My xj-s is running at the top of the "N" on the temp gauge. I'm thinking about overhauling the cooling system just so it's done and I don't have to worry about it (new thermostats, radiator, & Tefba coolant filters).

In "The Book", Kirby Palm recommends converting the system to a single pass radiator like this one: https://becool.com/products/62082 . But this involves merging the two top hoses somehow which I don't know how I'd do. There is also this one available from wizard cooling: https://wizardcooling.com/1976-1996-...inum-radiator/ . This one is attractive because it doesn't require the re-plumbing.

Am I going to see a significant cooling difference between these two radiators? And if converting the system to single pass is really worth it, how have others gone about the plumbing? Does anyone have experience with either of these aftermarket rads?

 

The plumbing for the single-pass conversion is, as far as I know, just a matter of a couple trips to the hardware store and auto parts store for some pipe to form a "Y" fitting and some straight and elbow-shaped sections of hose to mate it all together. I don't know of a set recipe; just takes a little "MacGyver-ing".

In the grand scheme of things, over 20 years or so, it seems to me that most V12 owners are happy with aluminum radiators....especially compared to a clogged-up original!

A few haven't been happy. Either the radiator wasn't the problem.... or they were trying to fix a problem that didn't actually exist.

I'd use a hand-held infra red thermometer to get a rough idea of actual engine temperature. "Top of the N" might be 180ºF or 210ºF or ...whatever. I wouldn't spend $700 on an aluminum radiator based on "Top of the N" alone, personally.

Agreed on the cooling system overhaul, however. Make sure to get the correct thermostats. And take the radiator to a professional radiator shop for cleaning. They might come back and say it's rotted out....they often are. Or you might get lucky and it just needs a good acid dip and cleaning for $100 or so.

Cheers
DD

 

Those tebfa filters are utter garbage. Your car may just need a good douche, I'm a vocal advocate for Metal Rescue (ph neutral rust dissolving solution) and spin-on filters.

This link may be of interest to you https://www.jaguarforums.com/forum/x...2/#post1925632

I've turned my coolant jet black with that stuff and flushes yet more rust/gunk out. The spin-on filter catches the fine silt now.

 

Doug speaketh great wisdom here. Check what the actual temperatures are first, if you can. Also, running over middle is one thing, climbing up and up is entirely another. In my case, I probably panicked, as I ordered a whole new cooling set right after I got my car--rad, fan, stats, hoses. I got the aluminium one from Wizard, and while the shop needed a couple of washers to fit it properly, it was basically drop in. And my old one was clogged up about a third with gunk. But anyway, as I said, I have a Wizard one, and it was bloody expensive, and so far seems to be doing the trick. I remember reading somewhere that the slots are bigger so they gunk up less, which if true would be good, as it's a job to access for cleaning. However, I'd follow Doug's steps first if I was doing it again: measure temps, get rad cleaned, and only then get a new rad.
Opinions on these forums are very mixed regarding the surrounding foam to block air and ensure it all goes through the rad. I don't have the foam, but as the gaps are hardly big in the first place, and the main time you need cooling is going slow in traffic, I don't really think it's needed.
I've heard mixed reports about coolant filters, however. My mechanic (who works on high-end European imports) said not to bother.

 

You can run an extension cord to an electric kettle and carefully dip the sensor in to see what the gauge says at boiling temp to! and if you like blowing crazy money you can have your gauges sent to an aircraft mechanic who will tune them properly but at that point its cheaper to buy the radiator.

 

Thank you all for the sage advice.

Hit the hoses and thermostat housings with an infra red thermometer tonight. With the temp gauge needle sitting just above the "N", Bank B T-stat housing was 214°-221° F and Bank A T-stat housing was 211°-218° F. Bottom return hose was about 189° F. Curious as to whether or not that is considered too hot.. I test drove the car for about 30 miles before i bought it and the needle was always below the "N", but after overhauling the fuel & ignition systems and repairing the centrifugal and vacuum advance mechanisms she's running a lot stronger, and seemingly hotter.

