My beloved XKR is my daily driver. I had been losing coolant when the car sat during the day after my ride into work. I kept it topped up before my return trip home, but I didn't make it last Thursday. I got the red "Engine Overheating" warning, plugged my OBC in and found that it was first at 120 degrees Celsius, dropped to 80 for a short bit, then up to 150. There were a total of 16 codes including oxygen sensors and fuel rail errors. I continued driving another 10 miles towards my service garage, but the car gradually lost power and then coasted to a dead halt. I waited about an hour, put in a gallon of water, the engine started roughly but with billowing white smoke and a coolant leak that seemed to come more from towards the rear of the engine. My service technician thinks the engine is shot (he isn't a Jag specialist, but an excellent and experienced mechanic). He found it was 2 quarts down on oil (last checked and topped up 4 weeks) ago and it looked as though oil was being pumped into the exhaust (white). I went by today, it started up, had initial white smoke but lessened as it ran. The current codes are only for one oxygen sensor (1 of 2 read zero), 3 cylinders misfiring and a fuel rail error. It is also displaying "Restricted Performance", but the engine seems to rev okay. I'm prepared to accept the worst and consider a full engine replacement, but I would really appreciate any thoughts or suggestions before I pursue that option. What could have been damaged with the overheating that would still allow the engine to start and run? I have zero confidence in the local Jaguar dealer from past experience with my XK8. Thanks in advance!

 

Oh boy... You sure picked a fine time to join us.

4.2's are pretty indestructible engines but you may have done it. The real question is chicken or egg, what happened first? Second is what's actually wrong and third what are you going to do about it?

First of all oil in exhaust make a blue cloud. Water / coolant is white. Either way you should be able to smell either oil or maybe coolant from inside the tail pipes after it's shut down. Coolant will contaminate o2's and kill them.

Personal thoughts being first find out the extent of the damage. That means a leak down test of the long block and pressure test the cooling system. You're spark plugs will give a good analysis of how that bore looks. If it passes those tests don't be afraid to fix the underlying coolant leak and move forward.

I assume from experience reading these forums that you had a slow leak somewhere and since these engine run on a very low volume of coolant you ran it low enough the coolant steamed off which made it flash a much higher temp. The higher temp caused the heads to lift which got your coolant to the combustion chambers as well as consume a lot more oil than normal. Greatest caveat is don't run these engine over temperature. If the cooling fan runs at full speed it's overheating.

All is not lost. Have your guy assess the engine and report back. XKR, XJR and S type R's all use the same engine so spares are out there.

 

Thanks for your quick response! A probably dumb question... Is it likely that the supercharger may have been damaged during this ordeal/episode? If it gets to the point of replacement vs. repair, many of the candidate engines come without the supercharger as well as the usual bits (alternator, etc.) The car will be going to a Jag specialist tomorrow. I'll let everyone know how it goes.

 

SC should be OK.

 

N/A engine use higher compression versus the //R stuff.

 

I assume your mechanic knows that you must get a replacement supercharged engine and not a NA used engine.

 

The shop will do an engine diagnostic on Friday to see what damage has been done and what options can be considered. They're capable of rebuilding or replacing. I didn't know what else I was going to use my retirement savings for. Good thing this came along to clear that right up. I've been enjoying Ranchero's great continuing saga on The Green Turtle and really appreciate the effort that has gone into sharing the tale on this forum.

 

The sad thing is if you end up far enough into it to do head gaskets the engine is coming out the bottom and it's almost more economical to swap the whole assy versus rebuilt it in place while the car is hanging on a lift.

 

I heard back from another shop that had done a nice job on replacing the transmission on my 98 XK8 some time back. They estimate $9000 parts and labor to replace the engine. Guess I know what ballpark I'm playing in... I did get a quote of $3,995 for a motor out of Oklahoma. A bit more detective work shows the company is sketchy with multiple complaints from customers. I'm hoping to hear from the shop on Friday. Stay tuned... thanks again for your comments - food for thought!

 

I would invest in diagnostic time. Figure up a plan with your mechanic and make them document what they find so you can make a cognizant decision.

 

While this is not the same engine....

