So, I bought this car knowing it had problems with overheating. I have done almost everything I can which includes the following: New thermostats, radiator/system flush, Water-Wetter and a new coolant temp sensor.

Basically, what I'm asking is... Is it time for a new radiator? Or is there something I may have missed?

Thanks, Peter

 

New radiator? Possibly, yes.

Or at least remove it for a professional cleaning. They often clog internally and externally.

But first....

- Under what conditions does it get hot?
- How hot does it get?
- Did you properly bleed the system?
- Did you use the *correct* thermostats?
- Have you checked the fan clutch?


Cheers
DD

 

It gets hot rather quickly when sitting, but even when driving it will get hot.

As to how hot, the bottom of the H. Which is an improvement as it was pegging out when I got it.

Yes, I believe I did. But for clarity's sake, what is the proper procedure?

I used 180F thermostats with the jiggle pins pointing up.

Yes, it did only went one revolution, if that.

Also, the electric fan works too.

 

Have you checked the actual engine temperature or coolant temperature when it's showing overheating?
Could it possibly be the temperature sending unit or the gauge itself?

 

When hot, the top hoses read in the 195F range.

The block was about 200-210F.

 

You might want to download Kirby Palms XJS book, it has a detailed section on V12 overheating. It's a free download. Close to 750 pages. Just do a search on the forum and you will find the link to it.

 

There are different opinions on what works for filling and bleeding but most owners follow the same basic procedure. Here's the process I used on my '88 XJS V12 and a few others. It's not difficult, just messy.

Elevate the front of the car about 8" and then elevate the left front another 2-3" beyond that. Set the climate control for max heat so the heater valve opens.

Remove the bleeder plug from the left radiator tank. You'll see an access hole in the radiator upper mounting panel. The plug is some arcane size but you'll find something in your toolbox that fits.

Remove the caps from the expansion/header tank and from the filler pipe at the front of the engine....up there by the A/C compressor.

Add coolant/water to via the filler pipe until it reaches the bottom of the pipe. Start engine, set heater control to max heat. Let it run at idle until it warms up. Peek inside the filler pipe every minute or so and top up as needed.

When the engine gets warm increase the idle to about 1000-1200 rpm (a helper is helpful here...or just wedge a little something in the throttle linkage to hold it slightly open for a high idle.

Let 'er run and run. Give the upper radiator hoses a few squeezes now and again. Keep checking your coolant level in the filler pipe and top off as needed. Eventually you'll see some coolant coming out of the bleeder. That's good. Wait a while longer and (hopefully) you'll see coolant *really* pouring out of the bleeder. (How much? It's one of those "you'll know it when you see it" things..very messy)

When it's *really* pouring out of the bleeder hole, put the plug back in. Wear some gloves so you don't get scalded. If you can't get the plug back in thru all the gushing, shut off the engine and do it....but I like to leave the engine running if I can. Not worth getting burned, though.

Top off the coolant in the filler pipe...I go right to the top but some fill just to the bottom of the neck... add a quart or so to the expansion tank if you suspect it might be low, button everything up, and yer off to the races. If you've overfilled the excess will be pushed into the atmospheric tank mounted inside the fenderwell. If you've *really* overfilled the excess will exit the atmospheric tank and end up on the ground.

Lower the car and clean the driveway :-)

Cheers
DD

 

Thank you so much for taking the time to make such an excellent write up!!!

Thankfully, that's what I've been doing, so it's good to know that I did it right.

 

The answer is Yes. It is time for a new radiator. Plus clean out the fins of the oil cooler and condenser in front of it.
Greg

 

Radiator is way past its use by date.

Also the answer to the thermostat wuestion from Doug, and yes, i did read your answer, but maybe this little write up will expand the knowledge a tad.

Also, I have included my bleeding method, coz as Doug said, there are many ways of doing it, and I hate hot coolant on my skin, haha.

