M O, THE TROUBLES I’VE SEEN!
M
y job as a diagnostic technician for a
vehicle extended
warranty company
takes me into automotive repair shops
across a wide area. I¡¯m sent to help
technicians in these shops make a diagnosis when problems occur and to determine the correct course of action to
repair the problem. The engines in today¡¯s vehicles certainly are more
durable and reliable than the engines of
the past, but problems and failures do
still occur. These problems may be
caused by manufacturing defects, failed
parts or neglected maintenance. Regardless of the cause, it¡¯s my job to
make sure an engine is repaired correctly and the vehicle gets back on the road.
Following is a small sampling of the internal engine problems I¡¯ve seen during
my service calls, along with their remedies. I hope you find them helpful in
dealing with the vehicles that come into
your service bays.
Ford Engine Noises
Diagnosing upper engine noises in today¡¯s engines with variable cam timing
can be difficult. The 2004-05 Ford 4.6
and 5.4L three-valve V8s are among
them. Early on, this engine family had
problems with VCT phaser and lifter
noises. The VCT phasers make the
most noise when the engine is hot, below 1200 rpm. Some light noise is considered normal. However, if the noise
goes away over 1200 rpm, the VCT
phaser could be bad.
Lifter noise can be isolated using a
stethoscope on different areas of the
engine block. Ford TSB 06-19-8 states
that if lifter noise is isolated to a single
cylinder, only the affected lifters
should be replaced. I disagree with this
approach, because any lifters that are
not replaced could easily start making
noise a few hundred miles down the
road. Now you have an unhappy customer and the job will have to be redone. It¡¯s much better to replace all
the lifters at the same time.
Ford Timing Components
The 2004-10 Ford F-150s with the 4.6
and 5.4L V8 three-valve engines are
also having problems with the timing
34
November 2013
O, THE
TROUBLES
I¡¯VE SEEN!
BY KENNETH HANNA
Internal engine troubles, that is. No one
would dispute that today¡¯s engines are
more durable and reliable than the engines
of the past. They¡¯re also more complicated
and technically sophisticated, which makes
an accurate diagnosis extra important
when problems or failures do occur.
Photo courtesy General Motors
components. The gasket on the oil
pressure-operated timing chain tensioner may blow out (photo 1 on page
36), causing a number of running
problems. The blown gasket will lower
oil pressure to the VCT system, causing diagnostic trouble codes to be set
and engine performance to be affected. The low oil pressure lowers the oil
volume going to the camshaft. This in
turn causes damage to the camshaft
and scoring of the camshaft bearing
caps (photo 2). The low oil volume to
the camshaft also causes scoring of the
camshaft bearing surfaces in the cylinder head. Over time, this ruins the
cylinder head and the camshaft.
This also puts a lot of metallic particles in the engine oiling system, which
then spreads them to other parts of
the engine (photo 3), including the
connecting rod and main bearings.
This doesn¡¯t normally cause an instant
failure, but over time the engine bearings will fail.
The best repair for an engine that
has become contaminated with and
damaged by metallic particles is to replace it with a new or rebuilt engine.
Trying to rebuild such an engine may
end up costing more than the price of
a freshly rebuilt engine. While it might
be less expensive, I would not recommend installing a used engine. It could
have some of the same internal problems you were faced with originally.
This engine design features two oil
pressure-operated timing chain tensioners. If an engine has no damage
from a blown tensioner gasket on one
side of the engine, be sure to check
the tensioner on the other side. Pull
the valve cover on both sides and
check the camshaft bearing caps for
scoring. Even if everything looks good,
I would still recommend replacing all
of the timing components and tensioners. Ford techs I¡¯ve spoken with are
not aware of any changes or improvements in the tensioner design. New
tensioners are supplied with the gasket
preinstalled.
There are several ¡°shortcuts¡± that
are sure to lead to comebacks. Never
replace one or both cylinder heads
without replacing all of the timing
components, including both timing
chain tensioners. Never replace just
November 2013
35
O, THE TROUBLES I¡¯VE SEEN!
one tensioner; always replace both.
And always check both camshaft and
bearing caps for scoring.
