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MG TD TF 1500 - cooling

Does anybody know why the vent hole behind the front transfer passage core plug was not drilled on some engines.
About a third of the engines I have worked on had not been drilled. All of these engines had borderline cooling which was cured by drilling one.
I know there is no pumped flow around the block and the bores are cooled by convection plus a bit of induced flow. Possibly the hole prevents an air lock in the block chamber.
Ray TF 2884
Ray Lee

This hole started life with the Wollsley block. It was intended to balance vapour pressures in the block.

I've rebuilt my XPAG 4 times, each time being sure that the hole was clear.

Gord Clark
Rockburn, Qué.
Gord Clark

Any photo of where this hole is located?
John Quilter (TD8986)

John,

Credit goes to Gene Gilliam.

http://www.ttalk.info/XPAG_Cooling_System.htm

Jim

James Neel

Yes both ends of the transfer passage, all engines have the rear one but a lot are missing the front.
Gene Gilliam shows both in his photos.
Ray TF2884
Ray Lee

Is this limited to the XPAG or possibly still a concern for XPEG engines?

Jim Rice

The front, even if it is there frequently gets clogged with rust and other debris.

Jim
James Neel

While you are in that front transfer passage hole, check for casting flash that restricts the flow of water from the water pump.

As you can see in these poor phone photos (sorry), this XPAG had a severe restriction, so I got in there with a die grinder and removed the casting flash.

Easy to see there will be a substantial improvement in the water flow to the back of the cylinder head.

Safety Fast

Tony
The Classic Workshop
Black Mountain
Australia




A L SLATTERY

In my opinion, the holes serve no purpose for cooling. The channel drops down from the pump and rises back up to the head and would trap water- without the holes, the channel could not drain and the block could freeze up and fracture.
JIM N

Hi Tony,

I agree with your comment re checking for casting "faults" while the core plugs are out. I once found a block which had bad a restriction at the rear. The cross section of waterway was about the size of my finger nail! I got a grinder and file and got rid of the restriction which was rearward of the rear core-plug hole on the channel/transfer passage. Strangely, that block had been like it from the factory .... perhaps 60 years! I wonder if that engine had always had cooling issues?
Jim, you make a good point. I have often wondered about their function. I always drill them out a bit anyway.

Bob Schapel
Bob Schapel

Gene Gilliams' illustration of the Xpag cooling water passages is the best I've ever seen. A lot of credit should go out to him for his efforts in explaining this! Quite easy to understand!
PJ Jennings

This thread was discussed between 11/08/2022 and 19/08/2022

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