It is now beyond cold here in the rustbelt. I drove my 03 STR to work two days ago. It was -20 degrees C outside. It was an hour and a half trip, during which it drove perfectly as usual. When I went to start it up, it cranked for a second and then nothing, the lights dim but the engine didnt rotate. I swapped the starter in the parking lot thinking that was the issue. Same problem. After pulling all the plugs, I found ice in cylinder #7. It looked like someone had forced snow down in the cylinder. It is still currently stuck and I am going to trailer it home tomorrow do thaw in the garage. Does anyone have any thoughts as to how this could have happened? The ice in the plug smelled remotely of fuel but not excessively, but not of antifreeze.

 

What were you using for coolant?

 

This happens every winter to certain models and certain brands of supercharged cars. I can recall 3-4 instances of it happening to Jags. You win the prize for being the first case this year!

What happens (and it took me 6 months of researching to believe that it's even possible) is while driving, airborne water vapour condenses and becomes ice, primarily in the intercoolers and tubing. After shutdown, residual engine heat melts the ice which then trickles down the intake tract into whatever cylinder happens to have it's intake valve open at the time.

At next start up that water, or ice in your case as it refroze, causes the engine to hydrolock. If you're lucky, warming the engine and cranking it with the plugs out will clear the residual water with no other harm done. If you're unlucky, the connecting rod on the affected cylinder(s) will have been bent.

As to preventative procedures, one method would be to prevent the intercoolers from going below the freezing point. Another would be to allow the engine to run at idle after a long cold drive while the trapped ice melts and flows through the engine to the exhaust.

I don't know of any reliable method of monitoring either. If you ask Jag, you'll probably be told that none of the above is even possible.

 

Plums: I am a super picky car owner, when I bought the car a few years ago I changed all fluids including coolant. It has Dexcool at a little stiffer than 50:50 mix, which was replaced last year.

Mikey: Thank you for the well put together explanation. I will try to google it again, (using "ice" and "engine" only brought up "internal combustion engine"). I couldn't believe it either when I pulled the plug. It just seemed so ridiculous to see what was clearly water. I will from now on make sure to idle it for a while before shutdown.

As for right now I am praying for no bent rod. It was going full force when it hit and stopped, so we will see.

 

Hopefully as it was only being turned on the starter no major damage has been done.

 

I believe Dr. Gross was the first to call it what it was, a frozen engine, somewhere on page 4. https://www.jaguarforums.com/forum/s...d-49183/page5/
Post 147 has a link to a similar instance on an X350:
https://www.jaguarforums.com/forum/x...engine-110573/

Mikey, has John seen the results of your research into the issue? I recall he was a staunch opponent of the iced-engine postulate.

In any event, they are both entertaining reads. Every time it gets cold as a witch's thorax (like this morning) I thank God none of my Jags are supercharged! (as well as every time I purchase tires, or renew brakes)

 

I think I was the biggest skeptic of all when the reports started surfacing.

My failing in understanding the issue was not taking into account that the supercharger is not doing much/any work while the car is cruising at steady state conditions. This means that little heat is being added to the air, yet the intercoolers are still doing their bit. Net effect is that yes, the air and any moisture it may contain can drop below freezing temps leading to ice build up while driving.

 

Wow, what an interesting thread. I'd never have thought such a scenario was possible. Here's hoping no permanent damage happened.

As far as monitoring, could you rig up a remote thermometer with the sensor on the outside of the most trouble prone area? While it couldn't tell you if ice had accumulated on the inside of the induction system, it should at least warn you when the conditions are in the danger zone.

On my old pickup, I was having lots of heat-soak issues at the carb. I made some modifications to help, and added a remote thermometer for monitoring:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I glued the little temp sensor to the outside of the float chamber. Ideally I'd have preferred a direct reading of the fuel inside the float chamber, but an external reading has worked well enough for my purposes. It records minimum and maximum values, so is very handy for monitoring without having to constantly watch the display.

Keep in mind the thermometer display in the link above is fairly big. Other models with sleeker displays are available. You wouldn't have to install it permanently, of course. Maybe set it up temporarily to get an idea what is happening.

 

Well the charge coolers will be circulating coolant at about the temperature of the SC radiator which will be close to ambiant air temperature not lower while the SC is not pushed.

The inlet mixture would be at about the same temperature as that on a NA car.
Am I wrong?

 

The TB is heated by engine coolant but then the SC intercoolers will make the air.... er, what temperature?

If it's very cold outside air it will have very little moisture (er, right?) so this has me overall puzzled. I don't see where the moisture comes from let alone ice.

 

Just to second JavV8 - cold air is dry air. I was out today and it is currently about -30C, trust me, the air is very dry. I have no idea how you would get enough moisture in the intercoolers (or wherever) to form enough ice to melt and lead to a locked cylinder.

