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MG TD TF 1500 - bubble bubble, toil & trouble?

After a hot 30 mile up-mountain ride (10,000' MSL)this weekend the temp gauge was 100C. I pulled in the garage and could actually hear the water boiling in the radiator! I have a good mix of water/anti-freeze & Water Wetter. Oddly, there is minimal, if any, drop in my water level after she cools and none on the floor. My overflow tube is clear I'm sure. My thermostat seems to open properly when I touch rad. with hand as she warms up. My question is how safe it is to let the water "boil" like that? Should I have pulled over and let her cooled down?
efh Haskell

Climbing Mt Equinox in Vt a few yeasr back, our temp was well into the Oil Pressure side of the gauge! IMHO, If you just pull over and shut it down, you would be asking for trouble,,,best way is to stop, face it into any breeze, keep it running and the temp should come down gradually.. Just stopping when it is sooo hot might lead to "Heat Sink" and a head gasket problem...

SPW
STEVE WINCZE

I have had some bubbling/boiling sounds at shutdown after a long hard drive, not that unusual. Of course at altitude you will boil much cooler with our non-pressurized systems. The coolant mixture raises this temp a bit, but if you were not steaming/blowing out coolant you were fine. I'm with Steve that shutdown would worsen the situation due to no waterpump circulation. George
George Butz

And, open the bonnet while it's cooling down. Makes a big difference. Bud
Bud Krueger (TD10855)

Ed,

Some point out that pure water will carry more heat away from the engine. There is truth to that.

A rich 50/50 antifreeze mixture will not boil till around 230F/110C.

I prefer the antifreeze. On hot days, cruising 70mph gets it pretty hot, but pulling right off the highway into stop and go traffic, I've seen it get up to that 230F mark, and no boiling.

It brings to mind a warning about hot turbo engines... not roar off the highway and shut it off blistering hot as the oil in the turbo does not set well with those temps.
Jim Northrup

Part of the problem is the 10,000 feet above sea level, compounded by the engine working harder up the grades. The rule of thumb is that the water boil point will decrease about 2 degrees for every 1000 feet, so you have lost 20 degrees on your boiling point - whether plain water or antifreeze mix.
You didn't say what your "good mix" of anti freeze and water is. A 50-50 is the best for increasing the boiling point, but the trade off is some decrease in heat transfer. The water wetter is just a surfactant and does not affect the boiling point, but theoretically will compensate some for this.

You could investigate a slightly pressurized system, if you are going to operate at this altitude a lot.

Dallas Congleton

Don't wish to be pedantic, but, it's a change in atmospheric pressure that affects the boiling point. Of course Dallas is right, the atmos press decreases with altitude and you might well expect water to boil at 80 deg C at 10,000 ft but the weather also plays a big part and if there are low pressure pressure areas about at the time you are out driving you might find the boiling point drops even further. Google "How does elevation affect boiling point" and you should find a table somewhere relating boiling point to atmos pressure. You should then be able to compare this with the weather in your locality and determine whether this is going to be a regular problem for you.

AJ

AJ
A R Jones


Below is a well thought out, albeit, long discussion that may assist those concerned with cooling system problems.

Cooling Systems Problems? - Possible Solutions
MG “T” Series, MGAs and early MGBs

MGs in general are notorious for having cooling system problems. The original design was, at best, marginal, even for the cooler climates of the United Kingdom. These cars when driven in the southern third of America or in modern day traffic, anywhere, will likely experience overheating problems. So, what can be done to improve the overall cooling efficiency of the system? Before you begin to make improvements you must first verify that car’s radiator is clean, the hoses are leak free, the fan belt is tight, all ensuring that the stock cooling system is operating at maximum efficiency. Additionally, be sure that the timing and carburetor air/fuel ratio are set correctly as these too, will influence engine-operating temperatures. The improvements that can be made are as follows:

1. The most effective, but most costly, modification is to re-core the radiator with a modern high-efficiency 3-row tube design core replacing the stock two-row design. This greatly improves heat transfer and will, in itself, likely solve your overheating problems. Most radiator shops can re-core the “T” Series radiators. The downside is that it will require the removal of the radiator and will cost upwards of $400.
2. If your car’s only problem is overheating when operating in slow or in bumper–to-bumper traffic but otherwise okay, then a replacement fan may solve your problem. My understanding is that the 7-blade plastic fan (Moss p/n 434-340 - $76.46 at LBC) that is used on later model MGBs will fit the “T” Series cars. I do not have any personal experience with this fan, but it appears to be a sound approach to solving this specific problem.
3. The most cost-effective modification that you can make is to convert the current “open-to-atmosphere” cooling system to a pressurized coolant recovery system. Please see Building a Pressurized Coolant Recovery System” below. Water boils at 212 deg. F or 100 deg. C (Higher, with antifreeze added, but for the purpose of this paper, we will assume that water and the water/antifreeze mix coolant boils at the same temperature).