I'm all for not spending $700 unnecessarily. My previous xj-s had a clogged radiator and a professional cleaning did the trick. But this one is so nice that I originally thought I might go a different route and go with a new aluminum one. Especially because I might be moving to Southern California soon which will no doubt require a cooling system that is totally up to snuff (hot and traffic). So, if one were to spend $700 on a fancy, shiny new aluminum radiator, would they be better off with something like the wizard, or a single pass?

Regardless, I'm taking all your words to heart and doing everything else I possibly can BEFORE I go ordering a rad. Correct thermostats ordered, and holding off on the Tefba filters after hearing about Vancouverxj6's experience.

Finally, and this may open a can of worms, but what type coolant should I run after I empty out the system for all this work?

 

While I don't want to judge your temperatures, especially as I'm not good with Fahrenheit (and can't even spell it correctly the first time), I wonder if measuring the water rails is better than the hoses. A while back I bought some temperature gauge stickers, the sort that change colour once a certain temperature is reached, and placed them on various parts of the engine to see how hot it got. Based on forum advice, I put some on the water rails, and those did indeed show the highest temps: nearly 100 C after a run, and just over 100 C after letting the engine cool (heat soak). The hoses were cooler. And the Vee itself was not overly hot at all.

If you do replace the rad, and I'm afraid I can't say whether single-pass or Wizard is better, it's a good idea to renew everything else as well. Check the main yellow fan for any signs of cracks, but might as well get a new one anyway. It should be a bit more efficient.

 

I picked up one of those aluminum rads on eBay, 179 they have gone up now, im quite happy.
I had to cut the bottom pegs, and make my own banjo bolt. other then that it fit right in.
I have a temp gauge attached to the back of B bank, and after 13 years my xjs regulates on its own now.
On the freeway going 55, 80, 100, it just sits now at 190! pegged there, sitting in traffic it goes up to 200 "thats in the back of the engine" anything over the fan comes on and creeps on down. its been hot over here in the Bay Area and now im not scared to drive anymore.
Now that I have pressure and that dang banjo bolt isn't leaking the thing is perfect. not a single problem with cooling.
I am a giant believer of a new slightly bigger aluminum radiators. I wasn't going to spend 700+ for one. this was a test to see if a cheaper one could fit and work and it passed my tests.
Iv been trying to find the bay store or link with the one I grabbed up, im having a hard time finding it. when I do ill post it.

 

So far whenever I have had a V12 that wasn't cooling it was usually down to 3 things: Fan clutch was weak, debris in between the radiator and condenser, radiator itself plugged, either internally or in the fins.

The previous owner of my 94 must have loved the beach, the find were completely full of sand. When I took the radiator out and held it to the sky I couldn't see through it. Literally knocked 2 lbs of sand out of the fins. After cleaning all the sand out, then the air could flow and no more heating problems.

 

I believe the stock style dual pass radiator was used in racing applications
The IPR metal spin-on filter is very high quality and compact, I use a large spin on unit like the blue model shown in my other post I linked to...that was a mistake there isnt any room for it!

As for replacement coolant anything 50/50 from a semitruck dealer thats CAT EC1 and ELC spec is great if you want no-silica no-acid stuff that is good for 750000miles.
I'll see if I can find my used coolant filter pics...if nothing else it gives you an idea of how how fine the particles can be.


This is a coolant filter at 1000km that was installed after flushing repeatedly with metal rescue and other cleaners as well as taking a shopvac/wetvac to the rad inlets. Needless to say I was quite thorough.

You can see it still collects 'mud' I can only imagine how much is or was built up inside the fins on my car.

 

This is all very timely for me as I think my car has been running a bit hot...per the gauge. I flushed it out best I could and used a product called "Blue Devil"; 3 quarts. My thermal gun readings are around 185 F at the themostat housings now, both banks, It has 180 F thermostats. At the water rails I had been alarmed when at one time I was seeing up to 250, but then I think it may be picking up the exhaust heat shield radiant heat (even though the laser dot was on the rail)? I seriously doubt the radiator has ever been cleaned, so I plan to pull it after I drive her a bit more. (Local shop won't give me a price; it's always a per hour charge and he says could be $300...that's just BS. I'm thinking I may de-solder the tanks, and rod it out myself. Then just have them solder it back up and pressure test it. Thanks for all the discussion. VancouverXJ6, could you provide a link or more info on you're IPR metal spin-on filter? I'm convinced after reviewing Kirby's book and this and other Threads, that filters are a very good idea.

