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pimpm3
pimpm3 SuperDork
4/13/19 9:58 a.m.

So I bought an NX2000 for the challenge.  It has sat unused for at least 4 years.

I recently drained the gas out, replaced the plugs and fuel filter.  Car started immediately and idles fine but has a misfire.

I checked the compression and it only has 60 psi on 3 of the cylinders and the misfiring one has 20 psi.

Can a car that was running and driving get low compression from sitting for years and years.

Do I have any options?  Marvel mystery oil?

Thanks

Knurled.
Knurled. MegaDork
4/13/19 10:05 a.m.

Drive it.

 

Yes, it can happen.  It can happen in as little as a month of sitting.  Driving it brings the compression back.

 

ProDarwin
ProDarwin UltimaDork
4/13/19 10:06 a.m.

I'm just posting because I want to know the answer.  I would think one of the folling could happen but would be unlikely:

1) rings stick somehow?  I would imagine if this was the case an ATF ring soak would probably free things up.

2) valve sticks and wont close completely

3) valve seal corrodes

SkinnyG
SkinnyG UltraDork
4/13/19 10:06 a.m.

I pulled an engine for a project and it sat for 8 years before I fired it up again.  It was a little cranky (no pun intended) and it smoked quite a bit, but it all cleared up with driving. I did nothing to it. I didn't ever check compression though.

Slippery
Slippery SuperDork
4/13/19 10:06 a.m.

Why did it sit unused? Is it possible that it sat because the engine was low on compression???

I would definitely try Marvel Mystery oil or some ATF and see if maybe the rings are stuck and that frees them. But my first thought is that that’s the reason it was parked. 

¯\_(ツ)_/¯
¯\_(ツ)_/¯ UberDork
4/13/19 10:12 a.m.

I'll add another option to the list- I've had good results with marine engine fogging oil.  Disable the fuel injection, spray into intake while cranking once a day for a while, then when the mood strikes you fire it up and go for a drive.

rslifkin
rslifkin UltraDork
4/13/19 10:20 a.m.

I'd try putting an ounce or so of Marvel Mystery Oil into the cylinders and letting it sit for a couple of days.  Then crank it over with the plugs out to remove any excess and go for a drive.  Once it's good and warm, run it through a few cycles of heavy throttle up to high revs and then closed throttle decel.  If the rings are sticky, the combination of those things should free them up. 

pimpm3
pimpm3 SuperDork
4/13/19 10:28 a.m.
Slippery said:

Why did it sit unused? Is it possible that it sat because the engine was low on compression???

I would definitely try Marvel Mystery oil or some ATF and see if maybe the rings are stuck and that frees them. But my first thought is that that’s the reason it was parked. 

Previous owner died unfortunately.  I bought the car from the shop owner where the previous owner worked.  The guy didn't have any other family and after he passed away the car sat in the back parking lot of the mechanic shop for the past 4 years.  

Shop is a BMW specialist, and has been in business for over 30 years.  Shop owner is a club racer and seemed very honest in my dealings with him.  He said the previous owner loved the car and drove it every day before he passed.

Knurled.
Knurled. MegaDork
4/13/19 10:31 a.m.

FWIW, when this happened to me personally, it was a Nissan 1600cc engine.  Sat for a month and when I went to go move the car, it cranked like the timing chain had fallen off.

I think the rings stick in the grooves, need to get everything hot and moving again.

LanEvo
LanEvo HalfDork
4/13/19 11:27 a.m.

Had a similar situation a couple of years back. Bought a parts car that (according to service records) had a freshly rebuilt engine when the trans broke. The owner parked it for 9 years and eventually sold it to me. I needed the engine for my racecar.

Compression was very poor and it smoked like crazy. We soaked pistons with Marvel Mystery Oil (MMO), let it sit 24 hours, then drained and ran the engine hard. Repeated 2-3 times and the engine came back to life: compression jumped up to normal range; no smoking; and zero oil consumption. Looks like stuck rings were the only problem.

I don't think there's any particular magic to MMO. I've heard of people having similar results with straight ATF.

Curtis
Curtis UltimaDork
4/13/19 11:28 a.m.

There are all kinds of home-brew treatments and all kinds of possible reasons.

most likely culprits in no particular order:

  1.  stuck rings
  2. rusted cylinders
  3. collapsed/damaged lifters/followers
  4. stuck valves not closing

In the case of the first two, pull the plugs and put something in; penetrating oil, marvel mystery oil, random motor oil, ATF, whatever.  Let it sit overnight.  Leaving the plugs out, crank it to get excess out, then do another compression test.  If the compression is higher, it's a ring seal issue either due to stuck rings (pretty common) or cylinder rust.  In both cases, drive the crap out of it with as much WOT as possible.

In the case of the last two, that can be difficult to diagnose.  If you can get a little machinist's ruler down beside the valve springs, rotate by hand and make sure they all have the same travel.  I'm not familiar with that valvetrain so I don't know if it's shimmed solid followers or hydraulic.  If that is your problem, you might have luck with some SeaFoam (which might be a good idea anyway).  Get a can of seafoam, pull off a vacuum line, and stick it in the can.  Then rev the engine several times like a kid revving his car at a stoplight.  You'll probably see all kinds of nasty stuff come out the tailpipe.

