Technical 1.1 MPI - white smoke from exhaust after new head gasket

[RampantParanoia]

Hi all,

My mate recently bought an 02 plate Seicento SX with 99k miles on it and the 1.1 MPI engine. The head gasket pretty much went immediately

I'm pretty handy and the engine doesn't look too complicated so I figured I'd help him do the head gasket rather than take it to a garage. When I took the head off most of the coolant ports were largely blocked with corrosion, so I can see why the gasket went! I got the head pressure tested and skimmed, and had some welding done as well as some coolant ports were eroded. I also replaced the water pump while I was in there as it didn't look great.

Once it was all back together I put some speedflush into the coolant system to get all the remaining corrosion out, then drained it and put antifreeze in etc. It seemed to be running fine although idling a little bit low, so I gave the car back to him. Within 20 miles he said that the EM light was flashing and it was intermittently losing power, so I did some googling and came across the phonic wheel learning procedure and had him do that. It didn't seem to work so I had him do it again, then it started blowing white smoke out of the exhaust.

I have no idea what's wrong but all signs lead to the head gasket again, but I can't see how it would have gone again so quickly?! Any ideas (constructive criticism on my workmanship is welcome!) ?

 

[RampantParanoia]

So we took the head back off and the exhaust port for cylinder 4 was coated in oil. We replaced all the valve stem seals and now the engine is running fine with no smoke.

 

[Ralf S.]

The white smoke sounds like a red herring... I'd guess the exhaust was full of water after the original HG failure and as it all evaporated out, it probably masked the oil smoke. It's good when it's not something you did wrong though..


Ralf S.

 

[dante giacosa]

be nice to know a bit more about that- I've never heard of a head gasket going on a 'Cento...

 

[Ralf S.]

I'm guessing that it was run just on plain water, rather than a 50% water/anti-freeze mix, judging by the amount of corrosion the OP says was in the coolant channels.

I'd guess the water corroded along one or more of the head's mating surfaces, and so technically it was a "head" failure rather than a traditional "gasket" failure.

Moral of the tale is "always use (50%) anti-freeze in the coolant" since the most important function of anti-freeze is actually corrosion prevention, rather than preventing freezing.


Ralf S.

 

[RampantParanoia]

I didn't see the smoke myself, the owner of the car described it so I think he saw grey smoke as white.

I don't think the coolant had ever been changed, the channels were hella rusty. The flush took a lot of it out though, and it's running proper antifreeze now.