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 Post subject: TC overheating- another question!
PostPosted: Thu Jul 05, 2018 3:20 am 

Posts: 24
I am sure this topic is done to death somewhere, just can't find it, so apologies for repetition

3 questions
1- should I replace the original 4 blade metal fan for, i'm being told, an mob plastic one, that apparently fits straight on and in the limited space available or

2- fit an electric fan in front of the rad, what type size etc I would appreciate advice on, does it have a switch to activate

3- I haven't yet done so but maybe try opening up the grill slats a bit, but reluctant to do so as probably damage the paint
the former spoils the original look, the latter doesn't

I do have a temperature gauge fitted it warms up quite quickly as soon as hills are reached, everything else has been done, new rad core last year took out core plugs [one was leaking anyway, and flushed everything through

Which is the better solution to keep it cool in the [very rare] english heat wave we're having just now

Cheers


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Thu Jul 05, 2018 4:06 am 

Posts: 18
Hi Tone,

I am not the best knowing one of the old MGs, because we own our TC just for a bit more than one year, but I have been told, and it is my experience too, living here in Bavaria with many mountains around, that there are normally no temperature problems with the XPAG.
Maybe the reason for overheating is a choked radiator and/or clogged channels in the engine. I would start to flush the system carefully, maybe with some acid and look whats gonna happen. Our TC never comes over 90°, even in hot weather climbing alpine passes.
One has told me, XPAGs normally run rather too cold than too hot...

Best regards
Lindi


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Thu Jul 05, 2018 6:22 am 
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Posts: 150
Lindi is right - overheating is not normally a T-series problem, especially since you have already replaced the radiator. The cooling system has a number of possible problems: the gauge, the thermostat, the water pump, the fan, the radiator, the radiator slats, the cooling passages, and the distributor.

You have already re-cored the radiator (3-row?) and flushed the cooling passages, which are good steps. I would then have your distributor rebuilt by a knowledgeable professional like the Distributor Doctor in the UK, or Jeff Schlemmer at Advanced Distributors in the US. This fix, along with EXACT timing adjustment (34 degrees total advance at 4,000rpm), usually takes care of overheating issues. I would also (carefully) check the accuracy of your temperature gauge. I would remove the thermostat, immerse it in water and bring it to a boil to be sure it is opening properly at the right temperature.

If your water pump blades have any wiggle at all, get a new water pump with a 6-bladed impellor. You can also fit an MGB fan, but to me that's really just masking the problem. Opening up the radiator slats fixes an issue if they are too closed to allow air to freely enter; an electric fan is not really necessary.

My guess is that if you attend to these things, you will figure it out. I must also point out that one of my TDs runs happily at an indicated 85 degrees, and another runs equally happily at an indicated 95. Nothing I have done has lowered the 95 number - water pump, thermostat, cleaning cooling passages and radiator, distributor, timing, etc. Go figure...

Tom Lange
MGT Repair


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Thu Jul 05, 2018 8:51 am 
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Posts: 784
Location: Southern California
I agree fully with the above. On normal days, my TC runs too cold. While climbing a mountain grade on a very hot day it might get up to 85 or so. The radiator in these cars is big for the engine size.

The only thing I didn't see mentioned is the possibility of combustion gasses leaking into the cooling system. Also check valve lash, as too much can cause hotter running. These are far less likely issues than timing or a clogged radiator however. I would definitely have the distributor rebuilt and curved for modern fuels, and take the radiator to be rodded out. Not just flushed with water, but the top tank removed and the core cleaned with metal rods.

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1949 TC8975 / XPAG 9609
http://www.mgnuts.com


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Thu Jul 05, 2018 11:40 pm 
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Posts: 35
Location: North East ITALY
on my TD and TC I have problem in summer days and on mountain climbing pas specially when I find a road red signal - it occur because cars are designed 70 60 years era- no queue no stop
Cured with a 6 plastic fan (ex modern Midget)
and a computer fan (or TWO)placed on the upper part of the radiator (a Switch ON OFF help a lot)
-that radiator space is free, and works only if car are in movement-engine fan rotation not cover this area
it works for me specially at stop with the engine on
from the cars modification NO overheating occour