 

https://www.iprresearch.com/IPR-High...-Ford-6.0.html

This one is from a company that does high performance diesel mods, it is the most 'universal' out of all of them, also the cheapest as its fairly basic hence why I recommend it for all other cars/trucks etc. They even have a nice metal Y pipe to help splice it in.

 

I knew when I bought my car that the radiator would have to be repaired or replaced - it wasn't overheating but the radiator was leaking where the core met the tanks on both sides. At the time I couldn't find a original style replacement under about 1000usd, and the local radiator shops I talked to wouldn't give even a rough estimate for repair / recore without me bringing them the radiator out of the car. I ended up buying a "single pass" BeCool radiator, don't remember the model number but quite likely the one linked to in an earlier post.

I went that route thinking at the time that it would be faster than getting the old radiator repaired (and no idea what that repair might cost), and the Becool unit was a lot less expensive than the original style two inlet radiators I had seen. Also some of the "hot rod" guys I know swore by the aluminum radiators.

In hindsight I probably should have gone ahead and got the old radiator repaired and cleaned out or recored, I think it would have been cheaper, faster and just as effective. Don't take this as a knock on the Becool radiator as it seems to be a very well made piece, no complaint at all with their product, but I think it's intended to be used with a V8 swap and for me adapting it to work with the V12 was quite difficult. As Doug said, a lot of McGyvering. I used soldered copper pipe to make the crossover pipe and tee fitting, I think it turned out well and has performed fine, but it took me WAY longer to complete than I anticipated going in (but so does everything else I do!). In the end I'd guess the extra materials to make the single pass unit work probably came to about 150 - 200 usd, not including the value of my time. And as far as the value of my time goes, I did (mostly) enjoy doing this and do feel proud of the end result, I would have rather been driving the car a couple months sooner and doing something else with my "spare time".

I guess a few things toward your bottom line - are you sure you need to do anything is a good first question? In my case it was clearly leaking and I had to fix the problem. To me it seems reasonable to be proactive for a car of this age. If there are reasonably priced radiator shops in your area getting the stock unit cleaned / repaired seems like a decent possibility, If not, my free advice is to go with the original style aluminum radiator rather than the "single pass" style, unless you are a much more skilled fabricator than I am or have a lot of free time to use on this project.

Hope this helps!

Eric

 

Anyone knows the size of stock radiator? I tried to measure it in the car and got about 32x18". Not sure about that 18.

 

What are y'all on about? You can get radiators for $300 on eBay now. Why would anyone get a $700 rad or modify the system for 2 hoses?

 

Right, that's why I was asking about the size. Here in south I'd like to buy as big as possible. There is one 31x19" right now, for $120. Too big, methinks.

 

Excluding mounting pins, overall dimensions are 17 7/8 by 31.5. Be careful that some places specify the core dimensions, not the overall including tanks. The modern radiators have thinner tubes, so they can dissipate more heat than older ones, so a modern core in your old rad might work well.

There is nothing wrong with the 2 pass system, and it will cool the car if everything is working right. I've driven in 40+C temperatures with the AC on and the needle stays where it usually does. It didn't before I cleaned the leaves and sand out of the rad, and changed the fan and clutch and replaced the shroud. If everything is working as the factory intended, it works fine.

 

Thanks! Although my old radiator may be not as bad as I thought it is. My distributor needed overhaul.

 

Update:

Just been waiting on parts. New thermostats just showed up today. They are Motorads and they have the jiggle pin. Will replace, bleed cooling system, and report back. But as of late she's been running right at the bottom of the "N" since the weather cooled down a bit, so it seems to me like the cooling system is operating right on the edge of it's capabilities and whenever it gets too hot outside it starts to lose control.