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MG Midget and Sprite Technical - Adding oil cooler?

I'd like to add a oil cooler and use a thermostat in the system, what's the best way to do this?

Use a thermostat in the adaptor on the filter head or a in-line in the hoses?

AndyB
a borris

On the 1500 it's easiest to get a sandwich plate with a built in 'stat.

Cheaper too!

Think Automotive 292, Worton Road, Isleworth, Middlesex, TW7 6EL, are the guys to talk to.

http://www.thinkauto.com/
Deborah Evans

I read in a book somewhehere that the thermostats are also availible through goodridge
S.A. Jones

Think Auto are the agents for MOCAL oil coolers and the distributors of aeroquip hoses in the UK.

They are generally cheaper than Goodridge to be honest.
Deborah Evans

Sorry, should have said it's a 1275!

Thanks on the phone to Think.

AndyB
a borris

Remove the external hard oil pipe, install 4 braided hoses, 2 from the block to the oil thermostat, 2 from the thermostat to the oil cooler, i used a 13 row mocal one, mounted in front of the radiator.

cheers
Brad
Brad (Sprite IV 1380)

Mines as per Brad's description. The oilstat (from Thinkauto) is mounted on the radiator upright using a small L-shaped bracket. Sorry, no pics to hand.
Jordan Gibson

Andy - Are you sure that you need one? Cold oil is a baaad thing....

If you dont know what your sump temp is how do you know that you need a cooler?
Toby Anscombe

Agree with Toby

I had capillary temp gauge in sump with A series. Max temp I saw ever was during multiple laps at speed at Castle Combe - around 120C. Came down rapidly when lifting off/braking for corner - 3 to 5C reduction in 5 to 10 secs.

Normally on road would see 80-90C depending on driving mode rising to 100-105 on long motorway journey.

So I never used an oil cooler.

Still don't with 142 bhp Kseries.

Certainly use cooler for a race midget.

Of course a 'stat prevents oil from being over-cooled, but you are carry extra weight/complication withour real need.

A
Anthony Cutler

Black car, south of europe summer traffic jams, you need an oil cooler, elctric fan, vents, etc...of course in scotland an oil heater would be a better idea. Brrrrrh
I think the extra weight of two hoses & a thermostat, would be what...the equivilent of a pie & a pint every day for a week?
Brad (Sprite IV 1380)

My experience is that an oil cooler was beneficial for maintaining good oil pressure. Before having one I used to notice a drop in pressure when doing fast motorway runs, my first track day at Castle Combe convinced me to fit an oil cooler and thermostat. The Castle Combe test day showed the constant high load on the engine would cause significant oil pressure drop, can't comment on oil temps. The fitting of the oil cooler and thermostat stopped the problem. I wouldn't fit a cooler without a thermostat as then most of the time the oil would be over cooled which is detrimental.
David Billington

Hi David

My Aseries oil pressure at revs reduce from around 70 psi to around 60 psi. It would recover back to 70 on a gentle lap. Not really a problem.

I would have worried if pressure was below 50 psi under high temp and load.

I guess there's an amount of personal preference in these decisions, as always.

A
Anthony Cutler

I was also noticing pressure drop on long high speed motorway cruises (like an hour @ 5500+rpm). I put a temp sender in the sump and found the temp was getting quite high so installed a cooler with thermostat. That did seem to control the pressure reduction.
Dean Smith ('73 RWA)

My car when purchased had a cooler but no oilstat (tut). Fortunately it was recently fitted (<500 miles). A 'stat was subsequently added as per the pic.


Jordan Gibson

Actually the more I look at that bracket the less I like it. Think I'll make something that doesn't have all the stress on a single screw head!
Jordan Gibson

I haven't tried a sandwich plate yet, but a significant advantage is that it helps get the oil up to temperature quickly. (Coolant warm up is much faster), and as such shouldn't be run with, or need, a thermostat. This might be a good application for hill climb and sprinters too, as it's always diffecult to get oil temp up before a run because the vehicle is staitionary.

But it does put an additional demand on your radiator. Although as Anthony points out, you need to be going fast to have high oil pressure, and typicaly that would equate to plenty of ram air thru the rad.

Sandwich plates are also much less prone to small or catastrophic leaks than the hoses required for an ari/oil cooler, and it's one less thing to un-plumb for an engine removal.

