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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