MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Oil cooler problems

Hi,
On the way home yesterday I suddenly got a whiff of hot oil. Being only a few hundred yards from home, and with nowhere safe to stop I kept going and got into the drive, engine still running, temperature normal but didnt notice the oil pressure guage reading. Turned off the engine, opened the bonnet and was quite surprised to see a lot of oil. Looked as though it was coming from the front of the car but was pretty much all over the engine bay.
This afteenion I had a proper look, and this is what I think happened: the lugs that hold the oil cooler on have sheared on both sides and the cooler has dropped down (it is "underneath" on my 1980 GT). This pulled the oil pipes downward and into the path of the electric fan, with predictable consequences. See photos for details.
I now have 2 dilemas.
1, how likely is it that the engine has been damaged due to lack of oil? There is just a drop apearing on the bottom of the dip stick so not completely run dry, but very nearly.
2, should I replace the cooler and all associated pipes or just bypass it with a single pipe? The oil cooler is difficult to get at, but I am trying to keep the car as original as I can.
Grateful as ever for any thoughts,
Stephen Elster






SJ Elster

Bad luck there Stephen-but you've answered your own question
If you want to keep the car original as you say, there's only one option really--

Replace the oil cooler and damaged hose

The cooler isn't all that hard to get at really, just poke the hoses down through the holes, screw them onto the cooler and lift the whole setup up into place and bolt it in ,then fill the cooler and hoses with engine oil and screw the engine ends of the hoses to the engine

Interesting that you smelled oil but didn't look at the gauge,but had time to look at the temp. gauge BUT hopefully it will be ok
How far does the oil show up the stick

If you want to check the oilpressure and see how your engine sounds before going any further you can do an emergency loop from the rear of the engine to the oilfilter housing using your remaining undamaged hose, bypasses the cooler by doing this, put some oil in the engine and see what you've got

willy
William Revit

You could run it up with just the starter motor with plugs removed to see if you can get oil pressure after you have filled and primed the circuit.
Mike
Mike Ellsmore

Thanks for those responses. Interesting question as to why I didnt look at the oil pressure gauge. I really dont have an answer to that, except that I only had a few seconds and my primary aims were to get off the road asap and stop the engine.
I will do the temporary loop to see how the engine runs, and I will use the starter motor to build up pressure before starting. That should give me enough info to work out if the engine is basically ok. If it is, I will order the cooler and new pipes. If it looks like an engine re build is necessary, I will probably look at getting a replacement engine and do both jobs at once. Probably also replace the radiator at the same time. Will need to consult the financial controller!
Stephen
SJ Elster

I'm surprised the racket of the fan hitting the pipe hard enough and long enough to cut through it didn't alert you, I did have that on the V8 with the underslung cooler once.

How much oil is left in the sump is the important thing.

As Willy says remove and fasten the hoses at the cooler with the cooler hanging down. Use two spanners, one on the hex of the cooler and the other on the union in such a position that you can squeeze the handles of the spanners together in the palm of one hand to turn the union in the appropriate direction(undo first image, tighten second), and that avoids any twisting force being applied to the ports of the cooler. That's the CB cooler obviously, but the RB is the same.






paulh4

Got the cooler and hoses out. Afraid I broke one of the hex attachments on the cooler, even though I was using the 2 spanner method. The cooler needs to be replaced anyway, because the mounting lugs are broken.
I drained the rest of the oil out of the sump and got about a pint out, plus some spillage. Not sure what that implies re internal engine damage, will have to see when I get it started.
Next step is to use the good hose as a bypass and see what the engine sounds like. That will have to wait for a couple of days because I have run out of energy now and have to work tomorrow.
BTW I didnt hear the fan banging on the hose at all. My latest theory is that it has been catching slightly for some time and gradually eroding the hose until it eventually reached bursting point.
All the best, Stephen
SJ Elster

Stephen, those oil cooler mountings can be pretty fragile and often fracture. Most of the time you don't need an oil cooler and many people put a stat in the system. However, I'd replace cooler and pipes, change filter, and replace oil. The BMC B Series engine is pretty robust, and from what you say you weren't far from home. My late Dad used to say if you could have only one gauge, he'd have a water temp gauge. Then, an oil pressure gauge. If the car had been running minus its oil for a while then the water temp gauge would have been running a bit high, but you say it was normal - one of the jobs of motor oil is to keep the engine cool. Then forget speedo, tacho and fuel gauge and just glue your eyes to the water/oil gauge (did they still have a combination gauge on an '80?)!
Peter Allen

Steven,
check that your oil cooler hoses have strap(s) and grommets as they tend to go missing with engine work and that the hoses are the correct length, those coming off and the new ones going on.