What are the actual temps when these engines are freezing? I know that once you get down below about -15C or so, the air gets very dry. After reading all the threads on this issue, and looking at the locations, I would think temps are really closer to -5-10C (I see it was -20C for the OP though), and you can get more humid air at those temps, but still, I just can't imagine where enough water would come from? Did the OP drive along the lake or is near the lakes, maybe the air is a bit more humid due to all the water? I've driven through thick fog, ice fog, blizzards and the like where there would be ample water being sucked into the engine, during both short and long drives, and have never experienced it on either of our cars. I also know that during the deep freeze that is called our winter, the IAT is well below freezing (had a code trip one winter and the freeze frame data showed an IAT of -32C). At a cruise, the air temps must be not much higher in the intercoolers since the blower won't really be working and making heat. I've actually put my hand on the coolers once after about an hour drive with ambient air temps of -35C and the cooler was actually very cold to the touch even though the engine was warm. That will freeze any water for sure. Maybe I do have water in my coolers that freezes but the engine cools down so fast it doesn't melt while sitting and just clears out after a driving. I really think there is some kind of unknown underlying fault leading to this. I just can't figure it out. It must require a very specific set of parameters that I bet we will never fully figure out!

 

WinterJag partial Quote:" I just can't figure it out. It must require a very specific set of parameters that I bet we will never fully figure out!" End Quote

Thats what I am thinking. Is this phenomenon restricted to SC Jaguars or are there examples of NA Jaguars experiencing this?

The charge coolers expose a lot more metal area, and somewhat "remote", above the engine than the intake on NA cars which maybe a factor.

 

I don't recall a post for the NA but I think there are 3 for the SC.

I haven't any idea how much water (minimum) is needed to cause whatever this is.

 

Here's a good reference for the potential volume of water suspended in the air:

Maximum Moisture Carrying Capacity of Air

Three key factors in this phenomena are:

1) the car must be driven for a sufficient amount of time for enough water to pass through the system

2) the duty cycle must be light enough that interior temperature of the intercoolers reaches temperatures below 0*C

3) if 1) and 2) are met the engine must be shutdown and left undisturbed for a long enough period for the ice to melt with the resulting water finding it's way inside an open intake valve.

Change any one of the conditions above and the game is off.

 

Winterjag: I dont believe there are any lakes or bodies of water in the vicinity of my drive; at least non that I am aware of.

I do however find this a plausible theory, aircraft at 10000ft+ altitude where it is -60 F require deicing heaters along the wing. I dont hardly ever push the car hard enough for the supercharger to produce boost, much less along a cold icy road. I just found it incredible that the engine locked itself after shutdown. Further more the ball of ice on the end of a spark plug was an obvious red flag. Unfortunately I filled the cylinder with rubbing alcohol trying to free the engine up and drive it home, so I think most of the evidence is gone. However I will boroscope each cylinder tomorrow before I begin the defrost to check for other collections of ice.

 

Is it possible for the coolant in the SC radiator to be below freezing under certain circumstances?

The SC coolant system is constantly flowing as the SC pump is on all the time irrespective of the load on the actual SC. It is also "mostly" separate from the main engine coolant system.

So when the ambient temperature is very low and the air has sufficient moisture content it might be possible for an ice build up in the charge coolers when the SC is not under load and therefore not producing heat?

 

I drove thru Illinois, Wisconsin, Minnesota, North Dakota, Montana and Alberta last week in my 2016 Subaru Outback. The temperature fell to -20C and below after Minneapolis. After driving in such low temperatures and dry air I was surprised to find water in the bottom of the air filter box. Of course the source was all the blowing snow I drove through.

 

I've done exactly that more times than I can count over the years and never had the problem. It all sounds plausible, but there must be some other factors otherwise both our STR and SV8 would be blocks of ice! Unless like I mentioned before, it is just so cold here that the residual engine heat isn't enough to melt any ice. Then when I start it up to take off the next time, it slowly melts and works its way through the system without issue. And your air/moisture chart you linked only goes to -25C, that's a lovely winters day here!

This I believe and have experienced. I've done the long winter drives across the prairies during brutal cold and nasty winds whipping up snow. It's amazing how snow will work its way into everywhere you can imagine isn't it! I would think in this situation that enough moisture would work it's way into the coolers and freeze, but after those long, lazy, cruise on for 5 hours, drives, I have shut it down and let it sit all night until the next day and no issues like this.

Based on all the ideas on the why of this problem, which all make sense, I have been in the exact situations before MANY times, never had a frozen engine. I still stand with the idea there is some other variable that needs to be met, what it is, who knows!

 

With a SC car that has a coolant system in good shape there may be enough contact between the charge cooler coolant system and the main engine coolant system to keep the charge cooler cooling fins above freezing.

If the narrow connecting pipe between the two systems was clogged with gel that would not be the case.

It would be interesting to check temperatures across these systems of the car in question after a cold day drive.

 

Any mods at all on the car? K&N? Cats? Exhaust? Anything?

Anything known not to be working?

Any codes at all in recent(ish) times?

Any other ideas?

It's clear this is extremely rare so I'm hoping to find something, however unlikely/weird, that may help in figuring this out.

Much as I am unconvinced by Mikey's scenarion it so far looks the only remotely plausible one, but I agree with others it's not enough or we'd have rather more of these happenings. (It also provides for why the NA engine seems not to suffer - not that there are many 4.2 NAs, but there are plenty of 4.0 NAs. Ohh... I don't recall a 4.0 AJ V8 SC with this... why not?)