Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: iansoutham on 26 January 2021, 17:39:18
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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.
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Do a leak down test on that cylinder with the valves closed and see if you get bubbles in the coolant tank :-\
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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.
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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.
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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?
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Just out of interest, does anyone know the minimum thickness for the X20XEV cylinder head? I know the original is 134mm
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I believe that Haynes references it :-\
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I believe that Haynes references it :-\
Genuinely surprises me in that, have book on side at home so will check this evening.
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The Omega one is one of last decent ones :y
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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. :-\
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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.
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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).
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Might just need the hose clamp under the reservoir tightening or replacing for the PAS .
sounds like your getting there with the engine :)
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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.
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well it's not a crappy old FORD :P
so probably just needs tightening :D
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well it's not a crappy old FORD :P
so probably just needs tightening :D
It's an equally old piece of Vauxhall rubber. Which can be cut off the metal ends it's crimped onto, then replaced with a nice new length of oil resistant hose and a couple of Jubilee clips. Easy. And cheap :y
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Had to tighten PAS pipe clamps by about 2 turns (bottom of pipe was actually free to move).
Cylinder head is skimmed 2 thou and my engineer says he has seen loads of these head gaskets failing on different cars recently. All have been redone within the last 5-6years (even from main dealers) and all showing signs of the metal fire rings being the problem so is wondering if the quality of the metal is the problem? Certainly, my gasket was in one piece and not bad condition but you could just see where it was getting past the fire ring.
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I've had the fire ring rust out on an OEM gasket
Also noticed at about 100K+ vauxhall 4 bangers had HG fails
2 thou is not much :)
I tended to flat/resurface heads myself in the past on a sheet of thick steel with emery glued to it with no issues .
cleaning up head bolt hole threads and a bit of lube on the threads ensures a more accurate torque
though I always go " click and a bit " :D
sounds like you are getting there :)
Had to tighten PAS pipe clamps by about 2 turns (bottom of pipe was actually free to move).
Had that a few times on Carlton's ,which is the same reservoir ,so thought it might just need a nip up on yours's :)
saves another messy job :D
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I've had the fire ring rust out on an OEM gasket
Also noticed at about 100K+ vauxhall 4 bangers had HG fails
2 thou is not much :)
I tended to flat/resurface heads myself in the past on a sheet of thick steel with emery glued to it with no issues .
cleaning up head bolt hole threads and a bit of lube on the threads ensures a more accurate torque
though I always go " click and a bit " :D
sounds like you are getting there :)
Had to tighten PAS pipe clamps by about 2 turns (bottom of pipe was actually free to move).
Had that a few times on Carlton's ,which is the same reservoir ,so thought it might just need a nip up on yours's :)
saves another messy job :D
Cylinder head height is now 0.5mm down from original height, any more would be too close to the inlets for my liking. I know you “can” go 2mm as have done that on my old Cav to get rid of corrosion but it had to run super unleaded and “pinked” like hell when cold or on normal fuel
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Well, it runs and drives again, just got to keep eye on the cam seals as they leaked originally when started but seem to have stopped now.
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maybe a bit of old coolant (from the HG fail) in the oil ways has worked through to the cam seals but now the oil, being thicker ,won't pass and the seals have seated again :-\
It's good you're up and running again though :)
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Both cam seals changed again, looks like I potentially missed a bit of contamination on the end of the cams whilst rebuilding it (in the cold and rain) so have changed them up, fitted new seals and all appears good so far. Time will tell....
Need to change the cam sprocket bolts though as they have been reused about 3 times now and the exhaust one is “wobbling” at the head when the sprocket is perfectly fine. Easy enough to do though.