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Engine Operating Temperature

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Crusty

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I was out in my BN7 a few days ago and the engine temperature started to increase rapidly. It normally runs about 185F, but on this occasion it reached 220F. I pulled over and stopped and let the engine cool down. When I checked the coolant level it was down and took about 2 litres to fill up. I set off again, but after a kilometer the temperature was back up to 220F again. At home it needed another 2 litres to fill the radiator up again.

I have removed the radiator, but there doesn seem to be any sign of leaked coolant on the fins. The radiator hoses don't show signs of holes either. The engine block held plenty of coolant; I would guess maybe 5 litres or so.
I have taken the radiator to a repair shop and the gentlemen who peered inside said he thought the radiator was blocked.

I am wondering what the cause of the sudden rise in engine temprerature could be.

I have been given three possibilities: blocked radiator, stuck thermostat and blown core plug in the engine block. Given the engine block had plenty of coolant in it, I am dubious about the blown core plug possibility.

I would be gtateful for any opinions on the problem and the three likely possibilities.

Crusty.
 
Engine tune (pinging can cause heating, as old gas ), dragging brakes, wrong fluids in diffs and trannys. Fan slip, sediment in block.if you see no spots on floor or white exhaust smoke not leaking or getting in cylinders.
 
I had a coolant loss issue that turned out to be the water pump. Although, unlike your issue, I observed coolant leaking onto the ground.
 
If it’s not on the floor then it’s going out the exhaust pipe …..blown head gasket etc .
 
It can overheat and blow out while you are driving. Then when you get home there is no longer enough in the radiator tanks to blow out on your garage floor.

A good radiator shop can tell you if the radiator needs to be boiled out or recored. Go to a good one and follow their advice.

While the radiator is out of the car, remove the water pump and inspect it to make sure the impeller isn't spinning on the shaft. Some of the replacement pumps years ago had plastic impellers that didn't hold up well. You'll need at a new water pump gasket to put it back together if everything checks out ok.

Thermostats are cheap, but if you want you can remove your old one, put in a pan of water and heat it up on the stove. Use a cooking thermometer to measure the water temp as it heats up. It should open at the temperature marked on the thermostat itself. If it doesn't open, it is junk. If it opens at too high a temperature it is junk. If it's good you need a new gasket to reinstall it.

Definitely check the fan belt. Make sure the sides are not all shiny or overly worn. If it all looks good, make sure it is tight enough.

Last year I flushed my block with an over the counter product. I pretty much just filled the radiator with water, added the product, ran it for a while, and then drained it by removing the lower radiator hose. Then I flushed it three times and the water was pretty clean on the third time through.

Once you put it all back together you should check and reset the engine timing.
 
The problem was the radiator. Thermostat and core plugs were fine. The radiator man asked me if I had put water wetter in the cooling system, as he said the bottom was clogged with a gluey,jelly like substance which prevented the water from circulating. I had put it in a while ago. In his opinion, water wetter was not a good idea if the car wasnt being used regularly as it tended to settle and congeal in the radiator. He does a lot of radiators for racing cars and they make a point of draining the radiator after each event to avoid the problem occuring.
 
Crusty said:
The problem was the radiator. Thermostat and core plugs were fine. The radiator man asked me if I had put water wetter in the cooling system, as he said the bottom was clogged with a gluey,jelly like substance which prevented the water from circulating. I had put it in a while ago. In his opinion, water wetter was not a good idea if the car wasnt being used regularly as it tended to settle and congeal in the radiator. He does a lot of radiators for racing cars and they make a point of draining the radiator after each event to avoid the problem occuring.
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Very interesting. I had not heard this before. Thanks for sharing.
 
Crusty - thanks for posting the results! So often guys post problems, we give possible solutions, then we never hear from the original poster again.

And I'd never known about the water wetter problem before - altho' I've never seen a need to use it.

I'm wondering if WW may have some problems with certain types of coolant.

Tom M.
 
I used to change thermostats in the spring 180*,
 
LarryK said:
I used to change thermostats in the spring to 160*, then back to 180* for winter. Daily driver in the coldest of winter to 195*. A little work but never covered radiator in winter. Lots of problems for overheating can start by not renewing antifreeze every two yrs.
Click to expand...
 
There is nothing wrong with water wetter in the right application. As well as racing cars, most of the radiator mans business is long haul truck radiators. A lot of the operators use water wetter due to the hilly nature of the country and the work the engine has to do. But these units are in constant use and high mileage. Our line haul operators trucks can do 1,000,000 Kms a year. My Healey would be lucky to do 1,000 Kms a year.
I originaly put water wetter in because I had an overheating problem about 8 years ago. It turned out the water pump was the culprit. After I replaced it and the metal fan with a 5 bladed plastic job, in went the water wetter.
The radiator mans advise to me was, make sure the radiator is clean and add a anti-freeze and corosion inhibitor nothing else. Although, where I live we dont have really need the antifreeze bit as it doesnt get that cold.
 
I bought a bottle of water wetter and never used it after reading the directions. IIRC, its effectiveness is greatly diminished when used with a 50 / 50 antifreeze / water mix. Its a great product for race cars using only water.
 
If it doesn't congeal in the bottle why would Water Wetter congeal at the bottom of a rad?
I've used it in my Healeys and race cars without a problem--or having to drain it out.
 
DerekJ said:
Thermostats do not affect the operating temperature of the engine.
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No only controls flow,, if stuck open or closed can cause overheat or cold rich mix.
 
No it isn’t. The thermostat simply determines the temperature at which the coolant first begins to circulate, which is totally different to determining the running temperature of the engine.
 
If the vehicle is running at 180* ( for example ), the 180* thermostat stays open. If the weather cools and the engine starts running cooler, the thermostat will close. If it is warm out, the thermostat stays open. But cannot cool engine as temperatures raise. That is why in winter ( in older non sensors carb cars, you would put in a warmer 190* thermostat, and in warm ummers 160* thermostat Drivers used to use cardboard in winter to keep radiators warm. Been doing this personally since the 50s. Without a thermostat engine runs too cold and will flush cylinders with fuel and ruin the rings.
 
FWIW, I've heard, from credible sources, that the optimal coolant running temp for many/most engines is 190degF. Both my Healeys will run too cool--less than the thermostat opening temp of 180--on cool days, but will start to overheat in traffic on warm days. Go figure.
 
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