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MG MGB Technical - Oil Pressure after oil change

HI Everyone,

Just had a little bit of a freak out as I just had time to search the subject. I changed the oil in my 79 B. Filled the oil filter with oil and mounted. I cranked her a few times and then started her. I ran her for about 3-5 minutes and somewhere in those minutes I checked the oil pressure gauge and it was not registering...

I read that the oil filter is the culprit. I bought the Wix oil filter from a great old store whose owners have MG's. Ive been able to walk in and pick up an engine mount if you can believe it or not...

This Wix oil filter is also mentioned on the Moss Motors online catalog. I am going to change the filter with a different one but my utmost main concern is the potential damage... There were no bad sounds or any smoke... What am I dealing with here?

On a side note when going to buy an oil filter at the local autozone store since they carried valvoline vr1, I found out there was a fram filter recall for the MGB filters as they were failing...

Thank you,

James
JRB Mr

Wix filters are one of the best you can purchase. The filter that fits the MGB is a common size and also fits many other American vehicles.

I can't see how the filter could cause a low pressure reading (unless it is visibly leaking) after the motor is running for 3-5 minutes.

Did you somehow dislodge the wire going to the oil pressure sending unit on the fire wall?
Steven 67GT

I am going to check when I get home. I just had to pull the clutch master cylinder and also ran a new clutch line. At the end of that all I did the oil. So it definitely could be the case and its what I originally thought untill I got bored at work and referenced this thread : http://www.mgexperience.net/phorum/read.php?1,1453358
JRB Mr

From earlier post I made:

I have been puzzled by repeated mention of oil pressure drops related to filter changes, and now have come across one possible cause. A long distance customer (79 MGB) called to say that he had taken his car to have the oil & filter changed, and on driving away had 10psi, instead of its normal 60, so he went back, gingerly. They admitted that they had put a modern 5W-20 or somesuch in, rather than the 20W-50 requested. They changed the oil and said it was now OK, so he drove off, NOT looking at the gauge, since it was "OK". Fortunately he was in the city and driving gently, because when he did look at it, it still had 10psi.
He called me, and then sent it the 100 miles up here via AAA.
The very small filter was a dead giveaway, since it was about the same height as the length of the standpipe. On examination, the standpipe had been in contact with an internal support in the filter, in fact bending it. The standpipe was effectively 98% blocked; if he had made one heavy acceleration run, he would most certainly have scattered the engine. Other filters may have similar but less drastic effects if the standpipe is a bit less restricted than this one was. A difference of 1/8" in the internal construction could give normal performance at low speed and total disaster at full throttle. I would recommend that any filter be examined to be certain that all internal components are at a minimum a full diameter away from the standpipe when fully tightened. I have noted that many parts listings list things like "MG, all, 71-80". This filter screws on to an A-series and may in fact be correct for that app, but it certainly isn't for a B. Be really careful if you let anyone but yourself change filters. I have long hated standpipes that could reasonably be expected to allow the possibility of total blockage under abnormal conditions, and have taken to cutting notches in the end of them so that even in a case like this it is impossible to block them completely. The same thing applies to oil and fuel pickup pipes, as in Magnette, where if the sump gets mashed it can block the pickup.

FRM
FR Millmore

Could not agree with you more FRM. The last time I changed oil, I found low pressure on start up. The engine was just ticking over, so I got out and had a peek. Sure enough, filter not screwed on properly, oil was spewing out. This is the most common reason for low pressure, ( after a change.) and probably the most forgiving on an engine! So here in Oz what would be our best 'Gold standard' filter? Australian members? Mike
J.M. Doust

I have thrown away a couple of new filters just for the reason FRM mentions, after measuring the internal dimensions and finding that the clearance to the top of the standpipe would be too small. I thought perhaps I was too cautious, but am happy I did it!

The trouble is that both the filters I have thrown away, of different brands, have been specified by the manufacturers as correct for the MGB engine.

You have to measure every single filter to be safe.

Tore
Tore

Just when I thought it was safe to do a routine oil change I hear that oil filters may come in contact with the top of standpipes.

In my experience I have never had a problem with Wix 51078, Motorcraft FL-300 or NAPA Gold FIL 1068 (Wix rebranded) filters.

Some owners have installed the Motorcraft FL-1A filter which is very tall and has additional filter material. There would be no problem with the FL-1 ever coming in contact with the standpipe.

However some have cautioned against the FL-1 because the top of the filter is too far away from the top of the standpipe.

Any thoughts on why the Motorcraft FL-1 may be harmful?
Steven 67GT

Not because it is too tall.
All that would happen is that the oil would eventually drain down to the top of the standpipe, as it will on the correct filter. Then it takes a few seconds longer to refill the filter, but this is mostly compressing air above the oil level. Meantime, as long as the oil level is at or above the standpipe (the job of the anti drainback valve), the oil will be coming from the pump and going to the bearings.

It is most important that everybody note what I said about erroneous parts listings above. "71-80 MG All" covers MGB, 1275 midget, and 1500 Midget - at least three different filters. MANY listings I found om internet show this!

