Greetings!

Sorry in advance for the long post, but want to give enough detail.

Just a little background first. Purchased my 2000 XKR knowing it was in need of an engine rebuild. It had spun rod bearings, so replaced the damaged crank and a couple of rods, a piston, all bearings of course, gaskets, etc. With updated tensioners, new chains, new water and oil pumps, things looked good when everything went together nicely and the engine fired immediately once the fuel pumps were also replaced. (dang ethanol!)

One upgrade I put in was a set of Total Seal rings with a gapless top ring. More on this later.

After some challenges with several coil packs going bad, the car was running great...until smoke started coming out of the drivers side exhaust. OK, it was apparent something was wrong, so the testing began. Since the smoke was light colored, the prime suspect were head gaskets.

1. Conducted leak down tests. First round showed driver side with only 2-3% loss, passenger side two cylinders with 7-8% two with about 3%. Ran a second test with some light lubricant into the low cylinders, and they came up to 2-3% like the other two.

2. It appeared pressure was building up inside the cooling system, but a combustion gas test came up NEGATIVE. No color change to the fluid in the tester.

3. On the day I did the combustion gas test, with the engine nice and warm, I ran another leak down test. As before the front two cylinders on the passenger bank came up with 15% loss, and it was clear that the pressure was going right into the crankcase. Did not oil them again to see if they would come up.

OK, so clearly there is something amiss with those two cylinders, but since no combustion gas is getting into the coolant at the reservoir, it does not immediately appear to be the head gaskets.

Back to the rings. During the build, the Nikasil looked great, an appropriate Flexhone was used to lightly prep the walls, and all rings were carefully gapped to Total Seal specs. The pistons received an anti-friction coating and piston to wall gap was nicely in spec. On initial startup after the rebuild, there was no evidence of smoke right away or after warm up. It seemed like everything bedded in properly and the car ran well.

No significant oil loss, and no smoke until a couple hundred miles were on the car and after the coil issues emerged and were dealt with. The break-in oil was also changed and synthetic went in.

Also, the smoke seemed to occur only after the car was warm, had idled for some time, and the throttle blipped, or pulling away from a stop. At one point, I actually thought there may have been a cracked head opening up after it got hot.

Sorry again for all the details, but I wanted to share the whole picture.

If anyone has an idea about what may have caused this issue or suggestion for solutions (hopefully short of pulling and disassembly) it would be appreciated.

Thanks in advance.

TC

 

My first guess would be that you damaged the nikasil by honing. I don't think it's very thick.

 

+1, my 1st reaction as well, did a search on how thin it was and saw this link that could be of interest:
http://www.engineprofessional.com/TB/EPQ408_18-22.pdf

 

Thanks for the replies so far.

Prior to using the Flexhone, I researched the impact it may have on the cylinders. It did not look like a problem, since there was so little material taken by the Flexhone in the process.

Nevertheless, I am going to use a bore scope to peek at the bad cylinders to see if there is evidence of damage. Also found a nearby company that can re-plate the bores.

Any other thoughts or stories from people who have experienced this kind of issue are appreciated.

TC

 

white smoke on one bank or 2, the post is none specific? mine does it on both if i do short journeys and then give it some welly. Put it down to water pooling in the exhaust just before the loop over the rear sub-frame. Long journeys cause it to evaporate, short ones and it collects utill the exhaust velocity throws it out the back and you get a white cloud. More pronounced on a cold day, almost imperceptible on a warm one unless its night time and you can just detect it in the headlights of the boy racer I've just embarrassed in-front of his girlfriend

 

Smoke started from the drivers side first, and typically only after sitting at idle after driving a while. If it were only moisture buildup I wouldn't be overly concerned, but with the high leak down from two cylinders, I am more concerned.

There also seems to be excessive pressure buildup in the cooling system, which led me to think head gasket issues. Just before starting this testing journey, the front radiator hose that has the T in it, (can't think of its official name), actually pushed apart at the T and dumped my coolant. Fortunately, I was going slowly and pulled into a parking lot right away. Hose slipped back on and with some additional coolant, got me home.

Still exploring before I pull the engine.

TC

 

White smoke does suggest coolant, but you should be able to smell the antifreeze in the exhaust. Oil smoke has a blue cast.