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MG TD TF 1500 - Thermostat question
| I am very close to getting my 1950 MGTD back on the road and I would really like to fire up the rebuilt engine for the first time. Time to connect everything, put on the new hoses and give it a try but now I had to take a good look at the thermostat housing and although it is an original in good shape it has no thermostat and a modern one will not appear to fit without some machine work. Anybody run without one and what are the consequences? I do remember reading that the TD ran cold so this could potentially cause a problem. Looking for some alternatives to putting out for a new one. Brian |
| Brian Smith |
| Hi Brian, I thought Canada was a cold place. Don't even think of running without one. A new one couldn't cost all that much surely. Cheers, Paul. |
| Paul van Gool |
| Brian I'm sure that the TD, unlike the TF, has no separate thermostat. What you describe as the thermostat housing provides the thermo-control. John |
| John James |
| The TD most certainly does have a thermostat. The housing itself does nothing but connect the outlet with the radiator hose. It originally was an assembly of the housing with a thermostat/sliding sleeve which covered the bypass when it opened when the coolant was hot. Most replacement housings are designed with either a giant circlip or a brass sleeve holding in a regular cheap thermostat. This arrangement does require restricting the bypass, as it has no sliding sleeve (see archives). You can then go to Kmart or wherever and get a $5 replacement when needed. The engine must have a 'stat or it will never warm up, the oil won't get hot, will have to run too rich, etc. |
| George Butz |
| Brian - Moss Motors has (had) a replacement for the original thermostat and housing as one. When I bought mine (several years ago) it was about $80.00 USD and I have been pleased with its operation. The thermostat is rated at 85° C (185° F) and I have found that it does an admirable job. If the price is a deterant, one can get a standard thermostat that is 52mm diameter (I believe that is the size, you can measure to be sure). Have a machinest open the recesed area at the bottom of the thermostat housing (recesed into the bottom flange) sufficiently for the thermostat to fit into and install it there. To make this work properly, drill about a 3/16" hole through the flange of the thermostat to provide a very small amount of by pass water until the thermostat heats up enough to start opening and then blank off the original bypass hose that comes into the side of the houshing at the top. Good luck - Dave |
| David DuBois |
| Thanks all for the info. I searched the archives as well and have tried something that was mentioned a while back. I knocked out the bar and then cleaned it up and then cut down a regular thermostat to fit into the top of the housing (nice snug fit) and I will try to find a way to fasten it in there. I have blocked the bypass and hopefully will be able to get this setup working soon. I will let you know how it works. Brian |
| Brian Smith |
| Brian - You can drill and tap for small set screws that will come through the wall of the housing just above the thermostat. Be sure to use some loctite on the set screws so they don't work their way on through. You should leave a small opening in the bypass, about 3/16" to get some circulation of coolant before the thermostat opens. Good luck - Dave |
| David DuBois |
| Hi Paul, It appears that you have little knowledge of "Colonies" other than Australia. Canada too can be very hot, and I suggest you have never been to Canada in the summer. As I write, the BC interior is experiencing massive and record forest fires as a result of long hot and dry periods. The hottest place in Canada for several days last week, was Whitehorse in the Yukon at 39°. Here in the East we too can experience long hot spells of near 40°, but in the East, this can be very humid and uncomfortable. I have replaced the "hand-chopper" TF fan with a pancake electric - thermostatically-controlled but with a manual by-pass. This is the best set-up one can have and I reccommend it, especially if one is in the position of replacing one's rad as Brian is. Regards, Gord Clark Rockburn, Qué. |
| Gordon A. Clark |
| Enlighten me! The TD is not a closed pressurized system as modern cars are. In other words over heat steam can readily escape via the overflow pipe as that is always open. I drove my car for the first time today a total of 13 miles and when I got home I thought the rad was leaking but investigation showed that it was coming from the overflow tube. Is this normal. Greg & Grimm |
| G.J. Cenzer |
