I have a electric water pump that I used on a BB Corvette. I was thinking of installing it my 91 12 cyl 5.3 in the lower radiator hose . I can see fitting one of these (Stewart elec water pump) is going to be a very tight fit. Any input on this type of instillation would be appreciated. I can't seem to find the archives part of the Forum.
Lawrence

 

Installing an electric pump on a Corvette is either a waste of money or a band-aid covering up an underlying problem. I imagine the same would apply to an XJS.

 

My BB Corvette ran hot, starting when hot was the problem, not overheating. Two changes SOLVED the problem FOR ME, gear reduction starter or/and a electric water pump. I believe Chevy even installed a starter heat shield @ some point. Of course I know there are some that probably ran their BB all day in 100f degree heat showing 180 0n the gauge, I was one that did not . END of Corvette heat explanation/story!
As for my Jaguar, I have no cooling issues. I installed aluminum rad, elect fans, Lutz 1 mod. 180 stats. My two Auto Meter gauges normally read 210F @ the back of each water rail, in contrast to my dash gauge reading below the "N". Florida heat!!!!!
With all that said , yes I have an electric pump (the one off the Corvette) sitting around I thought will work on the Jaguar. Why? Because I want after run water circulation, ie: electric fans run on. Hope that answer's the WHY's.
Lawrence

 

Corvettes, both SB and BB had them from day one for good reason. The BB Corvettes (1965-74) always ran hot in traffic from day one, particularly the '68 though '74 but coolant circulation rate was not the root cause or solution.

Not trying to be a jerk, but why?

 

.

i think the timing afterrun of an electric cooling pump is the best mod for Jag V12 ever, heat soak after shut down is bad for jag V12, sometimes cuasing seat drop, its a massive engine afterall.
there is a guy in Australia who makes a great kit, a timing and temperature module, along with a good looking pump system!

craigdavis.com.au

 

I believe http://daviescraig.com.au is the correct url.

Cheers

 

Well, adding to the mix, my LT1 powered XJ
has an electric pump from Mezziere.


Bend there over a decade. So far just great!!


Why? don't ask!!!:


Carl

 

Personally I think a properly bled cooling system is the best protection against valve seat drop whether the engine is running or shut off. 'Tis those hot spots caused by air pockets that cause valve drop....and an e-pump won't solve an air pocket problem.

But, if you like the 'belt and braces' approach, go for it !

All "IMHO", of course

Cheers
DD

 

It's true that coolant temps peak some time after shutdown due to soak back, but I can't imagine this alone being sufficient to drop a valve seat.

 

Personally I agree.

The notorious nature of the V12 cooling problems tends to make us hyper-focus on *coolant temperature* rather than *coolant flow*. Tis the later, not the former, that causes valve seat problems.....although I'm sure you could get coolant temp high enough to cause a problem if you really wanted to.

Cheers
DD

 

I've seen electric coolant pumps cause that very situation (ducks for cover)

 

read Allen Scott book ,"TWR and Jaguars XJS, and the problems they had with overheating V12s after shut down, especially when racing and come into pits for some adjustments or tire changing, rules say,for safety , engine must be shut off!

it was a major flaw in block/head design for cooling, they did fix it , but a lot of redesign of engine and system!

back then seems no one thought about an electric cooling pump, especially after engine shutdown!

also could have helped Grp44 race teams, and even Jaguar Grp C cars, most races that they lost was because of overheat!

 

I think the biggest problem with the cooling system is the lack of air flow thru the rad. Punch in a dozen louvers in the hood.

 

Punch a big hole in the front bumper too. In my experience you are 100% correct, it is all about clean airflow through the rad. Interestingly, my car ran cooler when it had the original old fashioned, bypass flow system, oil cooler (basically just a tube with wires welded on to give bigger surface area). This left large gaps above and below it for clean air to hit the rad directly.


