Head bolt failure and Coolant Loss on 2002-2006 Toyota 2.4L engines
john
the 2.4L engines, resulting in $4000+ of repairs, because head bolts
simply come loose by themselves. I suspect 2007+ engines will suffer
the same fate down the road.
"3/6/2008
Coolant Loss on 2002-2006 Toyota 2.4L, 2AZFE engines
The following information concerns the loss of coolant on some
2002-2006 Toyota 2.4L, 2AZFE engines. The location of this condition
has been noted at the rear of the engine where the cylinder head bolts
to the cylinder block.
It has been reported that stripped head bolt threads have been found
on some of these engines during tear down. When the two rear head
bolts lose their clamping ability they allow coolant to seep out at
the rear of the cylinder head.
To repair this condition, engine builders report using thread repair
tooling used for various GM engines. Specifically, Cadillac 4.6L
engines use the same threaded head bolts (Figure 1). The head bolts
for this Toyota engine may be reused if they are not damaged and meet
the following length specification.
Using a vernier caliper, measure the length of the head bolts from the
seat to the end.
Specified bolt length: 6.350˝ to 6.465˝ (161.3 mm to 164.2 mm). If
the length is greater than the maximum, replace the bolt.
This information was provided by the Engine Builders Association
(AERA)."
http://www.enginebuildermag.com/Article/3569/coolant_loss_on_20022006_toyota_24l_2azfe_engines.aspx
Hachiroku ハチロク
Yeah. Thanks, hey...
ransley
How did that happen, it seems they were over torqued when being made?
Hachiroku ハチロク
According to what I can gather, the threading didn't go all the way to the
top, and if the bolt starts to loosen at all it pulls out of the head when
it gets to the position where there aren't any threads to hold it in.
David Wells
wrote:
I would think that if many Toyota camry with this engine are showing
up with this problem that there should be a recall for the dealer's to
check for this.
Leftie
Not to be too obvious, but head bolts aren't supposed to just loosen
up in the first place. I'm guessing they skipped a step in assembly, or
had materials problems.
ransley
> On Sun, 14 Jun 2009 17:40:42 -0700, ransley wrote:
> > On Jun 13, 11:22 pm, john <johngd...@hotmail.com> wrote:
> >> Some owners would notice coolant loss and leaks on the back side of
> >> the 2.4L engines, resulting in $4000+ of repairs, because head bolts
> >> simply come loose by themselves. I suspect 2007+ engines will suffer
> >> the same fate down the road.
>
> >> "3/6/2008
>
> >> Coolant Loss on 2002-2006 Toyota 2.4L, 2AZFE engines
>
> >> The following information concerns the loss of coolant on some
> >> 2002-2006 Toyota 2.4L, 2AZFE engines. The location of this condition
> >> has been noted at the rear of the engine where the cylinder head bolts
> >> to the cylinder block.
> >> It has been reported that stripped head bolt threads have been found
> >> on some of these engines during tear down. When the two rear head
> >> bolts lose their clamping ability they allow coolant to seep out at
> >> the rear of the cylinder head.
>
> >> To repair this condition, engine builders report using thread repair
> >> tooling used for various GM engines. Specifically, Cadillac 4.6L
> >> engines use the same threaded head bolts (Figure 1). The head bolts
> >> for this Toyota engine may be reused if they are not damaged and meet
> >> the following length specification.
>
> >> Using a vernier caliper, measure the length of the head bolts from the
> >> seat to the end.
>
> >> the length is greater than the maximum, replace the bolt.
>
> >> This information was provided by the Engine Builders Association
> >> (AERA)."
>
> >>http://www.enginebuildermag.com/Article/3569/coolant_loss_on_20022006...
>
> > How did that happen, it seems they were over torqued when being made?
>
> According to what I can gather, the threading didn't go all the way to the
> top, and if the bolt starts to loosen at all it pulls out of the head when
>
> - Show quoted text -
This is something like I would think GM would have done, we has a 82?
caddy with the 4.1, everytime we went to the dealer there were 5-6
motors on the floor for the week they replaced under warranty, even my
dealer said the 4.1 was probably the worst motor gm ever made. Well
maybe the Olds deisel conversion and the Vega were worse but the caddy
would blow head gaskets starting at 40000 onward, several I saw on the
highway in meltdown mode, black and white smoke out the exhaust. Toy
has noted alot of issues with their "becoming #1 in sales but after
this much time selling a defect like this it is disturbing.
