White smoke when pushing over 5k revs?

[spinnaker]

Hi all,

A bit of an odd one that I noticed this morning for the first time. I have a 2005 C2S manual car which had an engine rebuild 5-6 years ago (block work and nikasil pistons done by Hartech, rest done by a specialist eslewhere). I have had the car about 5 months now and it has done 55k miles. 1500 miles of those are mine.

Not been doing much driving recently as working from home still. I have been doing school runs and pick ups 2-3 times a week but only a few miles each way. I keep the revs under 3k until the oil temp is up to 90 degrees. I haven't done any spirited driving over any real distance for a month or two I reckon.

This morning I took the car down a local A road and noticed clouds of white smoke from the rear when pushing over 5k revs. No lights/messages on the dash reported and it drives totally fine and without smoke at anything up to around 5k revs. No drips of anything on the driveway seen.

I checked on the way back on the same road and it did the same thing.

Any thoughts on things to check? I have done some searches but they mostly talk about white smoke clouds on start up and I don't see that.

Any thoughts?

 

[paul_mck]

out of both pipes you reckon?

AOS maybe?

 

[spinnaker]

I am not sure if it is from both sides to be honest. I have a rear dashcam so will try and get some footage from that to share. If anything I'd say it looked more like it was from the driver's side.

I did see mention of the AOS in other posts I have looked at but all only about starting from cold producing clouds of white smoke. And they usually talk about an odd squealing noise before anything happens.

 

[spinnaker]

Having just been out to check, the coolant level looks to be about 1cm below the min marker but I am not parked on a totally level surface. I can let the car cool and top that up but not sure if that suggests anything.

 

[Captain Lockheed]

before we hit the panic button, what was the weather like?

Can you do a few basic checks with the car static, give it a good rev in neutral - no load. Does the exhaust smell of oil or coolant? what about the tips, black with oil? white/grey? or normal?

 

[martin t]

Re the weather:

This morning was 'taters', so i wounder if you were merely seeing condensation, i.e. a vapour trail and nothing more?

 

[spinnaker]

The weather was indeed cold today. Probably 3-4 degree when I was on the road earlier. I would love for this to be steam but I think it looked too dense for that.

I'll be out in the car in the morning (can't escape to do this tonight) and will get it up to temp and give it some solid revs and report back. There wasn't an oil smell but I'm not quite sure what hot coolant smells like tbh! The same as cold coolant?

I have just topped the coolant up by 1.5l back to above the min level when cold and will see what the level looks like after a short drive tomorrow.

 

[Porkaholic]

Sounds reminiscent of my experience a few months ago after some recently replaced coolant pipes suffered from a failed clip as high revs circa 5,000 were exceeded. Looked like a load of white smoke exiting the rear, engine temp shot up and dash board lit up like a Christmas tree. Catastrophic loss of coolant but that was all, no engine damage as I shut the engine off immediately. The car had been fine until I opened up the taps and thar she blew!

So could be a bit of that going on with yours as something to eliminate possibly. The high revs putting higher pressure on the circulating cooling system and spraying out over hot components?

 

[spinnaker]

Thanks Porkaholic. Actually I think this sounds very likely to be the case. Your description sounds similar, albeit I didn't see any increase in engine temp or lights. It would fit with the need for me to top the coolant back up again. I guess I now need to look at where a leak might be.

Anyone have any suggestions of the key places around the engine where I should be looking? I guess the risk is that if the car is up to temp the coolant will burn/evaporate away before I can spot it.

 

[spinnaker]

So it does feel like this is a case of coolant spraying from somewhere when under load and then spritzing the engine and making smoke. There is a smell that I haven't noticed before. Weirdly it smells a bit herby... smells like curry plant if you have ever smelt that before. :dont know: I wonder if the smell is residual from yesterday?

I did the school run this morning without issues. Since getting back I have looked in the engine bay and despite the weather it is quite dry in there. I can't see any drips or seepage. I'll let the car cool down and then give it some revs to try and see where any drips might be coming from.

Does anyone have any good photos of where to be looking in the engine bay? There are so many pipes in there. I presume the coolant pipes will be the wider rubber ones?

 

[spinnaker]

Hi all, bit of an update on this one.

I topped the coolant to the max and have seen a small drip of rusty coloured water/coolant (i.e. not greasy oil) from the location in the image (sorry, not a great photo). When the car is cold a single drip just hangs there. I can't see where the drip is coming from. It is a wide rubber tube on the driver side.

I do wonder if this leak gets more severe when under load and sprays more fluid out and onto the hot engine which then creates smoke/steam. Does coolant smoke when burning off?

I'm sort of not sure what to do next. I reckon leaking coolant is the issue here. Should I go and have another hot run and then recheck the coolant level? Should I get a local indie to find the issue? Are there more checks I can be doing?

 

[TonyC911]

Are you able to have someone follow you on a run, to confirm if the smoke is coming from the exhaust or the engine bay?

If it is a coolant leak under load, then you will need to get it up on a post lift, when up to temperature, would be my suggestion.

 

[spinnaker]

Thanks Tony. That is a good idea.

So I have booked in with a local indie after speaking to them about this. I haven't needed an indie before now but was impressed with the knowledge on this. They didn't think it would be coolant and that it could well be the AOS.

I have driven the car gently for a few days on short trips. It feels exactly as it always has when driving and still no lights, noises or warnings. It doesn't do it at lower revs and seems to do it only when up to temp.

I'm going to wipe down the exhaust and check fuel levels again later. I also got a cheapy OBD2 code reader which I'll plug in to check for any codes.

Would be good to know if it is coming from the engine bay or exhausts so might well get the missus to follow close behind tomorrow to find out.

Thanks for the advice so far. Really appreciated. I don't like Gretchen being unwell.

 

[Pip1968]

Surely it has to be a coolant pipe or such like or your coolant level woud not have been below the minimum level. Once the car is warmed up the cooling system all has to be under more pressure. The higher revs may be shaking the poor connection or split more hence the more loss of coolant and a more visable result for you.

Just guessing here as I am merely a tinkerer.

Best of luck.

Pip

 

[TonyC911]

Thanks Tony. That is a good idea.

So I have booked in with a local indie after speaking to them about this. I haven't needed an indie before now but was impressed with the knowledge on this. They didn't think it would be coolant and that it could well be the AOS.

Would be good to know if it is coming from the engine bay or exhausts so might well get the missus to follow close behind tomorrow to find out.

Thanks for the advice so far. Really appreciated. I don't like Gretchen being unwell.

The AOS beginning to fail is actually a fair shout, it also takes a feed from the coolant on the 996, which I think is the same design on the 997 :dont know:

https://youtu.be/Bd73YLmT-vE

Skip to 3.40 for a basic explanation on the AOS on the 996 in this video. Careful not to go down the rabbit hole of watching this whole series of 50+ episodes... like I did! :grin:

Hope you get Gretchen sorted!