What is Head Gasket failure, a little lesson.

keithsfleet

I see a lot of people mentioning HG failure in a few threads and have the slight suspicion they have no idea what they are talking about.

I have a car in today in the very late stages of HG failure and thought I'd take a few pictures to show what it actually looks like and how to diagnose it. The owner brought it in as it was overheating and after checking the coolant and refilling, discovered it was disappearing quickly.

Head Gasket Failure is where the gasket that sits between the engine block and the head perishes and you get oil mixing with the coolant. Its also common if a car has majorly overheated for the head to warp, what happens then is the gasket is no longer capable of doing its job.

[IMG]file:///Users/ian/Desktop/20131025_160021.jpg[/IMG]Picture one is one of the first symptons of HG failure.
The creamy "mayo" on the oil filler cap that people talk about. This is what happens when oil mixes with coolant/antifreeze.
Just because this is here does not definitely mean your HG is on the way out. Cars driven for short periods can have condensation build up here as well and does not mean HG failure.

Picture two.
This is the radiator cap which also has the sludge on it.
This will appear on cars that are quite far gone in HG failure. The yellow cap is the expansion bottle cap and you can see it is quite dirty from the mix of coolant and oil.

Picture Three.
This is the dipstick and the oil on it is incredibly thinned from the coolant mixing with the water. It shouldn't look like this...

Picture Four.
This is one example of finding out how badly far gone the HG failure is. This is not the oil but the coolant. Its a considerable mix of oil.


The risk with continuing to drive this car is that the oil is so thinned and watery that it can't lubricate the engine components properly.
I hope this clears up HG failure for some people and i apologise if I've left a few things out or not gone into a enough detail but I've a steaming hangover:-)

dgt

They can also fail between the cylinders too. Many's a 1.2 fire has ended up failing between no 2 cyl and 3 cyl

Symptoms? Cranking over has a sound of lost compression, dead miss, sounds like a bag of spanners and sometimes backfiring through the inlet

https://www.youtube.com/watch?v=2uO9O9R8W5k

jca

Usually one of the very first symptoms is the heater stops working. Excess pressurisation and exhaust gases in the coolant stop or slow the coolant flow through the heater matrix. Sometimes you can hear gurgling behind the dash, especially in Toyotas.

keithsfleet

Sorry there is a good few things I've left out, I suffered with that hangover till Saturday evening...when it magically disappeared when I started drinking again.

Wheelnut

My gawd, that's a Nissan engine from the pre-Renault era, they're usually bomb-proof. How did he manage to kill it?

keithsfleet

Wheelnut wrote: »

My gawd, that's a Nissan engine from the pre-Renault era, they're usually bomb-proof. How did he manage to kill it?

Good spot, it is indeed a 1G almera.

No idea how he managed to kill what millions have tried and failed, I'd suspect neglect and prolonged overheating.
He didn't want any work done on it so I filled it with water and off he drove into the sunset.

sebastianlieken

Does Ian know you were using his computer? :P

[IMG]file:///Users/ian/Desktop/20131025_160021.jpg[/IMG]

Mar4ix

Usually if there is suspicious hg failure, but there is no signs yet, possible do sniffing test in garage, check evaporating gas from coolant. I think it cost 20 - 30 quid.

whizbang

This is one of the better ones, Nice one Keith, But

so I filled it with water

The buyer will think the oil is so clean it has to be a good one!

Cienciano

Great post OP, was just thinking yesterday that HG failure is something I need to google to find out exactly what happens/why it's such a big deal

jca

Mar4ix wrote: »

Usually if there is suspicious hg failure, but there is no signs yet, possible do sniffing test in garage, check evaporating gas from coolant. I think it cost 20 - 30 quid.

Ah. The old rover test.... Another one for the auctions.

jca

Cienciano wrote: »

Great post OP, was just thinking yesterday that HG failure is something I need to google to find out exactly what happens/why it's such a big deal

The labour involved is the biggest cost.

Heat_Wave

How can you trust a garage's word that the HG is gone?

