I am in the process of replacing my heater core (another post). Since I am draining the system for this I was going to pull the radiator and convert it to the 4.2 configuration that it should be. The PO had replaced the header tank with a 3.8 flavor and capped the bypass on the radiator. Couple of questions here. For the header tank have you gone with the ss version or the cheaper steel version. I am inclined to go with the ss (also looks better). For those of you who have ditched the two blade fan for the multi-blade do you have any recommendations for this? There are several options for this. I am considering converting mine which is still the two blade configuration. Mine is not overheating, but not having the correct configuration has been annoying. Thanks for the info, Skene.
Stainless: one and done.
For my money, you can’t beat the CoolCat fan and motor.
I went cool cat radiator and fan about 15?? Years ago. Jeez time flies. Anyway one of the best upgrades I’ve done. Never overheats. Even when I used to race.
Mine is aluminum as is the radiator. Its been fine.
Endless posts on this cooling topic. In my observation some truths that come up consistently. Any of the E-Type systems work at least OK if you don’t have AC, the cooling system is like new (no scale, proper cap, in other words, REALLY like new) and… you have a Cool Cat fan or one like it. After those touchstone truths more diverse opinions start to come up. It has been stated that many aftermarket tanks (especially 4.2?) aren’t correct internally. This causes problems with flow through and otter sensitivity - apparently.
I have a 3.8 with an early 4.2 system - pump, cool cat rad and fan, 4.2 intake and head flow. Recently someone said the 3.8 system is actually better, despite the factory changing to the 4.2 system - again, there seems to be some dispute. Solution - see above, any properly built and maintained original system will be OK with better fans and zero corrosion or junk parts.
I had not header tank when I bought my 4.2 car and and ordered a stainless tank from one of the usuals, but could never get the otter switch area to seal. The problem was the facing of the stainless tank was not flat due to warpage from it being welded on. Also the three bolt connections were through-holes into the tank and not closed connections. Both the warped otter connection plate and the through holes caused it to never seal and I tried just about everything: several cork gaskets, sealants, super tight bolts, etc. I put on an aluminum tank from Classic Jaguar with closed bolt holes and a flat otter switch face and the problem was solved. If you go with a stainless tank then check the flatness of the face right away and try and order one with sealed connection holes and not through-holes. Ask your vendor. I could not return mine due to having it for several months before installing it.
–Drew
Larry,
Cambridge Motorsports makes nice header tanks with the otter switch mount properly located.
http://www.cambridgemotorsport.com/historic/73823
I’ve considered making header tanks, but I back away from them because the piping is very subtle. I actually have an original tank on my bench at the moment, and I was thinking about publishing a page with borescope photos. The main entry and exit fittings are one continuous pipe that passes completely through the tank. The otter switch opening passes not only through the outer skin, but also through the main tube, so it senses flowing coolant. There is a slit in the tube that allows the system to be filled, and allows venting for expansion when in operation. There’s a baffle that’s separates top and bottom.
I’ve examined some aftermarket tanks where the fittings are just nipples and the tank insides are more or less open. I don’t see why that wouldn’t work, but Jaguar seems to have thought that the thermostat housing should connect directly to the radiator, and tunneling through the header tank was the shortest path from A to B. I’m not sure whether this even matters, but it’s something to think about.
The XJ-S V12 had the otter switch in a different spot, in the water pump inlet. Later on they changed that to a threaded temp switch because that otter switch is just asking for trouble. Since Cambridge offers this tank configured for either otter switch or threaded, I’d think you’d have to be nuts to opt for the otter switch configuration. The tank is obviously aluminum, you’re not sticking with concours originality already.
You have the dreaded Boeing blade?
The stainless one I have is like this. Got it on E-Bay from “just a guy”. The through pipe has a hole where the otter is located, so it seems it is made as an original.
As I have mentioned, I have your fan and radiator, no motif bar and all runs just great.
Seems like a lot of options here. The aluminum ones look good, but definitely a bit more on the pricey side. I do like the CC fan. I have the CC oil filter kit and love it. I am going to pull mine apart and audit what I need. One other question is the mounting bracket for the 3.8 header tank the same as the 4.2? The tanks are similar so I thought the bracket might be the same. I was hoping to reuse my bracket. Thanks again.
Suggest you check here: https://www.sngbarratt.com/us/#!/English(US)/FindParts/Families/XKE%20~2F%20E-Type/3
From the link it should be easy enough to determine by checking what’s on your car and looking at the pics. It shows different Part Numbers for 3.8 & 4.2.