At least you'll get fresh oil in your new oil cooler, the oil coolers don't drain on normal engine oil changes so further old oil residue and fresh oil dilution with them.

When an incident like this happens you begin to understand and value the extra protection that can be offered by better engine oils.

As Peter has said, and I'm sure you won't want to hear it, but MGBs unless used for track stuff or heavy towing don't need oil coolers and without an oil thermostat will be very often overcooling the oil (which again leads to a need for better quality engine oil).

As suggested I'd refill with fresh oil and filter and run the engine, chances are good for you. I'd use this oil as a sort of flushing and only run it until I was happy everything is fine with engine and new oil cooler (and stat) and then I'd do another thorough hot oil (and filter) change.
Nigel Atkins

As is seemingly often the case I was lucky in that one of the roadster hoses chose to leak immediately after rearranging them and running the engine to check the unions weren't leaking. I suspect it was an original as it had no markings and the other seems to have a date code of 9/87. Cut open out of interest the walls are pretty thick, but heavily crazed on the inside, more so than the outside. So yours may well have been similar i.e. walls gradually failing over time so not much damage needed to finally start leaking.

Separate gauges on the 77 and later, ironically with the fuel gauge centrally in front of the driver! Probably deliberate to put particularly the temp gauge to one side as owners do tend to get paranoid with these later 'narrow angle' gauges.

In my experience you have to lose a lot of coolant before you start seeing anything on the temp gauge. After such a problem on the V8 I fitted a coolant level sensor, and even though that was more than a decade ago without further problems I've not been able to bring myself to remove it. Easy on the V8 with it's plastic radiator filler plug to fit a long screw to sense the coolant electrically, I'd imagine the same could be done on the 4-cylinder even with the thermostat below.






paulh4

Update: Connected up the good hose as a bypass, filled with fresh oil, turned it over for a minute with no plugs and then started the engine. It started normally, no odd noises and oil pressure at about 60 psi as it usually is. I wont know for sure until I drive it for a bit, but it looks as though I may have been lucky and gotten away with it.
Will order new pipes and cooler, and wont drive the car until they are fitted - I had to take off various grills and splash guards, and the number plate, in order to get to the cooler and the old hoses, dont want to put all that back on now and then take it off again in a few days.
Thanks for all advice given, it really makes a difference being able to tap into the expertise and experience available here.
Stephen
SJ Elster

Firstly, apologies for spelling your name wrong last time.

Others will known and remember better here than me but either do a look at recent threads here or a search as IIRC(?) Moss for one sells the oil cooler pipe that is overlong, and as I put check you already have, or order, all hoses fixings, restraints and grommets.

If you're fitting an oil cooler then also fit a oil stat, originality would have had owners fitting all sorts of extras to their cars back in the day and anyway you're better off having a very slightly non 'original' well running car than a static or not so well running 'original' car.

I'm sure others would go along with changing even this fresh oil, and filter, before fitting your new hoses and oil cooler, hot oil change, why crudded up your new parts straight from fitting. Personally, if not already done in your ownership I'd take the opportunity to clean flush the oil system, with the oil cooler out of the system, that way if the engine oil system is clean it's just a matter of timely oil changes to reasonably keep it that way (using good oils of course :) ).
Nigel Atkins

Hi Stephen,
I note you don't mention removing the electric fan motor or fan blades. Getting the new hoses round these is difficult & will result in much bad language & cut fingers, never mind fitting the collar round the two oil cooler pipes in front of the radiator support panel.(Guess how i know, when i first did it some 20+ years ago? - much easier the second time when re-furbishing everything under the bonnet). On the second occasion, i fitted new grommets in the radiator support panel - these were extremely tight to insert in the support panel. I ended up cutting a small slice through the side walls of the grommets & then also coating the sides of the pipes/ insides of the grommets with some lubricant to enable me to push the hoses through as without i would have bent/dislodged the radiator support panel.
Cheers
Charles


1980 Roadster
Charles9

I've read before of people fitting the support panel grommets first and pushing the hoses through them. No way with my support panel, grommets or hoses, It wasn't even possible to fit the grommets over the hose fittings. I had to cut them and fit them round the hose and in the panel after feeding the hose through. Not that difficult, and that was on a freshly painted body so I was taking great care.

As to the fans and blades I've replaced the underslung cooler on the V8 in the past and not had to remove either. Maybe the front grille, but that's all. If you do remove the motors careful positioning is required on refitting as clearance particularly on the right-hand fan of the V8 is very limited.

