Knocking Sound Run Roughly Dark Transmission Fluid and Dark Engine Oil

It's making a knocking sound coming from under the hood? Transmission oil is dark color, so should I get a transmission oil fluid change or flush? It's running rough also. Should I get a Tune up? I haven't had a tune up in a long time. What consists of getting a tune up for it (I.e. replace spark plugs)?

My car has 334456 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
I am not sure how many miles your transmission has on it. I would say replace the transmission fluid but if its been more that 150,000-200,000 miles you may have to have a rebuild done on your transmission if you replace the oil. There are particles in your transmission at that point that are keeping your transmission running.

You probably do need to get a tune up including, oil change, oil filter, air filter, replace spark plugs and wires, I always suggest my customers (I do this to my vehicle faithfully also), put 1/2 can of sea foam in your engine before changing the oil. Let the engine run around 10 minutes but not more than 15 minutes. Then drain oil and replace oil filter. Do NOT drive your vehicle while sea foam is in your engine. Sea Foam will help with cleaning out sludge in your engine.

If you would like one of our professional technicians perform a tune up on your vehicle you may book one in your area at the link provided below.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

Low fluid will slow the cause the response time from gear shifting to become increasingly slow and difficult over time. You may even hear a light knocking sound if the problem becomes dire.
Low automatic transmission fluid can cause shaking. If the shaking is accompanied by the check engine light, it`s time to visit a mechanic. Drivers of manual cars might discover their clutch master cylinder is the source of the shaking.
The reason why transmission fluid changes from bright red to brown to black as it ages is that is it oxidizing. Oxidation is bad for transmission fluid. Dark brown or black transmission fluid is dirty and incapable of lubricating the hundreds of transmission parts. It will cause damage if you don`t have it changed.
When your transmission doesn`t have enough fluid, you may experience it stalling at red lights or stop signs. Though it should start right back up, taking your car to an auto shop for repair is key as your transmission lines may be leaking and may need to be replaced.
Strange Noises

If the sound resembles humming, buzzing, or clunking, you may be experiencing transmission failure. Bad automatic transmissions may emit humming, buzzing, or whining noises while manual transmissions have harsher “clunking” sounds.

One of the main reasons why your vehicle could be vibrating at idle could be due to worn out spark plugs. When a vehicle`s spark plug is faulty, it can interfere with the air-fuel ratio leading to improperly firing cylinders, resulting in a misfire while idling. Replacing your spark plugs will solve this problem.
Brown/Dark Brown

Brown and dark brown hues indicate that the transmission fluid is no longer viscous and it is oxidizing. Oxidizing means the fluid is filling with air bubbles and is unable to do its job. Change your transmission fluid right away when it`s this color.

What Color Is Bad Transmission Oil? A bad transmission fluid color oil is muddy brown, dark brown or black. If you notice this, schedule transmission maintenance as soon as possible before damage occurs.
There are many potential causes of burnt transmission fluid. One common reason is overheating due to excessive use or insufficient cooling. Transmission fluid can also be degraded by exposure to extreme temperatures, high mileage, or contaminated with metal shavings or other debris.
Low transmission fluid and worn-out gears can be the culprit – and computerized sensors and solenoids can cause clunking if they send the wrong information to your car`s gearbox.
Clunking, humming or whining sounds are signs of automatic transmission problems. Faulty manual transmissions will also give off loud machinelike sounds that seem to come out of nowhere. A clunking noise when you shift gears is a telltale transmission situation. Have a mechanic look it over.
Low transmission fluid and worn-out gears can be the culprit – and computerized sensors and solenoids can cause clunking if they send the wrong information to your car`s gearbox.
It could be an internal problem like a broken accumulator spring, or it could be a loose or broken engine or transmission mount. If you need further assistance, I recommend you have a certified technician, like one from YourMechanic, inspect your vehicle`s noise and repair any other failing component on your vehicle.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Knocking Sound Run Roughly Dark Transmission Fluid and Dark Engine Oil
ANSWER : I am not sure how many miles your transmission has on it. I would say replace the transmission fluid but if its been more that 150,000-200,000 miles you may have to have a rebuild done on your transmission if you replace the oil. There are particles in your transmission at that point that are keeping your transmission running.

You probably do need to get a tune up including, oil change, oil filter, air filter, replace spark plugs and wires, I always suggest my customers (I do this to my vehicle faithfully also), put 1/2 can of sea foam in your engine before changing the oil. Let the engine run around 10 minutes but not more than 15 minutes. Then drain oil and replace oil filter. Do NOT drive your vehicle while sea foam is in your engine. Sea Foam will help with cleaning out sludge in your engine.

If you would like one of our professional technicians perform a tune up on your vehicle you may book one in your area at the link provided below.

Engine in my truck is running rough, maybe oil problem?
ANSWER : Your problems are a common complaint voiced by other owners. You will need to have your engine checked for possible lifters that have collapsed and could damage the cam shaft in the engine. Some owners have changed oil types to a different synthetic brand and this has helped alleviate the conditions but did not fix problem. I would recommend contacting YourMechanic to get the noise verified and diagnosed to prevent possible damage or major engine failure. You said you use a lot of oil and have run low on oil before. You should check for possible piston rings causing this. Diagnosing the noise should be your top priority, and once the issue is identified, make the decision to overhaul or replace the engine with a remanufactured one. Proper diagnostics are the key to prevent engine damage.

