DISCLAIMER: I LOVE JAGUARS, MY LAST THREE CARS HAVE BEEN JAGS, STORY CONTAINS CONTENT THAT MAY OFFEND/UPSET JAG LOVERS, ALSO UPSETS ME






Hi everyone, my car has developed a strange new problem, the radiator boils over by the radiator caps. Long story short, I shipped the car to a new state for school. Don't laugh, but I meant to use my XJS as my school commuter car! In regards to the problem, sometimes, it happens after the engine warms up, and sometimes it happens after the engine turns off when I park.

I recently had a cooling system service done at the local Jag dealer before I shipped it (full flush and replacement coolant), as well as installed two brand new tight fitting radiator caps by Motorad (the Jag dealer charged me $40 for one, and I got the second one for $5 from Rockauto.) The dealer said the old caps were wrong, hence why these were replaced to address prior leaking. I also replaced the lower radiator hose, as it was shorn, but it surprised me it failed, because I recently replaced most of the hoses myself with URO Parts hoses on my car (within the last year, though I am from Texas, and the heat is insane). The car still does have (at least) a heater/"rear coolant valve" leak which tends to be noticeable if the car sits for a long time. There are other leaks (oil, power steering, possible transmission seepage, but the coolant leak is the most severe of all of them). Yes lol, I love my Jag so much, I still sent it to a new state with these issues.

(As a full disclaimer, when I first got to my new city, and checked out my delivered car, it may have overheated (whether the delivery people ran the engine too long, or whether I did, I'm not sure) but when I ran it, the gauge got near H, as the coolant gushed out. Then eventually, it started clanging. (YIKES). I have read all the horror stories about immediately pulling over to the side of the road above N, but long story short, I was working without three day's sleep, and I kept adding coolant and water every few minutes till I got stranded in the middle of an intersection when the sun just had started setting, and had the police and their wrecker send me to my townhouse where my roommates weren't at home. At this point, the engine and starter wouldn't even turn over. You have permission to lambaste me, as it is one of my life's biggest recent regrets. The good news is, fortunately, the engine no longer clangs, and the engine runs without any noise). Whoever said these engines are indestructible was RIGHT ON. They are built like tanks! Yet, the cooling system still leaks!

Needless to say after my stupidity, and the fact that the radiator caps were gushing, I feared the worst, a head gasket failure. So I tested the system with an engine combustion leak tester, and the dye stayed blue. To my surprise when I turned the engine off, and came back to the tester, it blew up in my face (fortunately, I was not scalded!), spraying all over the garage (which means to me the vacuum/pressure in the cooling system is pretty strong).


I haven't been able to drive my XJS since I shipped it, and moved out of state with it. I have been getting by in AVIS rentals because school has been keeping me too busy to do much diagnosis, and I am a bit clueless where to look next. As much as I love keeping the mileage down on my Jag (only 63K miles!) I would appreciate ANY advice on where next to proceed. For the record, it is a 1983 Jaguar XJS V12 H.E., and yes, I did -- I have side-piped it. Thank you!!!

 

Daytonc,

Sorry to hear of the problems that you've been having.

I'm wondering if that isn't coolant leaking, but just the car crying floods of tears of shame at being forced to wear those side pipes?! I admit I had a quiet sob myself when i saw them!

Seriously, I do hope you get it sorted. I'm sure there will be plenty of the usual cooling system experts chipping in to offer suggestions and advice.

Good luck

Paul

 

Sounds like you may have dodged a bullet when it overheated. The is a sticky on the forum regarding the cooling system that would be recommended reading; also Kirby Palm’s “Experience in a Book” has good info regarding the cooling system.
You first need to address all leaks, if the system won’t hold coolant and pressure you have a problem. Second, you have to verify that both the mechanical fan and electric fan are working correctly. Third, you have to verify that airflow through the radiator is not restricted. Fourth, verify that the distributor advance is not seized and that the timing is set correctly. The sticky and Kirby’s book will walk you through.

 

The above is exactly the order to check the overheating issue. Do not forget to check the distributor. The owners manual explains that the distributor needs to be oiled on about page 64?

But I think it should be oiled far more often. I’m sure the factory didn’t expect it to take 40 years to get to that mileage.
One more thing. Filling the radiator isn’t very straight forward. Follow the sticky.

 

Started clanging and then went away?

Possibly you dropped an exhaust valve seat due to the overheating, but by random chance it is seated or partially reseated, BUT, if that is what happened, it will happen again.

