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If it stayed cool on the 15 mile drive but overheated while stopped and at idle, the problem could be insufficient air flow or the water pump not circulating the coolant properly at idle speed.
So I would be looking at the fan, water pump or clogged cooling fins on the radiator
Try this: put a high speed fan in front of the car, directing the air flow through the radiator and with the hood closed, leave the car running at idle and see what happens to the engine temp.
ok so how does water pump go bad like that?? It isn't leaking idk if it has a weap hole like others do but I never had one have a weakened flow rate. They leak or squall like a scalded dog and lock up.
Just confusing idk
I'm currently rebuilding the cd-175-2 carbs
starting a new thread for that so plz read that also 🤓
Once back on car I want a yes no test for water pump. I'm thinking take too rad hose off and start car should fly out wherehose goes if pump is good right? Or another way to know for sure I'd try lol
Btw. Can I do away with all that water to the carb chokes and hoses to those blocks carbs bolt to etc sh@t ???
cant getpics to post here sighs.
I read a thread talking about some vacuum controlled valve being stuck?? I seen that it has vac lineto top of rear carb.
Yea walter I am getting a fail safe one when I replace it again.
I don't think the clutch fan is engaging like it's spose to but I'm not sure. Just idk don't sound right when car running.
I'm really leaning towards getting a pair of 10" electric fans and take metal fan and clutch off. They're made with a nice shroud tightly around em and that has to cool better than fan on itwith gaps n space at bottom of shroud ya know?
I have learned to Despise clutch fans as I've been left stranded by more that one of them (I was a slow learner). In fact, for that reason they are Forbidden on this place!
Either full electric (usually in pairs) or Old Tech belt driven.
(';')
1. If the guage is pegged on hot , there should be lot of water turmoil going on. Boiling and gurgling like crazy, spewing out the overflow, etc.
2. Failure to cool at a standstill is tough assignment I warm weather. It denotes three things. One or more in action. No water flow or not enough. Fan not moving enough air. Radiator tubes clogged, nt enough air passing through.
3. The space between the radiator and AC condensor is cluttered with road debris. Air flow and heat transfer restricted.
4. Sans t'stat operation may make an engine run hotter. Views differ here.
I have learned to Despise clutch fans as I've been left stranded by more that one of them (I was a slow learner). In fact, for that reason they are Forbidden on this place!
Either full electric (usually in pairs) or Old Tech belt driven.
(';')
yeah I nvr cared for them either.
Rather put dual electric fans wired direct to ign switch
1. If the guage is pegged on hot , there should be lot of water turmoil going on. Boiling and gurgling like crazy, spewing out the overflow, etc.
2. Failure to cool at a standstill is tough assignment I warm weather. It denotes three things. One or more in action. No water flow or not enough. Fan not moving enough air. Radiator tubes clogged, nt enough air passing through.
3. The space between the radiator and AC condensor is cluttered with road debris. Air flow and heat transfer restricted.
4. Sans t'stat operation may make an engine run hotter. Views differ here.
5. The engine has a mechanical issue.
Carl
well all ac stuff is off car atm most missing in engine bay capt compressor and seeing how much just lines are I doubt it'll have ac again lol.
Electric fans can't be a bad addition imo no matter what. And it would eliminate 2 causes at once right. Fan clutch and air flow thru rad.
I didn't hear any horrible typical boil over noises like other vehicles have but I tried to shut it down before it was doing that but idk. gauge was showing pegged anyways.
I don't want any possibility of it overheating if that's putting a digital gauge on it or whatever yk?
so a repair kit for water pump does what exactly??
I figure a new shaft bushing or seal but does it make it push more water ??????
1. I thought my post disappeared? but, it saeems to have found it's way.
2. My lump's E fans are computer controlled . Very nice. Temperature sensed. Off at speed, on at low speeds in hot weather and traffic. used when needed only!!! runs nicely at 90 + C. Engine designed for that temp. Full time partly defeats the purpose.
3 A leaky pump will cool as long as coolant is added. The kits fix the leak issue . Caveat, the impeller is the big "deal". Worn away or loose on the shaft and the pump does little or nothing.