Hachiroku
>> According to what I can gather, the threading didn't go all the way to
>> the top, and if the bolt starts to loosen at all it pulls out of the
>> head when it gets to the position where there aren't any threads to
>> hold it in.- Hide quoted text -
>>
>> - Show quoted text -
>
> This is something like I would think GM would have done, we has a 82?
> caddy with the 4.1, everytime we went to the dealer there were 5-6
> motors on the floor for the week they replaced under warranty, even my
> dealer said the 4.1 was probably the worst motor gm ever made. Well
> maybe the Olds deisel conversion and the Vega were worse but the caddy
> would blow head gaskets starting at 40000 onward, several I saw on the
> highway in meltdown mode, black and white smoke out the exhaust. Toy has
> noted alot of issues with their "becoming #1 in sales but after this
> much time selling a defect like this it is disturbing.
Actually, I was thinking about this.
At 40,000 miles my hachiroku needed a pre-emptive HG replacement.
Interesting because the 86.5-91 or 92 Supras had the same basic engine
design, and they also needed to have the HGs replaced. Of course, this is
a Yamaha engine...
Knowing then what I know now, I would have told them to pay for the HG on
the '86', since it is now apparent it was a congenital problem. Hey, it
was only $400 1988 dollars...
Hachiroku
According to what I saw, the threads aren't robust enough. The fix
appears to be Heli-coils. They sure as hell won't pull out!
Leftie
When Toyota actually produces bad designs like that, you know
they've finally replaced GM. ;-(
john
area of the engine another (that isn't anything new after Toyota
engines sludging for all those years). Overheating makes aluminum
alloy brittle and helps to make engine sludge.
Most head bolt threads don't go all the way to the top. Some are deep
inside the block. There are premium ARP 1/2" diameter studs that
people have used with good results in hot rod applications. In those
high performance applications cylinder head were held by nuts to the
head studs, not using head bolts.
john
their fingers to pick them up or something like that. And then turn
around and charge $4000-6000 for an engine replacement. ;) ;) ;)
john
john
Helicoil is great for many other applications, but for head bolts and
spark plug holes I would Time-sert.
Built_Well
> Some owners would notice coolant loss and leaks on the back side of the
> 2.4L engines, resulting in $4000+ of repairs, because head bolts simply
> come loose by themselves. I suspect 2007+ engines will suffer the same
> fate down the road.
==========
I'd like to point out that we still don't know what model
years are involved, despite the title of this thread.
Some 2004's do seem to be involved. But even with the
2004's we don't know what the failure rate is: 1 in a thousand?
1 in ten thousand? However, if it is 1 in 500, that would
definitely not be good.
Also, we don't know for sure if the head bolt problem
described by posters at CamryForums.com is related to a
partial threading issue. The partial threading theory
was brought up here; it was not brought up by the posters
at CamryForums.com , where it was suggested that the
loosened bolts could possibly be related to an excessive
heat spot near the head bolts caused by use of a plastic
intake manifold with a piece of foam rubber insulation.
It's possible that the partial threading found in * some *
engines and the plastic intake manifold found in all engines
are 2 totally different issues and may not be related to the
same problem. They may be different problems. Or it's possible
that both conditions must be present for the loosened head
bolts failure to materialize. We just don't have enough info
yet to know. Maybe the suits at Toyota know by now, but we are
just speculating as to:
(1) the model years involved and
(2) the cause.
I guess we also don't know how extensive the loosened
bolts issue is: 1 in 1,000? 1 in 500? 1 in 200?
Or one in five thousand?
John G Dole, you put down Toyota's coolant in the thread
titled "Coolant and ATF fluid changes on Toyota" without
mentioning that the coolant performed poorly only because
the test used old-fashioned, cheap brass copper radiators
with high-lead solder. Not revealing that fact about
copper brass radiators made me think you were trying to
do a hatchet job on Toyota ;-) [wink]
For other laymen like myself: copper brass radiators are
a relic from the past with no relation to today's aluminum
radiators :-)
John Dole, you're obviously a smart guy who knows a lot
about cars, but you seem biased against Toyota :-)