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Over Heating

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kfitz

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I have a 1966 BJ8 3000 that is always over heating. I have so far replaced the radiator with a new more efficient one, added a Texas cooler fan, new thermostat, checked the water pump, rebuilt the carburettors, and had cylinder head removed and cleaned. Yet the engine still over heats in traffic. It runs very well until stop and go traffic and then heats up very quickly. I am wondering if may be there is a blockage in the cylinder block which is effecting the circulation.

Does any one have any thoughts or suggestions of what I should try next? I am really at a loss as to what may be causing the problem or what I should try. Any help is greatly appreciated.
 
This sounds like an interesting problem. You will probably get lots of suggestions.

I don't think that blockage in the cylinder block is the problem.

Running at speed on the road puts the most demand on the cooling system. If you are SURE that it does not overheat on the road almost all of the things that you listed are working ok. In other words if the cooling system can keep it cool at high speed it should be easy to keep it cool at lower speeds. The one exception is the fan. In slow going the only thing that really affects cooling is the fan or the related air flow. Possibilities are fan mounted backward, belt slipping, missing shrouds, obstructed air passages in the grill.

Lastly, are you sure that it IS overheating? Maybe the temp gage is wrong. In hot weather it is normal for the car to run at 190 to 200 & even higher in slow going. Maybe 210 for short periods. If it is not boiling & loosing coolant there is not really a problem, but it can be disconcerting.
D
 
Sounds like blockage in the block. (probably rust)
If this is not the case look at timing too much advanced?
or Don is right, gauge shows wrong figures.
JĂĽrgen
BN2 56
 
Thank you Dave for the suggestions - the car runs fine at higher speeds and only overheats in stop and go traffic but boy does it heat up fast! It reaches boiling point quickly and then overflows. I thought it might be the thermostat so I have tried a few. I was wondering if adding an electric fan would help? I was hoping to find the source of the problem and fix it instead adding an additional fan but at this point I will try anything.
 
Another idea comes to my mind:
is the fan mounted in the right way ? A friend of mine had the same problem with a reverse mounted fan.
 
Maybe I missed this but where are you at? I mean are you in Las Vegas (hot man) or Minnisota (cool eh)? It should make some difference.

Even on very hot days my Healey does not overheat.

I have the radiator shrouds which are items most people leave off these days. But this won't do anything for a stationary car. Are you proof positive the radiator is good. Feel the front of the radiator on the sides, top & bottom, if the whole thing is clear of clogs it should all be uniformly hot.

I had a Toyota once that had the same problem. Turned out to be a clogged radiator. I was pretty confident the radiator was OK since it had just been cleaned. Found that after replacing the pump, thermostat, belts, temp sending unit ......

If it is the radiator then it is an easier fix than
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blockage in the block.
 
I'm experiencing the exact same condition with my TR3, and have done pretty much what you have done. Am still trying different fixes, and if successful, will let you know. If you have any luck, please tell me what worked for you.

As a footnote, I did mount an electric fan in front of the radiator, with a switch under the dash to activate when needed. The surprise was that it didn't affect the temperature as much as I thought it would.

Also, I've changed radiator caps from a 4-lb. to a 7-lb. That helped a little, but the 7 is not as deep as the 4, so I don't think I'm getting a good seal, and I'm going to try to find another. You might check to be sure your cap is indeed sealing as it should.

Mickey Richaud
 
The radiator is new so that should not be the problem. I did have the blocked flushed three times to remove some of the crude. The old radiator was rather rusty so think it may have clogged up the block a bit. I live in New York city where the traffic is bad but the weather is not too hot. The car overheats even when it is cold outside, even to the overflow point.

Thanks to everyone for the help - hopefully I wil find a cure to this problem.
 
Strange problem you're having.

The only thing that normally effect a car when stationary is the fan....or head gasket. Are you happy that a new one was installed correctly when the head was off?.
A quick check would be run the stationary car with the pressure cap removed and see if you have any air bubbles in the system. This is a good indicator if all is well or not.

As Dave pointed out it is unlikely that a blockage in the waterways is causing the problem, as it would manifest itself at all times of running, not just when you are stopped.

I think my favorite guess would be the Fan followed by a faulty radiator and possible suspect head gasket.

Sorry I can't be of more help, best of luck with your investigations.

Cheers
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Gents, I had a very similar problem when I first purchased my BJ8. The car had been sitting for several months (or longer) with only water in the cooling system. When I bought the car I immediately took it on a long drive in California summer heat to Yosemite. The car's temp started out fine but after a couple of hours had started overheating. Turned out the engine block had rusted and the radiator had become quite clogged - the radiator shop said it was the worst they had ever seen. I had the radiator rebuilt (recored) and it has never overheated since. Suggestion: If it isn't the fan installed backwards, get a radiator shop to flow check your radiator. If the radiator is partially clogged it will definitely cause problems.
 
