How hot is too hot engine wise?

In the thread about thermostats, someone ask "how hot is to hot?" and was never answered. I would also like to know, since I cracked head last summer becuz the car, in stop and go traffic, would heat up to just below, H. I could still see a SLIGHT bit of gauge background between the needle and the H. I am blaming the cracked head on this. I live in the high desert. Temps can reach 105-110f.

I am P&P the head, street cam with rebuild and DO NOT want to have this happen again. So, I am doing everything possible to reduce the possibility of this happening again. Found the carbs were leaned out by mech. that didn't know s... about what he was doing, but that's another story and from reading here, I now know that nothing cools like fuel. I have a '73GT with the 3 bladed fan. Should I replace the fan also and if so with what? I am adding a fan shroud, and replacing all the missing seals(?) around the radiator. Had the intake/exhaust manifolds Jet Hot Coated (also had vapor lock problems, so I figured, "might just as well" on the intake M. Will have "real" british" mech. friend of mine from England do the carbs and dizzy.

Have read Bob M's treatise on thermostats, and plan to go that route.

Like I have said before, this is one of my dream cars and therefore a FOREVER car! so I want to "do it right."

Thanks in advance for the input

Dave:

Be sure your radiator is cleaned and reconditioned by a competent radiatior shop. Don't know about a 3 bladed fan - I have a 5 bladed one. I also go by Bob Ms recommendations. I run a blanking sleeve and a 180°F thermostat. In hot weather, my temp needle goes just a tad past the "N" in the middle. Been doing it this way for over a year and haven't had any overheating problems at all.

tfisher7621 Wrote:

The local MG mechanic suggested strongly to me that I remove the sensor, have the hole plugged and wire the fans up directly to a switch in the cockpit. Then run it when in traffic by switching it on manually. What do you think of this idea? I guess you could prevent it from getting too hot. I had planned to put in a new thermostat and switch.

mabie1978 Wrote:

Things you can do when it's particularly hot are:
* make sure your carbs aren't too lean
* "short shift" (don't rev high before shifting to the next higher gear)
* as soon as you see the stoplight ahead turn red start coasting to let lots of air flow over the idling engine
* don't pull up to close to the car stopped in front of you - you don't want their hot exhaust feeding or flowing around your engine.

It doesn't often get over 100 around here, but it was around 102 a couple of days last week. I had to drive in the middle of the day those days and everything was fine though, obviously, the engine was a bit hotter than normal - 5/8 to 3/4 of the way up to "H" on the temperature guage.

A summer day that's 20 degrees hotter than normal can feel awful to humans, but shouldn't be then end of the world for cars. We operate around 98 degree and cars operate around twice that, so it should make only half the difference to the car!

Good luck with it.

-Desmond Mullen, Editor
"Current Listings"
http://www.naspecmgb.com

A properly sorted out B should not overheat or run hot. If all the parts in the system check out you should be good. Neither of my Bs run hot, or even warm, heck I have to carry cardboard in both my Bs to cover the radiator if it is even cool out to get it remotely close to operating temp, and for even hope of some heat in cool/cold weather.

If the radiator flow check passes, tstat and water pump are up to snuff, coolant is good, no clogs in the block, no head gasket leak, timing is on and the rest of the motor checks out, there is no reason any B should run hot.

Running an electric fan on my 80 and the stock motor mounted one on the GT. Both work quite well.

No problem when I was racing/autocrossing in 95+ degree weather on a hot asphalt runway.

How did you have vapor lock issues with a electric pump? I can see gas in the carbs expanding in the heat and overflowing into the engine.. and causing problems starting being too rich, vapor lock IIRC is air in the lines when gas boils. I guess similar effect, different condition

I would like to know the maximum temperature that the MGB engine is suppose to operate at also.

So far there has been a lot of information posted but no one has answered the question "How hot is too hot engine wise?" with a temperature.

The factory recommended that the hottest thermostat be at 180 degrees.
My twisted logic would suggest that the designed engine operating temp is arrived at somewhere between 180 and 200 degrees of coolant temperature.
If the engine cooling system is capable of always not allowing the temp to exceed the maximum operating temp of the engine when the thermostat is wide open, then it stands to reason that the designed temp for the engine/coolant is 200 degrees.
Once the stat is fully open the radiator should transfer enough heat to keep the engine at 200 degrees. If the radiator cools too much that the thermostat would begin to close.

When I was on the dyno with both my cars, as the motor heated up (and got warmer than 'normal', maybe 200-220 or so) the power went up a lot, but not sure what it was engineered for, maybe 195, IIRC, is the normal operating temp. I don't think running at higher than that for a long period of time is a good thing, but after putting a 195 stat in my GT, it did run a lot better warmer than colder.

oil cooler ?

i do not think i need one mine is cool as a cucumber while rolling

something that will really help is cold air induction..