Then you can do an oil flush if you want with one of several liquids.  The old school trick was to add a quart of diesel to the oil and idle it for 20 minutes.  Drain and refill.  There are motor flush products that are $8 a quart that smell alot like diesel.  I advise against ATF.  It won't hurt anything, but it won't clean anything either.  People assume that ATF is this wonderful, high-detergent stuff because they pull apart a transmission and everything is so clean.  ATF actually has less detergent than engine oil.  The reason a transmission is so clean inside is because it doesn't have to deal with a tenth of the junk that combustion gives to engine oil, not because of detergent.

Whatever you use, make it volatile but not overly flammable.  Make sure it evaporates at the temps the oil sees.  That way, (since you can never get it all out) the trace amounts will evaporate before doing any damage.  For instance, don't use Acetone or paint thinner.  It will boil at too low a temp and not only froth the oil (loss of oil pressure and damage) but acetone gasses boiling out of your oil vent is a recipe for big booms.  For this reason I either use diesel or one of the motor flush products.  You can use SeaFoam in the oil as a flush, it's just expensive and not sure it works any better than diesel.

If you use an over the counter flush, just follow directions.  If you use diesel, don't rev it or drive it.  Dump in a quart of diesel, idle it for 20 minutes, drain and refill.

pimpm3
pimpm3 SuperDork
4/13/19 11:34 a.m.

In reply to Curtis :

Great post Curtis.  I will give it a shot next week when I get a chance to play with the car again.

84FSP
84FSP SuperDork
4/13/19 11:34 a.m.
rslifkin said:

I'd try putting an ounce or so of Marvel Mystery Oil into the cylinders and letting it sit for a couple of days.  Then crank it over with the plugs out to remove any excess and go for a drive.  Once it's good and warm, run it through a few cycles of heavy throttle up to high revs and then closed throttle decel.  If the rings are sticky, the combination of those things should free them up. 

This!

Knurled.
Knurled. MegaDork
4/13/19 11:39 a.m.

In reply to Curtis :

The thing with the ATF detergents is that they're somewhat different detergents than engine oil.  If the detergents in the oil were working, there wouldn't be crud to clean out in the first place, so sometimes a different tack is needed.

 

Not that this is relevant to bringing back a engine that lost compression from sitting - any light oil will do.  MMO just has a funny name and a funnier smell.

iceracer
iceracer UltimaDork
4/13/19 1:54 p.m.

Surprised no one mentioned an "Italian tune up".

Streetwiseguy
Streetwiseguy MegaDork
4/13/19 2:16 p.m.

Just drive the snot out of it.  If it gets better, great.  If not, all the snake oil in the world won't fix it.

GTXVette
GTXVette UltraDork
4/13/19 2:43 p.m.

Look for Granville ? oil, Piston powered aircraft Benifit from fogging the cylinders It's amazing for releasing coked up rings, and can help an engine pass it's annual, Or Challenge.

rslifkin
rslifkin UltraDork
4/13/19 9:30 p.m.

MMO is effective for 2 reasons: it's a thin oil (much thinner than ATF) so it gets into places like ring lands easily.  And it does have some solvent properties, so that can help loosen up gunk.  Plus, it smells nice. 

Robbie
Robbie UltimaDork
4/13/19 9:45 p.m.

MMO

Mixed marital oil? Marvel mystery oil actually sounds worse.

AngryCorvair
AngryCorvair MegaDork
4/14/19 7:08 a.m.

I hear nitrous oxide is good for loosening rings

Knurled.
Knurled. MegaDork
4/14/19 7:44 a.m.
iceracer said:

Surprised no one mentioned an "Italian tune up".

It's in the First.  Berking.  Reply.

 

Jeez.

LanEvo
LanEvo HalfDork
4/14/19 7:52 a.m.
AngryCorvair said:

I hear nitrous oxide is good for loosening rings

I thought that was for floorboards?

Robbie
Robbie UltimaDork
4/14/19 9:20 a.m.
Knurled. said:
iceracer said:

Surprised no one mentioned an "Italian tune up".

It's in the First.  Berking.  Reply.

 

Jeez.

I'm not sure everyone knows that you drive Italian tune up style always. I know this may seem odd but to some regular folks "drive" and "Italian tune up" aren't always the same thing cheeky

Seriously, what is wrong with them?

Knurled.
Knurled. MegaDork
4/14/19 9:31 a.m.

In reply to Robbie :

I dunno, I think "italian tune-up" is as annoying a phrase as "that'll buff out".

 

Just drive the damn thing.  It'll sort itself out.  Idling in traffic isn't driving, you can do that in your driveway.  Don't focus on redline like the RX-7 weenies do, focus on load.  Find hills and use them.  Find onramps and find a new high score for the merge at the end.  But don't just putz around at low load all the time.  Get some pressure in those cylinders to blow those rings out of their grooves and grind them into the bores.  That will make the engine happy and the compression will come back.

iceracer
iceracer UltimaDork
4/14/19 1:42 p.m.

In reply to Knurled. :

Jeez.   You only said "Drive it",  Not beat the pixx out of it.

Maybe you are too young to know what a proper ITU is.kiss

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