4. An engine can cool somewhat sans pump function on the thermosiphon feature alone. Caveat, not to be relied on.
5. Our Jaguars have a feature that can get us home in an over heat condition. Pop the bonnet to the safety catch position. Far better ventilation of the engine bay. Best not at higher speeds....
1. I thought my post disappeared? but, it saeems to have found it's way.
2. My lump's E fans are computer controlled . Very nice. Temperature sensed. Off at speed, on at low speeds in hot weather and traffic. used when needed only!!! runs nicely at 90 + C. Engine designed for that temp. Full time partly defeats the purpose.
3 A leaky pump will cool as long as coolant is added. The kits fix the leak issue . Caveat, the impeller is the big "deal". Worn away or loose on the shaft and the pump does little or nothing.
4. An engine can cool somewhat sans pump function on the thermosiphon feature alone. Caveat, not to be relied on.
5. Our Jaguars have a feature that can get us home in an over heat condition. Pop the bonnet to the safety catch position. Far better ventilation of the engine bay. Best not at higher speeds....
Carl
oh ok. I don't visually see a leak at or near the pump. No leaks at all except the bad hose elbow I'm replacing.
So the impeller could be worn making it weak that makes sense. The repair kit would fix that also? Or is that just a new seal for leaks ??
fwiw when I came home from emiss shop I ran heater on speed 1 and while roasting me in cabin it did make the temp go down on gauge. Maybe that indicates the valve flow there thru heater core is working idk.
im pulling the fan what the PO called a shroud off and measuring for dual fans I think I can fit a pair of 12" ones so I'll have a 12x24" cooling area
I've never seen the repair kits for this engine. the last WP I resealed was decades ago for my Model A Ford. It did include a new shaft and impeller.
Since, then, I have replaced a couple on other critters not a Jaguar. No effort to DIY, I just bought a rebuilt one and turned in the old as a core.
My car is a lump. I messed up the GM shaft driven WP !!!! I was in deep. Saved by a custom designed electric pum0p for LT1 engines. So much better...
Yes, indeed using he heater core as a radiator supplement works. It isa but a smaller version...
Your reference to a shroud makes me suspicious. They play an important pat in cooling. One that is less than optimum will contribute to an over heat condition.
Get an IFR from HF or similar. Read the real temps in live action at various points along the coolant path. Your engine may be in range and the sensor/guage inaccurate...
I've never seen the repair kits for this engine. the last WP I resealed was decades ago for my Model A Ford. It did include a new shaft and impeller.
Since, then, I have replaced a couple on other critters not a Jaguar. No effort to DIY, I just bought a rebuilt one and turned in the old as a core.
My car is a lump. I messed up the GM shaft driven WP !!!! I was in deep. Saved by a custom designed electric pum0p for LT1 engines. So much better...
Yes, indeed using he heater core as a radiator supplement works. It isa but a smaller version...
Your reference to a shroud makes me suspicious. They play an important pat in cooling. One that is less than optimum will contribute to an over heat condition.
Get an IFR from HF or similar. Read the real temps in live action at various points along the coolant path. Your engine may be in range and the sensor/guage inaccurate...
Carl
I'll got an ifr otw.
Yes the PO put in an alloy rad and kinda hung the shroud on it. It isn't attached at bottom of rad and is not against the rad like touching it. I thought those had to be up against the fins in center of rad and fit almost the whole area so fan draws thru the entire or max area for cooling.
I'll get pics of shroud today
Checking temps with the infrared thermometer sounds like a good idea to confirm what's really going on with the temperatures. On my XJ6 SII engine, the temp gauge would creep up to 100 or 105C when sitting in traffic on a really hot day, and I would get various gurgling and other unpleasant noises. I changed thermostats, had the radiator boiled out and it didn't have any impact. The PO had removed the fan clutch and installed two cheapie 10" electric fans. I replaced one of the 10" fans with a 13" Spal Fan. $150 for the Spal, but it moves a hell of a lot of air.