1
2
GM Gradual Coolant Loss
36
November 2013
3
Photos: Kenneth Hanna
Some 2001-06 GM 4.8 and 5.3L V8
engines suffer from gradual coolant
loss (described in GM TSB 06-06-01019B). These engines have been installed in Silverados, Suburbans and
Tahoes, as well as several other GM
vehicles. The full vehicle list is included in the TSB. Symptoms the vehicle
owner may notice are a low coolant
level during regular fluid checks or oil
changes by a repair shop. The vehicle
owner may also notice a ticking noise
that sounds like a lifter, which may
cause him to bring the vehicle in for
diagnosis.
The likely cause of these symptoms
is coolant that¡¯s getting into the oiling
system through the cylinder head and
contaminating the oil. When diagnosing a lifter noise or coolant loss, the
easiest thing to do is remove the valve
cover, which may reveal the first sign
of a problem. Look for a pale yellow
sludge that has built up on the underside of valve cover (photo 4 on page
38). This sludge is caused by coolant
that has condensed on the valve covers
and other parts of the engine.
If the coolant leak is caught early
enough, permanent engine damage
may be avoided. But if this gradual
coolant loss is allowed to continue for
an extended period of time, major engine damage can occur. The sludge also
builds up in the oil pan around the oil
pump pickup screen and can restrict oil
flow. All of the sludge in the oil pan will
not drain out when the oil is drained.
The TSB describes the source of the
internal coolant leak¡ªa cylinder head
with a porosity crack that allows
coolant to leak into the engine oil. The
crack or cracks can be found around
the oil drains in the five cylinder head
bolts that are near the rockers (photo
5). These cracks are usually not visible,
but coolant will either pool or leave
stains in the area surrounding a crack.
When the cooling system is pressurized, you can sometimes see the
coolant bubble or start to pool in the
area (photo 6).
A damaged timing chain tensioner gasket on 2004-10 Ford 4.6 and 5.4L V8 threevalve engines can cause a number of running problems. The tensioner gasket
shown in photo 1 is blown in the right corner. The damaged gasket lowers the oil
volume going to the camshaft. This causes damage to the camshaft and scoring
of the camshaft bearing caps (photo 2). This engine also suffered extensive
damage due to metallic particles circulating throughout the engine oiling system. Some of these particles have accumulated in the oil pan (photo 3).
In this case, the head with the porosity problem was manufactured by a
company called Castech. Its cylinder
heads can be identified by a small rectangular logo found between the front
or rear rocker arms (photo 7). If you
find a leaking Castech cylinder head, it
must be replaced. If you can¡¯t find any
cylinder head coolant leaks via a visual
inspection, the heads should be removed and pressure-checked by a machine shop.
If you were not aware of this cylinder head porosity problem, some time-
consuming and costly mistakes could
ensue. Perhaps you might decide that
the head gaskets were the cause of the
coolant loss. Replacing them would not
repair the leak. Be sure to take the
time to make the right diagnosis.
Toyota Cylinder Head Bolts
Some Toyota models with the 2.4L
(2AZ-FE) engine have experienced
problems with the mating threads for
certain cylinder head bolts stripping in
the block. This engine is installed in
many Toyota models, including 2002-
O, THE TROUBLES I¡¯VE SEEN!
4
5
6
7
A telltale indication of coolant loss on 2001-06 GM 4.8 and 5.3L V8 engines is a pale yellow coolant sludge buildup on the inside of the valve covers (photo 4). Coolant leaks into the oiling system, creating the sludge. The leaks are caused by a cylinder head with one or more porosity cracks, usually found around the oil drains that surround the five cylinder head bolts
near the rockers (photo 5). You may see evidence of coolant stains or droplets of coolant pooling around the head bolts
(photo 6). The cylinder head porosity cracks may not be revealed during a visual inspection, so pressure-testing at a machine shop will be required. Cylinder heads manufactured by Castech have been identified as those most likely to develop
porosity cracks. These heads can be identified by the company¡¯s manufacturing logo, which is cast into the head (photo 7).
06 Camrys. Toyota TSB SB-0015-11
provides a complete listing of the affected years and models.