Also, do you think it's possible for a motor garage to actually 'create' a problem in order for you to fork out?

Interslice

Heat_Wave wrote: »

How can you trust a garage's word that the HG is gone?

Also, do you think it's possible for a motor garage to actually 'create' a problem in order for you to fork out?

Business would want to be fairly slow for them to invent it. Why you ask?

Heat_Wave

Interslice wrote: »

Business would want to be fairly slow for them to invent it. Why you ask?

I ask because.. a couple of days ago I was told my car required a new water pump as it was leaking, and yesterday I was told I need a new HG.

Drastic difference in price!

jca

Heat_Wave wrote: »

I ask because.. a couple of days ago I was told my car required a new water pump as it was leaking, and yesterday I was told I need a new HG.

Drastic difference in price!

Leaking water pump= low water level. Low water level means certain HG failure.

JohnBoy26

A car with hg failure will also usually be building up pressure in the cooling system. This can be checked by squeezing the pipe that goes from the rad to the engine. If it's soft and easy to squeeze things are normal.

If it's hard and difficult to squeeze however there is usually a build up of pressure caused by gasses leaking past the hg and into the cooling system.

JohnBoy26

If that engine got a roasting the rings could be damaged. It's rare that those engines suffer from overheating issues but I've seen at least two that have had overheating issues and hg failures. Both burned oil like mad afterwards.

JohnBoy26

Heat_Wave wrote: »

I ask because.. a couple of days ago I was told my car required a new water pump as it was leaking, and yesterday I was told I need a new HG.

Drastic difference in price!

If the water pump leaked all the coolant and the car overheated it is very possible that the hg is gone.

Heat_Wave

JohnBoy26 wrote: »

If the water pump leaked all the coolant and the car overheated it is very possible that the hg is gone.

The water pump had a 'tiny' leak. It was leaking very slowly. I was even told I could drive a short distance on it to a nearby garage as the water level was still normal.

Anyone have any idea how much a new HG should cost these days?

Mar4ix

Heat_Wave wrote: »

The water pump had a 'tiny' leak. It was leaking very slowly. I was even told I could drive a short distance on it to a nearby garage as the water level was still normal.

Anyone have any idea how much a new HG should cost these days?

Depend what car, 25 - 50 ish, i would worry more about labor costs, than a headgasket.
My advice, just go to diferent garage, and say nothing, just about water leak. See if other garage will diagnose hg failure.
If engine been overheated, has to do engine head test and skim, also good to be stem seals to change, work on head would be in range of 100-150 €, id say another 200 for labour, plus headgasket.... As i said depend what car, 50 ish, btw .... This could be handy time for timing belt , tensioner and waterpump change, as them have to go off anyway, so wouldnt be labor charge for timing belt change.

Heat_Wave

There's a head gasket and then there's the head, is this correct?

How common is it for the 'head' to snap?

dgt

Heat_Wave wrote: »

There's a head gasket and then there's the head, is this correct?

How common is it for the 'head' to snap?

They don't snap they crack. For example plenty of Avensis 2.0TD's back in the early 00's had to be recalled due to the head cracking. Bad design of head in this case, most replaced under warranty or for free by toyota if out of warranty

Heat_Wave

dgt wrote: »

They don't snap they crack. For example plenty of Avensis 2.0TD's back in the early 00's had to be recalled due to the head cracking. Bad design of head in this case, most replaced under warranty or for free by toyota if out of warranty

If it cracks in a bmw how much would you be looking at? My car is out of warranty

dgt

Heat_Wave wrote: »

If it cracks in a bmw how much would you be looking at? My car is out of warranty

What engine, year etc.....

irish bloke

RE: original post.

You don't have to have coolant leaking into the oil or oil leaking into the coolant to have HG failure. Both fluids can be appear totally fine.

Had a 1.9 dturbo pug 306 with cylinder gasses leaking into my cooling system causing excessive pressure, which led to coolant loss. This was latter stages of HG blow and at no time did fluids mix

dgt

irish bloke wrote: »

RE: original post.

