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MG TD TF 1500 - XPAG - Cooling by OIL !

OK,I am hopeful that this thread will solve a puzzle for me.

A while ago (years !) I found a reference that stated "around 40% of the engine cooling in an XPAG engine is actually performed by the oil system and the other 60% by the water cooling system".

Can anyone recall a similar reference, or comment on the accuracy of this statement ?.

I also wonder why the TC had a finned alloy sump, while the Y-Types of the same era had a finless alloy sump.

Thanks Octagonally in Anticipation,

Tony Slattery
A L SLATTERY

Tony

This link wont answer all your queries however it gives the history on how the XPAG engine developed in different model MGs.

http://www.mg-cars.org.uk/imgytr/pdf/enginehist.pdf

My thanks to Neil Cairns for his painstaking efforts collating this information, it answers many questions that appear in this forum.
G Evans

Tony the article you're looking for was written by Neil Cairns titled "Short Stroke Morris Ten Engine's Cooling" & published in Safety Fast. If you can't find it, post your email address & I'll email you a copy. It's a well written article on the causes of & remedies for overheating. Cheers
Peter TD 5801
P Hehir

Tony,
I doubt that that statement has any real meaning. One might measure the temperatures of an engine idling for a while and come to that conclusion, but that's about it. Even with an oil cooler, it wouldn't be that effective.
Oil has only a fraction of the heat capacity as water or water/antifreeze and the amount of oil circulating is much much smaller than the volume of coolant circulating.
Compare the surface area of thin cores and fins on the radiator in direct air flow, versus the oil pan.
In all actuality, the faster the engine runs, the more time the oil spends pumping and dripping within the engine and less time resting in the sump... so it spends more time picking up heat and less time shedding it.

My wife drove our supercharged '51 TD around Michigan International Speedway for 3 laps doing about 75mph, with the 5:12 rear end! I was expecting a rod would let go at any second. When we pulled off, the oil pressure was down to 10spi at idle; after it cooled down, it was back up around 30 something psi.

In my humble opinion, oil coolers and finned aluminum sumps are primarily for cooling the oil and keeping the viscosity where it should be.
JRN JIM

Peter - I would also like a copy of Neil Cairns titled "Short Stroke Morris Ten Engine's Cooling"...
Neil's articles are always worth the read. My e-mail address is SUfuelpumps@donobi.net
Thank you - Dave
David DuBois

Oops, right there at page 8 (I'm a slow reader) of Neil Cairns' book it says "cast iron cylinder heads cannot withstand lead-free petrol." I use ethanol free gas but it is also lead-free. Should I be putting in an additive?

Is this question OT or an unintended hijack? If either I'll ask it in a new thread.

Thanks.

Jud
J K Chapin

If you can send me a copy of this article, I would greatly appreciate it. dirtydish AT comcast DOT net
Frank Cronin

Here is Neil's article for "Short Stroke Morris Ten Engine's Cooling"

http://www.mgbits.com/contents/en-uk/Heater.pdf

Rod
R D Jones

Thanks Peter, Yes that was the article - I found it in my research articles.

So the figure is actually 50/50 between the water and oil. There is a lot of detail and great information in that article.

I still wonder why the Y-Type engines did not get the finned sump ?.

Cheers

Tony
A L SLATTERY

Jud: I think that is true but almost everyone has converted their heads to using hardened valve seats and valves? So nowadays lead free is not an issue?
Chris Couper

Yes but mine was last taken apart in 1974 or maybe even earlier. I wonder if "lead free" was thought of then? It runs great. Should I just drive (yup, I'm guilty of head-in-the-sand syndrome) or pull the head and inspect? I'm a pretty firm believer in if it ain't broke don't fix it.

Jud
J K Chapin

My reading of Neil's nice article indicates that the heat dissipation is as follows:

23 % of heat converted to motive energy
50 % of heat leaves via the tailpipe exhaust
5 % of heat leaves via radiation and heat soaking
11 % of heat managed by oil
11 % of heat managed by water

So, yes a 50/50 division between oil and water - but for a total impact of only 22 %

An interesting article
DLD

Yes DLD, precisely my point it is only 22% that we can "manage" through maintenance, and the correct oil is just as important as the correct coolant.

But back to the fins on the sump - how effective are they ?.

I found a reference yesterday where it was claimed the Cream Cracker TA's had sheet steel sumps and that led to higher oil temperatures on the track than when they were fitted with alloy sumps. It was a TSO article.

My general rule for oil pressure is 10psi/1,000 rpm.

So 10psi is fine at idle and 40psi is fine at 4,000rpm.

When it drops below that - I change the oil - quick !.

Tony
A L SLATTERY

No worries Tony. Thanks Rod. Hopefully Dave & Frank are now squared away. I was sure it had to be on the net somewhere. Cheers
Peter TD 5801
P Hehir

Hi Jud

I ran unleaded in my TD from 1974 well up through the late nineties, when I had the head rebuild.

According to my machine shop, there was no appreciable issues with the head. I did have it redone to hardened seats, just because it was offered by the shop.

I have done a good number of lawnmower engines that were not build for unleaded and have yet to see any issues with the valves on these.

Others may disagree, but I would go along with if it ain't broke, don't fix it. If you need a head gasket or have other reason to take the head off, change it to hardened seats at that time.
Bruce Cunha

Some interesting points made in the article on MG related engines.

However,as has been indicated before,the area of 'Known
'X' Casting Nos.' has included inaccuracies on TF casting numbers.

TF cylinder heads were not numbered 168422 and Wolseley 4/44s were not numbered 168425.

The TF heads had the numbers 16842 CAST IN with an additional number '5' STAMPED IN.The last digit '2' was ground off by the Factory and the stamped '5' inserted to indicate the improved use of larger valve heads.

Wolseley 4/44s had the numbers on the head cast in,168422.I suspect the late TDs also had this number.
In Australia,many TFs have had the original head replaced with Wolseley heads,168422.

Don't get me started on TF1500 heads which again are different in their totally stamped number.(water holes are offset on one side).

I have seen quite a few TF1500s advertised for sale
both in Australia and around the world,with a replacement motor,such as a TF1250 or Wolseley 4/44 motor.That's okay too,as long as the seller CLEARLY
indicates this point to the prospective buyer!!


Cheers
Rob Grantham
TF3719("Aramis"),TF9177("Athos").
R GRANTHAM

This thread was discussed between 07/04/2014 and 08/04/2014

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