I have owned a lot of different cars over the years and I can't remember any car that seems to through out as much heat as my 2003 XK8. I recently just replaced Tstat housing, radiator hoses and water pump. I monitored the coolant temp with my scanner and it is well within specs 196f to 201f in normal driving about 10 miles.

Call me crazy but, after a drive the car just seems to be very hot under the hood. No wonder coolant hoses and anything rubber or plastic fails in that environment. I have actually gotten in the habit of opening the hood after a drive to help cool things off (I think it helps).

Everything is working: fans, hoses, coolant level, etc...

Just looking for other opinions on the issue????????

 

it does run hot and with our afternoon temps near the100+ mark lately - I've seen coolant temps hitting 213-215 when I'm at a stop, but drops back down once I start cruising again. My morning commute is in the range of 197-203 - so I know the system is working.

 

I have opened the hood (bonnet) on my cars for many years. It probably helps, and certainly can't hurt.

 

these cars do not run hot. they dissipate heat very well which is what you are feeling. the coolant operating temperatures are often lower than contemporary and more modern regular use vehicles. i have also checked and the same is true for the oil temperature, does not get as hot as quickly. perhaps when this engine is tuned higher when used in other applications this changes due to more waste heat, but overall heat is not an issue. a lot of people are accustomed to being near a four cylinder engine which even when hotter than ours throws off less heat from the engine compartment possibly due to less surface area and better insulation and lower waste heat production. this engine reminds me of years ago when V8's were more common and you could always feel the heat coming off them even when they did not have an overheating tendency or other cooling issue.

BTW this is why oil is more critical for smaller displacement engines that run hotter as they are more prone to thermally break down the oil.

 

After a trip and I am back in the garage I pop the hood and open it. Same in Winter but thats mostly to discourage mice as much as possible.

 

I can only imagine that you may have a phobia about the car overheating, from something you have read or heard. I have had the car since new (06) and have never had it overheat, even when the fan module failed in the summer. I had a 63 E type that almost overheated during a college sports car club parade when it only had about 12,000 miles on it. I had a phobia about overheating for quite awhile. The fan blade on that car was essentially a piece of twisted metal strapping and moved hardly any air. The modern XK is much better designed and its design does include an alloy block, which dissipates heat much more rapidly than iron. Hence the sense that it is running hot.

 

The hotter you can run an engine, the LEANER it can run to some extent. Emission police love that the engine runs lean.
I would guess that the U.S. EPA would rather you overheat and sit on the side of the road. That way your engine is NOT running and you are NOT polluting the planet?????

just a thought.

bob

 

hotter and leaner increase NOx. Some efficiency is given up to keep these low as NOx is worse for the environment than CO2 and CO.

 

Just out of curiosity, what temperature would you expect the oil to run at? I tend to see it ~20 degrees hotter than the coolant (usually ~210-220 degrees F/100-104c)

 

the oil temperatures that i have observed at minimum one hour constant operation are usually 232-256 F with the higher side under situations where one is loading the engine such as when climbing hills. at the higher end one can see the pressure drop below the spec for a particular RPM. on flat highway at any speed maintained relatively constant, the temperature averages 236 regardless of ambient temperature. my four cylinder vehicles are often 5-12 degrees higher under this condition which is why i strongly recommend that if this type of engine specifies 20 weight oil that it be full synthetic. a 30 weight is still within operating range at 245 in conventional product which is why 5w-30 is the preferred oil for our vehicles, conventional or synthetic. i use the allowed 0w-40 since i have a lot of hills that i like to drive and know that the oil is getting hotter. if you are having a track day with the vehicle or some spirited driving, i recommend moving up to the 40 for obvious reasons. it is an amusing experience if i make a stop somewhere for ten minutes or so after driving some hills. upon restart the Real Gauge will chirp that the oil pressure is too low when i am stopped in gear until i drive for a few blocks. there are no blockages in the pickup and the factory sensor does no trigger. it is simply that the oil temperature was much higher than driving by often ten degrees or more due to the heat sink effect. moving the vehicle again thus running the engine and having airflow restarts efficient cooling. years ago in hot climates one might not be able to start the engine again as the oil would have thickened to rubber. this problem was largely over by the late 60's.

have fun out there.

BTW: please add your location and some detail about the car such as mileage, always helpful.

