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MG TD TF 1500 - Cooling problems

The summer has arrived here and it's 80 deg.

I've noticed that the temperature gauge has been climbing steadily since earlier in the year when it was running at about 75 and the car now "feels" hot.

It's now running at 90+. When it's idling for any time or climbing a hill it rises to the 3/4 mark on the gauge, (97.5 deg?) and when I switch the engine off it runs on.

Can anyone tell me if this is normal. The car was a California import and the Rad is stamped "Pacific" so I wouldn't expect any hot weather problems.

Thanks AJ
A R Jones

A T-series should not run hot; if a car does, there is something going on that can be fixed. First would be to check the accuracy of the gauge. Then to be sure the water pump is a good one, preferrably with 5 vanes. Look into the rad cap opening and see if there is any junk in any of the tubes; also check your distributor timing.

If you have junk I recommend having the radiator professionally cleaned out, and also removing the core plugs to get out as much rust as you can. There are also drain holes (much in the archives) that need to be clear. New core plugs (I sell brass ones) will close things up, and you shoulod be fine with a 50/50 blend of antifreeze and water. Unless you pull the engine, you will not be able to replace the core plug at the back of the block.

Tom Lange
MGT Repair
t lange

Advanced timing will also make it run on the warm side,,,, As far as "running on",, just get used to this,,,, When you come to a stop, keep your foot on the brake,,, depress the clutch and put it in first,,, and when you turn the key to the off position, bring the clutch up,,, this will stop the running on,,, a little practice and it will be a smoooooth operation,,


Hi AJ,

See Archives - the first thing to do is to make sure the static timing is advanced fom the WSM TDC advice, about 4-5mm on the CS pulley. Retarded timing is the main reason for overheating in our cars, and British summer weather is nothing compared to some of the temps found in the States!

Other 'solutions' will help, but only if the static timing is advanced first. Even Morris Minors at the time were timed around 4 or 5 degrees static advance. Goodness knows what MG were thinking, although modern fuels don't help.


J C Mitchell

just as a counterpoint to steve's post..10 years ownership, thousands of miles, some days 100F plus outside air run on..ever. check timing, cooling, etc...but an idea outside the box...a dragging brake can cause a warm engine.regards, tom
tom peterson

Is it a TD or a TF?? The rad cap wouldn't make a difference if it is a TD,,,,

Steve - I seem to be the only one to mention the radiator, so here goes: the radiator tubes are visible when you unscrew a TD cap, and rust often accumulates and blocks those cooling passages. Harder to see on a TF.

Tom Lange
MGT Repair
t lange

Thanks guys. The engine has just been out. The rad looked good and we had it on a test bed for some time and there seemed to be no problems. It's a TF.

I'll check the timing again. I can't remember what the pump was like, I'll have to go thru my photo library but I do remember having to scrape a lot of material out of the pump pipes. Perhaps it's going to be a new pump!

Any thoughts on trying a radiator flush?

A R Jones

Hi AJ,

From what you've said I suspect your engine is timed at TDC, as per CS pulley notch and advice in WSM. If that is the case your engine is running retarded, and will run hot. Turn the engine back around 4-5mm from the CS pulley notch, and then turn the distributor so the points are just opening. Unless there is a problem with the distributor bob weights/springs, your engine should then run cooler. What temp. thermostat is installed? From memory it should be 72F an uncommon rating nowadays. If in doubt run without one for a period, easy enough at this time of the year.

By all means then flush the rad.,fit an engine shield, insulate the carb. float chambers - all this will help. A five blade fan, electric or otherwise will not help, unless you are spending a lot of time in slow moving urban traffic - which I suspect you are not! When driving normally plenty of air passes through the radiator, which is why on modern cars the fan only comes on when the vehicle is stationary or slow moving.

If the water pump is an original type , keep it. If the impeller is turning, this isn't the source of your problem! The bearings are standard although seals are hard to source, and the standard replacement pump can be made to work, though of poor quality. See Archives on water pumps for further info. Racemettle, near Gainsborough in Lincs. make what appears to be a quality pump,Tel 01427 679784.

