might suggest a longer time to reach pressure.

Of course all these ramblings might be complete garbage...

Richard Atkinson

To avoid the mess when changing the inverted typ of filter , poke a hole in the top of it before draining the oil from the sump , by the time that's done and you've made up a new lube sticker and laid out the fresh oil and new filter it'll be nearly dry and only a few drops will come out when you remove it .

-Nate
Nate

Tim,

I have used a stock Unipart filter on the two occasions I have changed the oil in the past year. On both occasions my oil pressure was poor on startup. When I had the car in for some work at a local mg specialist recently, they changed the filter and oil and used a FRAM filter from what I can read on the side of the label. Since then the pressure builds up within a second or two even after a few days of being sat in the Garage. I think Moss sell the FRAM version in the UK.

Phil.
Phil B

Tim - I was thinking that perhaps the valve chose that particular moment to fail, so even going back to the old filter and oil (if you see what I mean) would not have improved things. I use newspaper worked under the filter from above to act as a sort of 'nappy' and catch what dribbles out of the filter in a sort of cup-shape, then poke it through to the bottom endeavoring not to spill it. Achieved a drip-less change for the first time in 13 years last week - then when topping up the gearbox managed to get the pipe down the side instead of in the hole! Punching a hole in the top first is worth trying - *after* one has confirmed that the filter will turn!
Paul Hunt

Well said Paul, but you forgot to say,

Punching a hole in the top first is worth trying - *after* one has confirmed that the filter will turn, - And that you have a new filter which is the correct type.

Tatty ( Non-member since 2003 )
Tatty

Up to now I've never started a service without having a new filter to hand. But now you have said that I will probably forget, thanks a bunch!
Paul Hunt

Your welcome ;)
Tatty

I've always had a filter to hand...but rest assured, a Morris Minor filter will not fit!!

Tim.
Tim Jenner

While we are on about oil filters, should there be some sort of up-standing tube that goes up inside the inverted cartridge? If there should be, my car has never had one. What difference would it's absence make? How is such a tube fitted onto the filter mounting?

Mike
Mike Howlett

There's a tube on mine, but I think it's part of the filter mounting itself. I don't know what difference NOT having the tube might make, perhaps the oil would not have to go all the way through the filter before being returned to the engine?

I have a third filter on its way from the club this week - I'll fit that and if it doesn't make any difference I will try to get hold of some 20w/50 (believe Duckhams still do it). This pressure relief valve - presumably the oil must be drained before it can be removed?

Tim.
Tim Jenner

Mike,
Just to make sure, you're referring to the spin-on cartridge, not the cannister -- correct?

If so, then not having the tube would allow the oil to drain out of the filter. That's why it's said not to use a taller filter than stock -- the oil will drain down to the level of the tube, leaving an air space that will need to be filled before you can get oil pressure. The taller the filter, the bigger the air space...

I've no idea how the tube is attached, but I'll bet it's pressed in.


HTH!
Rob Edwards

Thanks Rob, yes, it is the spin-on cartridge. Looks like I need to source a tube.

Mike
Mike Howlett

This thread was discussed between 18/04/2003 and 23/04/2003

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