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MG MGB Technical - Oil flex line and a near disaster.

The purpose of this post is to document a situation that happened to me with the hope that others can avoid a similar experience.

I own a 1977 MGB with a Weber carb and a rebuilt Ivor Searle engine, with 20k miles on it over eight years. The oil flex line was purchased around 2005 and has been on the engine since installation.

Last weekend my car suffered a catastropic failure of the oil flex line, the hose that runs from the block to the connector for the oil pressure gauge. Within 7/10's of a mile the line ruptured and I lost a minimum of 2 quarts of oil! No previous indication of a leak. I have since backtracked my route and saw oil on the roadway starting at a coffee shop parking space leading to where I pulled over after smelling oil and noticing zero oil pressure on the gauge. This wasn't drips, this was a consistent streak 4" wide over the entire distance.

I feel extremely fortunate that my car suffered no apparent engine damage.... after replacing the hose I have the same good oil pressure numbers and hear no scary engine noises.

Some thoughts I'd like to pass on. I'm sure my positive outcome was due to pulling over before major damage was done. I check my oil pressure gauge often and when I saw it at zero I immediately shut the car down. I'll be replacing this line every 2 year from now on as a wear part and normal maintenance. I'll also be carrying a spare line in my car.

I would like to hear if anyone has come up with an alternative to this line in a similar vintage MGB. I'm no automotive engineer, but having one end of this hose attached to the vibrating engine and the other fixed to the stationary bulkhead would seem to result in a failure eventually.

Thanks for listening!

Brian Denis



Brian Denis

The original flex line, on my '67B, lasted for over 30 years. I replaced it when I overhauled the engine in '93 just to be on the safe side. Several years later, as I was driving along the Pacific coast, I glanced over to the oil pressure gauge only to discover, to my horror, that the needle was falling like a rock towards zero! I immediately shut off the engine and coasted into a parking lot. After checking the oil on the dipstick, I saw that I was down by about two quarts. The flex line had burst and since it was a Sunday afternoon and I was 30 miles from home, I had to have the car flatbedded home due to the failure of a $15 part. I have since learned that for several years there were a number of substandard flex hoses flooding the market. These still show up from time to time. Moss has been very cautious in weeding these out and have even switched the source of the ones that they carry. Your best bet is to take your old line to a shop that makes up hydraulic lines. They can reuse your old fittings and make up a line that will last far longer than your engine or car. The cost is minimal. I've owned my B for over 41 years and this was the only time that I was left stranded. RAY
rjm RAY

thanks for the warning

probably rubbish rubber I'm afraid made worse when hidden under braiding

have a look at the thread I put up about parts quality IIRC Chris has put up a photo of a oil cooler hose

some of this rubbish rubber doesn't last 8 months let alone 8 years

I don't use 1/4" fuel line now but the modern 6mm stuff (and it fits better) as I've had at least three different lots split and leak within weeks, the last lot did last two years and I saw the split before it went all the way through otherwise the engine bay and exhaust would have been covered in fuel
Nigel Atkins

Nigel-
Ray recommended that "Your best bet is to take your old line to a shop that makes up hydraulic lines." Just in case you don't know where to find such a shop, Any garage that works on large diesel-powered lorries (that's tractor-trailers to us Yanks) should be able to tell you where you can get quality lines custom-fabricated at a reasonable cost.
Stephen Strange

I had the same happen-but luckily about 200 yards from home. I hate braided stuff-you can't see beneath it. Luckily no damage, but this had reminded me the replacement has been on for 3-4 years.....(And I have just had the engine out so could have replaced then...doh) hey ho easy enough to do!
Michael Beswick

I had an oil cooler bypass line (the one you have if no oil cooler installed) made up a local hydraulic shop and have no concerns about it. I have been intending to have the same done for the sender hose but have not done it yet. You've given me some inspiration!
Rob Edwards

I've heard of several similar failures of new-ish hoses recently, I think I'll stick with the ones that came with the car 23 and 18 years ago! OTOH these Teflon ones http://www.stevsonmotors.co.uk/oilpressurepipes&hoses.html are hardly expensive at £12 plus VAT & P&P, the standard rubber being £7. They are made by Cohline of Germany OE suppliers to MB, BMW, VW etc, and also MGOC and Leacy. I hope no one has had a failure from one of those two!
Paul Hunt

My earlier post on rubbish parts thread -

Recently I have had cars with fuel leaks from the braided hose from fuel pump to solid line and the oil pressure braided hose between block and bulkhead. When I stripped off the braiding to investigate, both had severe degradation of the rubber along the whole length of the hose. See attached image.

The lack of any cotton reinforcing in the rubber is, I think, a factor here. I now only fit ctton reinforced fuel hose marked as such - normally Codan hose.

The original galvanised wire braided hoses don't seem to be affected - only the new stainless steel wire ones.

AS an alternative fit the oil pressure guage line from an MGA - not as pretty but a damn sight stronger and NOT braided


Chris at Octarine Services

Stephen, my local NAPA parts store has the equipment to make up hydraulic lines for just about any application. I had a Polaris quad brought to me that had blown out one of the oil cooler lines that run to the oil radiator. On one end is an SAE fitting and on the other end there is no fitting at all. The oil radiator has barbed fittings on it. They were able to make up the line for it, but they were out of 300 psi rated hose. They used, instead 3,000 psi hose. No matter how much abuse this quad sees, I doubt that the owner will be able to blow out this hose. Parts for Polaris machines take a minimum of three weeks to reach me, so finding a place that can make up replacement items is a godsend. RAY
rjm RAY

Hi,

My Wolseley has a thin nylon? tube running from the engine to the gauge. The ends are finished with little brass olives, that crush onto the tube, when tightened. I've seen kits of this type at local parts stores. Maybe replace the rubber hose with a length of this nylon tube, with a curl in it to allow for vibration.

Herb
Herb Adler

Stephen,
thanks for the tip, we don't have so many of those types of shops in the UK any more in fact by coincidence I had to take my mate to such a place today and it was shut at short notice - the son is now running the shop and I guess he wants out of the business

for general info -
here's a supply of s/s braided Teflon brake and clutch hoses (from a place that some get their accelerator cable sleeving or kits from) - http://www.venhill.co.uk/Hoses_&_Cables_-_Car/MG
Nigel Atkins

This thread was discussed between 28/06/2013 and 29/06/2013

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