LS Engine Trouble Information – HSV & Commodore

Information Related To LS1, LS2, LS3, L76, L98 & L77

The LS engine range consists of modern pushrod V8s, which are known for their reliability. However, when issues do occur, car owners may ask questions such as “What caused the problem?”, “What could have been done to prevent it?”, and “How can it be prevented from happening again?” This article aims to provide information that will help car owners build awareness of some of the problems that may be faced while owning one of these engines.

One of the most common problems faced by LS engines, especially in older, modified engines, is hydraulic lifter failure. The first symptom of this may be a distinct knocking sound on one cylinder at idle, or a squeaking sound. If this happens, the car should be minimally driven, or even better, transported to a workshop or back to the place that did the work (since that is likely to be the cheapest place to have it fixed). Driving the vehicle like this can damage the camshaft lobe and cost more money to fix, as the squeaking is the sound of metal being scraped, which can also lead to cam and main bearing damage, as well as metal deposits in the oil pump. This damages the oil pump and further increases damage to the engine.

Sometimes, cars are driven for weeks with a knocking sound or are driven aggressively in an attempt to fix the problem, which can make a basic problem grow into a situation where the engine needs to be fully dismantled and rebuilt. This can make what started as a $1500 repair turn into a $9000+ repair. In addition to cam lobe damage, the lifter can fall apart and the roller wheel can bounce around the engine, potentially damaging the engine block or even cracking it. Sometimes lifters can break and the tapping can progress to the fall apart stage on the same day that the tapping is first noticed.

Most of the time, the cause of lifter failure is a worn lifter or ineffective lubrication due to engine oil deterioration, temporary or permanently low oil pressure (possibly from worn bearings), dirty oil, faults in the engine block tunnels, worn or faulty lifter buckets, high rpm when the engine is cold, or softened valve springs that need replacing. Sometimes, the tapping can be caused by a lifter that is spring loaded and has its spring mechanism jammed, making it solid, which is most common in old engines. Other times, the lifter roller wheel surface has failed (often due to poor oiling in the lifter bore) and this causes friction on the lobe, making a squeaking noise and damaging the cam lobe.

Lifters can be replaced with a wide range of aftermarket high-performance lifters, but these often suffer failures more often than desired. The best solution to prevent costly damage is to be vigilant and proactive in taking the car to be fixed when problems occur. Do not drive the car and cause secondary damage, as even if the engine is warranted, no warranty will cover damage from continued use once the failure has occurred.

The best preventative action is to listen for new noises often and don’t ignore any new tapping noises. When the engine has done over 100,000 km, change the lifters at the first opportunity. Changing them requires the heads to be removed and means the engine will also need new head gaskets and head bolts.

All high lift aftermarket camshafts with lift over 560 thou (thousandths of an inch) will result in a higher lifter failure rate. This is because these require higher spring pressures to prevent valve float, which puts extra pressure on the lifter. Using light rate springs is not a solution because then there is an increased rate of problems that result from valve float which creates hammering of the valve train. The main message is if you want to enjoy the benefits of a cam upgrade that gives you significantly more power then it compromises the overall engine reliability because of the extra rpm range. Once a car is modified for extra performance its important that the driver of that vehicle is sensitive to new noises and protective of it from secondary damage.

Link-bar lifters are not a solution, they may help with very high rpm valve float but that’s all. The bars prevent the lifters spinning in the bores but some engineers have suggested that the lifter guide system used from the GM factory is far better at controlling lifter vibration and if the guide/buckets are not worn the lifters cant spin anyway. The link-bar lifters let the lifters vibrated much more than the factory system and this can contribute to reliability problems from link-bars.

Noisy Hydraulic lifters can be caused by several reasons, none of which are due to a defective lifter and as a result, are not covered by manufacturers warranty.

1.  The most common cause is particles in the oil getting jammed between the lifter plunger and the lifter body, causing the plunger to become “stuck down”

The clearances between the plunger and body of a Hydraulic lifter can be as little as .00012”,  .003mm.  or 3 Microns (1/30th of a Human Hair)  Any particle larger than this circulating in the oil has the potential to flow through the lifter and jam the plunger in the body.  This is especially common after a rebuild where particles are left in oil galleries or crevices, and find their way into lifters.   Replacement of the lifters usually fixes the problem, as all the initial dirt has been captured by the lifters or the filter.

