![]() ![]() Remember: While checking these areas for leaks, we must also be sensitive to various mechanical and electrical considerations as well. There is a raft of common leak points to inspect following a path that addresses them all is our goal. The presence of an obvious leak, such as a cracked apply piston, should not stop you from investigating further. Any time a burnt clutch pack is found, all three circuits must be inspected methodically to discover and eliminate all the leaks - big and small. Like 3-4 clutch oil, AFL and line pressure circuits have common leak points. Since any pressure change in one part of the circuit affects the rest of the circuit, even small leaks at a few junctions along the way can add up to a big enough pressure loss to allow slipping.Įven if the 3-4 circuit is working perfectly, low or unstable line pressure (and AFL pressure, which affects line pressure) can cause slipping and burning. The 3-4 hydraulic circuit is quite long it is interconnected to D4, Forward clutch, 2 nd, 2 nd clutch and 3 rd accumulator circuits. Low line pressure and/or leaks of 3 rd Gear oil are the root cause of most 3-4 slipping. ![]() Relying on this routine each time you encounter burnt 3-4 clutches will give you the peace of mind that comes from knowing you addressed all the problem areas and a comeback is not likely. ![]() With an understanding of the circuits and components involved, a solid inspection and testing routine that covers all the bases can be adopted. We see the 3-4 burnup issue frequently, but finding the root cause can often be elusive.Īll it takes to successfully stare down 3-4 slip and burn - and the anxiety that comes with it - is a good map and a plan to follow. Cracking a pump cover during stator shaft installation or compromising an input shaft seal are common, self-inflicted wounds that lead to smoked clutches. Compounding the difficulty of diagnosing the original burnup is the fact that it is easy to induce new causes for failure during repair/rebuild. Since the cause of 3-4 burnup can be due to a single failed component or a combination of leaks, the repair that worked last time won’t necessarily work this time - or the next. But it doesn’t have to be an exercise in frustration burnt 3-4 clutches can be transformed from a dreaded problem into a routine money maker. Some technicians get frustrated and throw multiple Hail Mary replacement parts at the transmission when facing this issue. Tech hotlines and internet bulletin boards are often jammed-up with people pleading for help with this 3-4 roasting. Burnt 3-4 clutch packs are notoriously common in the GM 4L60/E family of transmissions. ![]()
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