James
J E G Eastwood 1

James,

I think what you're refering to is a oil/water intercooler such as was fitted to the MG Metro Turbo IIRC. I think the sandwich plate referred to in the thread is different in that it it has a built in thermostat and diverts oil to the oil cooler as required to control the temperature. It fits to the oil filter head and the filter then screws to the sandwich plate.
David Billington

Andy
Track me down up at Broomfield via Alan A to compare notes.
I fitted a 10 row one to the Frog (1275)at the end of last summer with obvious improvements to oil pressure which had dropped during prelonged faster runs . The pressure then remained constant at just less than 170oF. I am still running on the 74oF thermostat ex the 948 as the 82 degree one seemed to cause it to run too hot. Doesn't have an oil thermostat at the moment though and just covered the oil rad up during the winter along with part of the main one and everything seemed to be running at the right temperature including the heater. Any advice welcome though
John
J R Clark

David, yes thanks exactly. Funnily enough we call them 'dohnut' coolers at work (Ford Engine Engineering, Dagenham). I wasn't aware sandwich plate = thermostat, cheers.
J E G Eastwood 1

Jordan, i mounted mine on the inner wing,
Brad (Sprite IV 1380)

This is a bit embarrasing to ask?


I have a basic understanding of how oil coolers work, just not sure as to the order, the placements, and all the componets needed, there position with in the system and there direction of flow. Can someone explain this a little more. Basically how does the whole system hook up? Also how many rows do you guys run....10, 13, 16, 21 ?? and how do you determine the correct amount of rows needed.

thanks
prop
Prop***The End in 2012

Hi Prop

You could avoid all embarassment by using someone else's name when you ask a question... having said that, very few here know everything about all aspects of our cars... and we can all learn about things we thought we already knew.

The oil from the pump exits from a hole in the block behind the dissy; a banjo connection is used here - similar to the hydraulic joint on callipers; I guess it allows the oil outlet pipe to run close to the block and into the oil fitler housing; thence to main bearings, cam and head.

The oil cooler pipes replace the pipe along the block, so the oil flows from the back of the block, into the cooler, and thence to the filter housing. The oil cooler is normally sat in front of the radiator, or below the rad behind the front panel.

How many rows you need depends on how much excess energy you want to take out of the oil, and the expected ambient air temp. A racer in a hot climate will need many rows. In the UK, for motorway use, try 10 rows; maybe 13 for hot climes?

The best bit is, someone will be along that really knows about this... (I don't use an oil cooler!)...

A

Anthony Cutler

Direction of flow doesn't matter, however the connections to the oil thermostat are important, connect it up wrong & it won't work as intended.
Brad (Sprite IV 1380)

Anthony, are you describing the O.E. type layout or the one Think (Mocal) sell?

Or are they the same!

I was wondering about using one of those adaptors which screw onto the filter head, have an inlet and outlet for the cooler and a built in thermostat.

Has anyone used one and could you get the filter off after fitting, it's a struggle now and fitting one of these might not improve that! Any first hand comments?

AndyB
a borris

Yes; the sort that most people use and built from kit of parts or sold as complete system.

A
Anthony Cutler

Fitting an oil cooler on a 1500 right now (want to drive long distances in the south of France eventually so thought it would be a good idea) any suggestions on an optimum route for the pipes? using sandwich plate and pipes from MGOC.
James Ballard

At a guess (don't know anything about 1500's!) the pipes will only route one way, you won't have any spare length to take them a different route.

And if you are using swagged on ends, this means you can't shorten them! Just route them with a bit of slack (to allow for movement) and avoid rubbing or pinch points.

AndyB
a borris

there are 2 holes with grommets in the front splash shield for the cooler pipes to route through.
David Smith

James,
Just fitted a cooler to my 1500, i routed the pipes through the hole for heater air duct, there didn't seem to be any alternative, and i cut the end of the duct to ft around the pipes so that air was still fed into the heater, it was a bit crude but i still get air coming throough into the cockpit without the fan being on. I also cut some old water pipe to feed around the duct hole to prevent chafing.

Alan
A Pritchett

Andy
Local MGB dealer at Birchington made pipes for me to exact length required with whatever end fittings required to suit the route that you want to take them
John
J R Clark

I would suggest for a road car a 13 row by 235mm wide cooler.

This is absolutely ESSENTIAL on a 1500 (less so on an A Series car).

On the race car we use a 16 row by 235mm cooler - at Castle Combe (long straights power circuit) in +25 degree ambient air temperature, and at a rev limit of 8000 rpm, the oil temp stayed nailed at a perfect 105 degrees C.
Deborah Evans

I had a 13row on my 1500 and never had oilcooling problems... well to be honest i did have two watercoolprob. 1 when i broke of all the blades of the plastic cooling fan when driving like a idiot thrue a fort 2 when in an 50 min traffic jam in London in the full sun.

Had the mocal separate oilthermostat build in but lost all pressure for some reason?
removed it hooked up the hoses and all pressure was fine again?
Arie de Best

Thanks Alan,

was kind of what I was thinking. Any chance you could put up a photo of how you did it as a guide? I'm guessing the pipes fed into the sandwich plate from the top?

Thanks for the advice David. However, found no holes (grommeted or otherwise) in the splash shield. Will probably go through the air duct (seems logical).

