flushing engine after head gasket leak

PostPost by: jono » Wed Nov 06, 2013 11:32 am

I am hoping to have my engine running this weekend after changing the head gasket and, eventually, getting the valve timing back to square one :roll:

There has been water in the oil and visa versa. What precautions should I take to clean out the system?

I am going to use a cheap oil and new filter for a short time and then dump and replace with fresh oil and filter.

Coolant wise I was going to fill with a 50:50 mix of ethylene glycol and water then drain a re fill after a short time with 100% glycol coolant (Comma brand).

Does this sound sensible?

Two more questions - how long to run before I change oil and coolant?

Second, I think I read somewhere that you run the engine up to temperature for a few minutes and then let it fully cool before re torquing the head bolts after changing the head gasket - is this correct?

Thanks, all

Jon
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PostPost by: AHM » Wed Nov 06, 2013 12:05 pm

jono wrote:Does this sound sensible?


Oil, yes maybe worth letting the first bit run straight through.

Coolant
jono wrote:Coolant wise I was going to fill with a 50:50 mix of ethylene glycol and water then drain a re fill after a short time with 100% glycol coolant

Why would you do that? Water is a better coolant than Glycol.
Flush with plain water refill with 30% mixture.

Torque - after 500 miles.
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PostPost by: rgh0 » Wed Nov 06, 2013 1:12 pm

I check the torque after the first heat cycle. Then again after the first couple of hours running and then finally after first 500 km's. ( say 10 hours running)

Maybe more than necessary but I sometimes find a little movement each time up to that final check - beyond that they don't move.

cheers
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PostPost by: Jeff@Jae » Thu Nov 07, 2013 5:22 pm

Some head gaskets don't require a re torque, or at least just one check after a heat cycle, so that will depend on the head gasket used.
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PostPost by: david.g.chapman » Fri Nov 08, 2013 10:04 am

I have just re-torqued my head bolts after a new copper gasket and 110 miles running. Two of the bolts needed 30 degrees or so to get up to torque, so it's well worth doing. The three bolts for the timing chain case will also need a tweak to compress the cork gasket.

I have run Halfords classic 20/50 oil in my twink for many years without any wear issues - it's ?20 for 5 litres in the UK. I will change the oil after 500 miles as I have fitted new rings and valves.

Dave Chapman.
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