MGB & GT Forum

MGs don't have a radiator reservoir to auto fill. This could be problematic on long trips.

Has anyone retrofitted an autofill reservoir for the radiator, like more modern vehicles?

Kevin
1972 MGB Renovation Near Completion

This is what I have been doing for the last 35 years to help with the cooling system of the MGB & I have A/C on my MGs and it helps. I have all the stuff to change over.

I forgot to add pictures

Where did you get the reservoir? Assume it's pressured? If so, assume you are running non-pressurized cap on radiator? If so, where did you get the non-pressurized cap?

Late model MGB's do have an overflow tank!

I'm not sure what the question is. Expansion tanks were added to 1976 onward 'Rubber Bumper' models for a couple of reasons. Firstly the aperture in the rubber bumper was inadequate to provide the required airflow through the radiator and, secondly, the electric fan is a 'push' one, (i.e. in front of the radiator) which is infinitely less efficient that the traditional 'pull' mechanical fan. All chrome bumper MGBs had a traditional radiator cooling system operating at 10psi pressure.

I live in Malaysia and regularly drive my 1972 MGB roadster through the midday tropic heat between Ipoh and Penang (155 kilometres) and back without any issues. The only modification to standard is a 7 bladed radiator fan. This was fitted to solve overheating problems when stood at traffic lights or stuck in heavy traffic rather than overheating when driving along the open road. Given you live in California I would suggest just changing the mechanical fan to a 7 bladed one and I don't think you will have any overheating issues.

Hope this helps,
Rowan.

What I have in the pic. is an Austin America or Austin Merina, I have added the 77-80 copper tank and strap & I have used the larger Jag. XKE tank & don't tell anyone that I used a Triumph TR7 overflow tank on my 4.8 Rover/Buick Roadster, that is larger like the Jag. tank. Yes it is a sealed system with a blank cap on the radiator & 7/10 lb. cap on the overflow tank. With this setup the rad. stays full & you don't get the corrosion/rusty brown water. I have all the parts, if you would like me to supply them. With A/C & no overflow tank even with the 7 blade fan, you will have an over heat problem with just a traffic light or 2. There was a BIG steel fan supplied with the factory kit & it helped a bit but with the big fan & the tank you are much better off. The steel fan puts a big load on the water pump & it will need to be changed more often. What I am doing is put the late rad. & rad. plates & cooling fans, after I cut the lower pan up, in front of the rad. Some work to get it right, but I am RIGHT COOL in my A/C MG., soooooooo cool my lady had a thick blanket in a bag that is in the car for when I turn the A/C on!!!!!



Edited 1 time(s). Last edit at 2024-04-30 06:37 AM by mgv8glen.

@ Kevin Hubred

I really don't understand what Glen Towery is getting at in his post. An MGB engine overheating is nothing to do with the lights or A/C other than an A/C system makes the engine work harder. Also, I would ask why would you want A/C in a roadster (cabriolet in US English)?

If my MGB does not overheat with nothing more than a 7 blade fan in the ambient 35 deg C heat of Malaysia then you should not have a problem in the similar heat of California. Save your money and just fit a 7 blade fan. If you are still worried about water loss, put a bottle of water in the boot - sorry, trunk!

Cheers,
Rowan.

Rosen, I think that Glenn is telling us that after fitting the sealed cooling system he has no cooling problems in the heat even after waiting at two traffic lights in traffic. He also has a very efficient refrigeration system in his MG which you will realise reduces the effectiveness of the normal radiator due to the hotter airflow. He also says that the big steel fan overloads the water pump bearing which shortens the life of the pump. Glen is a highly respected member of the forum who has driven one MGB for 700,000 miles often towing a trailer with another MGB on it.

Hi Philip,

I don't doubt Glenn believes in what he says and I am grateful for your interpretation. In my time I have owned and maintained a 1978 MGB GT, an MGB Jubilee, a 1980 MGB Roadster and my current MGB, a 1972 Roadster so I think I also know a little about MGB cars. All the rubber bumper MGBs (driven in the UK) I have owned and maintained have had heating issues. I learned the value of the heater! If the engine is heading towards overheating slam the heater on - you cook but it gives an extra 5% or so of radiator.

My 1972 MGB, which I have only ever driven in Malaysia, used to head towards overheating after being stationary at a sequence of 3 or 4 traffic lights when it was fitted with the standard metal 4 bladed fan. However, since I replaced it 6 years ago with the PLASTIC 7 bladed 'hot climate' one, I have never had an overheating problem regardless of how many traffic lights I get stuck at. In fact, the temperature gauge never exceeds 'normal'. With regard to the water pump bearing, I would respectfully suggest variation in fan belt tension will have a much greater effect on asymmetric loading of the bearing than the actual fan. Further, there is very little difference in weight between the two types of fan and one could argue, because the blades are more closely spaced on the 7 bladed one, the centrifugal loading is more evenly distributed.

