Series 3 E Type V12 Overheating Fix(es)

E-Type
21

The v12 etype isn’t really known for overheating. There is a design flaw in that only one cylinder head has a temperature sensor. I’d drill and tap the left hand front water housing for a second sender and use a spare wire to take the reading into the cabin where you can display it.

A ;little additional cooling can be had by engaging the heater matrix. This flow does bypass the radiator however.

Solving heatsoak - a worked example shows how radiator water temperature, ambient airflow from the fan post shutdown and cylinder head cooling are related by the circulation of hot water.

kind regards
Marek

22

Michael. I’ll try the gates “super “ if I can find current model code. All the model numbers in that article are obsolete. The remark that the heater core bypasses the radiator is frustrating. I was just about to service the heck out of it to see if there was a flow problem there. I know any air in system leads to problems. I was thinking of adding a bleed valve at the heater because it is high point in the system. I also want to add coolant recovery tank to keep the volume in the system topped at all times.

23

I’m not sure how a coolant recovery tank will help. When the header tank is more than half full, coolant is expelled when the pressure in the system exceeds the cap pop-off pressure. I don’t see a mechanism for it to go in the opposite direction.

Air in the heater matrix loop can be purged by alternately opening and closing the tap/switch when the engine is running. Pointing the car uphill a bit would be helpful as the header tank will be a little higher relative to the heater box.

kind regards
Marek

24

All of them? It was just a year or two ago…

I’ll do some digging. I know there’s been some sort of hook up between Gates and Motorad. As an aside, Motorad has a new style called an “ultrastat” that I’m evaluating for Subaru applications. It’s a takeoff on the Gates weir gate design, but it has a new twist, it’s a “balanced linear valve”. At first I thought it was more of Motorad’s classic sales over engineering philosophy, but it does seem to have technical basis. The sample I have here has a unique construction twist. Unfortunately, it would take better instrumentation than I can afford to verify function. I’ll have to do a write up on that, too.

25

I appreciate your inputs. I am new to this engine, though I actually WANTED it so I could learn more about it’s design and maintenance. I like engines. My airplane has a 1340 C.I 700 HP radial. I have spent 20 years learning about it and it’s maintenance.

I did not think this model ( V-12 Series III) was particularly prone to overheating (I had a series one about 40 years ago that had some issues that I solved well enough to use as my driver.) I have been frustrated with the issue as it was unexpected. I thought I was going to be fiddling with Carburetors and ignition stuff. So far, only issue I am dealing with is the cooling. If I can’t solve this, I can’t drive it anywhere.

The car IS equipped with airconditioning and the Evap is very large, right in front of the radiator. However…I have the new Aluminum Radiator and double high output fans that are keeping the temp in the radiator rather low so I am not ready to tear out the air conditioning junk.,…… yet. I will finish the heater system flush and check out to further eliminate it as issue. I AM concerned that there is air in the system at this high point that is hard to “burp” out. I was thinking of adding a valve for this at the top of the heater.

Clearly the heat is building in the rear of the Heads as the temp differential from rear to front is about 15 degrees when the heat takes off. I have shut down to avoid boiling or extremes. The first event that got my focus WAS an over heat that caused boiling of the system, overflow etc. all for about 3-4 minutes. I shut down and had the car towed to avoid causing any damage. I started looking at everything to avoid doing this again.

I did a head leak check that came up negative…though I did this as recommended when the engine was warmed up, but not HOT. The test would be hard to perform if the coolant was at boiling temps, even dangerous. I may be doing this again soon to verify the test result.

I have not retimed the engine since static timing because of the other issues that have popped up, including all four carbs overflowing from float bowl valves. I ended up doing all four and resetting levels, which seemed to cure the problem. ( I am very suspicious of the work done by prior mechanics. Evidence suggests that they had NO Jaguar experience and were very sloppy. Every item I have found where there is evidence of some work, resulted in my having to redo work again to correct errors.)

What will be left? Tear off the pump to see if it is somehow not performing? I have replaced all hoses around the radiator. ( yes they were wrong and jerry rigged). Attempt flow checks through the heads while installed? Next, pull the engine and tear down, just to see what is going on? Maybe. It will be sad as the thing runs great at start through normal temps.

Finally, it does have the new distributor and ignition upgrade from the Opus.New radiator and fans. And the fuel system including tank were replaced.

image001.jpg

image002.jpg

26

Do you have this problem at idle or on the road?

27

On the road. At idle things stay normal. Because of one of your observations, I suddenly wondered about pressure. The cap on the radiator has the ‘release” valve on top. I do not know about it either. This leads back to those mechanics that clearly did not know or care to do a good job for the former owner. I just ordered the 13 lb conventional cap. If the old one was releasing early, I can think of several possible overheat problems. It will be crazy if this simple change solves the problem. I will report. Rick

28

I’m a bit confused. If this is a series three, it shouldn’t have a cap on the radiator. The one and only cap is on the header tank. Unless you’re seeing coolant spilling out, and unless you have to constantly replace coolant, the cap isn’t releasing.