No point in an oil stat unless perhaps you intend driving the car in very cold weather, just something else to plumb in and go wrong. It would be common knowledge by now if it was an issue.



paulh4

On my 1971 MGB I fitted an oil stat many years ago and would routinely feel the pipes that went to the cooler after a drive. The stat was supposedly manufactured to open at around 88 degrees C I seem to remember.

What I found was that during all normal driving, even on long journeys, the stat never allowed the oil to go to the cooler. Oil pressure always remained good. Only on really hot summer days did the cooler get hot. This to me suggests that an MGB in use in the UK doesn't need an oil cooler for 90% of the time. Not allowing the oil to reach at least 90 C is reckoned to be a bad thing, and on the MGF and TF the owner is told in the handbook not to rev the engine until the oil temp is up to those levels. I guess the MGB's cooler was fitted for the benefit of the hot states in the USA, which was their biggest market.

I have just bought this car back from the chap I sold it to, and the oil stat is still there. I wonder if it still works?

As for the V8, the RV8 never had one fitted and you don't hear of engine problems with those cars. I drove my GTV8 down to the south of France in mid summer without an oil cooler and it never showed the slightest signs of distress, the oil pressure staying up at a healthy 35 - 40 psi when the shade temperature was 37 C.

It was a different story on my 1275 midget where the oil pressure would definitely reduce in hot weather.
Mike Howlett

* ETA: I was still typing whilst Mike posted (and I was going to put 80c) *

I'd be amazed from what Stephen has posted before if he didn't refit an oil cooler, I'm not saying he's wrong to do so, his choice. I'd also be a little surprised if he fitted an oil stat but he may be more open minded than the more traditionalists here.

With the logic given - no point fitting an oil cooler unless the oil gets very hot (above its capabilities) just something else to plumb in and go wrong, as proven.

Also proven many more vehicles with the same engine, and probably greater possible requirement for an oil cooler didn't have oil coolers, it would be common knowledge by now if it was an issue. :)

* Those that have an oil stat fitted will be able to tell you how often the stat is closed, and not just in very cold weather, or even cold.

Following the logic also follows no point fitting a 'water' stat, less to plumb in and go wrong. :)

The oil stat does even more than the 'water' stat if you think about it, with an open mind of course. :)
Nigel Atkins

Mike,
the oil cooler getting hot is fine, I'd suggested that probably the temperature of oil inside it is below what the oil can cope with, your radiator would also be very hot both are just doing their jobs.

My guess is that oil coolers went in UK cars as more a marketing sportscar thing - and of course oils weren't as good at the start of the 60s as in the middle of the 60s, the 70s, and onwards.

A mate is just about to fit an oil cooler to his souped up Spridget (with a stat) as his oil temp gauge hit 150c during that very hot weather. He uses 10w-40 oil in his engine (as per the Driver's Handbook). I keep meaning to look up the figure the oil will handle to give him the margin.

Nigel Atkins

If I remember correctly, the B was not fitted with an oil cooler originally, but they found that the front crossmember blocked the cooling airflow to the sump so it became a standard fitment to avoid oil overheating.

I run oil coolers without thermostats on all my cars - they were standard fitment from new, so why would I second guess the factory?
Chris at Octarine Services

Chris have you kept your B exactly as the factory had it or have you made any changes or improvements anywhere on the car whatsoever?

How much of a difference in airflow around the sump is there on the factory RV8 that it doesn't require an oil cooler?


Nigel Atkins

No idea Nigel - but you are comparing apples & oranges, the V8 engine has different cooling characteristics.

Just saying that if the factory fitted them to my cars then they would have done so for a reason - they would have saved the cost if they could have!
Chris at Octarine Services

Must admit Chris the added factory cost is the bit that foxes me - but who knows what goes on ...

I was going to put something but the MG congregation would say as Captain Mainwaring that I'm entering the realms of fantasy. :)
Nigel Atkins

I seem to recall the oil cooler was fitted as a result of race experience, but I might be confusing that with the introduction of the 5 bearing engine.

Chris' point about the cross member blocking the sump is a good one. My dad for some peculiar reason bought a three year old Marina 1.8 in the '70s with the 18V engine and used to thrash all over Europe. Failures of road springs, reverse gear (Triumph box), clutch slave cylinder (a nightmare to replace), but the one thing he never had a problem with was the engine other than high oil consumption (he was told at the time BL kept changing the piston/ring design to eradicate the issue). No cooler fitted - maybe one would have helped?
Peter Allen

Stephen's problem is easy fixed-new cooler and hoses and forget about it
Every MGB that came here had a cooler covering a wide temperature range from stinky hot up north to our more cooler climate down here--not an issue


willy
William Revit

I can also imagine they became standard to placate owners complaining of low oil pressure in hot weather, much like people getting paranoid if the temp gauge needle is not bang on the N all the time, as modern cars are.

