I have a troublesome 2K XKR. 80K miles. The beast was in the garagelast week for an alternator swap and codes for misfire. I changed the plugs... old ones look fine, not too dirty. I noticed a puff of white smoke from the Left tailpipe at start-up after changing spark plugs which I dismissed as residue from the misfire. The car runs ruff @ startup until you blip the throttle... then all smooth. Then started to lose coolant. Today, LOTS of white, sweet smelling smoke from the left tailpipe. If 2+2=4, Head Gasket failure! Anyone got any other ideas I should check before I tear into it?

 

No pal... that is not a good sign..it's a head gasket alright...

 

Well... never done one on a Supercharged V8, so guess I get to see what the inside looks like. I have only put 2500 miles on the car since November... it is always broken! Time to buy the service manual now too.

 

It's available as a download. See the various links in one FAQ or another.

 

good time to check and/or replace all those brittle vacuum lines and put new o-rings in the Norma connectors, that's classic rough symptom at startup...pending no help from a misfiring cylinder. Also, the misfire may not be only a bad plug, water/fluid could be getting into the plug well, and I had a coil just up and decide to not work on me this morning...came home last night from work running great, this morning...it refused to do any coil duties. I pulled it, no cracks, no damage...just a failed electronic part due to time and heat I suppose.

I wonder how the head gasket could have failed...did you overheat the engine anytime?

 

not necessarily the head gasket.
as you have a Supercharged, it may well be the supercharger or intercooler.

First check all the sparkplugs again and see if one of them turned a different color (more white ish)
if only one of them is different, then yes it is a head gasket, and you immidiately know which bank it is.

 

How unusual would it be for a blown head gasket if the car has never overheated?

T in Dallas

 

I don't like to take things apart without knowing the diagnosis. I suggest doing a compression test to see if the headgasket is open. It sounds like it is but the test will at least help identify which head to pull.

 

Thanks guys for the advice and support... this is the best forum by far. I'm negeotiating a bit of a rough patch with the cars 'in the fleet' and have not had any time to do any testing. I parked the car, but moved it 2 days later... no smoke. It still ran rough, though. I do not know the car history back past 78K; I bought it off EBay last November. I have not gotten it hot, but one of the first failures was a coolant connector [o-ring / snap-type] that came loose and dribbled, but it snapped back into place]. The possibilities for previous abuse are endless...

Have not checked for coolant in the oil yet...

The smoke came out of the left tailpipe both times I saw it. Once just a little, once it was like a mosquito fogger! I don't know if a supercharger problem wouldn't show up on both sides or not, but a compression / cylinder leakdown test is in order. I have been so focused on trying to keep this thing on the road that I have not read up on the 'other stuff' to do... vac lines, hoses; sure. And there's squawk about chain tensioners, thermostat housings, etc. and other 'known problems' I need to research before I tear it down. If I'm gonna bust knuckles and practice cursing, I'm gonna do everything I can at once. I intended this to be my new daily driver... silly me!

It is over 100F here in North Texas every day [thats 38C to those in the metric locales] and has been, or been close, every day for 6 weeks, so repair time is limited to the mornings; not conducive to starting a major repair. Not to mention I am more than a little pi55ed at it right now. It has not gone more that 15 days between failures since I got it; not what I expected from a world class marque.

still working on getting my signature here... BC2K

 

Welcome to the forum!

You sound like a knowledgeable contributor!

You should have full authority by this time. The 10 post roadblock is to keep hackers out.

 

Update; No coolant in the oil; lotsa white sweet smoke on startup; 85% from left tailpipe and 15% from right. Is there a crossover pipe? ... or does Jochem00 take the troubleshooting lead. Couldn't find the compression tester, dangit, I think my brother has it.

BC2K

 

Well, you seem to have the right mindset, BlackCat. Though there is not a thing wrong with the idea of an XKR as daily car. You are also quite right about the possibility of prior abuse/lack of maintenance haunting you now.

My guess is you are right about the headgasket failure, but there are some things you can do to help solidify the diagnosis.
The first thing I would do is rule out the supercharger itself. It's just a blower to boost atmospheric pressure and more forcefully charge the cylinder. No coolant there. The intercoolers are a possibility, but not a very great one.

