Does a failing crank seal cause visible leaks on the driveway or garage floor in every case?
I have been told I need to replace the crank seal. Service tech discovered a leak. I haven't noticed any leaks on the garage floor. Could this be a small leak, where there's not enough oil leaking out to be on the garage floor?
My car has 150500 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
I like to classify leaks when I see them, and I think these identifications could help in your case. I use three classes of leaks:
Class 1 = slight wet residue leak around area with signs of a drip forming under the leak but does not drip on floor. (Does not require repair yet and may be normal)
Class 2 = moderate wet leak around the area with signs of a drip forming and does drip once or twice a day. (Recommend repair when possible and is not normal)
Class 3 = heavy active leak around the area with signs of a drip forming and actively dripping at least 1 drop a minute. (Recommend repair now; may cause failed component)
I recommend having the same technician show you the leak and then asking about its severity. If you do not feel comfortable with that mechanic, an independent technician from YourMechanic can come to your car’s location to diagnose the potential leak for you and replace your crankshaft seal if necessary.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
Oil leaks are often the most common symptom a car owner will notice when the seal starts to fail. When the crankshaft seal dries out, breaks, or cracks, there is room for oil to leak out. Even a small leak is enough for oil to accumulate on the engine. The larger leaks can make the oil drop to the front of the engine.
The most common symptom of a faulty crankshaft seal will be an oil leak. Depending on how bad the seal is, the leak could be small, causing oil to leak underneath the engine, or if it is a larger leak, there may be a puddle of oil in front of your engine.
Crankcase Ventilation Basics
If the engine is producing blow-by gases faster than the PCV system can dispose of them, an increasing surplus becomes trapped in the crankcase, causing excess pressure and inevitably, oil leaks.
Excessive wear which enlarges the crankcase bore for any reason may cause the crankshaft oil seal to leak. An undersize crankshaft could result in the same poor fit and a leak.
Yes. And it can be a bad source of an air leak, as can the o-ring on the dipstick handle top, dipstick guide.
Fortunately, the front crankshaft seal is easier to replace than the rear seal, with replacement costs starting around $200 and reaching $500 and above, depending on your vehicle and engine layout.
CRANKSHAFT SEAL LIFE-SPAN
Crankshafts seals do not last forever. If you are nearing 100,000 miles, then your crankshaft seal is near the end of its recommended service life. Manufacturers have a service interval that they recommend for most vehicle parts.
Crankshaft and camshaft position sensors can leak oil into the connector causing Check Engine Light illumination. The engine may also stall as a result. Leaking sensors should be replaced.
Automotive seals generally stay soft for about 10 years and 100k miles. Once they begin to harden that`s when they can develop leaks.
The crankshaft rear oil seal is usually hidden by the flywheel and clutch housing, so the only visible sign of a leak is a drip from the bottom of the clutch housing . Where the seal is leaking badly, there may be clutch judder or slip caused by oil spraying on the clutch. Replacing the seal is the only cure.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Does a failing crank seal cause visible leaks on the driveway or garage floor in every case?
ANSWER : I like to classify leaks when I see them, and I think these identifications could help in your case. I use three classes of leaks:
Class 1 = slight wet residue leak around area with signs of a drip forming under the leak but does not drip on floor. (Does not require repair yet and may be normal)
Class 2 = moderate wet leak around the area with signs of a drip forming and does drip once or twice a day. (Recommend repair when possible and is not normal)
Class 3 = heavy active leak around the area with signs of a drip forming and actively dripping at least 1 drop a minute. (Recommend repair now; may cause failed component)
I recommend having the same technician show you the leak and then asking about its severity. If you do not feel comfortable with that mechanic, an independent technician from YourMechanic can come to your car’s location to diagnose the potential leak for you and replace your crankshaft seal if necessary.
Can failure of a transfer case cause damage to a differential?
ANSWER : Hi there. Based on the mileage of your vehicle, its possible that the seal could have gone out on its own. A dynamic seal (seal on a shaft) will last for up to 80,000 miles on normal conditions, however, this depends on the engine load and where the vehicle is driven. Dirt and contamination can cause the seal to prematurely fail and causing the oil to leak out of the differential. First check the differential oil level. If there is no oil, then the seal was leaking and leaked out all of the oil. If the level is full or slightly low but within range, then the differential could have failed from either overloading the gears or causing an over-speeding condition and then an instant stop (usually when off-road). Its possible for the transfer case to fail and make the differential have a jolt to break a gear, but its more common to have the oil leak out or the gears to over-spin. If you need further assistance with replacing a damaged differential, then seek out a professional, such as one from Your Mechanic, to help you.