One of these vehicles may come into your shop due to engine overheating, a miss, a coolant leak or coolant
getting into a combustion chamber. If
you notice coolant leaking between
the head and the block under the center part of intake manifold, it could be
because of a stripped head bolt or engine block threads. This problem
seems most frequently to affect the
back three center head bolts.
Diagnose this problem by removing
the valve cover as well as all of the
necessary parts to gain access to the
head bolts. Check all of the head bolts
to see if any are loose. If you discover
any loose bolts, the cylinder head will
have to come off. How hot the engine
has gotten will have a big effect on the
38
November 2013
8
type of repair you¡¯ll need to perform.
If the engine block and cylinder head
surfaces are not warped, then an engine block repair could be considered.
This will require removing the engine
and sending it to a machine shop to install thread repair inserts.
If the cylinder head is badly
warped, it¡¯s a sure bet the engine has
been very hot for an extended period
of time, and attempting to repair the
block is not recommended. The better
option would be to install a rebuilt engine. A used engine replacement is
not advisable, as it may have the beginnings of the same problem.
Toyota Oil Consumption
The intake valve seat on this 3.7L Dodge
V6 head has come out of the head. This
type of failure typically occurs after
the engine has been overheated.
I visited a technician who was working on a 2004 Camry with the 2.4L
engine that was using over a quart of
oil every 700 to 1000 miles. He found
This GM 5.3L V8 engine
was brought in for repair
because it was making a
noise that was difficult to
isolate. After removing
the valve cover, the tech
isolated the source of
the noise by putting the
end of a stethoscope on
one of the intake valve
rocker studs. A pitted
valve lifter roller (photo
9) was responsible for
the noise. The damage
extended to the camshaft
lobe (photo 10). A complete repair required replacement of the cam shaft and all valve lifters.
9
that the oil return holes behind the
piston oil ring grooves were blocked
with carbon. This was causing some
of the oil to be pushed past the rings
into the combustion chamber. This is
a case where if you were in a hurry
and just put in a set of rings, it would
not cure the oil consumption problem. The oil ring return holes must
be cleaned.
Chrysler Valve Seats
The Chrysler 3.7L V6 engine has experienced isolated issues with valve seats
falling out of the head after the engine
has been overheated. The intake valve
11
10
seat in photo 8 on page 38 was in a
2007 Dodge Nitro. It had come completely out of the head, holding the intake valve open. I realize this is after
the damage was done, but if a Chrysler
3.7L V6 comes into your shop, this
might help you know what to look for.
GM Valvetrain Wear
Some mechanical problems don¡¯t
make enough noise to allow you to
detect the problem. A GM 5.3L V8
engine was brought into a repair shop
because it was making noise, which
was not loud enough for the tech to
isolate the source. The tech removed
12
The end of the crankshaft key has broken off on this 4.0L Ford V6 engine (photo
11). The vehicle was brought into the shop because of a no-start condition.
Whether the no-start was due to this broken part or something worse that preceded it could not be determined. The single-row crankshaft timing gear on the
engine is very narrow. This directs all of the force onto a relatively small section
of the crankshaft key (photo 12). Always check these parts for wear or damage
whenever the timing cover is removed for any reason.
the valve cover and pinpointed the
noise by putting the end of a stethoscope on one of the intake valve rocker studs. One of the intake valve
lifters had a pitted roller (photo 9),
and the camshaft (photo 10) was pitted as well. Both needed to be replaced. The tech ended up replacing
all of the lifters and the camshaft.
Ford Crankshaft Key
A 2007 Ford Explorer with the 4.0L
engine came into a repair shop with a
no-start condition. The tech found
the crankshaft key that holds the timing gear in position had broken off
(photo 11). The single-row crankshaft
timing gear is very thin and fits on
the end of crankshaft key (photo 12).
I¡¯m not sure what broke the crankshaft key because the engine also exhibited other major internal damage.
The key could have been broken due
to the other damage inside the engine, or to the gear being thin and fitting on the very end of key. If the key
and gear broke first, this is what
caused the rest of the engine damage.
If you get a Ford 4.0L engine in your
shop and are doing any work that requires you to remove the front timing
cover, check the crankshaft gear and
key for looseness. Even if these parts
look okay, it¡¯s probably worthwhile to
replace them as insurance.
This article can be found online at
.
November 2013
39
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