| Greg, the TD system is not pressurized as you mentioned. As the coolant expands with heat, it will flow out of the overflow tube and be lost. When the engine cools down, it leaves the system a bit short of a full capacity. To overcome this problem, I fitted an MGB overflow tank to my TD. I made straps to hold it to the battery hold back bracket. I used a longer hose to secure the hose (with small hose clanps) to the rad overflow tube and to the tank. I took the spring out of an octagonal rad cap so it will not hold pressure and fit it to to the tank. I also added a hose to dump the overflow from the MGB tank, if any, but since I never keep the tank more than 2/3 full (when hot), I have never seen any cooland dumped overboard. The original rad cap has to be pressure tight to make the system work. Now, the hot coolant flows into the overflow tank and returns to the system as it cools down. I dont lose any coolant. The secret of the push pull system is to have all the connections pressure tight, especially the orignal cap on the radiator. |
| Jim Merz |
| I wasn't quite as smart as Jim to get a MGB expansion tank, but I made up a coolant recovery system like his using some 2" PVC pipe and various fittings. I glued two pieces of pipe together and added the fittings for coolant inlet and overflow, plus a screw on cap and mounted the whole rig next to the battery. The coolant level remains right at the top of the overflow tube in the radiator since installing the recovery system, with no embarrassing piddling in the paring lots by the TD. Cheers - Dave |
| David DuBois |
| If you think about it the TD has an expansion tank already; it's on top of the radiator! Isn't the top of the radiator much larger than a modern pressurised one, just to facilitate the expansion of the coolant? I was always filling the radiator of my Y to the top when cold until I realised this. Now I only compensate for evaporation; much less! This does mean that when cold, the coolant level is lower than you'd expect it to be, but I can still feel/see it. If the system overflows it was too full and/or too hot? I liked Neil Cairns' comment on a similar Y-thread, it was something like: "what's next? an overflow facility for the additional expansion tank?". Jim's solution does upgrade the cooling system and will prevent evaporation-loss. |
| Willem van der Veer |
| The system that Jim and I have in our TDs was the idea of Skip Kelsey. The main thing that led me to it was the coolant mess on the bonnet and fenders after taking a run up to Abingdon Spares, about 150 miles. I had topped up the coolant before leaving home. The opening of the overflow pipe is just below the filler neck, almost in the direct path of the return from the water pump. Coolant is going to flow out of that pipe until some level is reached. The bottom of the overflow pipe is in an area where the airflow comes up through the engine compartment and out through the louvers. Spray coolant into it and you get an ugly mess. The recovery tank has solved that problem as well as eliminated the coolant loss. One other thing -- if you are using a Motometer to minitor your water temperature, you need to keep the bulb of the Motometer immersed in coolant to get a proper reading. This also solves that problem. |
| Bud Krueger |
| No I don't have a Motometer nor do I have a water temp gauge. I also don't know what is in the area that is where a 'normal car would have a thermostat'. I had added a coolant recovery system to my Rover P6B 3500S back in '83 so I am familiar with doing that, so I will follow that route. I have to figure out what to do for a thermostat following all the advice listed in this thread above. Greg & Grimm |
| G.J. Cenzer |
| <<with no embarrassing piddling in the PARING lots>> David, Very Freudian, that's all I'm saying! |
| Willem van der Veer |
| Thermostats: use one from a small block Chevy (Stant #45358 = 180 Deg. F., #45356 = 160 Deg. F.)once the original mechanism has been removed from the housing. It fits exactly on top of the housing. Add a third hose clamp just above the new thermostat to keep it from floating upwards. Pressurized Cooling System: Look in one of the hot rod magazines for accessory overflow tanks. Slim, stainless steel tanks that mount to the radiator are available. Make sure a new O-Ring is used under the cap and that it is lubricated with a silicone, 'High Vacuum Grease' or 'Valve Lubricant & Sealant'. Make sure it is the translucent form of silicone paste, not the pink or brown types. |
| S.R. Barrow |
| David, The TD was not piddling in the parking lot. It as marking its territory. SAfety Fast! Jim Haskins 1953 MGTD |
| J. M. Haskins |
| My overflow pipe dumps out way below the bottom of the rad down onto the front crossmember and appears to be slodered along the way down. Do any of you have a pic of what your overflow coolant recovery system looks like? Greg & Grimm |
| G.J. Cenzer |
| Am confused... you mean there is no thermostat in the TD? Or are originals no longer available. Haven't gotten into the engine yet and assumed the thermostat was where they were in MGA's? |
| g.b.lawson '53TD |
