sludge found now have engine knock

Messages
31
Location
Ma.
I bought a 1999 Nissan sentra with 120,000 miles. After owning the car for a while a noticed an engine knock on start up and when I am on the highway stepping and letting off the gas. I thought it was the timing chain so I took the valve cover off to look at it. What I found was that all non moving parts had a quarter inch of black hard crusty crud on it. It looks like it was a sludge problem at some point. I tried an engine cleaning treatment with no results. I am thinking the engine needs to be rebuilt but it passed emission testing no problem. Could it be the oil pump gone bad, any ideas?
 
Messages
715
Location
Ks
What cleaning treatment? auto-RX is popular here. To test your oil pump, go for a 20 mile drive. If you don't have to call a tow truck around mile 15, it works :) (if you oil pump was bad it would quickly cause the engine to seize, so no that's not it)
 
Messages
223
Location
California
 Originally Posted By: AdRock
you could try an oil change and replace 1 1/2 qts of oil with ATF. All the junk in the engine could also have clogged the pump pickup.
That doesnt work anymore. People used that method back in the day
 
Messages
1,589
Location
NC
Do you have an oil presure gauge. Im guessing you dont since you didnt mention it. I would argue that maybe it could be a pump going bad and causing a severe low oil pressure condition. my guess is this. If you have that much crud in your engine, it would be very likely that in some engines that the oil pickup screen could get clogged and cause again very low oil pressure. I dont know anything about nissan engines really but this case could be made for many vehicles. Maybe somebody that knows those engines coudl chime in. If that is the case you could drop the oil pan and see if that is the case. If not you could try some PP 5w20 oil for some short 2 or 3k mile changes as the detergent package seems to be pretty strong. If you change oil and filter with that oil and nothing changes you could have already ruined something. Not to scare you but i had a very similar condition in a suburban and once the knock started, it was about 5k and i spun a bearing. Hopefully you will have a better turn out.
 
Messages
1,589
Location
NC
Something else i forgot, i had an intake manifold leak in my blazer and cause alot of antifreeze to get into the oil and sludge things up pretty bad. I didnt notice it untill i started having a lifter stick on me. I used half a qt marvals mystery oil and two short changes and all seems to be good. The MMO unstuck the lifter in about 5 mins. The only thing that is different is that once my got good and hot the lifter noise went away where it sounds as if yours does not. That sounds like oil starvation or a bearing being worn. if it were oil starvation you would think you would hear valve train noise as well as the bottom end noise. Also if it is a bearing being worn badly due to debree or something maybe the thinner oil would be not such a great idea. im nust thinking out loud for ideas. Maybe somebody that actually knows somehting will chime in on the ideas.
 
Messages
43,729
Location
Ontario, Canada
I think this is a little too "advanced" for AutoRX, given that it needs TIME to work, and he likely doesn't have much. It needs an aggressive clean, something like Kerosene or Chemtool, something that is going to eat the crud off, but will require substantial clean-up afterwards.
 
Messages
14,776
Location
Illinois
I don't like saying this but if you have sludge and an engine knock it may just be a matter of time as it will likely get worse.
 
Messages
962
Location
San Antonio, Texas
 Originally Posted By: UberxG
 Originally Posted By: AdRock
you could try an oil change and replace 1 1/2 qts of oil with ATF. All the junk in the engine could also have clogged the pump pickup.
That doesnt work anymore. People used that method back in the day
It still works. I've known several people that have used this method with good results.
 
Messages
39,806
Location
Pottstown, PA
It was a thinning agent. You're pouring in 10 weight oil. It's got no detergent properties compared to motor oil. If he decides to score it (the formation) ..then the OP should be real dedicated to getting all of it out while cleaning. Either plugging the drain holes or ram rod'ing them with long handled bottle washers. I'd probably have the drain plug out and assuring that I didn't break anything loose that prevents liquid from getting there. I don't agree that he's on some "last leg". I've taken the covers off of more than a few engines where the moving parts were submerged in goo. We're viewing this knock remotely. The start up rattle is understandable with some oil passage/varnish/etc. issues. For all we know, the on:off gas thing is simple spark knock. I would still use Auto-Rx to fix this.
 
Messages
3,756
Location
CA
Would you really WANT to clean the engine with that much sludge? I would be worried about plugging up the pickup screen. I know many of them have a bypass but that just buys you time. Someone left a can of spray gasket sealer in the oil pan of my GN when I bought it. The screen was plugged, bypass worked as designed and I ended up with silicone in the main and rod bearing passages completely plugging them off. This thing may suffer the same fate.
 
Messages
6,991
Location
Everett, Washington
My Dad's Caravan has 16K with two full treatments of RX. One was aborted when I needed to do a timing cover gasket. It has 16k with Auto-RX and some with MMO, and some with just dino. I did not think it needed a new filter change every 1500 miles. Boy was I wrong...... I ran a dino run to see how it is doing. I changed the oil and filter and cut the filter open. The filter media is still covered pretty good. Just not as light and gooey as before. I have had the pan off twice. The oil pick up was fairly clogged and the engine tends to make more start up noise when the filter is getting clogged up. If the pan is not a nightmare to remove, I would have a look see to make sure the pick up screen is not clogged. At the very least you will know what is going on, because the junk in the pan don't lie.....
 
Last edited:

jrc2905

Thread starter
Messages
31
Location
Ma.
After reading the responses, “thanks”, here is some more information. When I got the car I took the oil pan off to fix the pan gasket. I noticed a slimy type of oil in the bottom of the pan but did not think much about it. The oil pick up was clean. I am not sure if the noise is getting worse or I am just listening more for it. It last for about one second when I start the car after it has been sitting for about eight hours, I also hear what sounds like valve chatter when I accelerate and de-accelerate on the highway. I know these sounds are not normal because I have a 1995 sentra with the same engine as this 1999 sentra and with 200,000 miles on it ran quiet. I am thinking about pulling that engine out and rebuilding the short block for this car. I did have some RX I bought in the past and put that in the car with no results.
 
Messages
39,806
Location
Pottstown, PA
The noise while decelerating is the odd one for me. If it's some load related thing (which regardless of it's origin, it should be) it should go mostly silent (comparably) when you let off the gas. The filter and some engine internals will give you the brief start up rattle after sitting. Auto-Rx would take quite a while to get rid of the harder tar like stuff, but if the noises were results of clogged passages or sticking components, I would suspect improvement. If it was the soft stuff, you would just keep plugging filters. Not to dwell on this any further, but you did leave it in for somewhere around 750-1000 miles, right? Just curious.
 
Messages
39,806
Location
Pottstown, PA
 Quote:
Would you really WANT to clean the engine with that much sludge?
It would depend. I get what you're saying, though. Some things are better left alone as you may end up in a cascading watershed of added costs "while you're there". In this case the OP is about ready to write off the engine for a short block, so his options are open on the current one.
 
Messages
6,987
Location
Michigan
Test oil for coolant contamination. Check PCV system Run Auto-RX thru it with something like Pennzoil Platinum that has alot of detergent.
 
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