Note some “Racing” oil filters only filter down to 27 Microns and may not be suitable for Hydraulic lifter engines.

2. Aeration of oil in the pressure chamber of the lifter can cause noise.  This may be the result of air in the high-pressure chamber of the lifter affecting valve train lash. When this occurs, valve closing velocity is increased, which causes the noise. Air can be present in the lifter at shutdown due to an aerated oil condition, or it can be ingested into the lifter during a cold start from a suction side leak at the oil pump or oil pump pick up tube o-ring. Oil aeration level, oil viscosity, time to achieve oil pressure, engine speed, and lifter design all play a part in whether lifter noise is observed. Once air gets into the high-pressure chamber, it will slowly be expelled through the very tight clearance of the plunger and body.  Aeration can be caused at high RPM by low oil levels or an incorrectly designed oiling system.  This will result in lifters becoming “spongy” and will significantly affect the valve train operation.

Cam Bearings

Cam bearings are inside the block and provide support for the camshaft as it spins. These are very sensitive to oiling so their health depends on regular oil changes and using the right grade oil. Plus being gentle on engine start-ups.  Once cam bearings need to be replaced the engine needs to be removed from the vehicle and pulled apart. So it is an expensive exercise. The best preventative action is to change oil at least every 7500 km or less and use top grade since fortified synthetic oil. This is very important as a cost prevention exercise. 1-2 more oil changes per year could save an early engine rebuild.

Valve Spring Failure

There are two main types of valve springs available: Single, and Dual designs. The single is one spring that supports the valve on its own; the dual has a smaller spring inside the original. The factory springs are single and often when doing engine upgrades the springs are changed to dual springs.

The advantage of dual spring is that if one spring breaks then the other spring will hold the valve up and prevent it from dropping into the engine.  If a single spring breaks it is common for a valve to be dropped which causes a huge amount of damage. Sometimes the valve is held up by the valve locks and the spring is just collapsed.

The amount of damage from valve spring failure depends mostly on when the spring breakage is detected and how it is driven after the breakage. If an engine is driven for weeks or thrashed on a broken spring its likely that extra damage is done, the most common is a valve can be bent which will require that heads removal and a new valve is fitted along with new head gasket, head bolts. If the valve head brakes off this will result in much more damage. So it is crucial that at the first signs of a broken spring that the vehicle is not driven or if there is no alternative it is advised that it is far safer for the engine at low rpm so stay below 2000rpm.

Symptoms of a broken spring vary and can be evident as an instant change in the engine that is noticeable as a loss of significant power mostly above 4000rpm. It may sometimes be evident as miss under load. Other times there is a constant miss.  If a valve has dropped it will be far worse than that the engine will seize i.e. it will not be able to rotate.

Springs break at all stages of their life. Some new cars have broken springs within 5000km, some with factory springs last 300 000km without breakage. It depends to big extent on luck but one thing can help spring life and that is avoiding high rpm on cold springs i.e. Always warm up the engine by driving gently until its at full operating temperature.  Also, valve floating which is loss of valve control by the spring at very high rpm, this can be caused in the worst way by burnouts on the rev limiter sending shock harmonics through the springs. This ages them fast and will cause much more frequent breakages. Another cause of trouble can be severely overheating a spring from an engine that is overheated. If the engine is ever severely overheated then replace the valve springs.

Damage can also be done by ‘mechanical over rev events’ which can happen from a downshift into the wrong gear forcing the engine rpm well over its rev limiter rpm. There can be damage from the valves floating severely and hitting pistons and a range of other things including valve seat damage. A race team in the USA reported that valve springs in race engines that were not overrevved (wrong gear selected) lasted 10 times as long as those occasionally overrevved. Often valve springs will be fatigued from a single over rev to the extent they will not hold pressure and be prone to breakage.

With aftermarket cam upgrades it is best to change the springs every 40000km and check them once they reach 20000km to make sure they are holding pressure. If the engine is revved above 6000rpm often it is best to check and change springs more often. The main thing to recognize is that valve springs have a finite life and a variable lifespan depending on how they are treated.

