NB8A Blown Headgasket :(

simon_mx5 · Postby **simon_mx5** » Wed Apr 13, 2011 4:23 pm

Hey Guys,

I recently blew a Headgasket on MX5, :cry:

was wandering if it were wise to replace it with a metal headgasket, or an aftermarket one which might work a little better, just wanting some opinions on this, if anyone here has had the same issue.

Ive checked the engine old, it doesn't seem to have any water mixed with it (thank god).

Also with the head coming off, is there anything that you would recommend changing, replacing?

The car is relatively Stock, but eventually would like to take it on the track every now and then

What are your recommendations??

( I know this sounds a little n00bie, I wont lie, I am

)

pcmx5 · Postby **pcmx5** » Wed Apr 13, 2011 5:44 pm

I would go with a check to ensure the head and the block are true, a standard headgasket and as the head has to come off a new cambelt. The water pump may also be worth replacing at the same time unless it was replaced in the last 50000 klms as it will add very little to the bill at the moment but will cost heaps if it fails later as you will again need a new cambelt and all the labour costs.

A good mechanic would also be looking for the cause of the headgasket failure (ie. looking to prevent it happening again rather than just fixing the result!)and would check the radiator and the thermostat at the very least.

Peter.

manga_blue · Postby **manga_blue** » Wed Apr 13, 2011 7:16 pm

What pcmx5 said.

When the head is off it's worth looking in the inlet ports and removing any dags and cleaning up bad bits of casting. A reasonably minimalist job with a broken round file and 120 wet'n'dry paper can find a few Kws. Mazda's casting quality is not always that great. Also worth checking that the manifolds, gaskets and ports line up OK. My old NA8 head had over 25% of the inlet port area closed off by mismatches, fixed by ovalling the mounting bolt holes and locating the inlet manifold with little dowels.

People normally take the head to a machining shop to get it cleaned, pressure tested, hardness tested and have the mating face ground back to flat. Valve seats should be checked and reground if required. If the manifold alignments are way out of whack they can fix that too.

Hellmun · Postby **Hellmun** » Wed Apr 13, 2011 10:09 pm

Must depend on the year model, on my NB8B I checked my exhaust and intake ports when I cleaned my intake manifold and originally put my extractors on. There was nothing I could improve. I was thoroughly impressed unless by some weird chance someone had cleaned up the head on a car with 35,000kms.

manga_blue · Postby **manga_blue** » Wed Apr 13, 2011 10:51 pm

Makes sense. I figured that whatever foundry made mine couldn't have stayed in business much longer. Inside the ports looked like Jenolan Caves. :roll:

simon_mx5 · Postby **simon_mx5** » Fri Apr 15, 2011 5:11 pm

Thanks for the info guys!!!

Appreciate it

had a chat to the mechanic, the head will be properly cleaned, and what not. also, has anyone had there head ported??

Postby **NitroDann** » Sun Apr 17, 2011 12:51 am

Everyone, nobody runs a stock head, cant make more than 80hp atw without porting even turbo.

Dann

Sarcasm, seriously though, if you take the head off, do yourself some justice and look at some cams, not headwork. Also Fix the dam problem that caused the blown head gasket, you dont need a stronger gasket, you need to find out why the stock one blew.

timk · Postby **timk** » Sun Apr 17, 2011 9:24 am

I'd go stock head gasket (it's metal anyway) but some ARP head studs if you are worried.

simon_mx5 · Postby **simon_mx5** » Wed May 11, 2011 2:42 am

I finally got the car back, the mechanic did some testing and I was lucky enough with no real damage to the head. Cars running awsome!! Only thing is to get rid of the slight coolent scent comming from the air vents

Sent from my X10i using Tapatalk

greenMachine · Postby **greenMachine** » Wed May 11, 2011 11:06 am

simon_mx5 wrote:I finally got the car back, the mechanic did some testing and I was lucky enough with no real damage to the head. Cars running awsome!! Only thing is to get rid of the slight coolent scent comming from the air vents

Sent from my X10i using Tapatalk

Leaking heater core! :shock:

Ever find out why the head gasket failed? They don't just 'do' that for no reason you know ...

The usual reason for a blown head gasket is overheating, the usual reason for overheating is lack of coolant, and I reckon the main reason for lack of coolant is probably a tie between blown radiator hoses and leaking heater cores. Please do not ask me how I know about this :oops:

simon_mx5 · Postby **simon_mx5** » Wed May 11, 2011 2:16 pm

I had previous cooling issues, top radiator hose giving up, thermostat, and also the radiator it self, the mechanic is guessing those previous issues cause it to happen.

Now to attend the next car meetup / cruise