Interesting temperature readings on radiator

Did you stick one of your better half’s cooking thermometers in there to see what temperatures they open and close at? Is the new T-stat at the top of the picture? if so that it might not be completely closing off the bypass might be part of the problem.

I’m wondering about the heath of you water pump. There are lots of alternatives but I know Coventry West rebuilds them with an upgraded impeller for somewhere in the neighborhood of $100 + shipping.
If I was going to remove the radiator I’d also pull the water pump and have it rebuilt or exchanged by CW. Access will never be better than when the radiator and fans are out.

John. Yes the new thermostat is at the top, with the longer reach of the foot. Between it and the new housing I’m fairly certain that the bypass is closed off.

The water pump is a question, and while the outside is not a great indicator it looks fairly fresh. Nice paint, etc. and no leaking or wobble to the pulley. So I guess it’s possible… but it shows no indication of failure

IR thermometers are notoriously inaccurate. Google it and check the discussion on emissifity. Bare steel and aluminum will give off different readings even if they’re identical temperatures, there are charts for this. Paint throws off varying readings based on it’s composition and thickness. Paints made for radiators are specifically heat conductive, not many people know this and use regular rattle-can black. Several coats on the fins can have an effect.

I use my IR for comparing brake drums and rotors and accept that readings are going to vary a bit. I wouldn’t suspect a cooling system problem on IR readings alone, I’m sure you aren’t. …just sayin.

I apologize since I missed this, but why do you say it is overheating?
Tom

The car is running HOT Trust me on this ok?? I know all about IR and gauges and senders. The car is definitely running hot.

A rough estimate of radiator condition is to remove the lower hose, put a garden hose in the filler, and if the water does not back up, but flows freely, through, it is probably ok.
Tom

1 Like

Hi Tom

Nice idea. Thanks. On the series 2 radiator the in is almost directly above the out, do you think that would matter?

No, the water should drain right out the bottom if too many tubes are restricted, the water will back up and overflow, or come out elsewhere like overflow tank or hose youremoved from the lower radiator.

Have you tried to manually block the bypass and assemble without a thermostat? Does it still overheat? If so then you know it’s the radiator fouled.

Do the same with bypass open. Still overheat? Then you know your bypass flow is too high.

Is your system maintaining pressure when hot? Cap venting too early? Then you have a bad cap.

I have an xk150 and series 1 4.2 etype. Both need thermostat with skirt that blocks the bypass when thermostat opens. Parts books always try to sell me the wrong thermostats.

Bob I forget what you may have done for any type of fan rebuild or upgrade. What you describe is very similar to my '68 when I first got it going. My original twin fans came on and flowed lots of air so I initially did not suspect them much. On a hot Houston day it would creep up toward the red and a couple of times puked a little coolant out of the expansion tank overflow.

First was new thermostat then system flush then water pump rebuild then new brass original type radiator. Helped some but would still creep up toward red after running for awhile on 90 degree day. I then got these Coolcat fans and it solved my problems. My fan fuse would get hot so my theory was the were tired and drawing lots of current plus I figured the new fan design would be more efficient. At the time I was surprised they solved my cooling problem but wanted to rule out fans and fix the hot fuse problem.

Couple of weeks ago I did the periodic coolant change and let it sit in the garage on 90+ degree day to heat everything up thoroughly. I added a bottle of Water Wetter just for fun too. It still hangs out around the M in NORMAL here in Houston and has never gone out of the NORMAL range since the fan upgrade.

My car does not have AC. My engine is original to the car and best I can tell from the original owner and the receipts they gave me it has never been out of the car or apart in a major way. I think it has around 60,000 miles (odometer broken when I bought it) and is probably not pristine inside the 51 year old coolant passages. My original radiator has some white deposits in the tubes that I can see thru the otter switch hole but looks pretty good for one that ran for 35+ years. I have owned my car since 2000. Just my 2 cents from my experience with this.

https://www.coolcatcorp.com/Merchant5/merchant.mvc?Screen=PROD&Store_Code=CEC&Product_Code=Coolcat10&Category_Code=CS

David
68 E-type FHC

Robert, l was/am not trying to dispute you, but I am trying to understand your issue. The information I have is basically your first post and your responses to Michael. You never state that it has boiled over, to me, that is significant. That tells me that somehow, it is getting rid of heat, or it is dry, which I do not believe is the case. You also said the top hose is not hot, only warm after 20 minutes of idle. And no pressure in the hose. If you needed the pressure to prevent overheating, and had a bad cap, it would be boiling out, but it is not. So it appeared you are building no pressure. Why? Not getting hot enough to build pressure? 20 minutes of idling and not boiling out, but getting too hot? How long until it does boil out? Your first post said the top of the radiator was about 100, later you said 200??? Just trying to understand.

