Safeguarding engine rebuilds from debris
By Steve Scott
Beware of what may be lurking in the dark.
Can you imagine the dismay and the sick, sinking feeling an engine owner and a reputable rebuild shop felt when the cylinder liner seals of a recently overhauled engine failed? Even worse when a troubled sight was revealed: sand tightly packed around the liners, contaminating the entire cooling system. Peering into the cylinder block where the liner once snugly fit, they could see a disheartening accumulation of debris above the lower receiver bore, with more littering the shop floor.
At the time when the engine was rebuilt, the owner was satisfied that they had spent good money to have their CAT 3406 or C15 engine built correctly. No expense was spared; they did not cut corners and all major components were rebuilt or replaced with brand new ones. The engine was rebuilt by a shop they trusted. The rebuilder and technicians that built the engine took pride in building an engine that was going to last and staked their name and reputation on it. Little did they know, the first time this engine started, the evils lurking in the dark were released.
Read this article with all images in the digital issue of Engine Professional magazine https://engineprofessional.com/2024EPQ3/#p=90
Regrettably, this isn’t an isolated incident. In recent months, we have seen and received reports of multiple instances of CAT 3406 or C15 engine components being damaged or engine failures due to casting sand and debris left in some new replacement cylinder heads. As these engines age, the current cylinder heads may not be reusable or possibly the cost of a new replacement head is more enticing than rebuilding the older cylinder head, so they opt for a new replacement head. However, the attraction of cost-effectiveness may conceal a hidden peril.
The intent of this article is not to cast doubt on any specific supplier(s), rebuilder(s), or their products. Rather, the intent aims to provide information to help safeguard engine owners and rebuilders from this hidden nemesis. This problem appears to be too widespread for us not to bring it to the industry’s attention.
The amount of rubble left in some of these new head casting is staggering, and it is not limited to casting sand. Reports of metal fragments and sizable pieces of slag were found coming from allegedly new cylinder heads on their engines.
In the pictures below, looking closer at the larger piece of slag displays an interesting outline.
Material analysis was not done on this piece; however, you can use your own imagination to decide what to make of it. My mind tends to wonder into what source of material are they repurposing to cast these cylinder heads? While the focus of the reports we have received have been on CAT 3406 & C15 engines, it is hard to believe these issues are limited to just these CAT engines and cylinder heads. What about the other engine manufacturers and the component castings they are producing?
The photos at the right show damage to the lower seal area of a cylinder liner and the lower receiver bore of the cylinder block attributed to steel shot peen. Investigation into the rebuild processes confirmed that the culprit was stray steel shot pellets inadvertently left within a new cylinder head.
The damage caused by this type of debris is not limited to the damage shown on these cylinder liners and blocks. Debris in the cooling system can wreak havoc on any of the parts and casting it contacts, including water pumps, oil coolers, thermostats, among others. Visual inspection of the casting ports may not be enough to detect the lurking threats and assure you have a safe cylinder head.
As we mentioned before, the intent of this article is not to cast doubt on any individual supplier(s), rebuilder(s), or their products. We do strongly suggest that new cylinder heads be carefully inspected and any gremlins that may be hiding in the darkness be flushed out before installing these new cylinder heads.
Read this article with all images in the digital issue of Engine Professional magazine https://engineprofessional.com/2024EPQ3/#p=90