I have an engine knock and my oil pressure guage is reading high, then stops shortly after starting to drive.
ANSWER : Hello,
You may want to inspect your oil pump to see if it may not be causing the problem. If it is not pumping or circulating oil properly, it may also cause this type of increase in oil pressure that may be sporadic as you describe. When you first start the engine, the oil pump needs to work a bit harder than normal at first the get the oil circulated through the motor to all of the places it needs to go as the oil is much thicker when it is cold. As the engine warms up, the oil becomes thinner and flows a bit easier, which may be what causes the pressure to come back down once it is warmed up. Please feel free to reach out to us here at YourMechanic or schedule an appointment to have one of our qualified mechanics come to your location to diagnose and inspect your truck.

My engine has a ticking knocking type of sound. It runs fine not buring oil or losing coolent. Sounds like the valves taping
ANSWER : On a 1998 engine with 147,000 miles, the noise could come from anywhere. I typically check the engine oil level when cool to verify it is correct. Then, I run the engine for 5 minutes, shut it off, and check the engine oil level again.

If after running it for a short time and the engine oil level is lower, then it is likely you have a sludge build-up in your oil return passages preventing oil from draining back to the oil pan. If so, maybe an engine oil flush is in order. At the mileage, sometimes an oil flush may do harm to your piston rings or may help. You never really know.

If the oil level is correct after running the engine, you should have an oil pressure gauge connected to the engine to verify that it is within specifications to factory numbers to verify the oil pump is working properly.

An engine tapping noise could be anything from connecting rods on the crankshaft to an engine valve lifter. If the noise is a knock-knock in a repetitive motion at a slow speed, I would suspect lower engine problem, like a connecting rod (which requires a complete engine rebuild). If the noise is at a higher frequency, then I would think you have a valve issue which could be repaired at a much lower cost.

Based upon mileage, the feeling of how the engine runs, engine codes (if any), and an unknown level of maintenance, it is difficult to determine the exact issue. You may need an engine repair, a new engine, more oil, an oil pump, or just live with it. I’d have a certified mechanic take a look at it to diagnose and fix the sound that’s coming from your engine.

Check engine on knocking engine milky cap but not in oil change loud knocking noise while driving and cold start up
ANSWER : Coolant leaks can be external or internal. If the coolant is leaking internally into the cylinders or crankcase, that will require a fairly significant repair. If the coolant is leaking externally, unless the leak is at the head gasket or the lower intake manifold, external leaks can be repaired readily. On the engine you have it was really common to have coolant leaks at the lower intake manifold, so common that the gasket there was completely designed and a different repair procedure was specified (higher torque on the manifold studs). To get the coolant leak diagnosed, please use YourMechanic’s coolant leak diagnostic service link. The knocking noise is obviously of concern. Unfortunately, typically, such noise is from worn bearings, connecting rods, and other major components. The noise might be accompanied by low oil pressure. My best advice is have the cooling leak diagnosed in case that is readily resolvable. The mechanic can evaluate the noise and if it is internal the engine will eventually have to be disassembled and rebuilt. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

lost all oil pressure, replaced the oil pump, low oil sensor, oil pressure sensor, oil pan gasket,
ANSWER : The fuel pump will not stay on if you loose oil pressure. This is why it is shutting off. The loss of oil pressure may be from bad crankshaft bearings or camshaft bearings. The engine oil pan should be removed and the oil pump needs to be checked to ensure that you put in the pick up tube seal to the pump and connected the pump to the block. Then remove at least one main bearing cap and inspect the bearings for excessive wear and crankshaft damage. If you need some help with this, consider YourMechanic, as a certified technician can help diagnose the issue with your oil pressure firsthand and help you fix it accordingly.

Loud knocking sound when engine is running
ANSWER : Internal engine components each have their own signature noise. An experienced technician can often get a good idea of what is causing a knock by listening to the sound. A connecting rod bearing usually sounds off when you rev the engine up to about 3000 RPM then back off of the throttle. A main bearing has a low pitched knock that is stronger when under a heavy load. Bad pistons will also respond to load, but have a higher pitched sound. There could be any number of other causes of your engine noise and the best thing to do is have an experienced ear on the case. Contact Your Mechanic to have a technician come to your home or office to listen to your engine knock and advise you on what to do about it.

Engine Oil (Not transmission fluid) leak behind the bell housing.
ANSWER : Hi there. The oil pan, oil filter, or the rear main seal (rear crankshaft seal) could be leaking. Check the oil filter and make sure that it is on tight. Then take a socket and wrench and check all of the oil pan bolts and see if any of them are loose. If the bolts are tight and the filter is tight, then the rear main seal is leaking, which will have to have the transmission removed to get to it. If you need further assistance with your engine oil leaks, then seek out a professional, such as one from Your Mechanic, to help you.