Cylinder Head Cracking

Hi,

I was hopeful that someone might be able to give me a different insight
into a problem that occurs with my dads celica.
The car has an issue where that around every 150000kms it cracks the
head into either the number 2 or 3 exhaust port. the engine is a 3S-GE
with TVIS. The only mods are a cold air intake to feed the factory air
box and a set of tri-Y long primary exhaust headers.
The car has done it to 3 heads so far and always the same problem. The
engine runs fine when the head cracks and still produces full power it
just pumps the radiator into the exhaust with a cloud of steam.
It has also has had the engine changed the last time it happened to a
jap spec motor. The car has had the water pump, the thermostat and the
radiator replaced that the car never has any heating problems.
It usually has the oil changed every 5000kms with the longest it's been
being 7000kms. The car does a lot of highway driving occasionally towing
a lightly loaded trailer. On average it does about 800kms per week.
About the only thing that has happened to the car other than normal wear
and tear is that the heat from the exhaust warped the blades on one of
the radiator fans.
The only thing I can think of is that the head gasket it not allowing
correct water flow to the head and causing a hot spot which causes the
cracking, But I'm not convinced this is the cause and the head gaskets
used are identical in water flow holes to the factory Toyota one.

If anyone has any ideas as to what could be the cause I'd be grateful to
fix this problem as my dad would like to keep using the car for work for
as long as possible.

Nick

On Mon, 05 May 2008 20:34:13 +1000, Nick Bourne <"nabourne at
tpg.com.au"> wrote:

>Hi,
>
>I was hopeful that someone might be able to give me a different insight
>into a problem that occurs with my dads celica.
>The car has an issue where that around every 150000kms it cracks the
>head into either the number 2 or 3 exhaust port. the engine is a 3S-GE
>with TVIS. The only mods are a cold air intake to feed the factory air
>box and a set of tri-Y long primary exhaust headers.
>The car has done it to 3 heads so far and always the same problem. The
>engine runs fine when the head cracks and still produces full power it
>just pumps the radiator into the exhaust with a cloud of steam.
>It has also has had the engine changed the last time it happened to a
>jap spec motor. The car has had the water pump, the thermostat and the
>radiator replaced that the car never has any heating problems.
>It usually has the oil changed every 5000kms with the longest it's been
>being 7000kms. The car does a lot of highway driving occasionally towing
>a lightly loaded trailer. On average it does about 800kms per week.
>About the only thing that has happened to the car other than normal wear
>and tear is that the heat from the exhaust warped the blades on one of
>the radiator fans.
>The only thing I can think of is that the head gasket it not allowing
>correct water flow to the head and causing a hot spot which causes the
>cracking, But I'm not convinced this is the cause and the head gaskets
>used are identical in water flow holes to the factory Toyota one.
>
>If anyone has any ideas as to what could be the cause I'd be grateful to
>fix this problem as my dad would like to keep using the car for work for
>as long as possible.
>
>Nick

A little detective work is needed on this one.

1. It must not be a problem with the head, you've replaced the head
three times. I'm assuming you replaced them with new, known good,
heads.

2. It must not be a problem with the engine block, you've replaced
the engine. Again I assume you used a new engine or short block.

3. I don't see how feeding cold air into the factory air filter box
could cause the head to crack, unless you use a blower to feed in the
air. So your mod to the air filter box shouldn't be the cause of the
problem.

4. Heads usually crack because of either over-pressure or uneven heat
distribution. If it always cracks at the exhaust port, then the
problem might be the after-market headers you've installed.

Go back to the OEM headers and see if the heads still crack.