But particularly the underslung oil cooler is only effective when moving, which is why the oil pressure does drop when stuck in traffic a long time. From my tests a fair proportion of engine bay heat comes forward to be recycled through the cooler and radiator in still air, and with a following breeze the effect is much worse. On a Bath to Bournemouth run many years ago the interviews at the end had to be curtailed as people were panicking for that reason.

As far as V8s go, Roger Parker has said from his Police experience "What hot oil pressure?" as sometimes it barely registers on the gauge. Maybe why their gauges went back to 80psi from 100, after originally being 60.
paulh4

My V8 shows 40 psi hot running and 25 psi hot idle.

But then it has an oil cooler!
Chris at Octarine Services

About the same as mine ... to begin with, then steadily drops in a long idle. Same as the roadster but that takes longer and doesn't drop as far.

What front cover do you have, Chris?
paulh4

Standard 3.5 SDI cover as far as I can remember - it is 25 years ago now!
Chris at Octarine Services

Here's a pic of the engine & gearbox ready to go in the car.


Chris at Octarine Services

Mine was originally the factory BGT, now with the Clive Wheatley cover. The oil pump depth varies between all three with the SD1 in between the other two. Because of the deeper gears I expected more flow and hence a higher hot idle pressure but that's not the case. Mind you it's a different block as well as the original had a slipping liner (supposed to be rare on a standard 3.5), so wear in the bores of the hydraulic tappets is an unknown quantity. One of these days I may get the original block relinered.
paulh4

Both of you second guessing the factory!

Good gawd whatever next.

The factory deemed the roadster unsuitable for the V8 and Clive Wheatley cover second guessing the factory, relly you guys and more into custom and modified than factory design.

I feel so let down, who can be relied on, black clouds are all around me.
Nigel Atkins

I fitted an oil cooler to the Midget about 10 years ago. The car operates in 100 deg. F weather in the summer time. What I have noticed the most is reduced oil consumption.
Glenn Mallory

Just to complete the story, and apologies for keeping the reading public in suspense for so long. I decided to put it back as it was when I got the car, which is as it left the factory as far as I know. Ordered new cooler and pipes but only got round to fitting them last weekend. All done now, with all gromets and straps in place and fresh oil.
Test drive went ok, oil pressure and temp guages normal, and no new noises.
The next 200 miles or so should indicate whether all is well or not, but cautiously optimistic so far.
I cleaned up the engine bay as best as I could but definitely still some oil on the rad fins that is difficult to get out - grateful for any ideas on that, because there is a slight smell that I could do without.
Thanks for all the help and advice,
Stephen
SJ Elster

As a 1980 with the forward radiator you have the option of spraying some degreasing solution on from the back then washing it out with a hose also from the back.
paulh4

Hi Stephen,

Before you follow up Paul's suggestion, i would recommend removing the dust shield / sound board between the back of the radiator & the front of the engine (assuming yours is still there - i have seen several later type MGBs where this is missing).
I degreased mine a couple of years ago & then sprayed it with some matt(?) engine paint with the result making it look more or less like it came out the factory. (I intended to fit a replacement board supplied by MGOC but was not impressed by the quality so refurbished the original).

Cheers,
Charles
Charles9

As Paul and Charles have put.

I'd use something like Autoglym Engine Cleaner, spray liberally, use a long handled radiator paint brush to gently aggravate, don't allow to dry, rinse off thoroughly with open ended hosepipe with lower pressure water. Shut bonnet (or leave open if dry warm day) walk away, have a mug of tea or whatever.

If the oil covering was a lot you might have to repeat this process but the actual cleaning time is just a few minutes.

You can also clean the engine this way with Engine Cleaner and rad paint brush. Cover any electronics with clingfilm, start rad end and go forward towards windscreen, don't let the Engine Cleaner dry. This time after you've finished rinsing straight away liberally spray the whole engine bay with something like Autoglym Vinyl & Rubber Care then walk away and leave to dry. You've just cleaned and polished the engine bay very quickly and easily. If you want to you can polish any bits missed when the engine bay has dried out and clingfilm removed.
Nigel Atkins

This thread was discussed between 16/08/2020 and 13/10/2020

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.