If, under all normally encountered driving conditions, your car operates at less than 212-degrees F, the open system is just fine. However, if on occasion, you exceed 212 degrees by even a small amount, the coolant in your radiator will boil, the steam generated will vent to atmosphere and when the engine cools it will contain less coolant and, hence, less cooling capacity. As this cycle is repeated, boiling will occur earlier in the cycle and with a greater coolant loss. If you do not top-up your radiator at frequent intervals, overheating will surely occur.

In an even worst scenario, assume that your cooling system is marginal for your car’s typical operating conditions. On a very hot day, you are driving on the freeway at 70 MPH and the coolant temperature increases to 212 degrees. The coolant will begin to boil, and steam will be created. Steam, being a poor heat transfer medium will exacerbate the cooling problem and, to make matters worse, the steam generated will be vented, resulting in less available coolant and a lower radiator cooling capacity. If the car is operated in this high speed, high ambienient temperature, steady state condition, engine-operating temperatures will continuously increase and continuous coolant loss will occur. Unless you notice that the car is overheating and pull over to let that engine cool you will shortly exceed the critical temperature and the engine will seize. A very costly repair!!!

How can a pressurized coolant recovery system help? This type of system, in use since the 1960s, performs two functions. First, it pressurizes the system and second it allows for coolant that would normally be lost to be recovered. By pressurizing the system, to say 7-PSI to13-PSI (typical radiator cap ratings) above atmospheric pressure, the water’s boiling point will be increased to between 233 deg F to 246 deg. F. Additionally, when starting a cold engine and as it warms and reaches its normal operating temperature, the coolant in the radiator will expand. The expanded coolant will create positive pressure in the radiator and open the radiator cap’s bypass valve and coolant will flow into the car’s radiator coolant expansion tank (aka - radiator overflow tank). Later, when the engine is shut down and allowed to cools, a strong vacuum will develop in the radiator that will open the secondary bypass valve in the radiator cap. This permits coolant to be sucked back into the radiator, thus replenishing the coolant level. This cycle is repeated trip after trip.

With occasional minor overheating, the increased boiling point of the coolant will eliminate the generation of steam and, hence, minimize permanent coolant loss. The result is less frequent radiator top-ups and the reduced probability of future overheating problems.

If a temporary problem is present or if ambient temperatures are extremely high (e.g. a worst case scenario), the pressurized system will allow the engine to operate and an elevated temperature above the coolant’s normal boiling point. If the engine can reach an equilibrium temperature of 220 deg F or less, the engine will operate without catastrophic damage. Ideally, an engine should operate in a temperature range of 180 to 200 degrees. The occasional operation of up to 220 degrees is not desirable, but a far better alternative to overheating and an engine seize up.

4. To help detect a real-time overheating situation, you should consider adding a visual and/or audible alarm system. On my TD, the radiator has a 3/8-inch NPT (tapered) female fitting installed on the engine side or the radiator. I used this fitting and installed a temperature sensor normally used operate a modern-day temperature controlled, electric cooling fan. The sensor has an internal switch that closes at 204 deg. F. The sensor is wired to a dash light and a mutable alarm. If I am not attentive to the temperature gauge, the high-pitched alarm will certainly correct that situation. There are, of course, other ways to accomplish this idea. The objective is to install a sensor/switch in the cooling system and wire it to at, least, an auditable alarm.

The temperature sensor switch that I used is NAPA P/N FS116 - $34.99. This switch has a 3/8-inch straight thread. It works, but you will be better off if you can find a switch with a tapered pipe thread. The mutable piezio alarm that I used was purchased from www.floydbell.com , P/N OC09-530-QO – $28.42.

