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MG MGB Technical - oil pressure line

In the never ending obsession with my '74B...I'm now focucing on oil hoses...I did the hoses to the oil cooler...(37 years is long enough)...Now I'm on to the vintage 10" pressure hose that drives the oil gauge...and was wondering is there any special procedure?...(i.e. since it presumabley drives the gauge via hydralics)...Also, is changing the oil pressure relief valve/spring worth the bother?...
Thx...
Pete

About 10 years ago I changed the cooler lines on my 74B and also the shorter one that runs to the preasure guage. Both were easily done and noticably reduced oil leachage in the engine area. I then went under the car and tighten the oil pan screws a little. Between the three things it does not leak much oil at all! Be careful of the cooler lines tho. Because the oil cooler is aluminum it is easy to break of one of the inlets on it. Bob. I do not know about the spring.
Bob Ekstrand

The relief valve is a pig to replace with the manifolds in place. That being said, you can match mark the capnut to the block just as it releases the last thread when being removed. This allows for you to line up the capnut when reinstalling it while you are pushing it in against the pressure of the spring. RAY
RAY

Pete. The new oil pressure lines seem to have some problems associated with them. While Moss Motors has stated, here, that they have noted only one bad line over several years, another vendor has had the oil pressure line on its "bad parts list" for a number of years. You can check it out here: http://www.motorheadltd.com/bad_parts.htm
along with some of the other bad parts they have found.

I know of several people who have, over the last few years, installed the new line only to have it split under the mesh covering due to the poor quality of rubber used in the construction of the new ones.

Motor Head offers a custom built line, but it is both expensive and requires that you supply an old line to salvage for the end fittings (as I remember it). I am not sure you are not just as safe using the old lines.

As to the oil pressure lines, good luck. The ones on my daughter's 77B lasted about three years before cracking--at highway speed on a rebuild having 2K miles on it. Keep an eye on the condition of your new lines. You might want to consider having the old lines rebuilt by a shop specializing in the manufacture of lines for fork lifts and other hydraulically operated equipment. That was the recommended solution to the poor quality of rubber lines being vended to the MG community several years ago and is something worth considering today.

Les
Les Bengtson

Gents, thx for the comments...This is a super site!...

Ray-I think I'll leave the pressure relief valve alone...at least until I have the exhaust manifold off to give me some room...I looked at an engine schematic drawing and it sure looks like that spring, when compressed, will a bugger...
Les-I've read some of the commentary on these new oil cooler hoses and worried the age and appearance of the original hoses merited a change...I kept the old lines and am going to visit a hydralic shop nearby that fabs new lines...to inquire...As for the small pressure hose...maybe I'll live with it...or see if my shop can rebuild...37 years on this little line scares me...

Pete
Pete

Pete. Excellent idea. Please be so kind as to let us know what you find out. I have, as some may remember, a new engine to build for my 68 GT. I, also, have two of the Moss oil cooler kits for the RB MGBs which, due to the "known problems" with the hoses, I have not bothered to install on my two 79 roadsters.

Thus, please let me, and the rest of our viewing public, know what you are able to find out. It will help all of us when we go into our local hydraulic shops and try to discuss new hoses with them.

Thank you. Les
Les Bengtson

Pete,

I have a 69 with the original oil line to the tube leading to the pressure gauge. No signs of any problems to date (crossing fingers, bowing to the west, lighting incense sticks et al as I speak).

I replaced my original lines to the oil cooler when I installed a new cooler five years ago. About 18 months ago I reclaimed the old hoses from behind the garage to cut off the fittings just in case I need to build lines in the future. The original hoses were still in very good condition, inside and out, even having some of the original Dunlop lettering clearly visible. Had I known that I would not have chanced my arm with replacements.

With the benefit of hindsight I would be inclined to stay with original unless I had reason to suspect their quality, ie some visible sign that they were failing (cracking, leaking at joins) or tactile evidence of stiffness, brittleness etc.

With the gauge one, unless you suspect it is affecting pressure readings, similar perspective.

I know that means a hose could fail and leave you mmobile at the roadside. Unfortunately, so could a new replacement. I guess I place weight in the old addage - 'if it ain't broke (or presenting clear evidence of impending failure) don't fix it.'

Regards
Roger
Roger T

Roger...Thx...My hoses too had the dunlop markings...but the rubber was very, very hard...almost brittle and I worried the underhood heating/cooling cycling had cooked them...we'll see...As for the small pressure hose, I'm going to wait a bit...as psi reads 40-70, as it has for 30 years...

I'm running out of things to mend...Gads!...
Pete

"match mark the capnut to the block just as it releases the last thread"

Do this after you have undone it by temporarily refitting *without* the spring.
Paul Hunt

I had to replace the oil pressure line due to its blowing out 25 miles from home on a Sunday outing. Fortunatly, I happened to be glancing down at the gauge at the time and saw it falling like a stone. I shut the engine down with 2 quarts of oil left in the crankcase and avoided any damage except for the $230 flatbed drive home. I ordered a new hose from Moss and it has held up ok for 5 years. I replaced my oil cooler lines with the stainless ones that include the Mocal oil thermostat. This allows the engine to warm up in just few moments. RAY
RAY

Hmmm, and here's me with the same hoses on both cars, 20 years and 50k on the roadster, and 80k and 15 years on the V8 ...
Paul Hunt

After 40+ years I decided to err on the side of caution and replace the hoses. Better to do it in my driveway than along the side of a dark road at night. RAY
RAY

I worry that old and baked rubber hoses combined with engine vibrations will result in a sudden crack......so I'm taking my chances with new while the old ones hang in the basement...
Pete

There have been problems with the aftermarket oil pressure lines. Check the archives. Hopefully the supplier problems have been cleared up.

I replaced mine some years ago and had trouble with leaks at one of the fittings from the start. Ended up using a worm gear clamp. Has worked satisfactory for years. Seems like a good application for an electric gauge.

Of course there are lots of debates whether to go oil cooler or not.
Robert McCoy

The problem with electric gauges is that you shift the weak link to the sender. I have replaced many leaking senders over the years and prefer the mechanical gauge. On the B you have a flex line running to the sender anyway on '68 and newer N.A. spec cars. RAY
RAY

I had a replacement hose fail and lost 4qts of oil before I was able to get off the freeway. The engine survived but it scared the heck out of me.
Getting a proper hose made up at a hydraulic shop is certainly the way to go. Apparently modern Chinese workmanship isn't quite as good as 1960's-70's British workmanship!

Cheers,
Rich
Rich McKIe

Does that mean when the hose comes from VB in a plastic bag marked " Made in UK" the bag is what they are talking about?...
Pete

No, that generally means it was made in the UK. Could be that VB decided to supply a quality hose rather than junk. If it is made by Mocal or another well known company you should have a good hose.
Mine had no markings and turned out to be a dud.

Rich
Rich McKIe

This thread was discussed between 22/06/2009 and 26/06/2009

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