Hope this helps,

J C Mitchell

I'm a bit surprised, I kept hearing that too advanced timing makes the engine run hot, not retarded...And on static TDC the engine runs like a dog. I only have heat issues since I advanced the timing, probably a bit much since I had no reference. But now I can climb hills in 2nd where I needed 1st before

Rgds Mike
Mike Fritsch


I have the Racemettle pump and it has mad a definite difference in the running temp of my 53, lowering it by 7-10 degrees.

James Neel

In my experience, retarded timing makes the engine run hot due to the incomplete burning of the fuel and that effect on the exhaust valve. However, If you decide to advance your timing, you can lean the engine some, which absent the cooling effect of the inlet charge may result in a hotter temperature, but is a more perferable hot because it allows the exhaust valve to transfer its heat to the head.

In general, on a stock engine with a Jeff Schlemmer distributor, I recommend static timing of 8 degrees BTDC, if pertronix equipped, or if your static timing skills are rusty, use 11-14 degrees BTDC at idle. Check for pinging by loading the engine by accelerating in top gear from 30 mph.

Dave Braun

Bruno 6 vane water-pump
Stainless fuel lines
Jet-Hot treated exhaust manifold
Pertronix 20 degrees advance @ 2000 RPM

Seems to be working for me. Very cool running for many years now.
This on a car that when first purchased ran very hot and had vapor-lock problems before the above was done.
David Sheward

Hi Mike,

It's been standard engineering knowledge for many years, as confirmed by Dave Braun, that retarded timing results in overheating and poor fuel consumption, yet the engine will run quite smoothly, deceiving many into thinking all is well.

How much did you advance your engine Mike? Too much advance will result in a 'harsh' drive, with excessive pinking and 'running on', which can in extreme cases lead to piston damage, but very unlikely in our low compression cars. Do not confuse the starter bendix rattle, which can sound like pinking under hard acceleration! - see Archives.

If you are still running hot, check 72F thermostat is opening properly on a TF, or get widely available conversion for obsolete TD type. Then the usual rad. flush, insulate float bowls to reduce vapour lock, engine shield, distributor bob weights and springs, fuel mixture, spark plugs, again see Archives.

Good luck,

J C Mitchell

An update.

Still quite warm here must have been about 80 degs today.

I had to stop on the motorway as the temperature gradually climbed almost to the "Full" mark on the gauge (110). It seems to warm up quickly rising to 85 in about a mile or so. It stays there for a while and then just drifts upwards to the 3/4 full mark over the next 6/7 miles. At 55 mph it rose to half way between 3/4 and full marks and the I shut it down for a while.

Checked the timing again and it seems to be fine. I think I sorted the "running on" problem by opening out the points. The dwell was on the high side.

I took the thermostat out and it's stamped 74 degs. I put it in a jar of hot water and it opens up ok. I'll flush it tomorrow and run it without the stat to see what happens.

I guess if that doesn't work I need to think about a new pump.


A R Jones

Hi AJ,

Sorry to persist, but when you say the timing 'seems to be fine', what doyou mean, and what point on the CS pulley are you referring to when the points open?

Also why do you think you need a new pump? Scores of T types (including mine) run perfectly well on a standard pump, at much higher temps. than those found in the UK!(was it really 80F in the shade today!!!) The Racemettle pump has more vanes on the impeller, but the effect on the water flow will be marginal at best, and the flow in a T type block is pretty slow anyway.

If you are reaching 110 on the gauge there is a serious, but probably easily solved problem. Everyone is trying to help you AJ, but info on the timing 'mark' you are using, must be the first place to start.

Look forward to more info from you,


J C Mitchell

AJ - Flushing the radiator in the car will do little to clean it out, unless you blow enough water from the bottom to the top, which will make one huge mess. At the very least I take out the radiator, turn it upside down and run lots of water throguh it, but I prefer to take mine to the radiator shop and let them do a professional job.