| I'm sure there is a GOOD way to dis-assemble all the hose stuff that is not described in any manual but exists in peoples experience. Would anybody like to share their expeience with me before I tackle this area of thermostatic control. Greg & Grimm |
| G.J. Cenzer |
| The TD was designed with an excellent, thermostatically controlled cooling system. Its operation just isn't written up in the manual. A bellows type thermostat opens to allow coolant to be pumped into the top header tank of the radiator. Prior to opening, the thermostat has a vane that is open to allow coolant to flow through the bypass hose. As the coolnt warms up and the thermostat opens, the bypass vane closes to cause all coolant to go through the radiator. OEM style thermostats are available from the usual sources. They are somewhat expensive, so many owners opt to replace the vane thermostat with a common one by removing the innards from the housing. Standard, simple, thermostats are, IMHO, the cause of a lot of the coolant problems that owners experience. Do your car a favor and stick with an OEM type. BTW, one of the thermostats (not the housing) is for sale on eBay right now. |
| Bud Krueger |
| Bud, I would like to keep my car as OEM, however, I just bought it in March after it had been sitting for 9yrs in an attached garage.I have the electrics sorted now and the pedals all snuffed up and the tranny shifter fixed, but I want to investigate what is in my thermostat area. The way things have been jury rigged on this car I want to make sure it's right in that area. The hoses are so short that I know I can't just disconnect a hose and peek in so I'm wondering if there isn't some advice as to a fail safe way to tackle this. Greg & Grimm |
| G.J. Cenzer |
| Greg, remove the two screws that attach the bypass elbow to the thermostat housing. Loosen both clamps on the upper (big) hose. Remove the two nuts that hold the thermostat housing in place. Hopefully, you'll be able to slide the housing up far enough into the upper hose to clear the studs that the nuts were on. Then remove the housing. At least that's what it says in principal. My upper hose is so stiff that I have to loosen the radiator stay rods, bonnet hinge and headlight brackets to be able to slip the upper hose far enough to remove the housing. It can be a pain, but that's how I have to do it. You can then look into the housing and see if the guts are in it. You can put it into a pan of hot water with a thermometer and see if it works. New innards are available. BTW, drain the radiator and block before you start. |
| Bud Krueger |
| Bud, Thanks for the comments. I saw the one on the eBay in fact I know who it is that's selling it, however I'm a bout tired of getting sniped all the time on eBay by people that never bid until the last 20 seconds and poof away it goes. Greg & Grimm |
| G.J. Cenzer |
| Brian I run my TD engine without a thermostat. This is my third TD ground up and none of them have ever had a thermostat in them. They all run fine; do not over heat even when driveling in the mountains in the summer months. Most of the restorers I talked to when I was getting into TD's did not use them either. They were not available to them in the early 1970's so they just left them off. It may take a little longer for them to heat up in the colder months, but I have never seen any harm from not having one installed. I can even see the coolant moving in the radiator when the engine is running; you can't see this if a thermostat is installed, unless it is open. Hope this Helps John |
| John C. Hambleton III |
| Thanks to all who have answered. Using info gathered here and also in the archives I have modified the housing to include a modern thermostat in the top of the housing after knocking out the cross piece and modifying the housing to accept the shape of the thermostat. My concern was how to keep the thermostat in place but that was easily covered by drilling two small holes just above the actual thermostat and using a couple of those small ring nails (trim nails?)pushed through the housing and just protruding above the thermostat. They are easily peaned over and the rubber hose and clamp cover them beautifully. Haven't fired it up yet but it is almost ready!!! Brian |
| Brian Smith |
| Brian - Don't forget to block off most of the bypass opening. Since the thermostat you are using has no way to close off the bypass, you will have to do it on a permenant basis. When I was using the type of thermostat that you are using, I blocked the bypass opening down to aslot about 1/8" wide. If that is not done, you can run into situations where the engine will overheat, because not too much water will be routed through the engine without benifit of passing through the radiator to remove excess heat. Good luck - Dave |
| David DuBois |
This thread was discussed between 26/06/2004 and 07/07/2004
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