Also, in checking items, can we assume the radiator is not clogged/dirty on the outside, and no one painted it with a paint that is prevent heat transfer?
Tom

Hi Tom.
Thanks again for your response.
The two temperatures are on opposite sides of the radiator with the fans running. 200° or so at the radiator intake and 100° or so on the front side of the radiator that has the air being pulled in against it.

The outside does not appear to be overly clogged or paint too heavy.

Hey David
Your story does sound like mine with trying lots of things. I’ve read that the old square motors were not all that great, but the round ones are said to be quite good. Did you have the square ones?

One of the members here did an evaluation of fans and motors and suggested that the round motors, with upgraded flex-a-lite blades are actually pretty good. So since I had the round motors I swapped the blades. Seems to move a lot of air

Yes my original motors are the square type with the white 4 blade fans. My fan shroud is still the original with no mods or additions since the Coolcat fans I got bolt into the original brackets and hook up to the original wires.

FYI the new radiator I bought back then is brass type and externally looks like the original but if I remember right has 7 more rows of vertical tubes than the original. It helped some but in my case the Coolcat fans were the final solution. If I was doing this again now I would look at having my original rodded out or re-cored instead of new but luckily I have not needed any radiator work on any of my cars in 10+ years so am probably out of touch on how repair costs compare to new. Like I said mine is a non-AC FHC so it usually does not see more than a half hour at a time this time of year since it is such a sweat box.

My other cars are Vegas (my first car), probably the most fragile engine of all time when it comes to overheating, so I became very sensitive about engine heat at an early age. Both the Vega and XK are of iron / aluminium configuration so I will always try to err on the side of caution when it comes to engine heat.

My Vega with AC that is my everyday summer commuter car in Houston has double the size of any stock Vega radiator. It also has an electric fan added in front of the radiator/condenser in addition to the original engine driven fan. I made a removable wire harness that I use to power the electric fan in the summer. Every May I unplug the wire going to the heater blower and plug my radiator fan harness into that connector. This way I can manually set the radiator electric fan from low to high using the heater fan switch on the dash. I have not touched the inside of this engine since 1992 and it is still running strong.

David
68 E-type FHC

I have yet to hear anything here that convinces me this engine actually IS over-heating. How many times have we heard about engines “over-heating”, when, in fact, the owner simply over-filled the cooling system, and the engine was simply pushing out the excess.

IR pyrometer readings are so unreliable as to be nearly useless. They will vary WILDLY based on the target material. You will NEVER get a decent reading on a radiator core, and the 100/200 readings cited are proof of that. I’d bet NEITHER number is actually correct.

How much coolant is in the system when cold? Is the header tank empty? Half-full? Full?

If you start with the header tank empty, and the header tank cap is left off, what happens when the engine “overheats”? Does it push coolant out of the header tank? If so, does it push some out slowly, or does it suddenly erupt in a geyser?

How do you know your temp gauge is anywhere close to correct? I’ve seen gauges and senders that were off by MILES. If you have not tested yours, you have no idea whether it is right, a little wrong, or massively wrong.

Once again, the S2 cooling system works extremely well, when all the components are in proper working order.

Regards,
Ray L.

Clever!

If I had the square fans I would replace, but I think the round ones, now with the new blades, are doing a good job moving air

So today I pulled the radiator and brought it over to a local radiator shop. He recommended a new core, as the copper/ brass fins were damaged in some areas and in some small areas actually flaked off when touched.

He did a flow test and estimates that it’s probably 30% blocked. He’s going to boil it overnight and recheck the flow. He says he’s reluctant to rod it out since he believes that it wouldn’t go back together again without creating major leaks.

When I questioned him about aluminum radiators he mentioned that even the well made ones are not repairable, and can’t be disassembled for roding out in the future.

If I could get my hands on a Coolcat quickly I’d probably do that, but I’m in California and it takes quite awhile to get here…

Ray, perhaps you missed this. I shut things down and let things cool off before it starts to boil over, as I don’t want to damage the head gasket, or worse. So yes, it’s never actually boiled over. But I’m not willing to let that happen just to prove to people online that I know what I’m doing.

But a car whose temperature continues to climb even while driving at speed, or shows no drop in temperature when the fans engage, is not healthy. Ive probably had close to 30 classic cars over the last 50 years, always doing my own work, and recognize a car running hot when I see it.