Rocker Bearings

The rockers sit on top of the valve train and transfer energy from the pushrod to the valve. They can develop a sideways slop from their bearings which can cause problems with valve spring breakages due to harmonics. They can also fly apart with their needle bearings falling out and ending up in the oil pan. Its best to inspect them for signs of sideways slop and there are Rocker bearing upgrade bush kits that can be purchased and installed in the factory rockers which tighten up the slop and also give the rockers better range of motion vertically. This is a very good modification to the stock rockers.

Timing Chain Tensioners – VE-VF

Many early model timing chain tensioners are broken and this gives minimal symptoms, often only being noticed during a cam upgrade. But it isn’t good, the bits from the tensioner can be scattered around the engine.

Some people change timing chains when doing cam upgrades but it is very rare for LS timing chains to snap. But if they do it can cause a lot of damage.  To replace the timing chain is not a simple job at the front of the engine. It requires the sump to be removed and a fair bit of extra work to be changed. Often the oil pump is also replaced at the same time so the cost is around an extra $1000.  Timing Chains can snap but its rare and usually from severe situations like a mechanical over rev.

Cracking Cylinder Sleeves

Read our article about Core Shift and how it happens at factory. The LS blocks are aluminium with cast iron sleeves. When manufactured these sleeves are bored where they sit and this often results in variations of thickness side to side.

This presents weak spots in the cylinders which are prone to cracking when pushed hard with boost. They may also crack when the engine is overheated or just after there is significant cylinder sleeve wear. We can bore and remove the old sleeves and install much higher quality sleeves in precisely the correct “blueprinted” position. This can then give an engine a new life.

Clutch VE V8 2006 To Around 2009.

Holden changed all the clutches to the LS7 Clutch in the Sep 2010 and likely all LS3 Manuals have it. But before that the factory slave cylinders let the system down and the clutch pedal often stays down after high load high rpm, it will slip at high rpm under load when it is starting to fail. The fix for this is not to replace the clutch alone but also the slave.

Vigilance

We cannot emphasize enough the importance of vigilance with your LS engine.  Maintain the cars oil in top condition <8000 km old and top-level synthetic oil of around 5w-30. If there is a new noise get the engine checked straight away. Often as inconvenient as it is to have a car off the road and flat trayed to a workshop in terms of time and money, its often a cost-saving exercise for you.  Even in vehicles covered by a warranty for the actual parts that fail the person in control of the vehicle, must take all reasonable precaution to minimize damage to the vehicle and/or the vehicle’s components/ parts when you or they suspect a failure may have developed. Continued use voids warranty cover for any repairs required as a result of the continued operation of the vehicle once a defect or fault has occurred.

Engine Abuse And Its Effects

No engine will be able to withstand abuse from long stints near or on the rev limiter e.g. during burnouts.  Circuit racing where the engine oil and gearbox usually get well over the safe range unless specific coolers are fitted.  As was explained above the frequent use of the engines near the rev limiter will age their components much more quickly and even an engine with all new parts could have any of them fail in the early period from harsh usage.  This could be as simple as not letting an engine get to full operating temperature before using it at full load and its full range of rpm. Thrashing an engine early in its warm-up cycle will age its components much faster.

On the other side of things, if the engine is overheating then shut it down and let it cool no matter where you are, arrange assistance, do not keep driving it as parts will be damaged. Even if the car cools and seems OK it isn’t. It is one large step closer to failure. We see many cars with faulty radiator caps, blocked coolant recovery pipes, bad quality replacement radiators, cracked radiators both near the cap and at the bottom, bad thermostats, bad quality replacement water pumps, air bubbles in the coolant (cars never setup properly with coolant levels). Never replace your water pump or radiator with items that do not come highly recommended. We aim to only use GM genuine water pumps, radiators or NATRAD radiators.

Oztrack offers an engine rebuild service for the LS range of engines.

We commonly rebuild with far better than standard parts and do a cam upgrade. We also have in house engine machining services including a Sunnen Honing Machine as well as CNC Boring & Milling machines.

These are priced from $8500  we can complete these jobs precisely and quickly.

Follow the link below for more info

OZTRACK | Oztrack Performance Online