Nissan Pathfinder with engine sludge

I recently purchased an 03 Pathfinder with 50,000 miles on it and a 3.5 L engine. I drove it for about 7000 miles and the cam sensor became filled with sludge and the cam won’t shift because of it. My mechanic replaced the sensor and changed the oil and filter after a short time but it happened all over again. I would like to know if there is an oil additive the will remove sludge from an engine. I have a feeling this could get expensive. I wonder if there is some easy fix.

Start changing the oil every 3000 miles and this product might help…

We bought this car and had a problem with it. We took it back many many many times. We were told they could not find a problem. The oil was clean and had been changed. However, after driving it, it began to hesitate. We put engine cleaner in it and changed the oil two more times. It ran great for about 7000 miles and then it started all over again. The cam sensor was changed twice. The engine oil was changed again. After a short time, the same thing happened. Hesitation, no power and upon examination. sludge in the engine. I am sure this problem must have started from the original owner not changing the oil. How can I fix it now? Will I need to change the engine?

Change the engine?? It would be easier and probably cheaper to simply move on to a better maintained vehicle. This one could turn into a real money pit…

I’m in agreement with Caddyman. If an engine is sludged this bad then its days are probably numbered anyway.

It could be this was a lease vehicle. Many people who lease have no intention of spending money on regular maintenance because they know they will be giving the vehicle up in a few years. The next person can pay the price for it.

Please explain what you mean by “the cam won’t shift” Also, the cam sensor is external on most engines that I know of and not exposed to engine oil. Please explain what you mean by “the cam sensor became filled with sludge”

Can you describe the problem better? Your description does not make any sense to me.

It ran great for about 7000 miles and then it started all over again. The cam sensor was changed twice. The engine oil was changed again.

Are you saying that you didn’t change the oil for another 7k miles??? If so…then…that’s where the sludge problem is.

If your engine has a sludge issue, you are going to need to fix the cause of the sludge.

What type of driving does your truck see?
Do you only drive a couple of miles a day to your office, and then back home?
Does the truck only get used a couple of times a month, and when its not used, its not used very much?

You might want to have your mechanic look at the way the truck is used, to see if the environment its used in is contributing to the sludge build up.

Also, have the mechanic remove the valve covers, and remove as much sludge in the top of the motor as he can, and then remove the oil pan, and clean out anything that is down below.

Doing this will get your engine as clean as possible, and you can start from solid ground at that point. Replacing the thermostat might also be a good idea, too.


There’s no additive than can be added to the engine to remove engine oil sludge. Once it’s in there. it’s in there.

The only way sludge can be removed from an engine is to disassemble the engine and physically remove the sludge with harsh solvents and a lot of scrubbing.


If there’s a LOT of sludge then Tester is right…the best way to remove it is to tear down the engine…Especially like that engine shown in the Ford commercial (the guy who abused his engine).

But Sludge DOES DISSOLVE in kerosene (main ingredient in engine cleaners). I’ve also seen it dissolve in a Solution of Rislone. There ARE chemical solutions…but they are NOT recommended for a severely slugged engine. The engine cleaners could do more harm then good.

No the dealer had changed the oil twice before we bought it. We changed the oil but the car still ran badly. We tried to take the car back just a few days after the purchase when it would not run over 28mph. They had processed everything immediately and we could not get our money back. We took this car to 3 different mechanics including a dealership. One said to change the cam sensor…it was changed. We took to another mechanic…they changed the other cam sensor. Now, the dealer said probably might need to change the engine. We don’t know if the extended warranty we bought is going to pay for this. We feel trapped with this vehicle. We owe a lot on it still We have driven it very little.

You could fill the crankcase with a few qts of old oil and the rest with KEROSENE…works like a charm…however…when you do these sorts of things to older engines you can actually wash away some of the thick gunk that is holding your engine together… In reality sometimes engine sludge fills in gaps between worn bearings and the crank for example…when they are removed sometimes you get or reveal other engine issues…

You have a rather low mile engine, so I am not worried about this procedure very much on this engine…and it deserves to be clean inside…

I havent had any problems using Kero in the past even on high mile engines…so dont sweat it too much.

There is a product called motor flush…which I SWEAR is a Qt of Kerosene… You add it to an engine that is already full of motor oil. The you start it and let id IDLE…NO DRIVING…and then drain…repeat if needed…that will wash out most if not all of the sludge. Flushing an engine is actually easy…just remember what I said about sludge holding things together…or more commonly…the sludge that is preventing your engine from leaking…lol. It can go bad…but I havent had any of them go in the wrong direction on me…I have heard about it though and it isnt without warrant.

Also severe sludge buildup is an indicator of abuse from the former owner…i.e. not changing their oil on time…or ever… I hate to see sludged up engines because there is no damn reason for it AT ALL in modern day. It is only severe abuse that causes this…so you may consider selling it. ALSO 50K is quite low miles…the prev owner really had to push his oil change to the nth degree to buildup sludge in that short of time…what did he replace the oil 4 or 5x in the cars lifetime? WHat a jerk…

It could be this was a lease vehicle. Many people who lease have no intention of spending money on regular maintenance because they know they will be giving the vehicle up in a few years. The next person can pay the price for it.

I worked with a guy who did this (probably still does). Lease a new car every other year…AND NEVER EVER changed his oil. Put about 35-40k miles in those 2 years…Never washed the car…almost never cleaned the car out…smoker…Those cars were trash by the time he got rid of it.

I agree. I purchased a 1955 Pontiac in 1962. The dealer had overhauled the engine just before I purchased the car. I continually had a problem with the passages in the rocker arms becoming blocked with sludge and then the rocker arms would chirp. Apparently the mechanic hadn’t removed all the sludge. In my case, the problem was caused by the car not having an oil filter. The oil filter was an option on the 1955 Pontiac engine, even though it was an overhead valve V-8 with hydraulic lifters. I did install an oil filter assembly that I obtained from a salvage yard. I pulled the studs several times and soaked them out. This improved things, but on a highway trip, the rocker arms would start chirping again.

I never completely got rid of the problem. My recommendation to the OP is that he/she move on and get a different car. I finally through in the towel and traded the car.