To summarize what I wrote in my first post,

It shouldn't overheat
1) Check gauge accuracy
2) Check water pump condition (5-vane preferred)
3) Check for clogged radiator tubes
4) Check timing (when I had a Mustang shop in CA I fixed more overheating problems by re-setting the distributor advance, than anything to do with the cooling system itself!)
5) Clean out water passages and drain holes, replace core plugs

Tom Lange
MGT Repair
t lange

Another issue to look at is lean running. While cruising after it is thoroughly warmed up, put the clutch in and shut the engine off- coast to a stop and check plug color! Maybe crank the main jets open a touch more for the time being- better to err on the side of rich, rather than lean... but keep checking plug color.

I added an O2 sensor to watch air/fuel ratio, but that's just me. ...still look at plug color, too.

The XPAGs originally called for a really tight point gap to get a long dwell.

I pay more attention to the ignition timing at full advance, rather than static or idle. Not sure what others run with twin SUs, but with superchargers, I stop at 25 BTDC.

Jim Northrup

Thanks for the updates, that was new to me. Mine is for sure advanced, though. I cannot detect pinging, but then there's so much rattle from the gear shift. It does rattle more than before, at certain rpms (before only in 3rd, now some in 4th).
From previous threads I assume its slightly too high and probably need to readjust. Cooling issues started after the timing advance in long drives at high rpms >4000 or in stop and go in hot weather. First can be controlled by slowing down to < 4000, second leads to boiling and spillover.
On my todo list....
Rgds Mike
Mike Fritsch


I agree with all your points, although I would hoped to have greatly reduced the overheating without having to remove core plugs, not an easy task with the engine in the car.

Jim, you're right about paying attention to the whole ignition timing range, but I was suggesting to AJ that he had to start somewhere, and static timing can be easily done at home without special equipment. Back in the 1970s I had persistent overheating with a TD - it took nearly a year before I found the bob weights and springs were stiff, and not snapping back when twisted!

Mike, all I can suggest is that you run through all the possible causes set out in this thread, and the Archives. The gear lever and rods are prone to rattle, and even if rebushed etc, the problem often returns after a period, especially under hard acceleration. Believe it or not, in the Archives you will find reference to retarding the ignition in order to reduce the rattle!!

If not already done 4-5mm on the CS pulley would be a good starting point for static timing, then check timing throughout the range. If your car is a TF, run without a thermostat for a while, if a TD get the conversion kit for the thermostat.

Good luck,

J C Mitchell

Still working thru the list of things to check but I was wondering, if the ambient air temperature is 80 deg at what temperature would you expect the engine to run?
A R Jones

John brings up a good point;
The advance weights in the distributer.
Mine had a broken spring when I got the car.
Check that one!
David Sheward

"I found the bob weights and springs were stiff, and not snapping back when twisted!"

"Mine had a broken spring when I got the car."

Those comments reinforce the importance of taking note of where the full advance is. Timing light will clearly display advance behavior revving from idle on up. Nice to actually visualize what is going on. I'm not suggesting installing a degree wheel or anything superaccurate, just nice to know it is actually moving a significant amount.

If it isn't pinging, then it isn't too advanced. Retarding timing will aggravate the problem. I wired up a "knocklight" to warn for pinging, but, that's just me again.
Jim Northrup

Now here's an interesting one - Jim, how does that knock light work ???

Thanks for all the other good points. I use a strobe light for timing, so I can see the advance. Just not sure about the max- the crank goes round twice for one cycle, doesn't it ? Does that mean 20 deg advance is actually 40 off the TDC then ?
Mike Fritsch

Some fellows from Australia put this together...
Attach a cheap Bosch type knock sensor to the engine and run a few wires. Also includes a shift light.

20 degtrees advance is 20 degrees out of 360, 1 revolution; not 40 out of 360, or 20 out of 720.

Jim Northrup

Update. Progress!

I cleaned the rad and flushed it, took the thermostat out and set the timing statically at 4-5mm advance and checked it with a strobe.

It's now running a shade over 85 degs. It goes up to 97 with a hard pull up a hill but it does now come back to 85 on the flat.

I'm still a bit worried about standing in traffic. Can anyone tell me whether a 7 blade MGB fan will fit the pulley in the photo attached please.

I'd also like to know from you guys that live in hot places like Texas and California what temperature your engines run at on 80+ degree days.