For the S3 E-Type, they relocated the otter to the lower hose. The fan switch senses at the pump inlet, which feeds both banks. This eliminates the problem of sensing just one side of the system, as you see with the V12 temperature gauge. If it was located in one or the other of the engine exit passages, then it would be possible for a thermostat to be stuck closed and the fan never would come on. It couldn’t be in the header tank either, because the V12 header functions as a simple expansion tank and doesn’t have the “through pipe” configuration of the S1.
As I wrote that, it occurs to me that if the through pipe on the S1 was completely open within the header, the cap would tend to lift. The position of the baffles and the size of the slots may make a significant difference to how the system performs.
Yes the brackets are different, tank mounts are different. Tank and bracket are 3.8 config in pretty good shape. Will probably sell them on ebay when all is done or will post here if there is any interest. Coolant is drained. Let the fun begin.
Michael, do you (or anyone) have an original tank that has been cut open, or it sounds like you at least have details of the inside. Do you or anyone have a detail description of the coolant flow through the entire S1 4.2 cooling system?
Tom
I can probably do a dissection of a tank after my thermostat project is done. If you have a specific question, I can try to answer.
Michael, I am just curious as to the flow of coolant through the S1 4.2 system. There are four radiator connections, three header tank connections, and three engine connections- not including the heater flow. Not exactly the most obvious coolant path.
I believe I follow the basic path of coolant out from the large thermostat housing to the RH inlet to the header tank. I believe the internal pipe you are referring to goes straight through the header tank and out the LH side to the top of the radiator. Then I assume the path is through the radiator, cooling it, and exits from the lower radiator outlet and to the water pump. The water pump then pushes the coolant through the engine and returns toward the thermostat housing.
- The front RH hose between the header tank and the RH upper (cool side) of the radiator. From what I can tell, and from what you said about the header tank, when it leads into the header tank, it is only connected to the through pipe by the gap around the otter switch, limited to little flow, so not really a connection. And why would we want to put cool water back into the hot side of the radiator, or hot water from the engine to the cool side of the radiator? So apparently it is there just to bleed air and be an expansion tank? If that is all, why so large a connection? Or what is its purpose?
- The small hose between the RH upper (cool side) of the radiator to the small connection near the thermostat housing. I have never had a manifold off and do not know the coolant flow through it. I do believe the thermostat bypass slot is near this connection. (I believe your Coolcats white paper says the bypass slot goes to this outlet.) Does the bypass flow path leave this small intake manifold outlet to this hose, go through the cool side of the radiator, back to the water pump, and to the engine?. Seems ridiculous, but, not knowing the flow and not knowing of another internal passage back to the water pump, possible? And of course, if not, what is this hose’s purpose?
- And assuming my bypass path in #2 is incorrect, what is the bypass path?
I will try this for starters?
Thanks,
Tom
You have a good grasp of how it works. Some specific replies:
-
The smaller hose between the header and the right side of the radiator is the primary path for filling the system with coolant. This can’t be done through the main thermostat/radiator connection because it passes all the way through the radiator. There is a slot in this passage to allow air to burp out as it fills, but the primary fill path is through the smaller hose on the right. The otter switch goes through the skin of the tank into the through-tube which connects the thermostat and radiator, it doesn’t connect to the fill connection.
-
The smaller connection to the radiator is the bypass connection. It flows through the cold radiator tank and back to the pump. This is the least weird part of the system. On the S2, this hose was rerouted directly to a fitting on the pump inlet, but the effect is the same.
Having the fill connection on the cold side, orthogonal to flow, is actually a best practice, since the cap is less exposed to lifting forces. You’ll find this on many cars, old and new. Mercedes header tanks connect to the lower hose, as does the tank on S3 E-Types. The 4.2 designers understood this, but the design is compromised by the through-pipe. If the engineers weren’t so dead set on having the radiator inlet on the left and the outlet on the right, it could have been much simpler and performed better. But as it is, the only path from the thermostat housing to the radiator inlet leads right through the header tank. I suspect the engineered “leaks” in the through-tube, which are required for venting and for the Otter, tend to lift the cap under some conditions, and there may be retrograde flow through the fill tube. Which is why there’s also a system of internal baffles. You’ve never seen something like this on another car, because it’s the dog’s breakfast. The good news is that all the right stuff is there, and it usually works ok.