FRM
FR Millmore

Pardon my ignorance, but what is the standpipe?? Can someone pointv to the [part number in the manual or a moss catologue?
Thanks
John
John Minchin

As I understand it the 'standpipe' is the pipe which the oil filter goes over. you can see it as part of the bracket (item 41) in http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=197
Bernie
B Anderson

Ah, thanks Bernie
John Minchin

My standpipe is 2" long, but the filters internal depth can vary even when the overall height is the same because of different arrangements with the bypass valve (or not, as on some Fram filters!). Volvo 3517857-3 is 2.57", as is Mann W917 who reputedly make the Volvo filters. However these are externally shorter than the original Unipart and Champion but still have plenty of clearance. The longer Mann W916 has 2.93" internally, Champion has 2.785", and Unipart GFE422/121 have 3.2". Mann 916 and Unipart have the same external height at 3.76".

If you don't have the standpipe then it isn't an issue, but then you are likely to get the filter draining, especially after some use where the anti-drain-back valve in the filter loses effectiveness. However longer filters probably have more surface area of filtration material, which is better than less. A bypass valve is essential, as cold pressures on start-up can burst the filtration material otherwise.
PaulH Solihull

Remember, standpipes differ in length - either because these spin-on adaptors have come from different applications/sources, or because POs have adapted or replaced them in the past.

Owners need to do the work Paul has described in respect of their own car's adaptor fitment and filter market.

For example, the adaptor on my car has neither standpipe nor built-in by-pass valve. I need filters with both features incorporated within the can.
Roger T

I've been running my car with the Purolator equivalent of the
Motorcraft FL-1A for decades without ill effects.

It is a whopping big filter (it holds about a quart of oil all by
itself) and so completely pre-filling it with oil is considered
mandatory.

If installed dry, it would take a while for the engine to fill it
and purge the air out after an oil change.
Daniel Wong

Napa Gold 1515...a WIX filter for 1/2 the price...
Bob Dougherty

Ok so I had bought an engine oil pressure test kit from Harbor Freight for $20. I just got around to testing it out this Sunday. The funny thing was there was no longer any oil in the engine ! The last time I posted on here and was checking the oil pressure after the oil change there was definitely oil on the dipstick. This time it was dry.

I bought some more oil, suspected the oil filter was not securely tightened and was sort of able to verify that. The car is parked on grass at the moment so it can be hard to see a big spill.

I filled it up with oil, took the oil pressure hose off where it attaches to the switch with the electrical connection and attached it to the gauge I bought. I cranked and no reading. I started her up and no reading... I took the gauge off and started, waited for the hose to spurt oil. Nothing...

I am going to change the oil filter asap and retry. Im pretty worried. I really dont want to do any damage.

Again, before changing the oil, pressure was great. Is there something Im missing here? Or is my assumption that there was a leak in the oil filter which led there not being enough pressure to be built up as to be registered on the stock gauge. Its just suprising as its supposed to be the right wix filter. I took it off last night and the rubber ring was on the mounting point and had come off of the filter base. Maybe thats the problem? Its just a o ring...

As others have stated, I actually used purolator and fram in the past with good results... I will go to Napa and try the Napa Gold.
JRB Mr

My other problem at the moment would be over filling the engine with oil. I would plan on filling up the new oil filter with oil but I dont want to overfill the engine.

-James
JRB Mr

It sounds like your filter base seal might have come loose upon installation. When you install the new filter make sure everything is in place and don't forget to lube the base seal with some engine oil before installation or it will be a bear to get off in the future. RAY
rjm RAY

You really should remove the spark plugs the next time you crank the engine to see if you have oil pressure.
Steven 67GT

Did you check the internal depth of your filter and compare it with the standpipe on the filter head? This (not enough clearance at the end) is about the only thing that can result in no oil pressure after a simple oil and filter change. I don't see how you could miss several litres of oil spraying around the engine and dripping onto the ground even if it *is* grass, and with a loose filter there would still be some pressure unless it hadn't been fitted at all.
PaulH Solihull

Ok so I ended up getting a new filter and again had to get more oil. All is good and the oil pressure gauge is indicating pressure.

Paul the Wix filter had more than enough clearance. The fram filter I fitted is not as tall and is working fine.

In regards to oil spraying around... This didnt occur while the engine was running, I would go back to the car in a few days and check the oil an it would be empty. Needless to say I will be checking the oil level tomorrow.

Really not sure what the issue was with the pressure not building up but with everything working correctly now Im going to let that perplexing question die with the original new filter that is now in the garbage.
JRB Mr

Fair enough as far as pressure now goes, but you can't lose a sump-full of oil from a stopped engine other than by the sump plug not having been properly refitted, or a hole in the sump elsewhere.
PaulH Solihull

Hi Paul. I agree but it's been a week and the oil level is looking beautiful. Strange... I even just ran out right now and checked the dipstick.
JRB Mr

I've got a 63ish B in Australia. I pulled the adaptor off an Austin 1800 and put it on. The Z23 Ryco filtre now sits with the open end on the bottom so it's messy to change. A few turns of the starter with the coil wire off after an oil change and I have pressure each time. No problems at all.
J Millsom

This thread was discussed between 22/11/2011 and 27/12/2011

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