!986 Holden Piazza head gasket

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sbs
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!986 Holden Piazza head gasket

Post by sbs » Fri Nov 26, 2010 9:12 pm

Hi folks,
I am thinking that I have a problem with the head gasket on the Piazza. I only use the car every few weeks or so and, upon start up and for the first two or three minutes of use, the car is sending out a fair cloud of what I assume is steam from the exhaust.
I don't think it is oil smoke as that would surely remain in the air, but the "smoke" coming out is dissipating very quickly. After the first few minutes the exhaust clears and everything seems normal. I have just done a 130 km. run in the car and the temperature guage remains steady and the car seems to be running fine.
So, any ideas what I might be looking at here? If it is a head gasket are they readily available? What kind of time should a mechanic be able to replace a head gasket in as I don't feel like getting ripped off.
Thanks for any help, cheers,sbs.

IZU069
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Post by IZU069 » Sat Nov 27, 2010 11:47 am

I suspect that is just condensation and hence quite normal.

Yes - steam disappears whereas oil or fuel smoke lingers - as in "evaporates" (or not) into the atmosphere. Eventually the wet exhaust etc dry out too.

Check for grey sludge under the oil filler cap.
Monitor your coolant level as well as oil level and color.
Or remove splugs & inspect, and ....
Try cranking with throttle down for 30-60 seconds with splugs removed (I suggest disconnecting the IgCoil else distributor to avoid ignitor damage). Water may geyser out, though that may require other splugs be replaced for pressurisation - eg either 1 or 2, and 3 or 4 since failures are usually between cylinders 1&2 or 3&4. Splugs not tight - just for the restriction. I discovered geysers from a leaking #3 cylinder during a compression test with air-hose adaptors in all splug holes.

Ultimately maybe a compression test...

But for now, let's doubt the head gasket, or cracked head.



For more detail....

If it is a weeping headgasket, remove the splugs and check. Water in combustion chambers cleans out carbon, hence cleaner splugs and piston crowns. [ Excess water bends conrods (do NOT push- or pull-start cars with water in bores - the wheels lock up for a reason!). ]
The leaking cylinders(s) should have cleaner splugs (if coolant is getting in).

Faulty headgaskets can involve any of: oil leaks, water leaks, & compression leaks - but it doesn't have to be all or a combination. Many say you will get oil in coolant or coolant in oil or cylinders - but not so.
Cracked heads can do the same.


Water leaks into cylinders are usually 2-way. IE - leak into bores whilst resting, and air into the cooling system whilst running. Hence removing radiator caps and looking for a stream of fine bubbles else coolant "pulsating" out whilst running is a good, er, bad sign. But do not confuse with normal purging of air after refills etc.

Grey sludge under the #710 (oil-filler) cap (and cam/rocker cover) indicates moisture from condensation or a leak. But oil can effect that too - I once diagnosed a Bellett-GT (G161-OHV) with a definite water leak due to grey "condensate", but it proved to be detergent oil.
[ Detergent oil in an old dirty engine is not good but is ok in an overhauled or clean engine. Changing from its Castrol GTX-2 (or GTX?) back to non-detergent oil (GTX? else XL etc) solved the problem - ie, it "fixed" the blown headgasket or cracked head LOL! ]
Water in oil turns it greyish and can cause froth. I think coolants do the same.


As to gaskets, I read they can be rare. (I think I bought the last Permaseal stocks!)

As to replacement, it's probably at least a 4-hour job. That was my turnaround time for the G-OHVs, but Piazza plumbing may mean much longer (despite not needing to redo valve clearances).

But the tensioned head should ideally rest overnight for final head-bolt tensioning (check) BEFORE starting the engine (alloy head).

In fact, I'd suggest you do it yourself if you are so inclined (with help - eg, torque wrench; a blade; straight-edge; wet&dry; degreaser or thinners).
But let's wait until a leak had been established. As I said, I have my doubts.
IZU069 - ISUZU means a lot to me.

sbs
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piazza head gasket

Post by sbs » Sun Nov 28, 2010 12:53 am

Hi there Izu,
Thanks for the advice, it will give me something to check out. The amount of vapour is rather a lot and I have no idea how I have got away with driving it down the local roads. It does disappear once the engine warms up.
I will run through your suggestions and see what the problem is. sbs.

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