A R Jones

AJ, one of the sometimes overlooked details in cooling problems is the opening of the grill slats. They have some adjustment and need to be full open, especially at idle. Not always the total solution, but part of the issue.
Worth checking-
Dallas Congleton

>I'd also like to know from you guys that live in hot places like Texas and California what temperature your engines run at on 80+ degree days.

I'm in NC which gets pretty darn hot (we're regularly in the 90s and even into the 100s F in the summer.

How hot does my car ('51 TD) run? It doesn't boil over. That's all I really care about -- if it's not boiling over, it's not too hot. More specific than that I can't say because I don't have a gauge and don't really feel the need for one!

Rob Edwards

My TD normally runs right around 85-90 degrees even in the South Carolina 100+ degree days. I installed a seven blade MGB fan on it primarily for vibration elimination. Are your blades on correctly?

Install fan blades correctly! Rear fan blade has offset holes. Reinforcing plates face forward,

Hope this helps.

Ed Stanfield
ECS Stanfield

Hi Ed,

Although you are correct about fitting the fan blades - no offence, but they cannot be fitted the wrong way round airflow wise, a common myth I'm afraid - see Archives. There is a very minimal difference, because of the slight curve in the blade but this would not account for the high engine temps. AJ is getting in much lower UK ambient temps., as compared to yours in South Carolina.


J C Mitchell

My TD has run consistently at 85 to 90 degrees since I rebuilt it 3 years ago.Last summer the temp rose to 100 up a 2 mile long 1 in 4 hill in north yorkshire during a t series weekend. I received advice from other T owners that my radiator slats were too closed so this winter I opened up the grill slats and what a result. My average temp has now dropped too 75 to 80 and instead of the temp climbing when driving at above 65mph it now actually comes down (UK ambient temps).

Cheers Chris
C A Pick


Not sure if it helps give you a better idea of what to expect, but I went out this afternoon on a 40 mile run in the hot clear sunshine we're currently enjoying. The air temp was around 25C, throughout.

Car's temp gauge stayed pretty much on 75C, occasionally rising briefly to 80C if I'd pushed it hard and then eased off. Mind you, the oil pressure was 10psi lower than I'm used to, most other days, which I put down to the unusual hot weather - hopefully someone will put me right if its not.

- Tom.
Tom Bennett - 53TD 24232

75C (167F) is too cold IMO -- not hot enough to drive the condensation & fuel contamination out of the oil....
Rob Edwards

Hello Jim,
you mentionend"While cruising after it is thoroughly warmed up, put the clutch in and shut the engine off- coast to a stop and check plug color!""
It is the first time I hear about such a procedure to catch the plugs in their high performance condition rather than adding some slow driving and idle running before the normal home stop.
Why is this? greetings, huib
Huib Bruijstens

I followed Jim's advise on checking plugs "at speed" many years ago on this BBS. When I first read his advise on this it was like a light bulb went on over my head! "Why didn't I ever think of that?!"
World of differance in what my plugs looked like!
Found I was quite a bit more on the "lean-side" than I thought I was.
David Sheward

Jim's method of shutting the engine off at speed and coasting to a stop is the only way to get a good plug reading at operation conditions. I owned/operated a motorcycle shop back in the 1970's, tuned a lot of bikes for top performance on track or street, and I was fortunate to have a state hiway in front of the shop. I could made the run and coast into the shop (sometimes in dark of night with track bikes) pull plugs, change the jet in the carb & make another run. Have also done it for cars.
memories --
A W Parker

Huib & friends,
If you want to find out how the air/fuel ratio is doing at highway speeds, the best way is shut it right off at high speed. Slowing down and idling may darken it up from running rich, providing a completely false and misleading reading.

By the way, don't switch sparkplugs and tighten cold plugs into a hot head, especially if that head is aluminum!

I paid a lot more attention to plug color on my motorcycles, like Al, back in the good old days. Burned finger were part of the price paid for owning a bike. Engine seizures were more common with high performance air cooled stuff.

Jim Northrup

This thread was discussed between 23/05/2012 and 29/05/2012

MG TD TF 1500 index

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