In a car that was going to a junk yard but had a running engine I drained coolant and left it running at idle for 30 minutes. I wanted to see if it would cease and how it would look internally after that. Visually, the engine overheated quite badly. It was also knocking when I shut it off. Then I took the engine out and performed full tear down. While that was much simpler 4 cylinder naturally aspirated engine, I was surprised how little actual internal damage was done. Oil was cooked, but all bearings and rings were fine. Block was fine. I would estimated that a new head gasket and machined head and that engine could be made a runner again. Cast iron block and aluminum head. VW 4cyl 2.0L NA engine. I know cast block and aluminum head are prone to warping in overheating scenarios, but in this case it didn't as far as I could tell with a feeler gauge.

 

+1 what Ranch said. It is always good to have contingencies worked out but the best approach is to first diagnose as completely as possible. Like SinF implies, it could be quite repairable but you won't know until you and the mechanic finish full diagnostic analysis.

Keep us informed though, this is good info for other members at the very least.

 

Uh, you cooked all the springs and rings, they all lost their tensile properties. The valve springs would probably be compressible with one's fingers, and the rings flop about uselessly after getting roasted that bad. The bearings, while they may LOOK good, lost all metallurgic properties and will now wear improperly.

 

I'm probably naively hopeful that it may be minimally damaged and need only a new head gasket. I'm also ready to hear a full top end rebuild is needed - or replace the whole thing. At this point it's just guessing and wishing. This has been the best machine I have ever owned and I'll do what I need to do. One of the silver linings is that my dormant 98 XK8 is now back up and running. I knew I couldn't let go for a reason. We could have a "guess the final cost" contest... )

 

Cost is hard to say without any data on what they find. Hoping their data is inconclusive beyond finding a leaking hose or water pump. You never went into where the coolant was going that you were losing the past couple weeks.

 

I don't know where the coolant had been leaking from or if it was an overflow issue. There has been an intermittent but persistent alert that the coolant hadn't reached the expected temperature. I was about to replace the thermostat housing and thermostat, hoping to correct that and to use it as an opportunity to see where the leak or loss was coming from. I was guessing (probably wrongly) that the thermostat was the primary culprit and that the coolant loss might have been from it not operating properly and causing overflow after turning the engine off. There was no sign of overflow by the coolant reservoir or at the radiator. It looked to be coming from mid engine. The hoses and connections all looked good from what I could see, but I haven't been underneath.

 

There is no overflow. Failure to reach temp is either the coolant was too low or the molded rubber seal on the T stat tore like mine did in my rebuild thread. The //R's have an aluminum housing that's a much better design versus the poor plastic base version. When you filled the coolant did you remove the 17mm Allen plug on top of the blower coolant passages to let it burp out or rely on the degas bottle to burp air out and just lower the level? Sounds like you had a couple issues you didn't want to delve into and it snow balled into this mess.

Auto maintenance is similar to surfing a wave. When you are doing it right you enjoy the ride but if you fall behind it will smother you in misery.

 

I am going to make a prediction.
The car will not require extensive work.

Seen one driven even longer on similar situation and the repair was minimal.

 

So, Friday is just about over, what was the verdict?

 

Since I'm bored, I will share my Overheat story;
I backed my Pro Street 75 Mustang (557cid / 9.2liter) out of the garage to bring it to a car show. While it idled for about eight minutes I cleaned up some junk out of the yard.... and then I went to leave. Well, I first noticed that the electric fan wasn't running so I quickly checked the temp gauge... Three Hundred and twenty! Holy Ballz! I shut down the ignition, opened the hood and gave the fan thermostat a whack and it started right up. DAMMIT! There was no coolant pouring out nor busted lines as I have Evans Waterless in it. I popped the cap off and it was right where it should be.
Anyway, I let it sit for about five minutes then started it up to circulate the coolant, and the temp dropped to about 270 or so right away so Shut 'er Down again and more sit time. Two more waits-and-circulates and it was down to 200f or so then I pulled it back into the garage and let it sit until another day.
Another day; I immediately drained the oil figuring it was at least scorched and refilled the 7 quarts. Hoped and prayed and started the engine......... Blue Smoke Everywhere.
BALLZ AGAIN!
The way I figure, it got hot enough to untemper the rings which caused all the blue smoke, baked the mains at least (probably rods also), untempered the valve springs (THAT'S gonna be expensive alone) and I'm sure baked all the gaskets.
I haven't returned to it yet as I've had a major issue with my back, but I will (hopefully soon) yank the thing out and rebuild it. I expect most of the hard parts will be fine, but those heads were almost new and very pricey.
All because of a failed $15 fan thermostat.
Have I said BALLZ! yet?