I would start by getting a simple tool called a 'combustion leak detector'. [I have one from Cal-Van Tools, #560, but there are others] It uses a chemical to test the airspace in the cooling system for combustion gases. To use it, you draw some coolant out of the header tank to make some room, put some chemical detection fluid in the tool and press it to the tank. With the engine running a small bulb is squeezed and continually draws air from the cooling system through the fluid. Within a short time, the fluid turns from blue to yellow if combustion gases are present. The only way for that to happen is a blown headgasket. At that point you know for sure, so the rest is mute. Then during the repair the other items like the intercoolers can be inspected. If no combustion gases are detected, then I'd start pressuring the cooling system and looking for pressure loss. The intercoolers can each clamped off individually to isolate them if leakage is noted.

In my opinion, if I'm doing a headgasket on a V8, I don't do one, I do both. Plus, I always send aluminum heads to a machine shop to be checked for cracks etc.

BTW, you have quite a friend in Tom, he seems to pretty well have your back!

Hope that helps!

 

you can also, drop a few drops of oil into the plug holes, and put the plugs back in, and see if the smoke re-emerges, that will let you know if you have damage on the cylcinder walls, or worn out rings.

If its a head gasket you can expect to find coolant in the oil or oil in the coolant.

 

I'm going to have to differ with that. It is very easy, in fact more common to have a combustion PRESSURE leak to the cooling system, and not have any involvement with the oil or crankcase. But oil and coolant mixing does happen sometimes.

Just my experience..........

 

The first muffler behind the cats is a shared muffler between the two banks. So, it will act like a crossover.

The combustion gas tester is highly recommended. Even the one from Snap-On is not too expensive. At least not when you want a confirmation.

Of course, you can always look for bubbling in the reservoir.

But, you sound like you know that flows can go three ways with a BHG. Into the coolant, into the combustion chamber, or into the oil. It does not have to go into all three.

Meanwhile, even during testing, keep the coolant topped off to minimise damage.

++

 

Well guys, its been over a month, still hot [103F] but I can't stand it anymore, so here's the update. I start all my cars every two weeks, the XKR no exception. first time, same as always, white smoke et al. then last time I tried, and its hydro-locked! Shoulda run it with the cooling system de-pressurized, I know, but didn't think of it [getting old sux]. Today, I pulled the 3rd plug back on the left bank, and got lucky, it blew the coolant out and turned over ... but... wouldn't start. doesn't seem to fire at all. so, I put the plug back, reattached the coil, same thing. Now what? I need to put it [uphill] in the garage. Also have an ABS light on, no trac control message. Hmmm 4 weeks, 2 additional failures... I wasn't kidding about the 15 day MTBF. Now I'm out of ideas [and altitude and airspeed]. What to check next guys? also, any comments on a good source for hoses and gaskets would be appreciated.

BC2K

 

Ok, I'm back. Had a beer, walked the dog, and decided to try again... this time it fired off and ran [whew!]. Shut it off after a minute, Rad cap loose. Next start will be when the path to the garage is cleared. I'll keep y'all posted.

BC2K

 

I suggest to never crank it again until you finish the repairs, push it to the garage. Hydrolocking is an instant trip to a bent rod, damaged bearings and a replacement engine. It is now obvious that you have coolant running into the cylinders. I do not know if the intercooler can leak but other than that, it has to be either a headgasket or cracked head. If you still want to do a compression test, pull all the plugs first, crank it then put back one at a time to prevent another hydrolock.

 

I do suggest the first thing to do is pull the intercoolers and get them pressure tested. Won't cost much and you may find a leak there. I have never seen an intercooler inside so I don't know if coolant can get into the air, but there has to be an interface somewhere for the coolant to cool the incoming air.

 

Any word if this was a headgasket failure or the intercooler was leaking? My car is having the exact same symptoms.

I was thinking it could be the chargercoolers leaking internally, but I know that would be rare.

Thank you!
Jim

2000 xkr coupe, 117,000 miles.
Owned the car since August 2009