Many thanks!
James Ballard

Engine power drops off at higher oil temps. I'm advised anything over 90C sees a drop off of power. So I'm surprised 105C is described as perfect - its probably at the absolute limit before power will fall off dramatically.

However.............., there isn't an extensive database of dyno testing with various oil temps to establish facts. It's also the case that is also not a standard place for measuring the oil temp - sump or in an oil line. The oil used would also make a difference.

What would be interesting would be to have an electric/electronic oil temp gauge wired up through a switch to two temp senders - one for the sump and the other from the oil cooler. Or to the cooler and from the cooler. The switch would be used so the gauge saw the reading from one sender and then switched to see the reading from the other guage. I'm trying to persuade Stack to produce a suitable loom and switch setup to be able to do this. I suppose a two sensor setup with a switch and a single guage could also be used to switch between engine oil temp and gearbox oil temp.
Daniel Thirteen-Twelve

Hi Daniel

How is engine performance affected by oil temp? I can see how it's affected by air-intake temp, but oil temp seems less obvious.

I would have thought that higher oil temps = less viscosity and therefore less power loss pumping oil.

A
Anthony Cutler

Hi Ant,

Hi embarrassed to say I don't know because I've never asked.

Since the dyno operators say power falls off after oil temp X I've always just made sure my car's engine oil temp is below X.

Anyone with a dyno who's done a lot of testing knows their stuff so I don't argue with them.

On the rolling road a few months back after getting everything set up for the final 'pull' I wanted a reading every 500 rpm from 4K (this engine felt like it had very good mid range power) through to 7K (peak power is 6K for this cam).

The operator advised what I was asking for was a 'very long pull' and checked if the oil temp would be ok since power fell off dramatically over I think 90C and the engine would get very hot.

So the long pull began (acutally a rapid succession of pulls) and the dyno operator me check oil temp every 500rpm increment. It wasn’t until the last pull (to 7K) that the oil temp needle really started to move fast on the gauge. During this last pull the oil temp climbed from about 82 through to about 93. I hadn’t been checking the water temp and this was just passing through 120 at the end of the pull.

For the record I have a road car with an oil thermostat and 16 row core.

I'd guess that the oil thins down to whatever grade it is designed to thin down to and then a hotter engine doesn't thin it any more or if it does it doesn't help (I'm not an oil expert).

I guess the engine oil temp is a better guide to the temp of the parts than the coolant temp is and that hotter parts have greater friction or tolerences increase to the detriment of power or, possibly most likely a hotter engine allows more blowby gas to be generated. This last point is interesting as I once saw a Sprite on the dyno that had clear plastic breather pipes. It was only at the top end of the rev range that anything appeared to be passing down the pipe but at max rpm on each pull there was suddenly a heavy mist of breathed gas.

Perhaps we all need to ask WHAT oil temp and WHY from all our varied dyno operators to get a view on this. I'm always very interested in testing data.

Daniel Thirteen-Twelve

James,
the pipes feed into the sandwich plate from underneath, I don't have any photo's at the moment, I will see if i can take some and post them in the next day or so.

Alan
A Pritchett

That'd be great if you could Alan cheers.

James
James Ballard

James,
Sorry about the delay, but here are the pics, I hope they will be of some use to you:

Alan



A Pritchett

James,
And the second one:



A Pritchett

James,
I should have added, I fed the pipes throughthe heater duct opening and they then go under the strengthening beam, at this point i intend to cut up an old radiator hose or something similar to go over the pipes to prevent them chafing on the bodywork and causing RUST.

Alan
A Pritchett

I used a different route.
On the image you see two holes, the lowest is factory made(1975 midget) and the top hole i made myself.
Ordered the proper grommets for it and presto!


Arie de Best

Daniel,
Look at the chart (image).
You're right about the viscosity going down with temperature, and the line does gradualy flatten; the oil doesn't get much thinner as temperature rises.

(this are graphs for turbine oils, T32 and T46)


Alex G Matla

Many thanks for the pics and advice everyone. I'm in two minds as to whether or not I should go through the heating air duct (might make it awkward to remove the duct when working on the engine) or go through the bulk head. I do have a set of correct size grommets to be able to go through said holes but they would require cutting first...

Requires further pondering!

James
James Ballard

Another option, I ran solid steel pipes from the oil cooler up and out through the side of crossflow rad cowling above the top of the mounting stantion. This is on my frogeye and I have an aluminium cowl section fitted to the front of the crossflow cowling to take the air from the bonnet opening, this made access to the oil cooler unions more difficult, the connections to the steel pipe were easily accessible in the engine bay. BTW the oil cooler was fitted to the panel in the crossflow cowling below the radiator.
David Billington

This thread was discussed between 19/03/2009 and 03/04/2009

MG Midget and Sprite Technical index

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