My friendly garage put on a good used head for me in my endless exhaust stud leak thing thats gone on since the dawn of the century. I'm learning as I go, could have changed the head but too scared of damaging the pushrod tubes.

I still get exhaust gases in the car through the heater. Its likely that its still my shonky repairs, although its quiet. Just wondering, before i fanny about even more with the exhaust mating, if it could be the head blowing a bit.

SO the question is, is there an easy way to tell? The car starts on the button and runs like a champ, its powerful for a 2cv, pulls really well. I was thinking these two factors might be slightly affected if one of the heads had a little blow? Thinking if so, it might need the lapping. (Is that a thing with the heads?)

I have re-torqued up the bolts correctly, after loosening them to aid the exhaust manifold mating.

If it's blowing because of a poor or eroded head joint, the smell is quite sweet through the heater - difficult to explain but once you've smelt it you will know what I mean, rather than exhaust leaks from around the front of the manifold or from joints around the heater exchangers.
If you take the plunge and take the head off, you need to look for blackening and pitting or erosion around the seat of the head where the barrel sits and if so will need remedial work......

Had a leaky head once on a car I bought. When I took off the exhaust right after the exhaust manifold, and looked down on the cylinder/head, it was easy to tell there was black deposits from exhaust fumes, on the barrel's cooling fins towards the head. It was quite loose though, and it did not run properly. After a cleanup and a proper mounting..., it's been running perfectly since.

I did not do any "lapping". Only cleaned it well and mounted according to the manual.

As for you're car, "shonky repairs" sounds like a good place to start.

Hi Ian,
Where do you have your breather pipe running?
Back into the inlet or a breather pipe?

My currently is attached to a long hose and sticks through a hole in the chassis just behind the gearbox. Before i secured it properly it would site on the vottom of the chassis in the recess below the steerinf rack, it started to smoke in the cabin, making its way through the holes in the chassis. I was convinced it was a leaking head until i had a moment of clarity...

Just a thought.

Thanks guys, thoughts appreciated. Seems its the exhaust mating still then, not a sweet smell. Oh well, back to the problem I will go.
I might take off the fan and see what i can feel in the various potential spots.

Easy way to find blowing joint is to spray a mixture of fairy liquid and water in a plant sprayer around joints and if it bubbles - bingo - there's your problem!

Aha, great idea!