MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Is the thermostat required 67 MGB?

I've recently had my MGB rebuilt. Up until recently (summer in sub tropical Australia) I've had no problems with overheating and the temp seldomly rises above 200deg F,and usually sits on about 180,even in traffic. The car has been fine the last 6 months (Winter / spring) but since the onset of summer I have noticed the car heats up pretty rapidly, particulalrly in even light stop start traffic.
The radiator was completely rebuilt and I beleive a new thermosat was installed in the rebuild so I figure it may just be the wrong type of thermostat for summer.
There are a few markings on it but none really make much sense (there is 180 written on it somewhere so that maybe the size).
I remember with some old cars it was often the done thing to remove the thermostat altogether for summer driving but I have also heard that this can be a bad thing. What should I do, get another allround therm, or have one for summer and winter or ??
Any feedback appreciated.......
Craig

Craig,

I've heard of cars been run without the thermostat as well but I believe the majority were involved in racing.

I suggest you try a new thermostat of 180 degrees. 180 works well year-round. I've been using one of these in my '74 with no problems. The one you now have may have a sticking problem and not opening properly. If you still get over-heating, then have the system checked out.

If you want to check out the themostat you have, heat up some water on the stove with a thermometer and see what temperature your 'stat opens (if it does).

Cheers
Simon

Simon Austin

Always try to run with a thermostat - if not - then
use a "blanking sleeve" in order to maintain
proper coolant flow and pressure.
Daniel Wong

Not sure what your local temperatures are throughout the year, but here in Los Angeles the temps range from around freezing to 115F. I use a 165-degree unit year round with no problems. In very cold weather the car runs a little cool but it never poses a problem.
Steve Simmons

Try dropping down to a 165* themostat -- sometimes the degree number is stamped in centigrade.

Up here in the North East, we're having a wonderfully mild winter so far, but I run a 165* year round -- using a piece of canvass in front of the radiator for really cold days.

I envy you your summer that seems much farther away than Australia here in January.
glg

http://hem.passagen.se/larsragnar/
Page 2
Ingemar

Craig. The 180 on the thermostat, most probably, indicates that it begins to open at 180 deg F. Thermostats reach the fully open point at 20 deg F above the initial opening point. Thus, a 180 degree thermostat begins to open at 180 degrees and provides full water flow at 200 degees. Thus, the indications you describe indicate that the thermostat and cooling system are working properly. A 160 or 165 degree F thermostat would open at the lower temperature and be fully open at 180 or 185 degrees. This means that they would be allowing full water flow through the system when your current thermostat is just beginning to open. Whether you would see any cooler running, however, depends on what temperature your engine runs at with full water flow. All a thermostat does is regulate the minimum water temperature, not the maximum water temperature. For a more in depth discussion of this, check out my website at www.custompistols.com/ and click on the MG section, then articles. The article on cooling system inspection will tell you most of what you want to know. Les
Les Bengtson

I've had defective thermostats. I usually test them before I install them to make sure they start opening at the indicated temp. It's not advisable to run w/o one as it slows down the coolant flow through the rad and thus cooling the a/f. If a/f runs too quickly through the rad it won't cool down.
Mike MaGee

Without a stat or blanking sleeve you can get too rapid flow through the engine which causes turbulence, local circulation, and hot spots. This doesn't usually show up on the gauge but can cause engine damage. If you can't easily find a blanking sleeve then I have found that with the stats we get in the UK at least, you can 'screw' the spring off and remove the wax pellet which leaves a hole about the same as a fully open stat, and what's more is reversible back to a proper stat again.
Paul Hunt

If you mount a expansion tank the temp will be lower.
http://hem.passagen.se/larsragnar/
Page 2 MGB Radiator image 1
Ingemar

How?
Paul Hunt

If you mount a expansion tank the temp will be lower.
http://hem.passagen.se/larsragnar/
Page 2 MGB Radiator image 7 & 8
Ingemar

Hi Craig,
In BMC's Confindential Technical Bulletin No.2A11,dated Sertember 29,1967,it is stated:"Where thermostats are removed,as is customary in hot climates,it is essential to fit a thermostat blanking sleeve,Part No.11G 176.If this is omitted,the resultant inefficient coolant flow and higher running temperatures may possibly lead to an engine seizure.
This bulletin was sent to all distributors and dealers of Mini Range,1100 Range,Austin Healey Sprite,Austin Healey 3000,Morris Minor 1000,Mg midget,and MGB.
Some other things you may want to check are;
1.Is the timing set properly?If advanced too far it can cause hot running.
2.Make sure the brakes are adjusted and not dragging.
These are just a few things you may want to try to keep your car running cool.
Good luck and good driving.
Tony
Tony Shoviak

By adding an expansion tank you effectivly increase the capacity of your radiator. Without the tank the radiator has 1 to 2 inches of open space at the top to allow for expansion. By fitting an external tank you increase the overall capicity of your cooling system and eliminate the air which is now in the top of your radiator. Ray
RAY

Once the cooling system has got up to temperature any cooling from the expansion tank is insignificant compared to that from the radiator, and there is no provision for water so cooled to pass back into the cooling circuit. Neither is the volume of coolant contained in the tank available in terms of increased capacity for the cooling circuit, coolant volume being transferred *out* of the cooling circuit into the expansion tank as the system heats up, of course. Where it does score is that the top of the radiator can be much closer to the top of the engine, with no additional space under the bonnet required for the radiator cap, which allows for a lower bonnet line on new designs. The coolant level in 4-cylinder chrome bumper radiators with a filler cap is easily maintained above any part of the engine, and the air gap performs the same function whether it is in the radiator or the expansion tank, so I submit that fitting an expansion tank to a standard chrome bumper car will have no effect whatsover. What is more, since there are many thousands of MGBs in hot climates without expansion tanks run perfectly happily, the fitting of an expansion tank to an overheating car would be attempting to dodge the real issue. The engine cooling circuit in a V8 is higher than that of a 4-cylinder (although the heater is the same and higher still), it also has a forward mounted radiator, which was why the V8 had an expansion tank from the start i.e. for chrome bumper models as well as rubber.
Paul Hunt

Craig,

I cannot see point in running without thermostat (just lowest you can buy) as this is best way to warm engine to optimum temp.

Running cool say 70-75 deg C will prob produce most power, but in my view the other critical temp is oil which should be say 100 - 110deg C.

The other consideration is heat for occupants!

An auxillary rad could be added say matrix from heater.

Water Wetter I like to use anyway.
Forlife coolant boils at 180deg C and also Evans Coolant which may have an advantage by reducing the need for pressure in system.

Paul
Paul Wiley

If it's just that the weather has got warmer, how about fitting a Kenlowe fan? My car gets warm in start stop traffic even in these decidedly non-sub-tropical parts, but the electric fan gives me peace of mind, particularly when inching around in traffc jams.
Steve Postins

My cooling system works, also when turbon loads 1 bare .
Ingemar

This thread was discussed between 03/01/2004 and 06/01/2004

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.