If you’re having troubleonly at road speed, a few things to check:

  1. Make sure both fans are drawing air through the radiator, not pushing it forward. It’s easy to swap the wires on the fan motors by mistake.

  2. Check the lower radiator hose very carefully. If the hose is soft, it can collapse under the suction of the pump at higher revs. That would choke off the water supply.

  3. Make sure your belts aren’t slipping

  4. Distributor advance weights may be binding. Check centrifugal advance.

  5. could be a damaged impeller

2 Likes
29

Thanks for the tips. I have disconnected the vacume pot on the distributor to be sure it is only advancing and not getting artificially retarded. It starts easily and warms up normally. Up to 3500 RPM seems quite normal and powerful, no pinging. I will be retiming again when I can figure out a reasonable advance at 3000 RPM. There are a lot of mixed remarks on this,

Cooling, I have been chasing my tail on this for several weeks. I can check off all your notes except “damaged impeller”. Funny, I am at that point here. I just did another run around after flushing the heater core ( I wondered if any blockage around there was an issue.) It was not blocked and flushed clean. I ran it again. Got hot after a 10 minute warm up. While chasing down a fan motor question, I had my head and body down there and happened to try something… I checked the heat on the rear and front of the heads, upper radiator, tubes and other spots.

While doing this…( with engine running at idle) . I noted that the bottom of the radiator is cooler ( 130 F) vs top. ()180F). The rear of the heads were at 205-210. Fronts were 200. This brought me around to one of my earlier concerns. If the thermostats are not functioning as required and are NOT diverting the coolant to the radiator while CLOSING the path through the cool diversion tube? I have been asking the forums what type and code thermostats are recommended at this time? The codes and numbers on these have swapped and are obsolete. It is clear that the Thermostat HAS to work correctly for this CRITICAL part of the cooling system to work. If the coolant is taking the short route through the front of the engine to the pump, not being diverted to the COOLING capacity of the radiator… then the EXACT problem I am having would be expected.

I think the pump is working because it is keeping the engine “cooler” while idling and the Pressure of the system is keeping all the hoses stiff and hot. I have not allowed it to boil (which happened once and is the reason I am so carefully trying to solve this). I was about to the pull the pump (: a lot of work) when I wondered about the thermostats and their purpose. and noted the RADIATOR temp differential.

This leads me to a more radical modifification question: In California, where it is hot, no freezing, why does the alternate diversion system even exist? It does nothing to help further cooling, except at start up to get the engine warm. If it was closed and standard thermostats were installed that open at … 180F, ALL the coolant would be delivered through the RADIATOR, which seems to be working very well. (I have the aluminum models with upgraded fans)… more, bleed openings can be included in the thermoststs to assure some minimal flow while the thermostats are closed. When open, they have no consequence.

The “damaged impeller” question now bothers me. I may have to pull the pump, just to look at it.I can think of no way to verify the amount of flow it is giving while in place. Thank you for your ideas. I will consider anything.

Rick

30

You need the bypass to provide circulation while the engine is warming up. Otherwise, there would be no flow when the engine is cold, resulting in localized boiling. In addition, you need circulation for hot coolant to reach the thermostats, otherwise, how would they open?

I understand that you think your radiator is working well, but the symptom is no flow, and a temperature drop of 50 degrees from top to bottom confirms that. You fans can’t be coming on in the conditions you describe. Do not rule out a blocked radiator or non-operating thermostats.

31

Sorry if you’ve already done this but pull the thermostats out and put them in a pot of boiling water and see if they open. :upside_down_face:

Then let the water cool and see what temperature they close.

Turns out, in the kitchen there’s a thermometer that’s just for testing thermostats. Who knew?

32

Did that. They open at 180. But I appreciate your response. I’m going to figure out if these are right size and fully close the bypass when they are wide open. Rick

33

Rick, after going back and reading your original post (#13 in this thread), I’m wondering if you might just have a bad temp sender or gauge? What overheating symptoms do you have, other than the gauge telling you it’s hot?

