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MG MGB Technical - No Oil Pressure

I thought it's not a bad day today I'll just take the B out for a little run and get some petrol. The nearest filling station is about 8 miles away but just before I got there I noticed the oil pressure gauge showed no pressure.My first thought was faulty gauge, then oil leak then shortly after that just before I got to the garage I hear this awful knocking noise.

I lifted the bonnet and checked the oil which was fine, took the top off the oil filler and there was a little steam coming out so I called the RAC who eventually towed me home.

Have I wrecked the engine, it's done nearly 100000 by the way. If I have what's it likely to cost to get sorted do you think.

Not a good day.

Adrian
A WESTFIELD

Adrian. I assume that you checked to make sure you had oil pressure on start up. That would mean that you lost oil pressure while driving and put something less than eight miles on the engine with low/no oil pressure.

The most common damage would be to the rod and main bearings. If you were hearing sounds from the engine, the crankshaft will, most probably, have to be turned down to the next undersize. If you are very lucky, that would be all the damage sustained. However, whatever caused the oil feed failure will also be part of the equation and you will not be able to find the cause of that failure until you strip down the engine. If the failure resulted in metal being distributed into the sump and various parts of the block, rebuild costs would go up significantly.

When my daughter's car failed in this manner, due to a cracking of the three year old rubber hose going to the oil cooler, the rod and main bearings and the crankshaft journals were the only damage. Like you, she heard a noise, glanced at the oil pressure gauge, and saw it drop to zero. Relatively easy, but not inexpensive, repair. The cylinder bores, after almost 100K documented miles, still showed traces of the factory honing marks and did not require rebore and new pistons. Hope you are as lucky.

Les
Les Bengtson

Adrian,
when you say the oil was fine; does that mean there was plenty in there and no sign of "cream" due to water contamination? How's the water in the Rad?
If these are okay it suggests an oil pump failure (which I think is unusual).

Like Les says I hope you get lucky and it's just the bottom end. Question is... are you fixing yourself or paying someone? If paying someone your best approach might be to replace with a recon unit (pay more for the recon, pay less in manpower just for an engine swap)

Best of...
MGmike
M McAndrew

I'm finding it hard to think what would cause sudden lack of oil pressure if there was no oil leakage. The oil pump drives off the camshaft and I've never known one suddenly fail. Normally, sudden loss of oil pressure would be because an oil cooler hose has ruptured and all the oil has made its escape!

If you have an "awful knocking noise" you have almost certainly damaged the crankshaft bearings. How much damage is impossible to tell without a total engine stripdown. As the other Scottish Mike said, a replacement engine could be a good option.
Mike Howlett

The awful knocking combined with no oil pressure for an unknown period almost certainly does mean a seriously damaged engine. At the least main bearings and big ends, but any component that would normally have an oil feed such as the top end and the rings and bores could also have suffered, as well as a warped block or head, so a regrind and new bearings may well be a false economy. I'd be resigned to a replacement engine, or a full rebuild to end up with effectively a replacement engine if you want to keep the numbers right.

As to what caused it, it could be the oil pump come loose, the pickup come loose, or a number of other things. Unless I found the cause on strip-down I would never feel comfortable with anything less than a full rebuild or replacement.
Paul Hunt

Thank you all for the replies. There is no water contamination in the oil and the rad water is ok.

I think you have confirmed my fears and as I am not good enough or have the space to tackle this my self it sounds like a replacement engine.

What is the likely cost and labour for a replacement engine and fitting it do you think.
A WESTFIELD

hoy Mike not so much of the Jocko here mate ;) ... It's an accident of life that I find myself in this fine location, Geordies rule...

Adrian,
there's a number of places offering rebuilt engines for around the £1,200 mark, this looks to be close(ish)(relative to the distance from here!!) to you
http://www.ebay.co.uk/itm/mgb-engine-/181646904072?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2a4affcb08

And about 4 hours to swap. You'll need to budget for a new clutch (no point taking the engine out and not fitting a new one), oil, antifreeze etc.

Best of...
MGmike
M McAndrew

Sorry Mike! I can talk - I may have been in Scotland for 35 years but I'm a South Londoner!
Mike Howlett

It's okay Mike I was only joshing...
I've been here 32.5 years which is way more than half my (current) lifetime but you can take the Geordie out of Newcastle ... ;)
London... hmmm I here that's way down south, must be a bit cold up here for you jessies ;)

best of...
MGmike
M McAndrew

Adrian. You might want to keep your old engine for several reasons. First, it may be original to your car and, if so, the engine number would be reflected on the Heritage Certificate. Second, the current engine has a known history and, you seem to indicate, has never been rebuilt. With any "reconditioned" engine, you do not, in many cases, know exactly what you are getting. A competent rebuild of your current engine will allow you to know exactly what size the crankshaft has been turned to, what size pistons have been installed, the compression ratio of the pistons, the quality and type of cam, whether it has duplex or simplex can and crankshaft sprockets, and a host of other small things which remain mostly unknown with a "reconditioned" engine--at least those from larger suppliers.

There was a fellow named Chris Betson who had a retirement business rebuilding MG engines. He called his business Octarine Services and everyone who posted about one of his engines had good things to say. Sadly, Chris got busy and seldom visits here anymore. But, I would recommend that you contact him, and possibly Peter Burgess, about what would best suit your needs and budget. Peter's book on the MGB engine is one of the best references on the MGB engine and its various states of tune. It also allows you to understand your options. In making your decision, ask about anything you do not understand and you will take more pleasure out of your new engine and feel more comfortable with it over the years. Many garages can remove and replace your engine if you do not have access to a garage and a hoist system.

Les
Les Bengtson

Thanks Les. It is the original engine and is on the Heritage Certificate so it will be worth looking in to.

At least this time of the year I can think about what to do rather than feel I must get it done as quickly as possible. I just feel an idiot for not looking at the instrument panel until it was too late. The car isn't concourse but when it's had it's MOT the garage has always said how solid it is underneath so I shall just have to bite the bullet and get it sorted,

Adrian
A WESTFIELD

Maybee it has simply broken a crankshaft - it wouldn't be the first -
William Revit

I think most engine replacement services work on the basis of an exchange engine, i.e. they get your old one to rebuild for the next purchaser in return for the new. Keeping the old, whilst desirable, would push up the cost considerably, unless you can get a cheap one off eBay to use as the exchange. As you seem to have the original engine as documented on the Heritage certificate there is an incentive to get that one rebuilt. You might even get a half decent engine off eBay to use as a donkey while you get yours rebuilt, then sell the donkey again.
Paul Hunt

This thread was discussed between 23/01/2015 and 25/01/2015

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