You don't have to have coolant leaking into the oil or oil leaking into the coolant to have HG failure. Both fluids can be appear totally fine.

Had a 1.9 dturbo pug 306 with cylinder gasses leaking into my cooling system causing excessive pressure, which led to coolant loss. This was latter stages of HG blow and at no time did fluids mix

That was caused by cheaping out on the head bolts from the factory. Those DHY blocks were very prone to firing a leg out of bed too. Unless you were chucking in some serious boost from a tiny turbo....

DHX stem seals go brittle with age and let oil into the cylinders. Currently rebuilding a head that went like that. An annoying job but has to be done

irish bloke

dgt wrote: »

That was caused by cheaping out on the head bolts from the factory. Those DHY blocks were very prone to firing a leg out of bed too. Unless you were chucking in some serious boost from a tiny turbo....

DHX stem seals go brittle with age and let oil into the cylinders. Currently rebuilding a head that went like that. An annoying job but has to be done

Long time ago since it happened me but top of one of the pistons was scored too as far as I can remember.

Engine was never the same after repair, hard cranking over which I suspect was compression loss from a poor repair. Sold it on soon after repair.

Great car to go though, had fuel pump tuned up too

JohnBoy26

dgt wrote: »

They don't snap they crack. For example plenty of Avensis 2.0TD's back in the early 00's had to be recalled due to the head cracking. Bad design of head in this case, most replaced under warranty or for free by toyota if out of warranty

It wasn't down to a bad head design. It was down to flawed casting/materials.

The Carina e had more or less the same engine but never had any head cracking issues because better quality materials were used to make the head.

Also the recall and free head replacement must of happened in the very early 00s. My neighbours Avensis suffered a cracked head back in 2005. he had to buy a new head nothing was done for free.

luckily the new head that was supplied by Toyota must of been improved by them because the car hasn't given any head issues in the 200k miles since it's replacement.

dgt

JohnBoy26 wrote: »

It wasn't down to a bad head design. It was down to flawed casting/materials.

The Carina e had more or less the same engine but never had any head cracking issues because better quality materials were used to make the head.

Also the recall and free head replacement must of happened in the very early 00s. My neighbours Avensis suffered a cracked head back in 2005. he had to buy a new head nothing was done for free.

luckily the new head that was supplied by Toyota must of been improved by them because the car hasn't given any head issues in the 200k miles since it's replacement.

To me that means the casting process wasn't good enough at the time, but eventually rectified.

Plenty of Lite Aces, Estimas and Camrys suffered cracked heads too. Almost all were 2.2's though

I remember walking into Malones in Navan about 2003 and seeing dozens of Avensis out back. Most were diesels needing heads. We were told it was due to a bad design by a technician working there.

Ask around and I'm sure you'll see it was the same all over the country; cracked heads and all replaced early on for free. Too many people are quick to dismiss this too but it was a very sad reality at the time for many owners.

Maybe you can answer me this: I'm seeing far too many new shape diesel Avensis (circa 09 on) puffing out lots of white smoke. Have you any ideas what may be causing that? Heard any recall issues?

JohnBoy26

dgt wrote: »

To me that means the casting process wasn't good enough at the time, but eventually rectified.

That's it was exactly.

dgt wrote: »

Maybe you can answer me this: I'm seeing far too many new shape diesel Avensis (circa 09 on) puffing out lots of white smoke. Have you any ideas what may be causing that? Heard any recall issues?

It's most probably the DPNR(Diesel Particulate Nox Reduction) system regenerating or else clogged.

Like many other dpf issues, stop/start urban driving plays a big part in these problems.

dgt

JohnBoy26 wrote: »

That's it was exactly.

Methinks you worked for toyota at some stage, how else would someone know this sort of stuff....

JohnBoy26 wrote: »

It's most probably the DPNR(Diesel Particulate Nox Reduction) system regenerating or else clogged.

Like many other dpf issues, stop/start urban driving plays a big part in these problems.

I thought this myself as a few were taxis that are ran round the clock. Looks similar to a serious hg failure however they kept driving on so not that anyway