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Thermostat questions

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I agree with Steve. I started with the sleeved thermostat, 6 bladed fan, and shroud from BCS. Didn't help. Then I looked in the radiator cap opening when the coolant was below the tubes and noticed several tubes were plugged with a clay-like substance. I removed the rad. and took to a re-core shop who took it apart and showed me that more than a third of the tubes were clogged. They put in a new core with 14 fins/inch, same number of tubes (3 rows). That solved the problem. Now it runs at normal temp. under all conditions.
 
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TimK said:
I agree with Steve. I started with the sleeved thermostat, 6 bladed fan, and shroud from BCS. Didn't help. Then I looked in the radiator cap opening when the coolant was below the tubes and noticed several tubes were plugged with a clay-like substance. I removed the rad. and took to a re-core shop who took it apart and showed my that more than a third of the tubes were clogged. The put in a new core with 14 fins/inch, same number of tubes (3 rows). That solved the problem. Now it runs at normal temp. under all conditions.
Click to expand...

Tim,
Had you been running Water Wetter? It can create a brown sludge after a while.
 
BJ8Healeys said:
Oh yeah, the only thing that finally fixed my overtemp condition for good was re-coring the rad with a modern, more-efficient core
Click to expand...

This was my experience as well.
 
steveg said:
Tim,
Had you been running Water Wetter? It can create a brown sludge after a while.
Click to expand...
No, but I also had not replaced the coolant for many years.
 
Followup -
Installed the Moss blanking sleeve with their 180 degree fail-open thermostat. The gauge shows hotter than the car's actually running.
TempGaugeCrop.jpg
Here, driving in 80 degree weather, I'm guessing the car's running around 190 but showing 205. Back in the garage the gauge immediately went to 220+ (yellow mark) indicated compared to a laser thermometer showing 198 or so at the temp sender in the head. The car did not smell or feel hot during this exercise.

What I'm assuming is the blanking sleeve creates a pocket around the sender which gets hotter than the water circulating through the thermostat.

Next step will be to remove the blanking sleeve and see how this thermostat acts. If the t-stat shows a correct temp, I'm going to experiment with a gradually increasing-sized hole adjacent to the gauge pickup allowing it to "breathe".
 
Followup2 -
SleeveCrop.jpgGaugeCrop.jpg
Decided to cut away the blanking sleeve except for the bypass hole area. Gauge is while driving on 75 degree day. No real diff.
T-stat: Moss fail-open (motorad) 180 degree.
Next - will remove blanking sleeve entirely.
 
Same t-stat without blanking sleeve, 78 degrees ambient. Same 200 degrees indicated as gauge picture above.
Next step - have ordered 160 degree fail-open motorad. Will run through same process next week.
 
steveg said:
Followup2 -
View attachment 27591View attachment 27592
Decided to cut away the blanking sleeve except for the bypass hole area. Gauge is while driving on 75 degree day. No real diff.
T-stat: Moss fail-open (motorad) 180 degree.
Next - will remove blanking sleeve entirely.
Click to expand...
What RPM was this pic taken? If it's idle, you have real good oil pressure, if at 2000 rpm or so, it's just like my well-worn engine when at operating temp.
 
80 ambient, 160 degree fail-open t-stat and modified blanking per picture above:
160_80amb.JPG
Now I'm feeling like perhaps my gauge is off. Next step will be to pull the gauge and test in boiling water - or remove fan belt, t-stat and test in situ.
 
Comparison between verified cooking thermometer and dash gauge:
Actual_189.jpg Indicated_220.jpg 30 degree difference!

Anyone know if it's possible to adjust the needle here - or is it delicate and best to leave to an expert?

PS - there's no oil pressure because I'd just turned the engine off.
 
I tried to 'adjust' the temp gauge on my BJ8. It's easy enough to pull the indicator off--it's an interference fit on the spindle--but, in my case the internals were off as well. Sent the gauge to West Valley Instruments and now both oil press. and temp are accurate--I gained 15lb. of oil pressure at idle!
 
I adjusted the gauge needle today after being unable to remove the bulb from the cylinder head. The needle is robust enough to pull with miniature needle-nose pliers or tweezers. It was necessary to remove the oil line connection from the back of the gauge in order to be able to pull the gauge forward out of the dash a couple of inches. The bezel rotates counter-clockwise for its tiny tabs to align with some notches in the case so the bezel can be detached. This is similar to the way the radiator cap rotates.
 
Comparing the British Car Specialists' sleeved Robertshaw 160d thermostat (left) with Moss Fail-open MotoRad - am going to stick with the Robertshaw design because it looks like it will pass twice the flow.

TwoTstats.jpg

Have ordered an EMP/Stewart 180d which is a slightly modified version of above Robertshaw:
SummitEMPStewart301.jpg
 
For what is it worthI have been following these threads about our cooling systems because I am about to reinstall my radiator and hoses. I went to a local radiator shop operated by a fellow who has been in this same location doing rad work for over 35 years. I asked him about a recor and what options I had with my existing radiator. During the discussion he asked me if the car had a full radiator fan shroud. I told him it didn't. He said that's the first thing I should do after reinstalling the radiator. His explaination is that a fan has to move a given amount of air and without a shroud the fan pulls that air from any and every direction. Without a shroud a very large volume of air that the fan pulls is not thru the radiator. therefore you have a massive inefficency for cooling. A shroud makes the fan pull its air from and thru the radiator. Somehow that makes alot of sense to me. And I have a previous case that demonstrated that. I have a 1970 Corvette. And those shark bodied Corvettes all have the radiator laying back on an extreme angle. It is very difficult to get good air flow thru the rad. Years ago when I had the rad out I reinstalled it without the full OEM shroud. It ran hot. It took me about a week to figure out what was going on. I reinstalled the full shroud and the car has been at proper operating temp ever since. I have an inquiry about this. Awhile back one of the forum members said that he bought a fan shroud from kilmartin. i got on their web site and I can't find a shroud. Can someone tell me where it can be found. Thanks, Dave.
 
The Kilmartin is not a full shroud. It's only a couple of curved strips that fit on either side of the fan and, together with the top shroud, form about 3/4 of a ring around the fan.

The radiator shop that overhauled my radiator said an oil cooler was the best way to lower the temperature additionally.
 
I agree with you Steve,
my gauge fail to give me the correct situation of the car, I have controlled it by Thermal pistol
(90°C=212F°) my 100/6 BN4 2,6 liter engine- with TEXAS plastic fan + electric 12"fan manually or thermostat commanded
temperature is take on the car static in garage, and after a warm-up little trip

TOP of radiator NOT exceed 94°-with little difference from LX and RX side
TOP Thermostat NOT exceed 92°94°
SENSOR reces NOT exceed 90-94°
under side of radiator not exceeds 50° (with the elect. fan ON)

THis appear good to me !?!??

Anyone can suggest how calibrate the Gauge to the correct reading??
I remember that around the gauge capsule, there are some brass screws
Cheers

PS: I can confirm the law:
Half hour trip=TWO hours of work in garage to arrange defectives
today FIRST trip with new plates- throttle linkages must be tightened and upgraded-
but happily I can return at home
 
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