With regard to the A/C radiator, I take your point. With any MGB adding one will compromise both the oil cooler and the radiator. For that reason, I would never fit one especially in a roadster. At the local car shows, people point out that I do not have A/C. My reply is always, "Oh, I have one - it's there" and point to the neatly folded soft-top.

Cheers



Edited 1 time(s). Last edit at 2024-04-30 04:02 AM by RHJ.

Hi Kevin,

I incorporated an overflow/auto-refill bottle to my '71 MGB. I used a Tudor plastic windshield washer bottle and bracket that I bought from Moss. For more info and pictures, see https://www.mgexp.com/forum/mgb-and-gt-forum.1/radiator-overflow-reservoir-install-75b.4694646/ , response #6.

As I see it, the original cooling system simply dumped hot, expanded coolant onto the ground. Later MGs had a pressurized overflow/auto-refill system using a metal tank. The plastic bottle overflow/auto-refill is light, simple, and emulates modern overflow/auto-refill systems.

Hope this helps and best regards, George

Kevin

If it helps, you can undertake a simple experiment to see if and overflow catch and return bottle or tank would help you and your car.

I have a standard 1973 BGT and was finding it dumping a bit of coolant via the radiator overflow pipe onto the ground after a long and hot run, especially when the temperature gauge may have strayed over the "N" mark if it had spent time sitting in heavy traffic. Some folks are ok with this and leave it as it is with the coolant finding its own happy level within the radiator. Other swear by coolant overflow and recovery systems.

Each to their own....However, I thought I would experiment with a simple 300ml drinks bottle by simply redirecting the overflow pipe through the lid as per the first photo. The pipe to lid is not sealed in any way so that some air can get into the bottle.

I checked that I had the correct radiator cap. It is the right hand one in the second photo that has both the upper larger rubber seal that sits under the top of the cap and the smaller lower seal. Together, these two seals enable the coolant to "return" to the radiator as the car cools after a run.

I then topped up the radiator and the third photo shows the most coolant that I now find gets dumped out into the bottle after one of those long and hot runs. However, with the above experimental arrangement, all of this coolant now returns into the radiator as the car cools.

My car now definitely runs cooler and better when on those runs and is happier sitting in traffic with the temperature gauge sitting at "N" and requires no topping up between 3k services so ......I am now fitting the overflow tank that was fitted to later cars which I found for £20 on ebay. If you want to do this, you move the double seal radiator cap onto the tank and have a simpler cap on the radiator as per the forth photo. The tank has its own separate overflow pipe to ground.

Why not try it for yourself and see what you think?

Tony

Hi everyone,

I think things have got a little out of hand and have strayed from the original topic.

Kevin's original post makes no mention of an A/C unit - Glenn introduced the subject of an A/C unit. I am not saying Glenn was wrong to do so but it has led to some confusion. In Glenn's case, installing the A/C system, given the space available, caused the radiator and probably the oil cooler to be masked by the A/C radiator thereby reducing the efficiency of the car's standard cooling system. At the same time, the A/C will increased the workload of the engine and, therefore, its heat output. So, the installation of an A/C system caused Glenn's MGB GT to overheat rather than the factors creating Kevin's problem with his unmodified MGB Roadster. As previously stated, I had a similar overheating problem in similar climatic conditions in my unmodified MGB Roadster that I solved by simply changing the mechanical fan from 4 blades to 7.

And so on to Tony's point. I have to confess I subscribe to the first group. I check ALL fluid levels (including brake/clutch reservoirs) on a monthly basis and before making a long trip and top up as required. After that it's just a question of monitoring the gauges, particularly the temp gauge, while driving to pick up a potential problem before any damage is done.

Everyone's car is individual to them and one should never criticise a person for modifications they may choose to do even if one doesn't agree with them. My MGBs, from the Jubilee onward were bought as Classic Cars. From my personal point of view, Classic Cars are working pieces of motoring history and, as such, they should be kept as close to factory original as is possible. This is not always economically possible. But I can count the modifications/alterations on my current MGB on the fingers of one hand and all, other than the 7 bladed fan, are the consequence of parts being no longer available.


Rowan.



Edited 2 time(s). Last edit at 2024-05-01 03:55 AM by RHJ.

The 65-67 Triumph TR4A used an overflow bottle, and all the parts are available, so I may try that TR4A overflow bottle Triumph was always ahead of the curve.

My '77 B has the expansion tank fitted as standard. I've also got a Revotech electric fan pulling the air through the radiator. Temperatures even in traffic hover just over the half way