M O, THE TROUBLES I’VE SEEN!
My 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
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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.
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
Photo courtesy General Motors
November 2013
35
O, THE TROUBLES I'VE SEEN!
one tensioner; always replace both.
And always check both camshaft and 1
2
bearing caps for scoring.
GM Gradual Coolant Loss
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--a 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).
3
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-
Photos: Kenneth Hanna
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November 2013
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
8
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.
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
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
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November 2013
This GM 5.3L V8 engine
9
was brought in for repair 10
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 com-
plete repair required re-
placement of the cam-
shaft and all valve lifters.
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
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
11
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
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