B's running very hot

[Stewart]

Took the B out to run some errands, get forced out of my lane by a idiot in a big SUV's who didn't look before they change lanes and to enjoy the sun and heat in the low to mid 90's today.

It ran normal for the first few miles then heated up to about 1/2 way between normal and hot which this time of year is some what expected. Unfortunately it continued to rise to about 2 needle widths of H and thankfully I reached where I was going before it went higher. Return wasn't quite as bad as the lights and traffic was better but still above where its previously run.

Radiator and hoses were replaced about a year ago T stat was replaced with a 180 degree failsafe t-stat from moss in march. Ran at normal to slightly above normal prior and immediately after T-Stat replacement but started to run hot within a few weeks of replacement. Is it possible that the T-Stat is stuck partially or totally?

 

[Geo Hahn]

I assume you checked the coolant level.

On most cars you can tell if & when the tstat opens by carefully feeling the lower radiator hose as the engine warms up. With the tstat closed there is no flow thru the rad and the lower hose, though not cool, will be noticeably less warm than the upper. Soon after the tstat opens the lower hose warms up quite a bit.

You could also feel the radiator but usually the lower hose is easier to get at. Be careful of fans, belts, fingers, neckties, etc.

 

[Guinn]

Neckties in a 'B? /ubbthreads/images/graemlins/lol.gif

 

[Stewart]

Yep coolant is good I'll check the radiator hose tomorrow and see what's up with it. The tie remark reminds me that I need to pull the instructions on how to tie a tie off the internet again as I have to wear one next week.

 

[jimd]

[ QUOTE ]
Yep coolant is good I'll check the radiator hose tomorrow and see what's up with it. The tie remark reminds me that I need to pull the instructions on how to tie a tie off the internet again as I have to wear one next week.

[/ QUOTE ]

You can always take the easy way out and get someone who knows how to tie the tie, tie the tie and loosen it enough to get off over their head so you can put it on and tighten it? Does that make any sense? /ubbthreads/images/graemlins/lol.gif Sorry, I'll just go back to what I was doing...

 

[JFC]

I'll take a bet that your thermostat is bad. Although I've not experienced it, I know quite a few people have reported new thermostats not opening properly. Not all that uncommon apparently. You can check it out by puting the thermostat in a pot of water, heat it up and see if the thermostat opens at 180 degrees.

 

[Stewart]

Fired her up to day to run errands and grab lunch. Waited for her to warm up a bit and checked lower hose and it was hot so the T-stat is at least partially opening. It took a while to reach normal but it stayed there the entire trip except while waiting in line at In and Out during the lunch rush but then it only went up 2 needle widths above normal then cooled back down once I was moving again but it was quite a bit cooler today low 80's vs. close to 100. I'm going to go ahead and change the T-stat just to be safe and check it before installing it.

 

[Loaf]

Hey Stewart,

I solved a similar prroblem by flushing my rad. I bought a bottle of do-it-yourself radiator cleaner - you pour it in and idle the car for a while, then change the coolant. Or you could use a flushing "T" - or take it to a garage and get it done professionally.

If your thermostat (and fan) is OK but the car is running hot it must mean that the radiator is blocked with crud... The only other thing I can think of is that your water pump might be worn out?

Loaf

 

[aeronca65t]

One additonal comment: be sure that you are not running too much pure anti-freeze in your mix.
For example, if you run 75% anti-freeze and 25% water, your car will run hot. That's because water rejects heat better than anti-freeze. Just a thought...

And for "Brit-car Formal", go with a turtleneck or a dickie-bow....much safer! /ubbthreads/images/graemlins/jester.gif

 

[shorn]

As a precaution, I recently pulled the radiator out of my 40 year old Healey and had a radiator shop boil it out. Cost only about $75 and it was relatively easy to remove and replace.

 

[Loaf]

I have removed the rad in my 1970 MGB - it was dead easy. Don't pay anybody to replace your rad unless you have no interest in working on your car whatsoever!

Loaf

 

[Stewart]

Radiator is new and I did install it my self. Running a 50/50 mix right now but if it still runs hot might go back to distilled water.

 

[78MGB]

Just a thought, but before I went back to 100% distilled water, I think I would pull the thermostat. I would probably just run it without it and see if it ran cooler. Of course, I am not saying to run it without a thermostat all summer or anything. You could put it in hot water, at least to the temp it is suppose to open, and see if it actually opens up as much as it should. Then again you could just replace it with a 165 degree. And if that is what you have, get a new one. Less than $10.

I put a 12 inch Hayden electric fan on the other day and it cooled her down. Mine usually does not get hot unless I just let it idle. No problem at a red light, but just letting idle for an extended period. Does not get to the red, but it goes past the "center line" if I don't get her down the road.

Let us know how you fixed the problem.

/ubbthreads/images/graemlins/cheers.gif

 

[703MGB]

If your rad is new. Then look elsewhere and running only water is not recommended due to rust.

Put a 160 thermostat. Change the water pump. And most of all flush the engine block it is most probably filled with crud.

 

[mgbmedic]

if you're timing is too advanced, it will make your b run hot.

 

[JohndeJong]

May be you should also look at the timing. When the timing is to much advanced your motor will run hot.
I don't know how many carburettors you have on your car If there are two they should be synchronised
Running hot when in line for traffic is a well known problem with English cars generally. Most people install an extra fan as well
Kind regards
John de Jong

 

[Phantomracer]

Do not run without a thermostat (at least use blanking sleeve) or the car will certainly overheat. Coolant will pass through the radiator too fast to actually remove enough heat.

If anyone runs with all water..a cooling additive should be added, like water wetter, just to ensure the system doesnt corrode with the pure water...it also should keeps everything lubricated..and might even live up to the claim that it keeps the motor cooler. Also you could just run a small % of coolant (say 20-25%) to inhibit rust.

Also check (or just replace it is cheap) your radiator cap to ensure the system is properly pressurized (if it has one that is). I have a 13# cap on my 80B.

Lastly..check/replace your sending unit. It could be faulty. Buy/bed/borrow/steal an infared laser thermometer to check your block for the actual temp. You could be getting a false reading.

Timing could be off..the engine might be running lean...or several other possible reasons the engine is producing too much heat.

Paul

 

[Stewart]

Ok finally got to take her out for what I thought was the last time before I break it down for P&B work. Ran up the Angeles crest hwy and it did run about a quarter of the way between N and H on the drive over and up to about half way between N and H while heading up the mountain for a while. After a bit it dropped back down to Normal and pretty much remained there which was somewhat surprising as it was being driven rather spiritedly through the twisties. It stayed that way the rest of the way up. On the return it remained at N while in traffic and on the freeway so I'm not sure what happened but it seems to be happy right now but then again it doesn't know its being torn apart tomorrow.

 

[Repro]

Do you still have the foam blocking the gap between the radiator and the radiator support panel. On the top and upper side of the radiator.
If not, a lot of the air will by-pass the radiator.
All the best, Ross.

 

[703MGB]

Heating up.

Last week I had a British mechanic install an overdrive transmission in my B (which will be described in an another post) and at the same time we changed the water pump because of a small crack close to where the alternator bolts on.

My car was not heating up (new everything radiator, hose, and so on) but the replacement of the water pump by an original MG one (made of cast iron with a bronze impellor) did made a difference now the temperature is even lower than before.

Apparently there is a huge design difference between the original one (cast iron with bronze) and the ones marketed by several suppliers that are made in Taiwan (aluminum housing and press steel impellor). The cheaper one would cavitates the water instead of circulating it.

So If your car is heating up I would certainly take a more serious look at the water pump itself even if it is not broken.

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