Maybe someone could shed some light on this issue. I have a series 3 with the 350 conversion. Temp Gauge does not act normal. When I first start the car it warms up normally to about 94 cel. If I turn the car off and then back on the car runs to 115-120 C thens returns back to 94 C. The car is running fine but is scaring the bejebees (NOT SPELLED RIGHT) out of me. I replaced the thrermostat and engine does not appear hot I can even touch the heads. Is this sound like a gauge or am I really in danger of blowing this motor . Thanks.

 

How much time elapses between turning off and then turning back on? If this occurs immediately it IS a bit odd.

However, if you restart the car a few minutes later then it's probably just "heat soak", which is perfectly normal.

When you turn the engine off there is still a lot of heat that needs to go somewhere. So...the coolant abosrbs the heat, as you'd expect, but since there is no circulation from the water pump and no cooling from the radiator and fan, the coolant tmep increases dramtically.

When you restart the engine the cooling process begins and the temp drops.

Cheers
DD

 

seems about right, when you turn the car off the fans/coolant sit there not doing much, the latent heat in the engine heats the coolant up, which then cools down...
do your fans run after you turn off the engine? maybe set them up on a thermostat so they keep running after the ignition is off to a set temp...
could also do the same thing with an electric water pump (read: expensive route).

Also maybe increase the fan cooling when the car is running so the engine runs a bit cooler... install louvers in the bonnet.. run a Co2 cooling system... there's a lot of options..

 

You did put in a bigger radiator/fan cooling system with the 350 aye? not just running the stock XJ6 gear?

 

Thanks for the feedback but today I drove the car cold and my stat went to 120 Cel and then backed to 90 in a matter of three to four minutes. I went to a shop and they checked upper hose lower hose and radiator and the shop said the car was running cold. I am completely baffled. I changed thermostat to 180 and even drilled a hole in it in case air needed to escape. I don't think an engine like a 350 would get to 255-260 without boiling heating up etc. Is it a gauge problem should I worry. The shop ran the car 20 minutes and it kept getting cooler it was actually below 90 at one point.

 

More then half of my jaguars have been converted to 305/350/327 engines. What I noticed about allot of conversions is they forget to add a 10ohm capaciter to their wire harness .. What kit did you use for the conversion?

 

I never put the conversion in it was done when I bought it. I wish I knew i tried to find out. Will that cause a misreading in my temp gauge.

 

Okies can u send me a picture of the motor mount. And a picture of the wire harness. I suspect that its missing the 10ohm resister.