 

When I first got my xk8 I also felt the engine compartment heat was excessive. I pulled the thermostat to check if it was too "hot" or failed. It was a new and correct one.. My engine runs right around 200 so the system is doing its job. My opinion is that Jaguar has sealed the engine compartment heavily to quiet engine noise. So the basic issue is how to get more ventilation into the engine compartment. One option would be to vent the hood just like they have done on the xkr. I found a few threads where this option is discussed. What I was able to do was that I had to replace my original radiator and I left off the "seals" off the new radiator. This allows more air to enter the engine compartment primarily via the now open sides of the radiator. I discussed this issue with Nissens who builds the radiators and they said the seals were not a factor in the workings of the radiator as the required seal is provided by the fan shrouds. While not a complete solution the engine compartment does seem cooler. I think removing the seals has allowed air flow over the exhaust manifolds and helps.

 

Nissens tech people are correct, however those seals might also keep dirt and water from splashing hot iron things like the exhaust manifolds. hood vents are a blessing and a curse. water dripping on things causes oxidation. when i push the car going up hills for sustained periods of time i notice two things always. the oil gets hotter, see previous comment, and the coolant temperature goes down. the pump is working faster at higher RPM and there is more airflow due to movement. we have a very good cooling system. add to this doing these runs on hot humid days with the AC running. these cars do not have a cooling issue. it is just that feeling the heat billowing out of the wheel wells shocks some people. just reminds me of the old American V8's only this one does not overheat and has AC too.

 

Thanks for all the replies guys! I know that everything (cooling) is working on my car. As I said, I had recently replaced the "usual subjects", Tstat housing, water pump and radiator hoses that were due for a change. After completing the repairs and monitoring the system I'm confident all is well. I guess it was just an observation I made and had to question it.

I was out for a 10 mile or so drive recently with top down (as always, at night 80ish degrees) and while stopped at lights I could feel the heat radiating around me. Normal, I wondered? Obviously, yeah, it is but, still I wonder how under hood components hold up in that easy bake oven.

Oldmots, I guess I do have/had a bit of a phobia to the car overheating based on a lot of posts I've read and bad experiences of fellow forum members. I'm over it for now, lol.

Cheers!

Andrew

 

great news, enjoy your car in this nice weather.

one small thing just to demonstrate that heat is your friend within reason. my oil is somewhat old, not excessive. most of my driving lately is 20 to 30 minute runs. oil fully warms according to my meter. the other day i ran a highway trip for a little over an hour both directions. noticed something on the return. when stopped the oil pressure at idle was slightly higher and at all RPM's. the oil pressure is also higher now during my regular driving at fully warmed oil. the answer: sustained heating of the oil vaporizes fuel contamination and it takes a little while. any racers will tel you that cold oil can damage an engine. in my case and for many others vaporizing the fuel contamination is beneficial. if you cannot do this regularly, changing the oil more often is a good idea.

most people have cooling system issues when particular parts age out and begin to show their wear and some their material weaknesses. all of those nice little hoses should be replaced at this age along with the water pump. this is basic 6 yr/60000 mile service for many cars when the timing belt (in our case tensioners) is replaced. some cars do not have hoses that age out such as the Japanese cars where aftermarket replacements are a step down. things fail for a reason. find the reason before it finds you and there is reduced inconvenience.

 

Another thing to reduce the release of heat into the engine compartment is to wrap the exhaust manifolds and catalytic converters. I have seen this done before on other cars with great success. Never tried myself...

 

my friend did this on his XK8 and his other collectible cars and it is the single most effective interior heat reduction strategy. there is significantly less heat coming through the firewall and the engine compartment is noticeably cooler. it is next to impossible to do without removing the cats and removing the manifolds makes it much easier. i am kicking myself for not doing it when i dropped the cats for the transmission removal. it will also make the cats work better.

 

It was 108 this afternoon in bumper to bumper traffic, and it remainded in the 195-197 range the whole time. I'm 'cool' with that.

Now I wish it would stop baking my hood grills....

 

I wonder if the perception of heat off the engine bay is related to whether the car has been out in the hot sun for a long period and effectively heating the surrounding area such that radiating engine heat has less of an opportunity to disperse, instead adding to the heat that's already there making the whole front clip ~200F.

I drive my car virtually every day in the Florida heat. When I start from the garage and make a trip long enough to bring engine to full temp I don't notice it when I return. If I drive it after it has been parked outdoors in the sun for a a few hours then I do notice when I park it in the garage.

You all with "winter" climates, do you notice it in cooler seasons as much as warm seasons? I am betting not.

So it seems more like engine bay heat saturation than excessive engine heat.

 

no matter how cold it is we notice the heat in the winter. perhaps in the cold temps the contrast is more noticeable. i think that in the hotter climates where heat avoidance is a secular religion adding heat to heat is not the most pleasant activity, former Southerner here. funny thing is that i see more cars overheat up here in the winter. strains on cars that are not well designed or maintained such as pushing through snow or running rich bring out the problems. first cold snap and the breakdowns begin.

 

What product did you use?