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MG MGB Technical - Oil pressure

For years I have been using Castrol 20/50 with a Fram PH43 spin on filter. The oil pressure has been consistent 75 lbs running and 50 lbs at idle. The other day I changed my oil and now I am getting weird readings. Cold (50 degrees F ambient is cold in San Francisco) the gage read 50 lbs, I began driving and the gage climbed to the usual 75 lbs and then dropped down to 50 lbs, after a short distance it began rising only to fall again. In two recent trips about 100 miles each the above continued to happen.

Before the oil change everything was normal, it was only after changing the oil that readings began to fluctuate.

Any ideas?

Lee
1970 MGBGT
LS Sheldon

I am no expert but are you sure the filter is on tight enough. Is there the same amount of oil in the engine as before? I had a similar experience when I changed the oil for the first time since getting my B. The cause was not enough oil before my oil change. The pressure was 60 when warm. It showed max on the dipstick but the dip was the wrong model for the engine. I needed another litre!!! To date no apparant damage done. After the oil change and the right amount of oil now a constant pressure of 75 when running and 65-70 when idle.
Other than that perhaps partially blocked pipe or pump not working as it should?
/Moss
Moss

I would try installing a NAPA 1068 filter and compare what the readings are afterwards. The problem may that the filter has a restriction. It could also possibly be a faulty oil bypass valve, but I seriously doubt it. RAY
rjm RAY

Nothing different in changing the oil. Same amount of Castrol 20/50 same new Fram filter. Reading on the dip stick right on the full line when cold - same dip stick that has been in the car for the nearly forty years I have owned the car.

Since everything was normal before the oil change I can only guess faulty filter as Ray said or possibly an error at Castrol. The 20/50 quart plastic containers have always had a red cap. Now, all of the various weights of Castrol have black caps. The black caps previously were for 5/20. I will also check with Castrol to see if this could be the problem.

Ray where in California are you? Are you planning on Reno in June?

Lee
LS Sheldon

Hi Lee,Had the same problem on my '73 bgt even getting dry starting, I also was using Castrol classic XL20/50 oil & fram filter, I changed the filter to a Champion C102 & problem solved Wouldn't chance a Fram filter again. Also read somewhere of certain filters restricting oil flow. Regards Bill.
wm griffiths

Lee,

We can only speculate, but many people have no respect for Fram filters. In my experience on MGs, the Fram check valve does not do anything, meaning that they drain out almost immediately if you have the mounting type that is upside down. I now use the Mann W917, which I buy by the case for about $4 each.

Since you had this problem when you changed the oil and filter, I would suggest you change the filter again, and if that doesn't fix it, change the oil again and see what happens.

Charley
C R Huff

As a sudden change it has to be something you have done, highly unlikely to be the oil, which leaves the filter. Some Fram filters were sold by a well known supplier as having an improved anti drain-back valve, but I found them worse the the previous Unipart/Champion/Halfords I had been using. I tried a K&N which quick pressure at startup throughout their life, but are very expensive. Mann 917/Volvo were as good as K&N but at half the price, albeit still twice the price of the Unipart etc. However they are significantly shorter than all the others, and also I have had two out of four (two years apart from a Volvo main agent so hardly likely to be a batch problem) that didn't seal on first fitting and chucked a cupful of oil out before the pressure pushed the seal into position (I assume). This is despite the seal being oiled before fitting, and only half a turn after contact, so I'm reluctant to try those again. Filter length can be critical where you have the inverted type with the anti drain-back tube sticking up from the head, you need a *minimum* of 1/2" clearance between the end of the tube and the end of the hole in the filter.
PaulH Solihull

This weekend I will change the filter. This brings up an interesting point that may have been brought up previously:

What manufacturer and model number screw-on filter are you using?

Lee
LS Sheldon

Side issue but still relevant - what is an anti-drain back tube? I ask because I thought changing the oil with Cooper (screw on upside down type) I had created a mess. When screwing off I thought that alot of oil all came out before I could turn it up the 'right' way to remove it away from the car....
/Moss
Moss

The anti-drain back tube is the bit sticking up into the middle of the filter in the left-hand drawing.