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Tue May 07, 2019 5:34 pm 

Posts: 29
Location: Kansas City and Richmond VA
After reading all the posts and doing other additional research, help is still needed with the following problem that TC0820 is having:
Driving causes massive overheating to the point of boiling and spewing steam. This occurs in less than 4 miles of city traffic driving at air temperature of 60 degrees F..
This occurs now after a total rebuild of the engine at a prominent shop. Details on the engine build, below.
Conditions for troubleshooting during shop diagnosis are as follows:
Valve gaps set for 0.14 inlet, 0.15 exhaust according to Crane instructions
Ignition is standard Lucas with rebuilt distributor and timing set to the curve in manuals which advances to 32 degrees @ 3200 rpm. maximum of 35 degrees at 3500 rpm
The thermostat is the original type -- that blocks the bypass until the verified opening temperature of 160 degrees. The test was also run with NO thermostat and the bypass blocked off.
The water pump is new with bronze body and with sealed bearings and six bladed bronze impeller. Blades position is slightly angled.
Radiator is new with 4 rows in the core, no leaking coolant, and grill slats are set wide open.
The fan is original 4 blades and creates full force of wind through radiator. Fan belt new and tight.
In addition to the engine fan, also a floor fan was run that forced the equivalent of 50 mph of wind at the front and grill/ radiator during the test.
Carburetor mix is slightly rich.
-------------------------------------------------------------
The engine was Soda Steam blasted clean, bored +0.20 inch oversize, new Moss crankshaft, Main bearings & caps alignment bored, pistons & con rods balanced, cylinder head CC'd., polished & ported, valves & seats ground, springs balanced.
Crane camshaft was installed that has slightly modified lobes and cam angles.
Engine block has One (1) vent bypass hole present and open in the water galley core behind the exhaust manifold.
-------------------------------------------------------------
Any help that can be advised will be appreciated.
Octagonally yours, Robert Griffey


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Tue May 07, 2019 7:16 pm 
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Posts: 784
Location: Southern California
Since you mention city traffic driving, the first thing I would check is the timing at idle / low RPM. You should be around 5-7 degrees BTDC at idle. If it's retarded then it will definitely overheat. You could advance the timing a bit and see what happens. I would also check cam timing just to be sure. Not sure what you mean about a "vent bypass hole".

Does it run cooler at speed?

_________________
1949 TC8975 / XPAG 9609
http://www.mgnuts.com


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Wed May 08, 2019 4:36 am 

Posts: 29
Location: Kansas City and Richmond VA
Thanks for the advice.
Will check ignition timing and camshaft timing in the next few days, as well as carb mixture.
At speed it just keeps getting hotter.
There is supposed to be a hole in the casting behind the rear core plug that allows water from the galley passage into the main passages surrounding the bore jackets. Said to be a key culprit in overheating if missing the hole or the hole is blocked [not sure where the references to this are].
Also a comment to drill an additional hole in the casting behind the front core plug to allow more circulation, but did not do that yet because I thought it would not be needed.

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Octagonally Yours --
Robert Griffey
The Octagon Whisperer
Kansas City and Richmond VA


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Wed May 08, 2019 10:35 am 
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Posts: 328
Location: North America
There is an article in the resources section of this website for reference to the hole in casting behind the core plug.
http://www.mg-tabc.org/library/the_hidd ... assage.htm

Could be cam timing off or exhaust gas leak into coolant, as already mentioned. There is a fairly simple test to check for exhaust gasses in coolant. Statistically speaking, most XPAG overheating is from not enough distributor advance.


 
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 Post subject: Re: TC overheating- another question!
PostPosted: Sun May 12, 2019 4:42 am 

Posts: 29
Location: Kansas City and Richmond VA
Results of this forum discussion have been very positive -- and successful for most of the solution to our problem with overheating.
We replaced the bronze six bladed water pump with a stock original water pump built by Roland "Butch" Taras, but doubt that alone solved the problem.
Adjusted the mixture of the carburetors to make for leaner burning, also doubting that was much of the problem.
Then advanced the distributor -- which was a very considerable amount, in order to correct what we now suspect to have been a few degrees retardation of the camshaft timing.

Now we start, run and shut off correctly.
Running at 1800 rpm idle, but with a floor fan blowing onto the radiator, the temperature stays at 165 F. Without the fan, same idle, the temperature is 175 - 180 degrees F.
Glad we did not have to open the engine further for such things as drilling extra holes in the water jacket or replacing the camshaft.
(Chance to do all that on the next engine build.)

Thank you all very much for very helpful contributions !!!

_________________
Octagonally Yours --
Robert Griffey
The Octagon Whisperer
Kansas City and Richmond VA


 
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