c_r_thomson 0 Posted November 1, 2006 Finished my carb conversion last week after replaceing my HG, water pump, belts etc. I had the symptoms of a HG blow straight away but had this down to a buggered pressure cap so this was replaced at the weekend. Driving home from work today and lots (I mean LOADS) of white smoke started pouring out of the exhaust!!! Coasted it back to the garage and had a look. The pressure in the coolant system was massive and i've lost most of the coolant that was in there. Do you reckon the pressure cap i fitted (from a 405) caused the pressure not to release thus blowing the gasket or is the new water pump causing the pressure build up. Utterley gutted that i'm gonna have to strip the car and take the head off again!!! Share this post Link to post Share on other sites
hengti 2 Posted November 1, 2006 did you have the head skimmed? Share this post Link to post Share on other sites
c_r_thomson 0 Posted November 1, 2006 Yeah, the head was skimmed Share this post Link to post Share on other sites
c_r_thomson 0 Posted November 1, 2006 Before i put the new cap on it ran fine until you gave it some high revs. This is gonna be expensive!!! Share this post Link to post Share on other sites
jim21070 2 Posted November 1, 2006 Sounds like a crack somewhere to me, either a liner or in the block causing the liner to drop a bit and upset the amount the liner protrudes out of the block to form an effective seal against the head gasket fire rings. My old 1.6 engine had a block crack caused by cold spell and no anti-freeze and it gave exactly these symptoms. Any coolant in the oil? Check the liner protrusion very carefully and critically inspect the block when you next have the head off. Just where the gasket has blown and how will give some valuable cluses as to the cause. Post up some pictures. A cracked head could also cause this. Share this post Link to post Share on other sites
Beastie 1 Posted November 1, 2006 (edited) I'd say that you can discount any idea of the pressure cap causing the head gasket to blow. I'm not sure what the compression pressure is on these engines is off the top of my head but I'd expect to see at least 150psi on a compression tester even on well used engine. Add to this the pressure caused by enough combustion energy to move a car and you can guess the sort of pressure the head gasket is desgined to withstand between the bores and the water jacket. If you succeeded in pressurising the cooling system sufficiently in excess of that so that the head gasket blew then it's going to look like your hoses have been attacked with semtex and there's not going to be much left of the expansion bottle or the heater matrix The two most likely causes of regular head gasket failure in my experience (given that you have already had the head skimmed and assuming that this was done properly) are either a patch of corrosion on the alumininum head adjacent to the gasket grommet on one of the cylinders or else insufficient liner protrusion. I have seen cylinder heads which people have taken for granted simply because they've had a skim. However sometimes the aluminium bears damage which is deeper than it's practical to machine out and somehow it has gone unnoticed. The liners must protrude above the deck surface of the water jacket. If they don't then head gaskets won't last very long. As already said this could be caused by a cracked block allowing the liner to sink. Although I've seen plenty of cracked blocks I have not myself seen a crack which has caused a liner to sink though. I have seen plenty of aluminium blocks which have distorted over the years and which need machining to restore correct liner protrusion however. edit: I've attempted to answer your head gasket query but of course as Jim points out: The gasket could be fine and the head could be cracked. Only one thing is beyond any doubt: The head needs to come off for careful and methodical inspection. Edited November 1, 2006 by Beastie Share this post Link to post Share on other sites
c_r_thomson 0 Posted November 1, 2006 The only crack i had was beneath the headbolt by the brake servo. just blocked it up with some liquid metal. So, engine rebuild? cost? Anyone with a good mi16 for sale? Share this post Link to post Share on other sites
huzzer 0 Posted November 1, 2006 I have just finished rebuilding the head on my 1.9 for the second time in two months! Suspected liner seal failure/ cracked head or block or something else similarly as bad. Turns out it was the head gasket that had failed after a thousand miles! Unusual but true. Got the head gasket cheap from the internet and was probably rubbish quality! Share this post Link to post Share on other sites
Beastie 1 Posted November 1, 2006 The only crack i had was beneath the headbolt by the brake servo. just blocked it up with some liquid metal. Sounds like a good place to start the investigations then: You may well be running with one less headbolt than everyone else! Share this post Link to post Share on other sites
c_r_thomson 0 Posted November 1, 2006 Ah well, head off then. I'll post pictures when i'm done. Thanks for the help guys Share this post Link to post Share on other sites
matt1900 0 Posted November 3, 2006 I have just finished rebuilding the head on my 1.9 for the second time in two months! Suspected liner seal failure/ cracked head or block or something else similarly as bad. Turns out it was the head gasket that had failed after a thousand miles! Unusual but true. Got the head gasket cheap from the internet and was probably rubbish quality! yeah i'd agree with that, do your self a favour and get a proper head gasket from peugeot, i fitted a cheap one from csf and it started pissing oil out the back within days of being fitted. i got a genuine one and you can instantly tell the difference in quality just by flexing it slightly. Share this post Link to post Share on other sites