Nick Bourne wrote:
> Hi,
>
> I was hopeful that someone might be able to give me a different insight
> into a problem that occurs with my dads celica.
> The car has an issue where that around every 150000kms it cracks the
> head into either the number 2 or 3 exhaust port. the engine is a 3S-GE
> with TVIS. The only mods are a cold air intake to feed the factory air
> box and a set of tri-Y long primary exhaust headers.
> The car has done it to 3 heads so far and always the same problem. The
> engine runs fine when the head cracks and still produces full power it
> just pumps the radiator into the exhaust with a cloud of steam.
> It has also has had the engine changed the last time it happened to a
> jap spec motor. The car has had the water pump, the thermostat and the
> radiator replaced that the car never has any heating problems.
> It usually has the oil changed every 5000kms with the longest it's been
> being 7000kms. The car does a lot of highway driving occasionally towing
> a lightly loaded trailer. On average it does about 800kms per week.
> About the only thing that has happened to the car other than normal wear
> and tear is that the heat from the exhaust warped the blades on one of
> the radiator fans.
> The only thing I can think of is that the head gasket it not allowing
> correct water flow to the head and causing a hot spot which causes the
> cracking, But I'm not convinced this is the cause and the head gaskets
> used are identical in water flow holes to the factory Toyota one.
>
> If anyone has any ideas as to what could be the cause I'd be grateful to
> fix this problem as my dad would like to keep using the car for work for
> as long as possible.
>
> Nick

Thanks for the ideas guys and we'll try to source a factory header but
last time we tried they were all cracked or not available. Didn't try
toyota but we might be able to get one for a different later model car.
I don;t know if they still support cars from 1986 for things like that.

Just to update you with a couple of details i missed.

1. When the engine was replaced it was with a long motor(Full motor
minus manifolds), this is the last one to crack. it wasn't new but came
out of a low k'm rear hit fount cut from japan and had never been opened.

2. The cold air feed is directed into the factory air intake to make
sure water was not ingested by the motor and is feed from behind the
grill to keep it high for the same reason. But I'm sure this can be
ruled out.

3. The factory cast iron header went into the bin years ago as it was
full of cracks. Second hand one were not available due to cracking and
the after market headers were the only option. the head design does put
the pipes for 2 & 3 cylinder close together though, and i had thought it
might be to much heat in the pipes.

4. When mounted in the car the motor is angled back at about 10 degrees
making the exhaust side of the head the highest and what i would think
to be the most prone to vapor locks.

5. we have always used the same head bolts on the car and they have been
tightened to what was said in our workshop manual. No one ever mentioned
or any manual that the head bolts stretched and we would need new ones.
We also have a haynes manual and the factory manual for the motor/body.

6. When we replaced the head we check the head and block for warping /
high spots etc and we have never found any. ( It's something i consider
a must when working with an alloy head on a cast iron block)and we have
tried the factory head gasket, as when it occurred for the second time
we thought it might be a gasket fault so we compared the after market
type to the factory and the gaskets were the same. I had thought that
the water gallery holes in the head were not opened up enough and most
of them are blocked not allowing water to flow through the gasket but
the factory was the same.

Don't know if any f this was useful but it might shed more light on it
for you.

On Tue, 06 May 2008 15:22:01 +1000, Nick Bourne wrote:

> 5. we have always used the same head bolts on the car and they have been
> tightened to what was said in our workshop manual. No one ever mentioned
> or any manual that the head bolts stretched and we would need new ones. We
> also have a haynes manual and the factory manual for the motor/body.

Hmmm....everything I have ever read said use new head bolts. With a little
luck, this is your problem! ("Do I feel lucky?" Well, DO YA, PUNK!!!

On Mon, 5 May 2008 22:49:20 -0500, "Ray O"
<rokigawaATtristarassociatesDOTcom> wrote:

>
>"Nick Bourne" <"nabourne at tpg.com.au"> wrote in message
>news:481ee2bb@dnews.tpgi.com.au...
>> Hi,
>>
>> I was hopeful that someone might be able to give me a different insight
>> into a problem that occurs with my dads celica.

snip
>
>Also, you should be using new head bolts every time the head is removed as
>they are designed to stretch when tightened. If you are re-using the same
>bolts, they may not be supplying correct torque.

I'm missing something here Ray. If the head bolts are designed to
stretch when tightened, wouldn't they stretch over time with heating
and cooling cycles? That would result in less than the designed
compression of the head gasket and leaking or blown head gaskets after
a few years.

Also I would think that reusing the head bolts would result in warped
heads due to the above uneven compression. The effect would be the
same as applying the correct torque on only some of the bolts. But I
don't see how it could cause cracks through an exhaust valve seat.