Can an Opel Astra head gasket leak be repaired without a new gasket?

Hi all,

I've an Opel Astra F (yr 1992) with 187K miles on clock. Head gasket
was replaced 40K miles ago (with a head skim). A routine inspection
revealed that the coolant is now being excessively pressurised again
with gurgling at start-up only (the pressure holds in the expansion
tank when car is parked for days, so no leaks here). Engine runs fine,
no misfires, no visible exhaust vapours, no oil scum, no overheating (I
keep the coolant topped up - about 1/2 pint every 200 miles or so). I
decided to check for combustion gas bubbles in the coolant so I started
the engine with expansion cap removed and could see none. I then drove
the car for a bit to warm up the engine, with expansion cap loosened.
After that I could see bubbles at high revs. It would therefore appear
that the head gasket only leaks above a certain temperature, which
makes me wonder if one of the bolts is loose, allowing the head to lift
sligtly with thermal expansion.

Can a head gasket change be avoided by re-tightening the head bolts?
It not, even though the car is in mint condition, are second gasket
changes generally successful (assuming there's still enough material to
skim). If they are successful, would I get another 20K or 30K (mechanic
who changed it the first time would charge around 300 euro now, with
timing belt, plugs, oil etc included)?

Thanks,
John.

 

chances are either a cheap gasket or they didnt renew the head bolts.
if its been blowing at all, then chances are that combustion gasses have
burned the gasket away. re-tightening is dubious at best, but especially
after so many miles.
you didnt say what engine, but fromage/mileage it isnt worth a lot, so dont
throw large sums at it. why not just drop in a new gasket yourself and see
what happens?

Mike

 

Thanks for the feedback Mike. It's a 1.4L petrol. I think I'll give a
new head gasket with new head bolts a go. Nothing much to lose and it's
an economical little engine - it still averages 50mpg, which seems to
be better than some friends' newer cars with the same engine capacity
and similar journey lengths. Apart from the intermittent gurgling sound
just after start-up , you'd never know there was anything wrong (great
pickup, running smoothly etc.) although I now know that will change if
the gasket isn't replaced very soon! I guess it's in the early failure
stage.
John.

 

if it were me, I would probably whip the head off and take it from there.do
make sure that you slacken the head bolts off in the right order. crack them
1/2 turn each in reverse order of tightening. then do it again. then slacken
completely. although i wouldnt bother with a skim for this age of car,
theres no sense in risking a warped head. worse case tho' is a cracked head.
this will leave you with the buggeration of disposing of the car (scrap) or
hoping a breakers will flog you a head only. (ask to see the head before you
buy, beware of 2nd hand heads out of autotrader-son has had some very bad
experiences with cav heads this route.

new bolts? your choice. if you think you have experience to tighten the old
ones down ok without overdoing it, then use the old ones. I am talking a
bodge here, but given the age of car its a reasonable one and a do-able one.

Mike

BTW, dont forget to give the pistons and head a good clean to get rid of
carbon while its off-can make a heck of a difference!

 

Thanks for the tips Mike.
John.