Blown head gasket. What to do.

ricky-pinky · Postby **ricky-pinky** » Thu Apr 13, 2017 4:11 pm

Hi All,

I have a blown head gasket in my series 2 NB. However, it is an intermittent problem. If I start the engine and watch for bubbles in the radiator overflow tank, sometimes it will blow a few bubbles and sometimes it won't. Sometimes I can drive it 50 km or more and it doesn't overheat, and sometimes it overheats after 20 km or so.

So, what to do. I figure I have two options.

1) Do the job properly. That is replace the head gasket and service the head while it's off the engine. And if I decide on this option I'll have a go at DIY, although my previous experience only extends to push rod or SOHC engines with cast iron heads.

2) Do the cheap (and nasty?) fix with Bar's Leaks Head Gasket Fix. Bar's have a couple of products for blown head gaskets but I am thinking of using this particular one because it is recommended for small leaks where it is possible to drive the car for 20 minutes or more before it overheats. Also, it is compatible with antifreeze so the cooling system doesn't have to be flushed to remove the old coolant.
Has anyone had any experience with this stuff. A youtube search found a few of positive experiences with this particular product, as well as a couple of negative ones from using this type of product.
And just to make it clear. I intend keeping the car. I am not wanting to do this so I can sell the car to some other poor unsuspecting sod.

StanTheMan · Postby **StanTheMan** » Thu Apr 13, 2017 4:34 pm

a head gasket will cost you less than $100 depending on where you get it.

a head shave will cost you about 120-150 if you o for the full 1mm shave to increase your CR a bit while its off

probably a few other bits & pices. it will be less than $300.
maybe depending on when your timing belt was done & waterpump that might add another few hundred.
if you are going to totally refresh the head......could be thousands.....where do you stop.....

the patch up jobs only delay the repair & might also give you grief.

DOHC cams are not much different to SOHC.....apart from having to line up 2 cam sprockets instead of push-rods or dizzy's
there is a load of info how to line it up on this site. And other sites

you need a torque wrench as well.

its not that hard
plenty of help here too if you ask

smy0003 · Postby **smy0003** » Thu Apr 13, 2017 6:54 pm

Don't use any magic sauce bottle which promises to fix your head gasket, they will just gum up your engine and most likely not work anyway.
As Stan says, it's not the end of the world. A few scraped knuckles and a few hundred bucks.

Check out Beavis' video:

Todd77 · Postby **Todd77** » Thu Apr 13, 2017 10:32 pm

I would be double checking it is the head gasket for sure. Could be thermostat sticking and water boiling in head, then pushing water out. Does it pressurise cold when you first start it? Does it run smooth?

StanTheMan · Postby **StanTheMan** » Fri Apr 14, 2017 8:57 am

Todd77 wrote:I would be double checking it is the head gasket for sure. Could be thermostat sticking and water boiling in head, then pushing water out. Does it pressurise cold when you first start it? Does it run smooth?

Very good point ive had that happen too

hks_kansei · Postby **hks_kansei** » Fri Apr 14, 2017 11:09 pm

The additive stuff like chemiweld and the rest is really only best used in engines that you're about to bin anyway.

It stops the leak, but also collects in every corner and clogs up the radiator and stuff.

It doesn't come out with a flush either, when my gf rebuilt the engine in her kingswood it took an acid dip to clean the sh*t out (even then it wasn't 100%)

Mr Morlock · Postby **Mr Morlock** » Sat Apr 15, 2017 1:15 pm

Bear in mind that a blown head gasket can do real damage to an engine. You cannot fix it with band aids. It may be fixable at reasonable cost and saving the car for more life on the road. Used cars today are worth very little and an MX-5 actually brings a reasonably good price. In the old days people apparently put bananas in the diff to reduce the whine- I was sceptical that it worked.

ricky-pinky · Postby **ricky-pinky** » Sat Apr 15, 2017 7:17 pm

Thanks for the responses guys.

The unanimous consensus is that the Bar's Leaks fix is bad news, so I won't go down that route.

Getting to the point raised by Todd77 re the thermostat sticking. The first time the engine overheated was back in January and the intermittent nature of the problem, and the fact that the car doesn't get dríven very often, is what has caused the long time it has taken for my diagnosis. I did, in fact, change the thermostat and it initially appeared that this solved the problem. But a few drives later it overheated again. Eventually I just started it up a few times and let it idle, blipping the throttle occasionally and feeling the top radiator hose to see that it was getting hot, meaning the thermostat was opening. A couple of times I witnessed a few bubbles coming into the radiator overflow tank, but the engine did not overheat. But I guess driving it on the road generates greater pressures in the combustion chambers and so causes greater leakage, leading to enough coolant being displaced from the radiator to cause it to overheat.

So it seems I will just have to pull the finger out and take the head off.

Thanks again for your interest.

Aiming Faster · Postby **Aiming Faster** » Sun Apr 16, 2017 12:13 am

I also had a headgasket leak, before I removed the head I poured some Lifter Free into the sparkplug holes, #3 didn't drain down to the sump!
That means gummed rings, probably a 'normal' situation if it's been getting coolant water into the cylinder every time it's heated up then turned off.
Cleaning ring lands requires pistons out, escalating to a hone if cylinder isn't pitted, or bore and pistons if it is. That far and it's bearings, oil pump etc.
I skimmed 1mm from head and block combined (crank measured good at 260 000 km!), weld corrosion before valve job, water and oil pump, timing belt and (adjustable) gears, rebored for 10:1 pistons/rings 1mm o/s, gaskets and a proper clean. Running in oil first, 2x oil filters, on it goes!
Near $1500 without labour, just so I could enjoy the finished project!?!
Runs nicely now I'm happy to say, good compression and well sealed. Worth it? Should've swapped the engine.

ricky-pinky · Postby **ricky-pinky** » Sun Apr 16, 2017 4:26 pm

Hi Aiming Faster,

$1500 for an engine rebuild is pretty good value, and a pretty good DIY project too.

Unfortunately I have got to the age where a rebuild is too much for me to take on. I don't really have the facilities to lift an engine out, and I'm too tight to pay for it to be done professionally. (My car isn't pristine enough to spend that sort of money on.) However, the engine runs smoothly enough, pulls okay and there is no evidence of any coolant in the oil, so I'm prepared to have a go at doing a head gasket, and regrinding the valves while the head is off. That ought to keep it on the road and reliable for a few more years.