Doug

 

Thermostats stuck shut/,incorrect?

 

That was your first mistake.

Apologies for having to say this, but it is important for you to know if you are going to keep the XJS. The odds that any Jaguar dealer in the US has a tech or mechanic that has ever worked on an XJS, or who has any genuine knowledge of the XJS, are close to zero. Dealer business models don't support servicing cars outside of warranty, and really don't support cars whose engineering is close to 30-50 years old. I would state with a high level of confidence, that whoever worked on your car at the dealer, doesn't know the proper fill and bleed procedure of coolant on the V12, and even if they did, the Service Manager wouldn't allow them to put the time in required. Sad but true.

The XJS is in a no-man's land from a service perspective. It doesn't yet have high classic values like the E-Type that justifies paying an independent Jaguar Specialist with knowledge and experience, and it is too unique and complicated to be serviced by a glorified Jiffy Lube that is a modern service department at a dealer.

When people post to this forum asking "should I buy this XJS?', the most frequent answer will be, 'if you do your own work, yes. If not, no.'

The V12 is bulletproof if it isn't overheated. I hope you are correct and no serious damage occurred, but if it ever overheats in the future -- STOP -- and get it towed home. AAA plus membership is very cheap insurance.

Best of luck, and fingers crossed.

 

Sorry to hear about your problem. Hope you get it sorted out.

REF: Post #7

Jag Dealer. I have also found this to be true. The Tech's at the dealership are younger and inexperienced with the XJS. Even with my 96' XJS with the 4.0 I-6. So I'm sure it is double/triple so with the V-12. I'm 73 now and developed neuropathy in my legs (and I'm not even diabetic). I don't work under the cars anymore. But fortunately, I have an independent shop nearby who's Tech's have a lot of experience with the XJS. And the cost is about half of what the Dealer charges.

 

Thanks everyone for their advice! The fans are working, and the radiator is pretty clean (I try and keep my car clean as possible)

But it is especially interesting RGK20m3 that you suggested the distributor, as I recently did a spark plug job and had to remove it. The distributor dial I thought I put back correctly, but it's possible I didn't. I will definitely take a look at Kirby's book and look at it further this weekend! I also am going to check the coolant mixture (The dealer previously used their new orange OAT coolant) and see if it's anywhere near correct, as I did added a lot of water/coolant haphazardly when I was stupidly tired.

And yes, I hear that dealers are NOT a good place for old Jags, but most of the shops in my home town have little experience with the brand of Jaguar in its entirety. In the past few years, I also got lucky with one of the two dealers (Barrett Jaguar) in town as they had an old shop foreman from the 1990s who oversaw the XJS work. Unfortunately, and it meshes with what you guys were saying, that dealer lost him (he retired I think), and they stopped accepting my work. My service advisor flat said, "no sir, we won't touch anything that old," almost as if I hadn't been a customer of his for years! Oh well, I guess management told him to push the XJS customers away after they lost the old foreman. As for the other Jag dealer I recently used, I saw a bunch of new faces, younger than the car! (yikes, I know, but actually I'm younger than the car too, yikes).

All in all, it sounds like Kirby's manual is my best hope, as well as looking at the distributor. I don't have many of my tools with me since I am in a different state for school, but I'll see what I can find out, and update this post when I do! Thanks again everyone!

 

Haha, funny you mention that Paul. When I was stuck in the intersection, the police officer told me as he waved at traffic, "I bet it sounded good with that Corvette Exhaust!"

I smiled, "Yeah, almost like a 60's A/C Cobra"

Honestly, side exhausts are such a weight saving improvement imo, the old system goes up by the rear suspension and over the axles and it's so heavy. And in my case, it was 40 years old and rusted beyond recall!

When I get it back on the road and this cooling issue sorted, I definitely should post a sound clip of it though! Thanks again everyone.

 

AND,

If its got as HOT as you say, and been purging fluid as I understand it, the radiator is internally full of crud from the block, FACT, and common as Cold Beer down here.

Timing is a mongrel, and I do it "my way" as I am simply not brave enough to be under that thing with stuff spinning at 3000 rpm in front of my face. Read the attachment.

A couple of others to help calm you down.

As said FIX THE LEAKS. If it cannot hold pressure.fluid, it will suck air on cool down, then the system is basically screwed from there on.

REMEMBER

These are SIMPLE cars with equally simple systems, DO NOT overthink things.