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[iansoutham]

As per title, I give up.....

Got all the other bits done on my car, new front crank seal, alternator swapped out, timing belt changed,  all engine oil leaks gone, running well, geometry perfectly straight and now it looks like the head gasket is about to blow in number 3 cylinder. Starts on 3 cylinders whilst it clears the bore then runs fine. Seems to be losing water but no external leaks and compression test cold shows good pressure holding. Lots of white smoke/steam out the back (but not filling the sky amount, yes this could just be cold weather).

Pulled the plugs (replaced 3 weeks ago) and number 3 is “rough” whilst the others are all the same. Bores look okay down the plug holes with a torch so suspect early stages.

Changed the head originally in 2015 when it went then and swapped to a known good head as original was badly pitted and removing top left exhaust nut snapped the stud as usual.

So looks like next week I may be ripping it all to pieces again.

[dave the builder]

Do a leak down test on that cylinder with the valves closed and see if you get bubbles in the coolant tank 

[iansoutham]

Have a sniffer so will do that first but also planning the leak down as well and have a cooling system pressure tester so can test both ways and also for pressurisation with the engine running.

Is just more work and expense I can do without.

[Nick W]

Have a sniffer so will do that first but also planning the leak down as well and have a cooling system pressure tester so can test both ways and also for pressurisation with the engine running.

Use the cooling pressure tester first. Then bodge up an adapter to use it with your compression tester hose(or weld a fitting to an old spark plug) and use it to pressurise each cylinder in turn. 30 minutes max. At least fixing an I4 is much less work than doing a V6

A boroscope is handy for proper inspections inside the cylinder, but a £6 snake camera attachment for your phone is good enough.

[iansoutham]

Use the cooling pressure tester first. Then bodge up an adapter to use it with your compression tester hose(or weld a fitting to an old spark plug) and use it to pressurise each cylinder in turn. 30 minutes max. At least fixing an I4 is much less work than doing a V6

On the bikes, I have a spark plug with a metal tyre valve brazed in and use a pressure gauge to get up to pressure normally so was thinking of the same this time?

[iansoutham]

Just out of interest, does anyone know the minimum thickness for the X20XEV cylinder head? I know the original is 134mm

[Doctor Gollum]

I believe that Haynes references it

[iansoutham]

I believe that Haynes references it

Genuinely surprises me in that, have book on side at home so will check this evening.

[Doctor Gollum]

The Omega one is one of last decent ones 

[Doctor Gollum]

Ok, it says 134mm with a maximum of 0.05mm distortion across the face. Same distortion across the block face.

No mention of minimum thickness beyond the above. 

[iansoutham]

Well, have done a block test in work today and it went green within 3x pumps without the engine even running so definitely coming apart at the weekend.

Just need to do some check before I attack it to confirm ”where” the problem is.

I have this head and the original so will get the best one and go from there.

[iansoutham]

Well, that was fun....

Head finally off and confirmed cylinder 3 as intake port all messy compared to other 3 inlets where all nice and clean. Head gasket looks okay but can just see initial signs of gasket going between waterway and chamber on inlet side with lack of carbon (washed away) on cylinder head surface. No visible signs of cracks on cylinder head surface or inside inlet ports on number 3.

All being skimmed Tuesday and everything being cleaned out (breathers, etc) due to mayonnaising throughout intake and breather system. Block to be checked and faced. Will then go back together and see what happens.

Also need to look at PAS bottle and pipe as appears to be slight leak (probably pipe from bottle to pump going hard).

[dave the builder]

Might just need the hose clamp under the reservoir tightening or replacing for the PAS .
sounds like your getting there with the engine 

[iansoutham]

Might just need the hose clamp under the reservoir tightening or replacing for the PAS .
sounds like your getting there with the engine 

I can only hope....

I run old Fords and the low pressure pas pipe on those normally goes hard meaning that the pipe no longer seals and the clamp can no longer hold it tight enough.

Am going to clean it all up and see if the pipe is still flexible. If it is, will attempt a tightening, of hard, would need replacing most likely.

[dave the builder]

well it's not a crappy old FORD 
so probably just needs tightening