DanoMax

I bought a used 94 GXE with 170,000 miles for my son. Now at 180000 miles the valves rattle and tap and the oil pressure light is on. It only tapped in the beginning but would clear up with an oil change and then come back after 2000 miles or so. I am told by the shop it needs to be opened up, cleaned out, and the oil pump replaced. I have plenty of compression in the cylinders. Oil pump replacement costs $200 for pump and $400 labor. Two Nissan parts departments told me they haven't sold an oil pump in over a year. Do I really need one and how would I clean out the sludge so the oil will flow freely?

jwtarbaj

You might try using some GUNK engine cleaner additive or similar product. This is added before you do your oil change and gets rid of that type of build up. Just follow the directions. My dad was getting a little tick in his 200SX SE-R and I gave him a bottle and he said it went away. Be warned that this stuff can loosen enough debris/buildup in the engine to possibly clog oil passages and/or cause leaks.

CandiMan

iTrader: (1)

What gets me is, if it's sludge why doesn't it tap soon after a oil change instead of 2K later. When sludge is present it's there until removed by whatever means. Sludge doesn't decrease with a oil change, does it? The oil pump is kinda like a fuel pump, unless it goes out right they will slowly start losing it's pressure as a sign of it wearing.

You can try shimming or replacing the oil pump regulator valve which shouldn't require removal of the pump, just removal of the oil pan

BUT, and I repeat but if the motor flush didn't work and you're planing on opening up the engine try ATF mix with eng oil. If you really want to be bold use a little diesel fuel and eng oil. Use these just as a motor flush, not a substitute for everyday driving and when removing let the oil drain for about 30mins before installing the plug. Remember you asked

FYI, the oil pressure switch is rated at 4-5psi or even lower (I think) before turning on the light, which is totally rediculous.

jwtarbaj

Remember that oil contains many detergents to clean your engine internals. This could possibly be why it takes 2K miles. After the fresh dose of oil the detergents clean it up enough to stop the knock but don't last as long because the motor is just SOO dirty.

DanoMax

The tap was not present on purchase as the oil was clean. It showed at about 172000. Tried Marvel, then changed oil, went away for 1000 miles or so, tap came back. Changed oil every 3000 til 180,000. Now tapping joined by rattle and oil pressure light came on at aide, went away with higher RPM. Then last week, light stayed on with rattle and tapping. Garage wants to drop pan, clean engine, replace oil pump to tune of $600. That's where I am.

CandiMan

iTrader: (1)

With all that's happening now I'm leaning more towards a oil pump issue. With you using Marvel, and a couple oil changes within 8k of ownership the oil should be relatively clean. I don't know how handy you (or your son) are with tools, but a few hrs of your time and a few dollars in parts you can try what I suggested to see what happens.

Tick Tock

SeaFoam would be my first choice to try next. Then replace the pump, if necessary.

I have used this before with good results on motors that have had unknown prior maintenance/care. Try a couple applications - the stuff runs about $5-6/can. I use it also in the gas tank every oil change.

No, I don't have any vested interest in SeaFoam - just a long-time user with good results.

Let us know which route you go and the outcome.

http://www.seafoamsales.com/motorTuneUpConsumer.htm

jwtarbaj

If the problem is that severe one of your oil gallies is probably clogged, most likely leading to the valvetrain in the heads. Cleaning it up is necessary but will it unclog you that is the important question. If it is a clogged oil galley it must be cleared or you will still have the noise.

DanoMax

FYI, I decided to do a used engine swap on my Max. I needed a timing belt anyway, so I got a used VG30 for $600 with 87K on it and will replace that timing belt & waterpump. I also have a whing power steering pump, so the engine guy is also sending a pump for $40. This will cost me $400 for timing belt etc, $600 for engie, and $550 to swap it out. I also gotta figure new belts and hoses, fluids etc. I figure I can get a couple more godd years out of the car and raise mt resale value some. For about $600 I get a better engine instead of taking the chance that the low oil pressure damaged something. Opinions?

Engloid

Yeah..by my calculations, you're WASTING $600 on another engine that you will still replace timing belt and stuff on for another $400, than $550 in labor to do the engine swap. So that's a total of $1550 to end up with an engine that has 87k on it??? Sounds like they're raping you, especially on the $400 for the timing belt, which is really easy with the engine out of the car. Many shops will do it in the car for that much money. I guess they didn't mention changing the crank or cam seals? They're cheap, and it's a good idea to do it with the timing belt. An oil leak can ruin the belt and more.

That doesn't sound like a good option to me.
My advice:
Get NEW lifters and put them in. If it's time for a timing belt, do it at the same time. Lifters often start ticking at the mileage you have. It won't hurt anything or leave you broken down on side of the road, so don't get in a hurry due to the ticking.

For oil pressure...check the sending unit, as they do go bad. I have NEVER heard of an oil pump failure on a vg30 engine. It is not much more than 2 gears, which are driven directly off the crank. If they fail, you will likely not even turn over the engine enough times to overheat and do bearing damage.

Also, try using some of the stuff you put in before an oil change..and run it for about 5 mins, then do the oil change. That stuff works well. I've heard of people using kerosene in this way also.

I have 190k on my 92 max, and it runs great still. It's never left me on the side of the road except for a battery failure one time.

Mr.Mike!

Hello. For what it's worth. Get a case of ATF and a couple of oil filters. Drain the oil. Add 4 quarts of ATF. Start engine and let it idle for about 5 minutes. once it warms up, change the rpms between idle and 3000 rpms. shut off the engine. Drain out the ATF and swap oil filters. Refill with ATF, run for another 5 minutes or so. Drain the ATF and check the color. If it is nice and red, then swap the oil filter and refill with 10w30 engine oil. If it is still coming out dark and dirty looking. Keep doing the ATF oil changes.

Why ATF? Automatic transmissions have alot of little valves and passages that MUST stay clean. If they get crud build up in them the transmission will not shift/operate correctly. ATF is a fluid lubricant that is very high in detergent and will clean where it flows.

Once the engine is cleaned out and you are running on normal engine oil I would just do the oil changes more frequent than 3 months or 3,000 miles. My guess is the person or people before you did not maintain the engine very well, and now you are having to do a LOT of catch up work.

HOpefully some of this will help. Good luck

- Mr.Mike!