Hello friends, please help! My 2008 XJ8 overheated today and my mechanic says he thinks I may have ruined the engine; at only 40K miles.

Background first: the low coolant light has been coming on for a few months; I usually top off the expansion tank and then everything is okay for a few weeks, then repeat.

Today I am driving in about 85 degree outside temp, with A/C on. low coolant light is on. A/C goes hot, check the temp gauge, I am in the red. Turn off the A/C and exit to feeder road, heat gauge goes to center (appears normal), but I can tell the car is hot because I smell coolant. I limp the car along at low speed to the first mechanic. pop hood. The plastic piece on the hose coming off the expansion tank is broken. Car won't start. Makes a funny noise when turning over. Mechanic says it looks real bad, but can't look at it until monday morning. It's going to be a long weekend. Any thoughts would really be appreciated. And I know I should not have neglected the light, so please go easy. Also, I was thinking the gauge may have been sending me a false signal if the fluid level had dropped below the sensor? If so, could running in the red for 10 minutes at low speed fry the motor? I am praying for a second chance.

 

Maaaaaaate, you are NEW, and SAD, BUGGA.

I have just cracked a JD, and will have a serious snort for you and the car.

These alloy engines "can" be forgiving, but I reckon from what I have read many, many times in your post, you have used up most of the "Cats" 9 lives.

Hindsight is awesome, and we all have it.

The temp in the Red for that long, and in 85 heat, will certainly have done some serious damage.

Sad part to add, so has the transmission, as the cooler for it is in the radiator, and so is the power steer cooler. Both those items will more than likely be just fine with some nice fresh fluid.

I "luv" plastic on cooling systems, NOT, and I really do question this at times, but being an S Type and X300 owner I have plastic all over the place also.

I also suggest reposting this in the X350 section, someone there with waaaaay more specific knowledge on that model will offer some suggestions.

One of the Moderators may see this and move it for you.

 

I was once guilty of ignoring a similar issue on my Toyota 4runner where the temp gauge would creep up off and on. The day it went even near the borderline of the red zone, I pulled off and shut it down immediately. You have to pull over the very instant a gauge goes red, whether you think it's false or not.

Sorry this has happened.

 

Any engine with aluminum heads should have the heads torqued back to spec just after any over heat. They tend to warp after that. It may be that the head(s) did warp and you got coolant into a cylinder. Pull the spark plugs and see if any gets pumped out while cranking. This is best done a little at a time with somebody ready to soak up any coolant that comes out. Best of luck!

 

Only time and diags will tell

First step is to get the codes using the sdd
Next step will be to pull all the plugs and check the cylinders with an inspection camera
If there is no water in the bores the next step will be to turn it over (by hand)
Next is to check the compression which will let yo know if there is any head damage
If the compression is off it may just be a re-torque of the heads but if this fails the hads need to come off and the expense starts
Next repair the coolant system and replace the trans and engine oils
Both oils need to be collected and checked for water

If all seems ok you can then start it and check the trans is ok

Hope it goes well

Cheers
34by151