HTH!


Rob Edwards

Because of the valve and tube you should always get a mess as you are unscrewing the filter ... unless the valve is faulty. If you don't have the tube you may be able to reduce the mess by punching a hole in the top of the filter and leaving for a few minutes for it to drain. Then hope you can unscrew the filter ... (slacken short of leaking from the seal first!)

I have a V8 with a hanging filter but that is just as messy as the roadster upended, but more of a pain as oil runs down the outside and with gloves I have no grip. The ZS is even worse as not only is that hanging, but under the car, so I get oil running 'up' my arms whilst unscrewing to boot. Out of the three the roadster upended is easiest to deal with, and a few thicknesses of paper under the filter head forming a bowl deal with the majority of the leakage.
PaulH Solihull

Lee, I live in N.CA, about 200 miles up the coast from San Francisco, in Fort Bragg. I doubt that I'll be making the Reno event due to medical problems. I haven't driven the B in over 2 months and am going through withdrawal. RAY
rjm RAY

Now I understand...
/Moss
Moss

THE RESULTS! BAD FRAM FILTER.

I went back to Kragen's Auto Parts and asked for a top quality filter that would replace the PH43. They said to try their own brand called WIX. According to them, it is an up-scale filter. Whether that is true or not I decided to give it a try.

After installing the new filter, the oil pressure immediately went to the normal readings. Obviously the filter was the problem.

The is the first time I have ever had a defective filter. It does not seem that any damage was done "I hope". I will be emailing Fram and informing them of the problem.

Personal to Ray. I get up to Eureka and Arcata about once a year on business, Fort Bragg is a little out of the way. If you get close to San Francisco let me know. My treat for lunch. Sorry to hear you are having some medical problems, I hope you will be well enough to make it to Reno it should be a lot of fun.

Lee
LS Sheldon

Glad that worked out, Lee. I think Wix is a respected brand, which isn't exclusively Kragen's.

Fort Bragg would be right on your way if you took Hwy 1, and that is a good MG route. You could also get some good beer in Fort Bragg at the local North Coast Brewery.

Charley
C R Huff

NAPA and WIX are the same filters! I understand that WIX makes the filters for NAPA. Both are among the best you'll find in the market place. PJ
P Jennings

PJ
Thanks for the info on WIX. It makes my choice more acceptable.

Charley,

Fort Bragg is on the coast on HWY 1 not HWy 101 and a little out of the way. You are correct - great MG roads. Definitely not for my 40' motor home. HWY 1 has some turns so tight it would be impossible. Heading south on 1 there are no guard barriers and sheer drops down to the Pacific Ocean. I love the road for a day trip in the Jag or MG - definitely a NO NO in the MH.

If anyone is ever in the area it is one of the most spectacular rides you would experience- ocean views and the giant Sequoia trees. It should be a must for anyone using sport cars to SUV's.

Lee

LS Sheldon

You may find this interesting, from Barney Gaylord's "MGA Guru" site:


P.S.
NAPA filters are made by WIX, some of the best in the world.
Fram filters are (mostly) built to be cheap and are likely to be the worst in the world.

Filter quality varies widely, and is NOT necessarily commensurate with price. There is a nice web site where someone did a lot of research, cutting open various filters to investigate the inner construction and filter area and quality of the parts. Fram earned the place in the bottom of the bucket without question. See here:
http://minimopar.knizefamily.net/oilfilterstudy.html
T Aczel

US 1 is about the only road that I travel these days. It's a mile from where I live and is the major artery for all traffic, coming and going. You'd be amazed at how many 40' motor homes use it, mostly driven by senior citizens. RAY
rjm RAY

Lee,

RAY is right about Hwy 1. I've driven 60 or 65 ft tractor-trailers over that road, though I will certainly admit it takes a lot longer than 101.

The coastline road in Oregon can be even a bit more of a challenge with a truck because you have to drive in the center of the road through the arched tunnels to have enough vertical clearance.

Charley
C R Huff

This thread was discussed between 10/01/2011 and 16/01/2011

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