When I had to change this for the OEM replacement, the new oil cooler was a typical "radiator" looking type, which was taller then the original and entirely filled the gap between the condenser at the top and the cross member at the bottom. This had a noticeable effect and led me to search for more and better airflow, which I achieved by slotting the front bumper.
Greg

 

I suppose Grant Francis has put more miles over the road
with a V-12 in the hottest climate than most.

It would be interesting to hear his viewpoint.

 

Just got the email from Greg in France.

Been otherwise occupied, hanging outdoor Christmas lights, YES DEAR.

I have looked at e/pumps many times over the years, and never went any further.

Not to say they dont/wont work, just the HUGE amount of work to install one on the V12. Then came the temp controllers, which in those days were flaky at best, NOT for me.

My HE had issues in the early days, NOT overheatng, just not as stable as I liked it. The PreHE was/is SWEET.

I fitted e/fans. Ford Twin Thermo Pack from a 1998 Aussie Falcon. My factory fan exploded at very high speed when the hub locked up, and the bonnet got vented seriously.

There are many, many issues with the V12 cooling system that is pure and simply the fault of the owner/mechanic/carer, and I make NO apologies to any people I may upset by that statement. OK, the factory could have done better, MAYBE, but we are talking 1982 for the HE, and what was available then, is way different to today, so we must be fair in the bagging of what Jaguar did.

There was NO internet back when I got this car, so I went it alone, and yes I made some stuff ups, but common sense saw me thru.

Our summers are usually 43c+ for weeks on end, so things get tested seriously. When we went "Walk About" for 12 months and drove the coast road of this island we call home, some of the conditions were "unprintable" here. We saw 50c+ temps regularly outside. The V12 stayed cool, and HOT shutdowns never had coolant spewing out, or restarting issues, it just did what a V12 should.

I have written many Word docos on the cooling sytem "fixes" I have done over the years, and they are available for anyone that wants them. PM me with your email address and I will oblige. Too big for attachment mostly, until I work out this PDF thing, HAHA.

 

Cooling the IC engine has been an issue from it's
inception.


I've seen it compartmentalized in to three inter related
components:


1. Coolant flow.
2. Air flow.
3. Oil temperature control.


Grant:


I use a free program that emulates MS "office". Libre!!
I do my ever decreasing word processing with that program.
It's too bar includes "export to PDF". I can convert doc to pdf there.
I do that on occasion for my daughter. Her allegiance to MAC
precludes her from that useful function.


The "real" Office can probably do that as well. I've not had it for decades!!


A master of this stuff? Not even close....


Carl

 

Referring again to older Corvettes, both SB and BB, I've never seen one genuine case of overheating/hot restart problems traced to coolant flow issues. By design, the stock OEM pump circulates the coolant 35% faster than minimum required rate under worst case conditions. Causing it to circulate faster will improve nothing. Overheating issues are almost always traced to airflow inadequacies or poor heat transfer. Not coolant circulation rate.

Hot starting problems, when speaking of low cranking speed, can be a battery, wiring or starter motor that are not up to snuff when a hot engine is brought into the mix. Hot coolant is not a direct factor. Adding fans and pumps too cool things off faster after shutdown might appear to work, but work against the owner by draining the battery.

 

One of the things I'm curious about is the XJS V12 experience versus Series III sedan V12 experience, with respect to cooling. The Series III seems to have a larger, more direct airflow path to the radiator via the larger, higher grille opening.

When I get my Series III V12 assembled and running I'll let everyone know. My impression is that Series III V12s just don't have as many cooling issues....but it's hard to say because there are nowhere near as many owners to hear from

Cheers
DD

 

That's been my experience, basically.....a stack-up of degraded parts. Starter motor weak, battery cable and/or connection at the starter, grounds, etc

A few times over the years I've come across engine that were rebuilt with incorrect piston clearances that ultimately result in very slow cranking when hot....but that's stretching the conversation a bit



Right. My experience is that exhaust heat that cooks the starters, thus the shields used on so many cars (before someone throws them out...and then wishes they hadn't....$2500 for a genuine 426 Hemi starter shield!)

Cheers
DD