General Head gasket gone, or something else?

[adrian2006]

Hello,

The past week, i've noticed my Bravo has been jerking a bit when my rev's go over 3,000. Yesterday my heater stopped working, only blowing cold air.

I had a look under the bonnet today, checked the spark plugs and air filter - all of which were ok. I did notice however, that the radiator built up pressure and when I took the cap off it was overflowing. The first time I started the engine the heater worked, but was soon blowing cold air after a couple of minutes again. There was a small amount of water spurting out of the exhaust, but not as much as I would expect if the head gasket has gone.

I don't know if these problems are related, but any ideas would be much appreciated.

- V-reg Bravo; 54k miles -

Many thanks,
Adrian

 

[manic_monkey]

A little bit of water out of an exhausnt isnt normally a problem, if it only happens when you first start. Its easy to get a bit of condensation in there, or just water off the road.

If the engines hot, the radiator shoud be slightly pressurised, because of the thermal expansion of the water. When my head gasket went, the build up of pressure was great enough to push the water out with the radiator cap still on.

A good simple test for head gasket failure is to take the radiater cap off, then start the engine. If you get a load of bubbles, smoke, or the water is pushed out with some force, then i would say the head gasket is knackered.

 

[mountainmachine]

Did you check the oil? Whats it like, whats the cap like, has it been using lots of oil or water? Overheating past 1/2 way?

 

[jug]

I did notice however, that the radiator built up pressure and when I took the cap off it was overflowing.

for future reference, dont do that ever again. if you didnt have a head gasket problem doing this is a good way to cause one. when coolant gushes out air gushes in causing air locks and overheating and preventing hot air in the vents. also it is now impossible to determine if the coolant level was low because even if it wasnt before it will be now.

ok so what should you do? you need to bleed and top up the cooling system. to do this you will only need to use the bleed screw on the heater matrix hose. this will give you hot air at the vents again. if the hot air then stops coming out the vents after a while (may take a few days) it means there is air in the hoses again, which means you either have a coolant leak or a head gasket failure.

since your hot air stopped working before you decided to do 'a gusher' we can assume there is probably a leak or head gasket failure, so we should expect the hot air to stop working shortly after you bleed and top up the cooling system. keep an eye on the temp gauge, if it gets inbetweeen half way and max, stop driving and switch off the engine. the damage caused by overheating can work out expensive, switching the engine off before it overheats is free.

 

[Tomasso]

:yeahthat:

Once you bleed the system, you might also check for:

1) Oil and/or gasoline in the coolant (floating drops of oil, colorful signs of gas)
2) Coolant in the oil (brownish buttery substance under the oil cap)

 

[ryann143]

hi guys i have a similay issue. can anyone advise where the bleed screws/valves are on a 19td 97r 100sx brava?

cheers

 

[jug]

one on the radiator, but that wont help you get air out the hoses, the one you really need to use is on the hose going to the heater matrix. this is pretty much the highest point in the coolaing system. it is a thinnish hose at the back of the engine bay behind the engine. iirc the bleed screw is positioned on the hose inbetween the engine and bulk head. if you check along the length of all the hoses you will find it. it is a small black plastic piece that can be turned using a flat bladed screwdriver.

remember, you can only bleed the cooling system with the engine running.

 

[ryann143]

thanks alot mate il give this a try and see how i get on. i notice alot of bubbles in the water and there is a constant trickle of them. maybe a head or something else. but il try all cheaper options first. if this doesnt work will it defo be the head gasket or is there maybe a cheaper alternative.

just replaced radiator as was overheating and was completely rotten.

cheers

 

[jug]

since you've just replaced the radiator and have not bled the cooling system correctly since, and did not have this problem before replacing the rad, i would say it is almost certainly a simple case of bleeding and topping up the cooling system.

if this problem was there before you changed the rad, then i would be more likely to consider head gasket failure or a coolant leak elsewhere.

 

[ryann143]

the car was overheating previously and held no water what so ever. the guy i bought it from did well to disguise this.hopefully bleeding will resolve this. il let u know how i get on. thanks again mate

 

[jug]

oh, in that case it doesnt look good

if its losing coolant and you cant find a leak, it must be the head gasket.

 

[ryann143]

sorry forgot to mention that the radiator i replaced was completely crumbled and he used silicone sealer to disguise this. fingers crossed bleeding will resolve this or it could be an expensive trip to my local garage which i was dreading.

the fan used to come on now doesnt and no hot air either.

 

[ryann143]

also when filled with water before changing the rad it just came right out the bottom of it.hence the replacement

cant really complain tho....got a 97r td 100sx 2 owner car with 86000 for only 500 and has mot til june. i thought the price was low and gave it a good test run letting it idle for ages and then driving and the temp gauge didnt rise above half. mite need to pay him a little visit sometime soon lol:bang:

 

[jug]

thats good news. the silicone radiator would definately explain the leak, and since you havent bled the cooling system yet that would explain the overheating and lack of hot air in the vents since the rad change.

if the fan doesnt start working post another thread and we'll get that sorted.

 

[ryann143]

cheers mate much appreciated

 

[ryann143]

hi guys have tried bleeding could only find the screw on the radiator. can you help me locate the 2nd one as i have missed this. im probably being very stupid lol

 

[jug]

anyone got a pic?