help .. think head gasket is gone

by **shaneh** » Mon, 26 Sep 2011 7:58 +0000

had the car running there yesterday for a while and it heated up over the halfway point.
took the cap off the rad after it had cooled a bit and revved the car ... coolant was bubbling and spitting out of the cap.
think the head gasket is gone and it blowing the coolant through some of the coolant tunnels.
there is also a slight miss not even a full miss ... i cleaned all the plugs ad the problem was still
there ...
while taking out the back 2 plugs i noticed oil collecting in the hole the plugs go down .. is this a common problem?
think i need a new rocker cover seal and head gasket :evil:

not happy
anyone ever done the job before?

by **twisty** » Mon, 26 Sep 2011 8:52 +0000

First off the rocker cover seal leaking a little is common enough and really easy to replace , on the head gasket i would expect the car to be overheating when driven due to gas causing airlocks in the cooling system , also check the oil for any coolant in it turning it white,when you cleaned the plugs were they all the same colour ?

A slight miss can be caused by high tension leads getting a little old , some wd40 or replacing them should help , also check the sparkplug gap it should be 1.1mm i think.

btw if it is the head gasket the mx5 motor is as easy as they get to work on so dont be too worried

by **mx5ash** » Mon, 26 Sep 2011 8:59 +0000

I wouldn't jump to any conclusions about the head just yet. Are You getting large amounts of smoke (white or blue from the exhaust)?
is there any mayo like stuff in the oil cap?
Air bubbles in the coolant is fairly normal and can also cause overheating. You need to bleed the system of air. I'd start there.
Cam cover gasket is a simple and cheap job.
Are spark plugs themselves black and wet with oil?

by **Steve** » Mon, 26 Sep 2011 9:13 +0000

Is it overheating still? any oil in the coolant? Might be just the water pump firing it out when you rev it? No harm in changing your thermostat and watching the needle.
Try removing the ignition leads from the coil's posts and clean out the posts with a Q tip, it might cure your miss (are your ignition leads recent?)

by **shaneh** » Mon, 26 Sep 2011 9:26 +0000

i checked it over well when buying for the white around the oil cap and all that craic ...
thermostat pipe is broken but bodged together although i think it still reads right ...
im getting it compression tested this week before i do anything else with it.
it is still overheating even at idle .. theres a new rad in the car so i think it has overheated badly
before which caused this.
it is very mild and could be driven day to day but tbh i want to drive it hard thats what its baught for.
the car isnt smokey really at all.
theres a set of blue ngk leads which i dont really like the look of on it they look old alright and probly were dameged by oil sitting in them for a while.
the plugs were very black when i took them out but all of them were equal ...
hope i didnt miss any other questions.
cheers for the help

by **mx5ash** » Mon, 26 Sep 2011 9:32 +0000

Bleed the coolant system of air, system could be full of air especially if rad has been replaced. Replace thermo stat, leads and plugs and I'd say it will be good. Really doubt hg is gone.
When bleeding you need to have hot air on in car and fan blowing, rad cap off, car running and if possible front raised slightly.

by **shaneh** » Mon, 26 Sep 2011 9:47 +0000

forgot to say the coolant looks rust as if its just straight water in the rad for a while ...
il try that tomoro lad .. how do i bleed it is there a bleed valve?

by **mx5ash** » Mon, 26 Sep 2011 10:26 +0000

No just run the car with rad cap off, hot air on in car so water circulates through heater core, and if possible jack up front or at least have it level. If your worried about the coolant then before you bleed it take the drain plug out the bottom of rad, drain all the water out and flush out rad for a few mins with a hose. Refill with coolant then bleed the air out as above.

by **shaneh** » Mon, 26 Sep 2011 10:33 +0000

will do it tomoro lad ... how long should i leave it running for?
what if it starts overheating again on me then

by **charged_rs** » Tue, 27 Sep 2011 10:14 +0000

do as ash suggests , about 15 to 20 mins idling.

you really want the rad fan to do 2 or 3 cycles ie ..coming on and turning off.

make sure water is flowing through the rad once the car is up to temp

by **shaneh** » Tue, 27 Sep 2011 11:57 +0000

had it ticking over a good while an the water came into the rad and fan on and off ...
gave it a rev and coolant shot about 6 inches up ..
done a compression test and the 2 middle cylinders were own on compression ..
i think the gasket is gone between 2 cylinders or into a cooling jacket.
anyone know who makes thin steel head gaskets just while im at it haha

by **sidewaysreilly** » Wed, 28 Sep 2011 12:28 +0000

if you rev the engine, the coolant is gonna shoot out. You need to get a friendly mechanic to presure test the system via the rad cap .Start there first before diagnosing all sorts of other problems........... its probably a simple fault you dont understand.

by **shaneh** » Wed, 28 Sep 2011 12:38 +0000

my friend is in college doing motor maintainence said its defo the head gasket .. he phoned his father whos a mecanic and he says its most def a leak in the head.
theres bubbles in the cooland constantly too ... its the head gasket

by **charged_rs** » Wed, 28 Sep 2011 2:04 +0000

well , if you ae convinced.....

i reckon its an airlock

what were your compression figures? wet or dry ?

by **shaneh** » Wed, 28 Sep 2011 8:23 +0000

i got 10 ... 9 ... 8.5 and 10 kg/cm2
we did it spinning the engine with the leads unplugged and the throttle on full