Are these oil leak problems related?
ANSWER : If the oil filter housing is integral to the oil cooler, or the housing had to be removed to service the cooler, a professional mechanic with knowledge of the limited service life of rubber seals would have absolutely (guaranteed) replaced the filter housing gasket that you are now belatedly finding leaks. However, if the leaking gasket is in an assembly that was not touched, or is not part of the cooler, they might be on reasonable grounds to have not fooled with it. These cooler configurations vary (from Mercedes Benz model to model) so, having the advice I just gave, you can just simply ask them what configuration you have and go from there. The bottom line is, if indeed, the gasket that is presently leaking was "right in front of them" while they did the warranty work, it should have been replaced simply as a matter of course. Indeed, the weak link on modern engines has become gaskets and seals. The engine will mechanically far outlast the gasket and seals but the problem is to replace all of them (once they all leak) you have to literally take the engine out of the car and take it apart just to put all new seals in. Please let us know how we can help further on this issue.
My mechanic is saying the timing chain is bad (causing oil leaks). Does a timing chain cause oil leaks? What are your thoughts?
ANSWER : Hi, thanks for writing in. Timing change themselves cannot cause an oil leak but the timing chain cover can cause an oil leak. In order to replace the timing cover gasket, you will have to remove the serpentine belt and anything that has belt driven. This includes the alternator power steering pump air conditioning compressor and crankshaft pulley as well as the water pump. Once all of this is remove the timing cover can be removed and the gasket can be replaced. I would strongly recommend having this job performed by a professional as many parts are required to be removed in order to even access the timing cover. Here at YourMechanic, we can have a technician come to your home or office to perform this replacement for you.
I have been having cold drinks every morning I cranked it up a few times and then I guess when it gets heated up it cranks but now
ANSWER : Hi there. Sometimes when it gets cold outside, the fuel system will loose pressure and cause a cold starting issue. Another cold weather issue is sometimes caused by a cold start injector. This part is located on the cold air intake, which is found on the intake manifold. It is a fuel injector that is controlled electronically. The cold start injector works only when the engine has a cold start, or when the engine’s temperature is below a certain point. When this happens, a computer tells the injector to inject more fuel into the mixture that goes through the cylinders to the engine. You might want to have a professional mobile mechanic come to your location and complete a car is hard to start inspection.
Could a leaking master cylinder cause the brakes to go to the floor very suddenly? 2004 Pontiac Grand Prix
ANSWER : Hi – yes, a master cylinder problem, or a leak in the brake system anywhere, could cause "sudden loss of pedal". Check your brake fluid level first for low fluid. If fluid gets low enough that air gets in the system, the brake pedal will be VERY weak or spongy – air compresses, brake fluid does not. I would recommend a brake system inspection before driving any further by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs.
Crank seal leaking
ANSWER : Hello! I suggest getting a second opinion of the source of the leak, because a crank seal will not leak a fluid other than oil. The leak may be from a transmission seal, which is located almost "face to face" with one of the crank seals, so a leak from there could easily be confused as coming from a crank seal. I suggest having a certified technician, such as the staff provided by YourMechanic, inspect the leak to clarify which seal is leaking, and recommend the best path to repair.
Rear Axle Seal Replacement – What type seal?
ANSWER : Hi there, thanks for writing in. I recommend buy the Toyota OEM part. Although we could go into high detail as to the precise technical differences amongst the various and competing aftermarket seals you are describing, such will not change the conclusion at all. Generally speaking, aftermarket parts are NOT as good as the factory OEM parts. Large car manufacturers spend hundreds of millions of dollars, indeed billions, developing the technologies used in these vehicles and ALL of the parts are extraordinarily carefully engineered to fit very precisely and perform specific functions. In the aftermarket, they try to duplicate that, but more often than not, it does not work. Toyota OEM quality in particular is not duplicated well, if not at all, in the aftermarket.