A few thoughts:

Be sure lower hose is not collapsing...it should be reinforced or contain a wire spring (the lower hose is under suction....if an improper hose is fitted, it may "suck" closed).

Be sure you do not have too much anti-freeze (more than 75% will cause overheating, due to the poor heat rejection qualities of anti-freeze).

Be sure timing isn't retarded....this can cause overheating.

Try running it with no thermostat...or a colder thermostat (I'm running a 160F in NJ).
 
A common big Healey cooling problem is caused by using a too short radiator cap. The wrong cap screws on & looks normal but it's inner sealing surface is too short to reach the sealing surface in the radiator neck. A correct cap will measure about one & one quarter inches from inside of top to bottom of sealing surface. The NAPA # 703-1411 cap is the correct cap.
D
 
Thanks to everyone for all of the suggestions. I have tried a new radiator cap that appears to have a much better seal, the old one was a bit loose, but still is running hot.

I do have a question - if it is indeed a clogged cylinder block, as the old radiator was rusted out, wouldn't this effect the car at all times? The car runs great when moving and only heats up when stationary or in slow traffic.
I can only think it must be something to do with the fan as the radiator is new.
I installed a fiberglass texas cooler fan - would a metal fan be a better solution?

I will also check the timing to make sure that it is not retarded.

Again thanks for the help!
 
These cars, not just Healeys, will get hotter sitting than when moving because of the low air flow when sitting. That's one of the reasons for the air deflectors added to the sides of the radiators with the 3000s. It keeps teh air from going round and round the sides of the radiator. Also, because the car's at idle, water flow is slower.

I have a Texas Cooler on my BN4 and it seems to work fine. The main thing about the stainless steel fans is that they flatten out at high RPM and take less power. This is minor, though.

cheers.gif

John, BN4
 
Lots of good ideas are offered. Heat exchange from the block seems normal since things seem to be overheating. My sense is that the problem is either in flowrate to the radiator or radiator heat exchange to air. If you tried running without a thermostat and the problem remained I think it can only be a radiator problem or flow problem from another cause. Suggest you increase rpm to see if the pump is really putting out the gpm needed to keep the engine cool at idle. Then look hard at the radiator (painted black but without excessive coating, new blockage and radiator cap).
 
The only thing which ist left over is to remove the core plugs, water gallery lid and check if there is excessive rust in the block.
remso BN2
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I think you're right. If the block were plugged or the head had blockage, you would have overheating issues all of the time (or worse).

Many people incorrectly think anti-freeze is a better coolant than water. It is NOT. If you have more than a 25 to 33 % mixture, dilute your anti-freeze to that level and see if your car doesn't run cooler. I see you are in New York, so you may actually have to practise the Summer/Winter ritual of changing your anti-freeze.

My next suspect after the cheap and simple dilute the anti-freeze would be the water pump. If the impeller blades are erroded, it might not be capable of moving enough H2O at idle to keep the car cool.

As a bench mark, my Healey lives in South Florida, has the original radiator (reconditioned) and will sit in traffic all day at 200 degrees and run 170 degrees down the highway at 70 MPH
 
an update - I put on a new radiator cap which has a much better seal then the last one. I also replaced the missing shrouds in front of the radiator. The car appears to be running better, below 160 on the highway and around 212 in traffic. I need to run it a bit longer in stop and go to see how it will fair, but at least it is running a bit better.

Again thank you to everyone for the advice - I really appreciate it.

Good weekend to all.
 
I found an auxiliary fan mounted to the cross-members in front of the radiator to be very helpful in traffic situations--I have a manual switch that I turn on BEFORE the car begins to heat up if I am in stop-and-go situations and I am able to stay ahead of it.

But the biggest challenge that I had was overheating under load--high speeds and/or hills--especially in last summer's heat when on the road to Tahoe and back. When I returned home I began to experiment with timing and found that by advancing the timing somewhat (about 40-42 degrees at 4500 or so rpm's) I could eliminate some of the problem. But the ultimate solution was to have the radiator professionally cleaned--that knocked about 10 degrees off the guage overall and at the end of the summer I was able to sustain high speeds & uphills with no difficulty.

I think our cooling systems are marginal at best and getting the temps down is dependent upon dealing with all of the contributing factors: Mixture, spark, airflow and water circulation.

Best--Michael Oritt, 100 Le Mans
 
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