(PS – I installed one of these alarms in parallel with the low fuel level warning light. I now have an audible and visual warning when the fuel level is low)

5. One last suggestion; there is a product called Water Wetter, made by Redline and available at Advanced Auto, Amazon.com and other places. The manufacturer claims that, when added to your radiator, your car will run up to 30 degrees F cooler. I don’t believe 30 degrees, but online testimonials claim actual cooler temperatures. It is most effective when used with water only (e.g. no antifreeze). It is supposed to contain anticorrosive and water pump lubrication agents. I have no personal experience with Water Wetter, but for under $10.00, it may be worth a try.



Building a Pressurized Coolant Recovery System

The design objective is to construct a small sealed chamber that can be pressurized by the stock cooling system. This pressurized chamber will act, in many ways, like a miniature radiator. Also included is a radiator coolant expansion tank that will store the overflow coolant.

The items required are as follows:

1. Two 2-inch copper plumbing end caps.
2. 3-inch section of 2-inch copper pipe. (Items 1 and 2 are used to make the pressurized chamber and can be purchased at a commercial plumbing supply house.)
3. Standard, small or large size, new or used brass filler-neck for a copper/brass radiator.
4. Mounting bracket made from a 1”x3” strip of brass or steel sheet metal with screw mounting holes drilled about 1/4-inch from each end.
5. 7-PSI to13-psi radiator cap, sized to fit the neck.
6. New or used small size coolant expansion tank. (A junk yard is a good source)
7. 2-inch length of 5/16”-copper tubing.
8. Two lengths of 5/16”-rubber fuel line (length to fit) and 4-hose clamps and a length of rubber tubing for the expansion tank’s outlet to atmosphere


To construct…

1. Drill a hole, with a size that matches the diameter of the radiator’s brass filler-neck (item3) in the flat end of one of the 2-inch copper end caps. (A spade-type wood boring drill bit will work)
2. Place the end caps over the copper pipe and solder together.
3. Drill a 5/16” hole in the side of the end cap without the hole for the radiator neck, about a ½-inch from the end. (This assumes that you will be mounting the chamber upright. If you are going to mount the chamber on its side, drill the hole in the bottom of the end cap)
4. Insert the 5/16-copper tubing (item 7) in the hole about half way and solder in place.
5. If mounting upright, solder the sheet metal mounting bracket (item 4) to the bottom of the chamber and centered on the end cap.
6. Insert the radiator neck (item 3) through the hole in the top end cap and solder in place.

The pressure chamber is now complete.

Assemble as follows:

1. Mount the pressure chamber at a convenient place in the engine compartment. I mounted mine on the topside of the passenger side frame rail.
2. Mount the expansion tank in an inconspicuous spot. On the front and right side of the toolbox, the backside of the frame cross member, just below the radiator are good places.
3. Using an appropriate length of rubber fuel line, connect the end of the radiator’s stock 5/16” overflow pipe to the 5/16” copper tubing installed in step 4 above. Secure in place with hose clamps.
4. Connect the Expansion tank to the 5/16-inch inlet/outlet pipe on the radiator neck (item 3 above) using the appropriate length of fuel line and secure with hose clamps.
5. Fill the expansion tank to the cool level mark. Fill the radiator to the bottom of the filler neck. Screw the original chrome radiator cap onto the radiator and the new 7-PSI or 13-psi radiator cap onto the copper pressure chamber.


You’re Done!!! Happy Motoring!!!

PS – If you have any questions, please call me at 843-838-0822 – Frank Grimaldi
Frank Grimaldi

Frank, I might suggest a simpler approach. Have a look at http://www.ttalk.info/Tech/Overflow_tank.htm . A 50/50 mix of anti-freeze will get the boiling point up to a bit over 220F. Water wetter is a fine additive to water. It's already in anti freeze. Bud
Bud Krueger

Frank
What would be the source for a filler neck?
Thanks
Edward
E.B. Wesson

Frank, had my radiator done in modern 3 core and no problems so far. Around the Twin Cities the cost to re-core runs about 600 plus. I think it was worth the cost. Had the radiator out to do an engine rebuild so removal at the time was not a problem. The radiator is not to tough to do on a TD,TC the TF, another deal.
Tom Maine (TD8105)

Edward,

The source of the filler neck was a junkyard.

Frank Grimaldi
Frank Grimaldi

Frank
Thanks, I do junk yards too.
Edward
E.B. Wesson

This thread was discussed between 22/08/2011 and 28/08/2011

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