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Help to validate my theory?

Richard Winters
Ontario Jaguar Owners Association *

forum user since 2011-09-10

 

I own a 1952 Mark VII. Since I purchased the car in 2005 I noticed when purchasing the car that the 3,4 L engine was overheating at idle only. A couple of years ago, whilst living in Europe, I replaced the water pump and installed a high performance XK-120 pump. Before re-coiling the radiator, I inserted a sump pump in a 20 gallon drum and coupled hoses to the cooling system inlet and outlets and rinse the motor to ensure that all the cooling passages would be clear of rust and scale. I got the radiator rebuilt by a quality shop and purchased a new thermostat. Naturally all of the hoses were replaced and the system was checked for proper pressure. Additionally I ran a mixture of 60% glycol and distilled water and added some special cooling fluid. Still overheating at idle.....Last week, I performed extensive work on the car: Overhaul the fuel supply system (dual tanks, lines, new copper fuel lines etc...). The car was converted to negative ground so both SU fuel pumps were replaced. During this time period, I flushed the block again and replaced the original cooling fan by a flex fan designed for and XK 120 model. I hoped this last operation would fix the problem. Throughout these operations the timing was checked and at every flush the thermostat was removed and checked on the kitchen stove. Still overheating at idle. At this point I am concluding that the cause of the problem is the use of "unleaded fuel". I will speculate that lead has properties that favored a cooler running operation for those engines. At this point,I guess I will try a thermostatically actuated electric fan to be mounted in front of the radiator. I hope that this will solve my problem. Did anybody who will read these lines ever face a similar problem with an older XK engine?



RRW

Help to validate my theory?

George Camp
Jaguar Society of South Carolina *

forum user since 2002-11-24

 

Sorry but fuel is not your issue. After reading what you have done i suspect a blown head gasket.

JCRC SE
JCNA VP

Help to validate my theory?

William Brady
Jaguar Owners Club, Inc. *

forum user since 2004-02-15

 

If the car is running good otherwise I would think blocked water passages are the problem, the only way to really find out is by removing the head. Usually the rear passages just get blocked from years of storage, even with the head off it is difficult to clean them out.

Jaguar affectionado and etc.

Help to validate my theory?

Richard Winters
Ontario Jaguar Owners Association *

forum user since 2011-09-10

 

George and William: Thank you for your observations and advice.

If the car had a blown head gasket would there not be traces of the coolant in the oil and a rough idle?This is definitely not the case. The engine runs smoothly even at idle.

I suspect that the procedure suggested by William is the only way to clear the cooling passages?
Is there not a chemical liquid much stronger than radiator flush that could be introduced in the cooling system and that could "penetrate" the cooling passages over time assuming you would leave the engine non operational for several months?

RRW

Help to validate my theory?

Phil Wright
Jaguar Club of Pittsburgh *

forum user since 2002-11-30

 

The water pump could be re-circulating the hot engine water by way of the bypass hose back into the engine instead of the radiator. The radiator could be a bit clogged and the water takes the path of least resistance. The thermostat should regulate this, but not always on an old engine. Clamp off the bypass hose (needle nose vise-clamp) and see what happens. It's a cheap test. If it seems to help, you can "test" it further by inserting a tight fitting plug with a 1/4" hole (in it's center to let some water through) in that hose. Remember this is only a further test to see what happens under driving conditions. 15 years ago I tested an E-type this way. Works fine now, but I think it still needs a few more years testing.

If it's not blowing out water, your temp gauge might be in error and it's not overheating. I use a hand held infra-red thermometer to instantly get temp readings everywhere. About $30 at Geeks.com. I use it everywhere to confirm readings.

I hope the problem isn't more serious.

Phil.


Help to validate my theory?

William Brady
Jaguar Owners Club, Inc. *

forum user since 2004-02-15

 

Richard, usually once they block the residue hardens and even with the block stripped it is still difficult to get out. Even when you use the many types of flushing liquids the loosened parts block up even more places. But, you could try, little to lose.

Jaguar affectionado and etc.

Help to validate my theory?

George Camp
Jaguar Society of South Carolina *

forum user since 2002-11-24

 

A hea gasket or cracked head can send exhaust gas into the coolant with no trace in the oil.

JCRC SE
JCNA VP

Help to validate my theory?

Richard Winters
Ontario Jaguar Owners Association *

forum user since 2011-09-10

 

Gentlemen,

I appreciate the valuable information and I may have to deal, not with a single problem, but with a highly probable combination of problems..... Will revert early in 2012 when I return to Canada.

Again, Many Thanks.


RRW

Help to validate my theory?

Jim Morton
Carolina Jaguar Club *

forum user since 2007-11-21

 

RWW
I too have improved the cooling of XK engines by reducing the recirc water flow as Phillip suggests.

Measure the recirc hose inside diam and buy a copper pipe cap of the type you sweat solder to copper plumbing. Cap od should match hose id, obviously. Drill a 1/4" hole in the cap end and push it into the hose at either end, but preferably a straight run. Cap cannot migrate out of the hose run nor can it flip sideways.

Jim Morton
Carolina Jaguar Club
mortoncjc@mindspring.com
336-324-6532

Help to validate my theory?

Robert William Lovell
Jaguar Club of Southern New England *

forum user since 2008-01-12

 

Greeting Richard,

Before you start looking for some combination of problems.......

Any chance the timing is off? Worth checking and it won't be the first time this had led to overheating.

Unleaded fuels has NEVER been a problem in any of my Jaguar engines.

Good Health to You and Yours, Bob Lovell


Help to validate my theory?

Richard Winters
Ontario Jaguar Owners Association *

forum user since 2011-09-10

 

Greetings Bob,

Thanks for the input, worth double checking.
Will proceed step by step using the process of elimination starting with the most straight forward tasks. As I mentioned before will return home for X-Mas and will revert to all on this blog. I appreciate the help of all the members. BRGS-Richard.

RRW