That did the trick and I never had any overheating problems again, even in the midst of summer. Each fan was set up with a fan controller to come on at about 90C. A poor shroud set up can contribute to an overheating issue, but I'd be surprised if it's the cause of your rapid and extreme overheating. I did not have a proper shroud setup with the electric fans and they still did their job very well.. I placed the 13" fan closest to the radiator inlet pipe.
Checking temps with the infrared thermometer sounds like a good idea to confirm what's really going on with the temperatures. On my XJ6 SII engine, the temp gauge would creep up to 100 or 105C when sitting in traffic on a really hot day, and I would get various gurgling and other unpleasant noises. I changed thermostats, had the radiator boiled out and it didn't have any impact. The PO had removed the fan clutch and installed two cheapie 10" electric fans. I replaced one of the 10" fans with a 13" Spal Fan. $150 for the Spal, but it moves a hell of a lot of air.
That did the trick and I never had any overheating problems again, even in the midst of summer. Each fan was set up with a fan controller to come on at about 90C. A poor shroud set up can contribute to an overheating issue, but I'd be surprised if it's the cause of your rapid and extreme overheating. I did not have a proper shroud setup with the electric fans and they still did their job very well.. I placed the 13" fan closest to the radiator inlet pipe.
Is funny you mention the cheapie 10" fans I was going to get a pair of those 12" ones I guess now I need to get something better.
yea I never have heard any noises like I would associate with a pegged temp gauge in other vehicles so possibly the gauge or sender is faulty
I have a auto meter 2" temp gauge I may install in place of the smiths it actually gives a number. Granted it's in C reason I changed it for a F one in my 62 Buick but it's better than a guess lol.
Iirc I seen a couple senders located on the lower RH side of the engine that didn't have a wire on them looked like oil senders but idk. Didn't see them til I pulled carbs off to rebuild.
I'll get pics for U guys I forgot about that lol
Installed aftermarket aluminum radiator that I bought off EBay from a guy who had it installed in a XJ6 previously. Had it and the overflow container cleaned and pressure tested before installing.New flat pressure cap; new 13lb pressure cap on overflow. Here's what I did to cure my overheating problems (1975 XJ6C 4.2L)Installed two 11” puller electric fans (from RODPARTSDEALER on EBay) with a Davies-Craig temperature control system (DC-0444) that has a probe installed in the upper radiator hose directly into the coolant (DC-0409). This system turns each fan on one at a time with a 10 second delay to not draw initial heavy current.It has blue digital led readout to show current coolant temperature, and a way to set the “on” temperature.It can be in either Fahrenheit or Celsius.It also comes on whenever the A/C clutch picks.Installed new 160d thermostat and have the electric fans come on at 175d.Still may have to adjust that as I learn how the engine likes to run in the Florida Summers.Always had cooling problems in the past like all other 4.2’s.
Installed aftermarket aluminum radiator that I bought off EBay from a guy who had it installed in a XJ6 previously. Had it and the overflow container cleaned and pressure tested before installing.New flat pressure cap; new 13lb pressure cap on overflow. Here's what I did to cure my overheating problems (1975 XJ6C 4.2L)Installed two 11” puller electric fans (from RODPARTSDEALER on EBay) with a Davies-Craig temperature control system (DC-0444) that has a probe installed in the upper radiator hose directly into the coolant (DC-0409). This system turns each fan on one at a time with a 10 second delay to not draw initial heavy current.It has blue digital led readout to show current coolant temperature, and a way to set the “on” temperature.It can be in either Fahrenheit or Celsius.It also comes on whenever the A/C clutch picks.Installed new 160d thermostat and have the electric fans come on at 175d.Still may have to adjust that as I learn how the engine likes to run in the Florida Summers.Always had cooling problems in the past like all other 4.2’s.
thanks for calling out part numbers that sounds like a nice setup as well.
When you say new flat cap is that the one above the tstat ? Have a pn for that mine don't seem to want to lock in place just spins around gets sorta tight then almost flies off coz it went past the catch.
Note the extension at the rear. As the stat opens this extension piece closes off the bypass. If the thermostat doesn't have this, hot coolant escapes down the bypass and avoids the radiator,. The same happens if no thermostat is fitted.
06-16-2018, 11:39 PM