34

Thanks to all for responses and Ideas. I’ll keep you posted. I did a flow check on the Pump. It is putting out tons of flow and pressure. After checking this, I used the idling cold engine to drain the system in about 40 seconds, all 4 gallons. Why? Because I wanted to further check the new radiator flow for possible blockage. Not the issue. Water flows though it from both top sides straight out the bottom without restriction clean and neat. So finally, I am back at the beginning… thermostats. Clearly they were changed when the new radiator was installed. They appear to be the correct models for the car in size and design. They have the small jiggle valves, 74 degree C marking. Made in England ( maybe that’s what is wrong) and say WAXSTAT on the top. I have tested them. They do open at about 78-80 C.( not at 74) I have been carefully measuring the housings and these thermostats. Clearly, when they are FULLY open, they do reach the lower bypass opening with a small excess ( 1/32 inch). However…

They only start open at 78c. The temps have to get up to about 96c before they are fully open AND the lower cap is fully extended. At any intermediate temps, the main valve is open, but shy of the bi-pass closure by as much as 3/8 inch. The only way the bi-pass is closed is when the temps are way higher than 74C. so… having read all the articles and remarks you kind people have offered…I think I have to modify these or find new ones that fully CLOSE the bypass at 80C. To do this, I will add metal discs to the lower plate that add at least 5/16 to it’s height. Then, when the upper valve is open about half way, the lower bypass will be closed. This will force more of that nice hot coolant through the device which may cause it to fully open and depress the lower plate. The small spring on the lower portion of the device should allow the added extension to apply pressure to that plate, which may be beneficial. I was thinking to use rubber, but decided that any deterioration of the rubber seal would put unwanted material into the cooling system. The closure of the bypass will force ALL coolant through the radiator that seems to be working rather well. I fitted an override switch on the dual fans to turn them on, even if the fan relay does not function. This way, I can hit the fan override anytime the temps are a notch above “normal”. I will report as soon as I complete the revision and test it out.

Rick

35

Rob, I used a laser temp measuring device to look at various temperatures of the engine. I have learned that this tool is surprisingly accurate. I have calibrated it with alternate temp gauges, etc. When the engine is warmed up and idling, the interior gauge runs in the middle to upper part of “normal”. This conforms to the measurements at the various sensors including the actual temperature sensor on the therm housing the adjacent temperatures of the heads and the hoses at the thermostat. The differential temp of the rear and forward part of the heads differ a little as might be expected. Testing the thermostats in boiling water was also a clear measure of the gauge accuracy. Boiling was at 212 degrees F. at boiling ( water) the thermostats were wide open as we would want. This equated to the 100 C boiling point. Coolant can run at up to 220 F though we do not want to test this limit needlessly. It causes a lot of damage and does not take into consideration that there are as many parts OVER this temp as under. We do not want to run our rear cylinders at boiling temps… ever. No cooling occurs and damage could be imminent.

The event that started all of this was an actual boil over of the brand new car ( to me) on it’s first 15 minute drive. I shut down. I knew what could follow. We had some steam, coolant blowing and the interior dash gauge ran up over the top end. All in a hurry. I will focus on the thermostat issue to be sure they are operating as would be required. If that does not solve the problem… I will have to dig deeper.

image001.jpg

36

The radiator seems clear. What about the rest of the system?
I do not understand why you need to modify a thermostat. Have others had to? The bypass as well as the main valves are proportional. So i would not be surprised if the bypass was not totally closed at 80C.
Tom

37

I have not been able to identify a currently manufactured thermostat model that will open fully and close the bypass at 80c or less. So, I am looking into modifying one that will work. I will do another head leak check today at high temperature. I had no evidence of leak at normal temp under 1500 rpm.

38

The flow of water generally isn’t an either/or with regard to the bypass/radiator. The job of the thermostat is to maintain the minimum temperature. The job of the radiator is to drop the temperature.

Here is a screenshot of the car stationary warming up and then being driven off.

The bottom graph is water flow. 65000 means negligible flow and 0 means infinite flow (it is actually the gap between measured pulses).

PWM2 and PWM3 are the water flow in the Abank (bypass and rad)
PWM1 and PWM4 are the water flow in the Bbank (bypass and rad)

As you’d expect, there is no flow to the radiator before the thermostats open (PWM3&4 are at 65535), but the thermostats don’t open together, the flow through each head isn’t identical and on the far right of the graph, one of the bypasses gets sealed off but the other isn’t.

Don’t expect it to just be crystal clear with a 1:1 mapping between input and output. Note also how little the actual temperature is changing, even though flow is.

kind regards
Marek

thermostat opening
thermostat opening1613×1210 124 KB

39

In general, I believe thermostats are designed to begin opening at their “rated” temperature, and will take time to reach fully open. From the past reading I’ve done, the time between beginning to open to fully open could be a difference of ~20°F (~36°C). I guess that difference depends on the heat source and how quickly it’s increasing in temperature. So while the thermostat you have was “late” in opening by 4°C (96°C vs 78°C), reaching fully open by 96°C seems reasonable to me.

40

I agree with Rob. Mike Frank’s site shows how the thermostats behave.
The graph shows 82’c thermostats btw and the graph shows they start to open at 79’c.

kind regards
Marek