|
|
|
My temperature guage on a B20 Amazon (1966, later engine), does work. It starts cold and then correctly rises on warm up, stopping somewhere in the middle. All good so far. However on long drives it will then start a regular cycle of sweeping right to the hottest end, staying there for 5 seconds, and then sweeping back to the middle. It will do this continually. I have replaced the thermostat which didn't solve it.
Do you think I should go to the expense of getting a new guage, or is something else the culprit?
Tom
London
|
|
-
posted by
someone claiming to be mckenzie
on
Sat Jan 8 04:21 CST 2005 [ RELATED]
|
|
Seems to me that your sensor is in the throws of going down. Have you ever removed it from the cylinder head? It could be the wire from it to the guage has a problem or is grounding. The original guages are bullet proof. I have the originals in both my 1962 and 1966 Amazons.
mckrobin@hotmail.com
|
|
-
|
|
|
mckenzie;
What wire going form the "sensor" to the gauge? Be advised, on BOTH of your Amazons, those are not sensors nor are they wires connecting them to the gauge, they are an end fitting (soldered closed), on a capillary tube filled with ether. Grounding has ZERO to do with your temperature indicating system. The ONLY thing electrical about it is the light at the gauge which lights it when lights are on.
I wouldn't want you to be (another) owner who thought he could just "unplug the connector" when removing an engine. Compromise the sealed system ANYWHERE along the way, it's toast, and you'll be looking for a replacement.
I stand by what stated before: If the gauge reads at all, the entire system is FINE!
Cheers
|
|
-
|
|
|
Tom;
Not! If the gauge is working at all, its fine...what can go wrong...its beautifully simple, working on one of the first accepted scientific principles, that warming things expands them... (very few evolutionary steps above a rock!)...the calibration may be a little off, but you can easily check that (submerge sensor bulb in confirmed boiling water, observe cal mark) Reference: 
...then just remember that for instance "the gauge reads a bit low etc.". I would say the gauge is reading exactly what the engine temp is...so you may want to try another tstat (buy only quality units!)...have you done a system flush lately?
Cheers
|
|
-
|
|
Got to disagree that "if the gauge is working at all, its fine."
The gauge could be working fine but the capilary tube may be shot and I don't think they can be replaced separately.
My gauge was cycling also. Flushed the system, cleaned and flow tested the radiator, changed the thermostat, etc., all the basics.
Before changing the head gasket and as last resort, I replaced the gauge with a new one and everything was normal again.
Turned out that the cooling system was operating properly all the time.
--
'86 745T, '72 144E, '70 145S, '68 122S Estate, '60 544
|
|
-
|
|
|
Those gauges work or they don't, period.
It could be low water or bad pressure cap allowing a bubble to form in the waterjacket. This will have steam in it and as the water level surges the probe is alternately wetted and "dried" causing severe fluctuation, however...
I suspect a hyper-gauge. Try blocking off half of your radiator first and see if that doesn't stabilize things. My Dodge with a turbo Cummins is renowned for this little issue. Lots of "fixes" but the best I've found is blocking part of the radiator to keep a slug of cold water from closing the thermostat which then opens and gets a slug of cold water and closes and etc. ad naseum. Blocking off part of the radiator reduces the temp differential of the slug of cold water when the thermostat opens (so it doesn't spastically close again).
--
Mike!
|
|
-
|
|
|
Your scenario is entirely possible and one I hadn't thought of although it even happened to me with a Mazda pickup after I upgraded to a two core heavy duty radiator. Went back to the single core and the cycling stopped.
My comments were based on my experience with an original equipment car and how the problem was resolved. I still have no reason to believe that the gauge in my 122 was not shot.
Does that Dodge use a mechanical or electrical gauge?
--
'86 745T, '72 144E, '70 145S, '68 122S Estate, '60 544
|
|
-
|
|
|
As it happens the Dodge ('97 Ram 2500) has electrical gauges but the root cause would still be the same. I put a large chunk of heavy cardboard (waxed stuff for produce is good as it doesn't break down from rain as fast) between the condenser and radiator... blocks about half of it. Isn't good for charge density (turbo intercooler also slightly blocked) but, hey, it's COLD out!
I wouldn't expect a pinched line to cause the wild fluctuations, rather a sloow response, and in effect a damping to whatever is causing the wild fluctuations.
--
Mike!
|
|
-
|
|
|
Good post! But I can see a scenario where the gauge might do as the others
mention, specifically if the tube is pinched so that response is slow both
going up and coming down. I doubt if this happens very often though.
I'm all in favor of cardboard since they quit putting roller blinds in front
of the radiator. Matt B sent me a roller blind, more or less as a pattern.
(It was badly biodegraded!) But I would like to refit my 66 122 wagon with one.
The hard part will be finding a sturdy enough blind with a wooden core that is
narrow enough. The cardboard cores can be cut to length but I am not so sure
about the wooden ones. Also the "stay down" feature would have to be disabled.
--
George Downs Bartlesville, Heart of the USA!
|
|
-
|
|
George,
On my PV, the only thing that was left of the radiator blind was that bracket (?) that holds the roll, a piece of rotted cloth, the wooden strip that held it down, and a few feet of chain. I found the luggage compartment cover of a Bronco II, cut that down to size, reused its roll-up spring mechanism and fitted that into the pull-up bracket. The rest of the installation was straight forward. My main problem was finding a chain thin enough to fit through the places it's supposed to go through. The one I ended up with is still a little too thick and rough to move smoothly through the bulkhead and fit into the latch under the dash, so I reused the piece of original chain there and attached that to the thicker chain, which moves all right through the little tube on top of the radiator. It works fine, but is mostly a conversation piece because I don't drive the car in winter.
Bob S.
|
|
|
|
|