Lots of good advice above. None of which is applicable when you are sitting in a 5 mile long stop and go train of cars going nowhere fast. Which is where I was this afternoon. The MGB motor, from what I can tell, is very poorly designed in the area of heat dissipation. Hard to tell why. Makes no sense. All this was well understood forty years before it's design, so why would they miss such a basic part of engine design? And yet the V6/V8 conversion guys are using the same old radiators with no over-heating problems whatsoever. On bigger, more powerful motors.

I know I sound like a broken record at times.. but I hear daily about the underengineered cooling system in the B. I just have not experienced it (well I have, but there was a cause..that was fixed..now it is back to running cool).

The hottest I have driven, in stop and go boston traffic is mid or so 90s, both my cars may get a click above normal, thats it.. on my 80, once the fans kick on, 10 seconds or so later I see the needle come back below normal.

I still think with a motor with the coolant passage ways cleared out, radiator in top shape, coolant at proper % water/coolant, good water pump and t-stat, no head gasket problems, engine in proper time, carbs set right.. everything set right... a B should not run hot or overheat regularly. There has got to be something out of spec..somewhere.. causing the problems. Fix the problem, not the symptom

Not sure if it matters, neither of my cars, at this time, have padding under the bonnet. Not sure if that would retain more heat than the naked sheet metal.

If a B overheats/runs overly hot, check the system, fix it, should be back to normal(I know..easier said than done some times!)

Either I got lucky with the only 2 MGBs made that don't run hot (or even normal most of the time).. or my mechainc has some kinds of clue that escapes us normal folks on how to make the cars run in the normal range.

Interesting thread, and something I have wondered in the past on this board. In the mid 60s, according to Clausanger, the factory changed to a 165 t-stat, to keep oil pressure up. Went back to 180 right around the time that the emmisions started to become a factor. A hotter running car will run cleaner, no doubt, but when this engine was designed, was it designed with the cooler temps that cars ran at in the 40s and 50s? Is it possible that the hotter running engines along with air pump rails are causing these heads to crack. Too much heat for an ancient design? I n a 160 in my 3 main engine, and it runs so much nicer in the summer (around 170) than it did with the 180 I used to run.

I have a dual electric puller fan kit that I've started to produce that will definitely keep your engine temperature under control. In traffic on a hot day the temperature can be anything you want it to be and is controlled by an adjustable thermostat. Use the manual switch and leave it on for going up a pass. Recently, on Gary's Run we went over Ochoco pass when it was 98 at the bottom. My car ran at 202 with a 195 thermostat. Some of the other guys were 212 to 220. I have also found that manually running the fans for about a half a minute before I shut the car off really reduces the amount of hot soak that happens in the hot weather. Check out my original thread on the fans. http://www.mgexperience.net/phorum/read.php?1,778199,779986#msg-779986
PM me if you want to hear more.

Dan, that fan setup that you make is sweet. Excellent workmanship.
As the British would say "A Bristol installation".
Your system enables the stock MGB radiator to provide enough heat transfer efficiency that that 195 thermostat that you are running does not have to open all the way and the temperature is still under control.
NB::::::: The 195 stat that I hot water tested was about half way opened at 205. It did open all the way at 215 degrees.

On Gary’s Run Green B never went more than a needle width past the N. The car has a rebuilt engine, new water pump, a rebuilt/re-cored radiator with a 165 degree thermostat and is in good tune.
I went with the re-cored radiator because the rad shop had a core that they could use that is suppose to transfer heat better than the stock one.

Currently the car has a 180 stat and the hottest reading I can find with a SnapON infrared digital thermometer is 198 degrees. This is at the spark plug bases. The lower thermostat housing always seems to read about 195.
It would be nice to have a clear thermostat housing so that the stat could be seen as it cycled between open and closed.

I think many times the MG cooling system is blamed for overheating when in fact the system is not up to speed and the engine tune isn’t spot on.

i have a factory 2 fan .. , i put a dial a temp sensor on and dialed the temp down untill the fans start when the needle is at midway.. run a 160 Tstat ,, on a 90 degree day at road speed the needle if a bottom fish , then i am stopped in the construction zone it hits midrange and the fans keep it there , i broil but the engine stays at midrange and the fans cycle.. some times the # 2 fan will not start and it runs one fan as i understan the homemarket machine had.. and still cycles
a cold air induction will help while sitting , even hot air off the asphalt is cooler than underhood air..

if it looks like a long wait i switch off and get out the lawn chairs ... or switch off and throw the doors open and cuss a lot .

If you are running the 3 bladed fan, you need to get rid of it.

That is the ONE stock cooling device on an MGB that needs replacing.

Go to the later plastic or metal bladed fans that are 6 or 7 blades.

B