V12 thermostat fiasco explained.doc

Bleeding the V12 cooling system.doc

Also ensure the Banjo fitting on the RH top of the radiator is not clogged up, This is COMMON, and an easy fix.

Being as how Fleming is an '89 car, is HE a Marelli or Lucas ignition system??

 

Make sure your electric fan comes on regardless of whether the AC is on or not. This caught me out, did my frikn head in. There's a sensor near the lower rad hose on the front of the block, Short this fan should come on.

 

Grant, I did read your documents before I bought the thermostats to make sure they were the correct ones. Also, Fleming has Lucas ignition...

Hoppy, when I first got the car, the aux. fan wouldn't come on regardless of the temperature. So, I hotwired it from (I think) the green/brown wire to the red wire of the fan.

All in all, I think I'm gonna get this radiator rebuilt/recored/rodded. Thanks guys for your input!

If you guys have anything else to add, please do! I'll post the result here when he's fixed!

 

Good decision, but forget rodding, whatever that is, it is a recore you need.
Greg

 

Before I go through with this, is there a place that sells new "stock" radiators?

All I have found are the super-pricey aluminum radiators...

 

David Manners, SNG Barratt, Coventry West I expect. But if you have a local car radiator place, they will be able to recore your current rad, no problem.
Greg

 

Put on a New Set of Hoses for the New Rad

Or at the very minimum, a New Bottom Hose.(inc the small one on top of it)

That won't be a job you would want to be doing while stuck at the side of the road.

 

Whilst you are waiting for the radiator AND the barmaid to refresh the drinks.

Being Lucas, remove the distributor cap, an experience in itself, and ensure the "mechanical advance" mechaism is not siezed in the "retard" position, which is the most common position. That will rob you of about??? 15deg advance, and any engine will run HOT, and the V12 especially.

Having scibbled all that, I still reckon the radiator is the main culprit. Recoring is the way to go, but sadly, shops doing this are getiing thin, thanks to the alloy/plastic throw away radiators that have been around since the early 2000's.

The replacement of hoses, and belts, as OB mentioned, whilst ALL that room is available is a smart idea.

 

Ooh, that's a thought.. I had read something about that, but wasn't sure if it was related.

I also have another problem.

You see, when I first start the car (When it's cold) it will fire right up, and I can hop in and drive. But after driving for a little bit, and the temp is at the bottom of the H, I can pull into a parking lot, leave it for 5 minutes and the darn thing won't start. What'll happen is I turn it over, fires, revs then dies. I have to hold my foot down on the throttle just to keep it running, and when I do so it sounds really sick. Yet as I hold the throttle down, I can hear it running better and better, and the rpms start going up, then I can take my foot off the throttle and it will idle perfectly. If I take my foot off prematurely, it'll die...

Anyone have this problem?

 

That list is loooooong.

My initial thoughts, based on your original post.

The engine is in fact running HOT. Shutting it down, and leaving the bonnet closed, creates a HUGE heat soak. This heat soak boils the fuel in the rail. When you start it again, the injectors are NOT getting raw fuel, they are getting an aerated fluid, and they hate that.

Holding the gas pedal down induces huge amounts of air, the new fuel from the tank cools the rail, the aeration ceases, and the beast livens up.

I would not be running that engine until this overheating is sorted. A dropped valve seat on 5 or 6B is knocking on your door right now.

There are many other reasons for that odd running after a shut down, but until that cooling system is sorted 100%, you and us, are just chasing our tails.

 

Okay, that makes sense.

But here's the problem. The radiator shop is an hour's drive.

Now, I don't feel comfortable removing/reinstalling the radiator, so I'm going to have the shop do it.

So here's the plan. (And yes, I know I'm pushing it, but I don't have a truck and trailer...) My father and I will remove the hood (That way the shop won't have to and less risk of messing it up), then with the hood off, we'll drive it to the shop. I figure we can really get some air moving in there with the hood off.

So, is that an overly stupid idea? Because at this point, I'm spending all the money I have just on this radiator, so it's not like I can rent a U-Haul...